Undersampled images , such as those produced by the _ hst _ wfpc-2 , misrepresent fine - scale...

it s nice to work with well - sampled astronomical images . a well - sampled image can be readily resampled to various scales , orientations , or more complex geometries without loss of information . its spatial resolution is well - understood , permitting a clear analysis of the relative contributions of information and noise . further , many image processing algorithms will only work on well - sampled data . in some cases , however , it s not practical or even desirable to obtain well - sampled images . given detectors with a finite number of pixels and significant readout noise , one may prefer to trade - off resolution for increased field size or photometric sensitivity . both considerations were central to the design of the _ hst _ wfpc-1 and wfpc-2 cameras , to give examples of instruments that produce undersampled astronomical images . wfpc-2 in particular has generated the largest library of high - resolution optical astronomical images to date , but ironically the severe undersampling in the wfc system , and the still less than critical sampling of the pc at all but the reddest wavelengths , limit the resolution of _ hst _ observations as much as the telescope optics , themselves . there is no magic that can undo the undersampling in a single image ; analysis of such data always requires respect for their peculiarities . at the same time , it may be possible to obtain additional observations with the same camera system that contain information lost in the original images . for example , if the camera can be offset by a fraction of a pixel over a sequence of exposures or `` dithered , '' one can observe how the structure of objects in the image varies with respect to their positions on the pixel - grid , and thus recover details not contained in any single image . this suggests that one might construct a well - sampled super - image from a set of undersampled , but dithered images . in general , when the size of a pixel is important with respect to the intri

We present a method for obtaining well - sampled astronomical images from a set of undersampled but dithered images. The method is based on the _ hst _ ( wfpc ) system, which has been used to produce high - resolution optical astronomy images, and is a good example of an instrument that can be used to obtain well - samples of astronomic data. We show that this technique can be applied to a wide range of spectral parameters, including the pixel.

undersampled images , such as those produced by the _ hst _ wfpc-2 , misrepresent fine - scale structure intrinsic to the astronomical sources being imaged . analyzing such images is difficult on scales close to their resolution limits and may produce erroneous results . a set of `` dithered '' images of an astronomical source generally contains more information about its structure than any single undersampled image , however , and may permit reconstruction of a `` superimage '' with nyquist sam


We investigate all feasible mathematical representations of disformal transformations on a space -...

the study of new kinds of symmetries associated with equations of motion is crucial in modern physics , since it can elucidate hidden features there and help us find new nontrivial solutions to the involved equations . we quote noether s theorem , gauge choices and the theory of the angular momentum operators , as some important examples from a lengthy list describing physical properties of a given system that can circumvent the cumbersomeness of solving equations of motion . the same reasoning can be applied to disformal transformations . the increasing literature on this issue has revealed new physics beyond bekenstein s initial proposal . motivated by the results we have previously obtained in ref . , we show here that disformal transformations can be defined not only as purely geometric transformations , but they allow for distinct representations ( algebraic , geometric and group ) in general . in this way , we gather each mathematical aspect of disformal transformations of metric tensors in a unique object . by constructing an abstract operator acting upon the tangent spaces of a manifold , it is possible to see that it takes the form of a space - time geometry , a genuine algebraic tensor or a group element . this unified description of the disformal maps shall be illustrated by means of the diagrams in sec . [ secmach ] . the aforesaid operator singles out a preferred vector field ( or a set of ) to deform a previously defined tetrad frame . therefore , depending on the choice of a such vector , the physical notions of time , energy and momentum can be altered . as we shall see later , new trends in quantum - gravity phenomenology , for instance ref . , point to this direction . naturally , one can also interpret the new formalism developed here for disformal transformations as purely mathematical ; nevertheless this is already sufficient to attract attention on its own . notwithstanding , from the physical point of view , there has been a growing interest i

We present a new formalism for disformal transformations of metric tensors. The new formality is based on the theory of angular momentum operators, which are a set of algebraic and geometric representations, in general. It is shown that these representations can be defined as algebraic, geometric and group elements.

we investigate all feasible mathematical representations of disformal transformations on a space - time metric according to the action of a linear operator upon the manifold s tangent and cotangent bundles . the geometric , algebraic and group structures of this operator and their interfaces are analyzed in detail . then , we scrutinize a possible physical application , providing a new covariant formalism for a phenomenological approach to quantum gravity known as rainbow gravity .


Mechanism of nuclear reactions on au induced by b ions at energies above coulomb barrier was...

the study of nucleon - nucleus and nucleus - nucleus collisions is a source of experimental data , which are extremely important for scientific and technological application . there are multiple questions addressed in the context of e.g. , design of accelerator driven systems of energy amplification and nuclear waste utilization , astrophysical studies , radiological safety , etc . which can not be answered without knowledge of collision cross section . a typical characteristics of the nuclear structure of interacting nuclei can be revealed at energies near the coulomb barrier . particularly , the study of reaction mechanism concerning complete fusion ( cf ) and incomplete fusion ( icf ) , as well as the transition between them is important in the view of understanding the interplay between such two dominant modes of the nuclear interaction . in the frame of the dynamic model , during the amalgamation of the projectile with target nucleus the complete - fusion cross section reaches a maximum at the energy for which the angular momentum , imparted to the target in the entrance reaction channel , lower than some critical value , . according to the model , above this critical momentum the collision become more peripheral and compound system can not exist . with increasing the incident energy , incomplete fusion channels , when the different parts of the projectile can captured by the target , become more probable . among the reaction products there are some , which are originated due to two different mechanisms : projectile break - up and nucleon coalescence during the thermalization of the composite nuclei produced in the complete and incomplete fusion . this processes are assumed to be a peripheral and at considerable low excitation energy in the course of the interaction target and projectile . in the work it was observed the increasing of icf contribution at high energies and angular momentum , imparted to the system , exceeding the limit value for fusion process w

We study the reaction mechanism of nucleon - nucleus and nucleu - nuclear collisions at high energies. In this work, we observe the increasing of icf contribution at high energy and angular momentum imparted to the system, exceeding the limit value for fusion process w.

mechanism of nuclear reactions on au induced by b ions at energies above coulomb barrier was studied by induced - activity method and -spectroscopy . the cross sections of the reaction fragments from au induced by b ions were measured at bombarding energies 137.5 and 255.5 mev . the fission process was investigated by using multimodal fission approach at the energy 137.5 mev , and pure symmetric distribution at 255.5 mev . it was observed that the transferred linear momentum provides the informa


Two spin - dependent structure functions and for the inclusive spin - half baryon production in...

in the development of our understanding of the hadron production mechanism , the inclusive one - particle production by electron - positron annihilation plays the same role as the deeply inelastic scattering does in our learning of the nucleon structures . experimentally , a number of electron - positron colliders have been operated and will be constructed at various center of mass energies . on the theoretical side , a series of parton fragmentation functions have been identified by jaffe and ji , which characterize the information about the inclusive hadron production . therefore , it is worthwhile to explore the possibility to measure them , expecially those spin - dependent ones , by the inclusive one - particle production in electron - positron annihilation . to study spin physics related to the inclusive spin - half baryon production , it is usually needed to monitor the polarization of the produced particles . if we are restricted with the inclusive hyperon production , it is quite feasible to measure the polarization of the produced particles . in fact , a series of experiments have already been done at fermilab measuring the polarization of the inclusive hyperons in fixed - target experiments . we also note that some preliminary results on the measurement of the polarization at cern lep have been existent as well . because what can be accessed directly by experiments are structure functions , we explore in this paper the relation between and , two spin - dependent structure functions for the inclusive spin - half baryon production by electron - positron annihilation , and the quark fragmentation functions defined by jaffe and ji . without loss of any generalities , we consider the inclusive hyperon production for among the hyperons the particle is of the largest production cross section and its polarization is the easiest to measure . the advantages of measuring the polarization of the inclusive hyperon are also realized by several groups of authors in diff

We study the polarization of the inclusive spin - half baryon production by electron - positron annihilation in fixed - target experiments. We consider the inclusion hyperon production for among the hyperons the particle is of the largest production cross section and its polarizing is the easiest to measure.

two spin - dependent structure functions and for the inclusive spin - half baryon production in electron - positron annihilation are studied in the context of qcd factorization as well as in the naive quark parton model . as a result , it is found that the sum of and is related to and , two quark fragmentation functions defined by jaffe and ji . in connection with the measurement of quark fragmentation functions , the possible phenomenological consequences are discussed . spin - dependent struct


Nonequilibrium states induced by an applied bias voltage and the corresponding current - voltage...

nonlinear conduction in correlated electron systems such as one - dimensional mott insulators and two - dimensional charge - ordered materials has been of great interest in the past few decades . they offer intriguing subjects of nonequilibrium physics in condensed matter and possibility for novel functions of electronic devices . for example , in a typical quasi - one - dimensional mott insulator , srcuo, a dielectric breakdown has been observed experimentally by applying a strong electric field . a dielectric breakdown has been reported also in an organic spin - peierls insulator , k - tcnq [ tcnq = tetracyanoquinodimethane ] . for another organic compound , ( bedt - ttf)(ftcnq ) [ bedt - ttf = bis(ethylenedithio)tetrathiafulvalene ] , which is a quasi - one - dimensional mott insulator , metal - insulator - semiconductor field - effect transistor device structures have been reported, where its field - effect characteristics are different from those of band insulators. so far , theoretical investigations on nonlinear conduction for interacting electron systems that are initially insulating in their equilibrium states have been done by several authors. in general , these studies are classified into two approaches depending on whether an external force is written as an electric field or a bias voltage. the former approach is to consider electron systems without electrodes . the electric field is usually applied with open boundary condition, or equivalently with periodic boundary condition by using a time - dependent magnetic flux. in one dimension , oka and aoki studied the hubbard model under a strong electric field by the time - dependent density - matrix - renormalization - group method. one of their important results is that the dielectric breakdown of mott insulators is interpreted as a many - body counterpart of the landau - zener ( lz ) breakdown. this is known to describe the breakdown of band insulators where the one - particle picture holds . the threshold

We study the dielectric breakdown of mott insulators under a strong electric field by the time - dependent density - matrix - renormalization - group method. The di Electric breakdown is interpreted as a many - body counterpart of the landau - Zener breakdown in band insulator, where the one - particle picture holds.

nonequilibrium states induced by an applied bias voltage and the corresponding current - voltage characteristics of one - dimensional models describing band and mott insulators are investigated theoretically by using nonequilibrium green s functions . we attach the models to metallic electrodes whose effects are incorporated into the self - energy . modulation of the electron density and the scalar potential coming from the additional long - range interaction are calculated self - consistently w


In standard treatments the eddington luminosity is calculated by assuming that the electron -...

the eddington luminosity plays a fundamental role in our understanding of accretion phenomena and , as a consequence , of the agn physics and evolution . in turn , it is also clear that agns played a central role in galaxy formation , as testified by several empirical scaling relations between the mass of the supermassive bhs at the center of stellar spheroids ( i.e. , bulges and elliptical galaxies ) and global properties of the spheroids themselves . in standard treatments eddington luminosity is calculated by assuming that the electron - photon cross section is well described by the _ electron scattering _ thompson cross section . here we discuss the modifications to this simple picture by taking into account _ _ opacity also : due to the dependence of emission on the _ square _ of the gas density , it follows that the associated absorption cross section increases _ linearly _ with the gas density , so that eddington luminosity is correspondingly reduced . it is then expected that this opacity source will be important in the range spanned by _ cold accretion solutions _ ( see , park & ostriker 1999 ) . these high - density conditions were certainly present at the epoch of galaxy formation , thus a quantitative estimate of the reduction of eddington luminosity as a function of ambient gas density and temperature is of direct interest when modeling the early stages of galaxy formation ( see , e.g. , haiman , ciotti & ostriker 2003 ) . in the following discussion we often refer to formulae provided in ciotti , ostriker & pellegrini ( 2003 , hereafter cop ) : eq . ( 1 ) there will be indicated as cop1 , and so on . let be the bolometric luminosity associated with an accretion rate of , where is the accretion efficiency and is the speed of light . the _ momentum transfer _ to the gas electrons per unit time , frequency and volume at the radius is given by ( e.g. , see krolik 1999 ) : where is the number of photon electron interactions as given in cop1 , is the electro

We present a quantitative estimate of the eddington luminosity associated with an accretion rate of, where is the accrescence efficiency and is the speed of light. The bolometric luminosities are calculated by taking into account the opacity, which is a factor of the gas density. In this paper we discuss the modifications to the simple picture by taking in account _ _ the _ electron scattering _ cross section. We also consider the dependence of the absorption cross section on the gas densities, as well as the.

in standard treatments the eddington luminosity is calculated by assuming that the electron - photon cross section is well described by the thomson cross section which is gray ( frequency independent ) . here we discuss some consequence of the introduction of free - free opacity in the eddington luminosity computation : in particular , due to the dependence of emission on the _ square _ of the gas density , it follows that the associated absorption cross section increases _ linearly _ with the g


We numerically model fragmentation of a gravitationally unstable gaseous disc under conditions that...

there is no detailed understanding of how super - massive black holes ( smbhs ) gain their mass , except that it must be mainly through gaseous disc accretion . the standard accretion disc model shows that accretion discs must be quite massive and cold at `` large '' ( sub - parsec in this context ) distances from the smbh . many theorists pointed out that these discs should be unstable to self - gravity , and thus must form stars or giant planets by gravitational fragmentation ( e.g. , * ? ? ? * ; * ? ? ? * ; * ? ? ? * ; * ? ? ? * ; * ? ? ? * ; * ? ? ? this creates a dilemma for the field , as star formation might be a dynamical , very fast process which may result in a complete transformation of the gas into stars . the smbh would then be starved of fuel . have recently demonstrated that star formation can not be quenched by stellar feedback , unless one is prepared to grossly violate constraints that we have from agn spectra . suggested that the feeding of smbhs proceeds via direct accretion of low angular momentum gas that settles in a small scale disc . such a disc would be too hot to allow star formation . the size of this `` no - star - formation region '' is pc , and is weakly dependent on the smbh mass . however , one realistically expects that an even larger amount of gas settles at larger radii where it could collapse and form stars , or it could accrete on the smbh . therefore the fate of these self - gravitating discs is still very much interesting . current observations provide new impetus for theoretical work on the topic . have shown that many galaxies host `` extremely compact nuclei '' ( ecn ) star clusters located in the very central parsec of galaxies . closer to home , in the centre of our galaxy , about a hundred massive young stars , mostly arranged into two stellar discs of .5 parsec scale , circle the super - massive black hole named sgr a . these stars are suspected to have been formed in situ , as evidenced by the lack of stars outside the

We present a new model for the formation of super - massive black holes ( smbhs ) by direct accretion of gaseous discs in a small scale disk. This model is based on the assumption that the gas is a compact nuclei, and thus can be used to form stars or giant planets. We show that the accrescence of s spherical objects is dominated by a large number of ecn star clusters, which are located in the very central parsec of galaxie.

we numerically model fragmentation of a gravitationally unstable gaseous disc under conditions that may be appropriate for the formation of the young massive stars observed in the central parsec of our galaxy . in this study , we adopt a simple prescription with a locally constant cooling time . we find that , for cooling times just short enough to induce disc fragmentation , stars form with a top - heavy initial mass function ( imf ) , as observed in the galactic centre ( gc ) . for shorter coo


We investigate the phase structure of gauge theory in four and five dimensions with one compact...

now that the higgs - like particle has been discovered in large hadron collider ( lhc ) , one of primary interests of particle physics is to understand mechanism of dynamical electroweak symmetry breaking . to settle down the unsolved issues including the hierarchy problem , there have been proposed several promising courses including supersymmetric , composite - higgs and extra - dimensional models . among them , the gauge - higgs unification with extra dimensions produces brilliant dynamics of gauge symmetry breaking , called the hosotani mechanism , with the higgs particle as an extra - dimensional component of the gauge field : when adjoint fermions are introduced with periodic boundary condition ( pbc ) in gauge theory with a compact dimension , the compact - space component of the gauge field can develop a non - zero vacuum expectation value ( vev ) , which breaks the gauge symmetry to its subgroup spontaneously . this phenomenon originates in the non - abelian aharonov - bohm effect . there have been proposed a number of bsm models directly and indirectly based on this mechanism recently , the same phenomenon has been observed in a different context . as well - known , the imaginary time dimension is compacted in the finite - temperature ( quantum chromodynamics ) qcd . when the adjoint fermion is introduced with pbc in the theory , it was shown that exotic phases appear , where the color trace of polyakov line takes non - trivial vev leading to the dynamical gauge symmetry breaking . this can be interpreted as realization of the hosotani mechanism . further study is now required to understand detailed properties and phase diagram for this case . as for the five - dimensional gauge theory on , lattice simulation is still at the stage to understand the nature of 5d pure yang - mills theory . first attempt was done in ref . and recent progress was shown in ref . . at the present , we have no detailed investigation on the phase structure of the five - dimensiona

We study the phase structure of the five - dimensiona in large hadron collider ( lhc ) by using the yang - mills theory. The x - ray photon is introduced with periodic boundary condition and the color trace of polyakov line takes non - trivial vev leading to the dynamical gauge symmetry breaking. We show that the vevac is not a non - zero vacuum expectation value, but a ve - like component of the gauge field.

we investigate the phase structure of gauge theory in four and five dimensions with one compact dimension by using perturbative one - loop and pnjl - model - based effective potentials , with emphasis on spontaneous gauge symmetry breaking . when adjoint matter with the periodic boundary condition is introduced , we have rich phase structure in the quark - mass and compact - size space with gauge - symmetry - broken phases , called the split and the re - confined phases . our result is qualitati


We consider ( generalized ) kolakoski sequences on an alphabet with two even numbers

a one - sided infinite sequence over the alphabet is called a ( classical ) _ kolakoski sequence _ ( named after w. kolakoski who introduced it in 1965 , see ) , if it equals the sequence defined by its run lengths , e.g. : here , a _ run _ is a maximal subword consisting of identical letters . the sequence is the only other sequence which has this property . one way to obtain of ( [ eq : kol ] ) is by starting with as a seed and iterating the two substitutions alternatingly , i.e. , substitutes letters on even positions and letters on odd positions ( we begin counting at ) : clearly , the iterates converge to the kolakoski sequence ( in the obvious product topology ) , and is the unique ( one - sided ) fixed point of this iteration . one can generalize this by choosing a different alphabet ( we are only looking at alphabets with ) . such a ( generalized ) kolakoski sequence , which is also equal to the sequence of its run lengths , can be obtained by iterating the two substitutions alternatingly . here , the starting letter of the sequence is . we will call such a sequence a kolakoski- sequence , or kol for short . the classical kolakoski sequence of ( [ eq : kol ] ) is therefore denoted by kol ( and by kol ) . while little is known about the classical kolakoski sequence ( see ) , and the same holds for all kol with odd and even or vice versa ( see ) , the situation is more favorable if and are either both even or both odd . if both are odd , one can , in some cases , rewrite the substitution as a substitution of pisot type ( see ) , which can be described as ( limit ) aperiodic model sets . by this method , kol is studied in and shown to be a deformed model set . the case where both symbols are even will be studied below . it is the aim of this article to determine structure and order of the sequences kol . this will require two steps : first we establish an equivalent substitution of constant length for kol and analyze it with methods known from the theory of dyn

We study the classical kolakoski sequence of ( [ eq: kol ] ) by iterating the two substitutions alternatingly, i. E., substituting letters on even positions and letters on odd positions. This is done by using the koloski- koleos, which are a generalized model set. We show that the _ koliosi _ is a deformed model set with both odd and odd positions and that the same can be said for all kol with odd and.

we consider ( generalized ) kolakoski sequences on an alphabet with two even numbers . they can be related to a primitive substitution rule of constant length . using this connection , we prove that they have pure point dynamical and pure point diffractive spectrum , where we make use of the strong interplay between these two concepts . since these sequences can then be described as model sets with -adic internal space , we add an approach to `` visualize '' such internal spaces .


The stable clustering hypothesis is a fundamental assumption about the nonlinear clustering of...

the stable clustering hypothesis is a basic assumption in cosmology about the nonlinear clustering of cosmic matter ( ) . it states that the mean physical separations of particles in highly non - linear regions do not change with the expansion of the universe . in terms of the scale factor and the comoving coordinates , the hypothesis equivalently states that the relative pair velocity in the comoving coordinates cancels out the hubble flow , i.e. based on this assumption plus self - similarity , it is predicted that 1 ) the power - law index of the two - point correlation function on sufficiently small scales is related to the power - law index of the linear power spectrum as , and 2 ) the n - point correlation functions scale with as ( , , , , , , , ) . based on the first prediction for clustering on small scale and the linear theory prediction for large scale , a phenomenological fitting formula has been found for the nonlinear power spectrum ( , , , , ) . this fitting formula has been applied to study a wide range of non - linear clustering problems , notably the gravitational lensing and the non - linear clustering of galaxies . there have been many attempts to verify the stable clustering hypothesis with numerical n - body simulations . in their seminal work , efstathiou et al . ( ) tested the hypothesis [ eq.([eq1 ] ) ] and its two predictions with a set of scale - free n - body simulations of particles . they concluded that their simulation results are consistent with the hypothesis , but it is not difficult to imagine that the accuracy they could achieve is quite limited for the limited resolution of this first generation of simulations . subsequently , many improved simulations with to particles have been used to solve this problem ( e.g. , , , , and and references therein ) . as shown by jain ( 1997 ; his fig.2 , fig.3 and fig.8 ) , his simulation results of the mean pair velocity have just approached the stable clustering condition [ eq.([eq1 ] ) ] at th

We present a numerical simulation of the nonlinear power spectrum with to particles. Our results are consistent with the stable clustering hypothesis and with the linear theory prediction for large scales. We also show that the accuracy of our simulations is quite limited for the limited resolution of this first generation of simulations, which is based on the phenomenological fitting formula.

the stable clustering hypothesis is a fundamental assumption about the nonlinear clustering of matter in cosmology . it states that the mean physical separation of particles is a constant on sufficiently small scales . while many authors have attempted to test the hypothesis with cosmological n - body simulations , no consensus has been reached on whether and where the hypothesis is valid , because of the limited dynamical range that this type of simulations can achieve . in this _ letter _ , we


Merging binary neutron stars ( bnss ) represent the ultimate targets for multimessenger astronomy ,...

with the discovery of binary black hole ( bh ) mergers by the laser interferometer gravitational wave observatory ( ligo ) , the era of gravitational wave ( gw ) astronomy and multimessenger astronomy including gws has begun . as the advanced ligo and virgo detectors approach design sensitivity in the next few years , exciting discoveries are expected to be made , including binary neutron star ( bns ) and ns bh mergers . due to the absence of baryonic matter in these systems , stellar - mass binary bh mergers are not expected to produce bright electromagnetic ( em ) counterparts to their gw signal ( but see , e.g. , ) . instead , mergers involving nss are expected to link the em and gw skies . furthermore , these mergers are also of wide interest as they offer a unique opportunity to constrain the equation of state ( eos ) of matter at supranuclear densities ( e.g. , ) and provide a prime candidate astrophysical site for the production of heavy elements in the universe , via r - process nucleosynthesis in the matter ejected during and possibly after merger ( e.g. , ) . mergers involving nss are expected to generate em emission across the entire em spectrum and over a variety of timescales . detection of em counterparts will enable the identification of the host galaxy and its position within / relative to the host , which will provide valuable information on binary formation channels , age of the stellar population , and supernova birth kicks . additionally , by measuring redshifts , em counterparts can determine the distance to the source and help alleviate degeneracies in the gw parameter estimation between distance and inclination of the binary . moreover , combined gw and em observations can prove the connection between short gamma - ray bursts ( sgrbs ) and bns or ns - bh mergers ( see below ) , revealing crucial information on when and how a sgrb can be produced . finally , even without a gw detection , em counterparts can reveal exclusive information on the v

We present a new method for the detection of short gamma - ray bursts ( sgrbs ) in binary neutron star ( bns, ns and bh mergers. This technique is used to detect short - wavelength gam - radiation bursties ( gr ), which are expected to produce em emission across the entire spectrum and over a variety of timescales; however, the e - emission can be detected by using a single - source -.

merging binary neutron stars ( bnss ) represent the ultimate targets for multimessenger astronomy , being among the most promising sources of gravitational waves ( gws ) , and , at the same time , likely accompanied by a variety of electromagnetic counterparts across the entire spectrum , possibly including short gamma - ray bursts ( sgrbs ) and kilonova / macronova transients . numerical relativity simulations play a central role in the study of these events . in particular , given the importan


The exclusive meson production in a proton - nucleus collision , leading to two body final states ,...

hypernuclei have been studied extensively by stopped as well as in - flight reaction and also by reaction . the kinematical properties of the reaction allow only a small momentum transfer to the nucleus , thus there is a large probability of populating -substitutional states in the residual hypernucleus . on the other hand , in the reaction the momentum transfer is larger than the nuclear fermi momentum . therefore , this reaction can populate configurations with an outer neutron hole and a hyperon in a series of orbits covering all bound states . during past years data on the hypernuclear spectroscopy have been used extensively to extract information about the hyperon - nucleon interaction ( which could be quite different from the nucleon - nucleon interaction ) within a variety of theoretical approaches ( see , e.g. , ) . alternatively , -hypernuclei can also be produced with high intensity proton beams via the reaction where the hypernucleus has the same neutrons and proton numbers as the target nucleus . first set of data for this reaction on deuterium and helium targets , have already been reported in ref . more such measurements involving heavier targets are expected to be performed at the cosy facility of the forschungszentrum , jlich . the states of the hypernucleus excited in the reaction may have a different type of configuration as compared to those excited in the reaction . thus a comparison of informations extracted from the study of two reactions is likely to lead to a better understanding of the hypernuclear structure . theoretical studies of the reaction are rather sparse and preliminary in nature . they are based on two main approaches ; the one - nucleon model ( onm ) [ fig . 1(a ) ] and the two - nucleon model ( tnm ) [ fig . 1(b ) and 1(c ) ] . in the onm the incident proton first scatters from the target nucleus and emits a ( off - shell ) kaon and a hyperon . subsequently , the kaon rescatters into its mass shell while the hyperon gets captured

We present a comparison of the results obtained from the two - nucleon model ( onm ) and the two- nuCLEON model ( tnm ), which are based on the one - neutron model. The two approaches are derived using the same data as the one in the first approach. We show that the two methods can be used to extract information about the hypernuclear structure.

the exclusive meson production in a proton - nucleus collision , leading to two body final states , is investigated in a fully covariant two - nucleon model based on the effective lagrangian picture . the explicit kaon production vertex is described via creation , propagation and decay into relevant channel of (1650 ) , (1710 ) and (1720 ) intermediate baryonic states in the initial collision of the projectile nucleon with one of its target counterparts which is modeled by the one - pion exchang


In this note , we first discuss some properties of generated -fields and a simple approach to the...

the role of -fields in probability and statistics is well known . a -field generated by a class of subsets of a give space , also known as the generated -field , is defined to be the intersection of all -fields containing that class . however , a constructive approach to obtain the -field generated by finite number of subsets has not been well studied in the literature . indeed , no easy constructive method is available . it is a challenging task to construct a -field generated by , say , four arbitrary subsets and to know its exact cardinality . given a finite class of -distinct sets ( see definition 2.2 ) which are also atoms , we discuss a simple approach to obtain the generated -field based on the partition induced by the given class and then look at the -field generated by this partition . in this direction , we first obtain the cardinality of the induced partition by a finite class of such sets . using this result , we obtain the cardinality of the generated -field . when all members of the induced partition are non - empty , the cardinality of the generated -field is , a known result in the literature ( see ash and doleans - dade ( 2000 ) , p 457 ) . let denote the set of real numbers . then the cardinality of ( also called cardinality of the continuum ) is given by where is the cardinality of the set of natural numbers . one of the fascinating results in measure theory is that there is no -field whose cardinality is countably infinite . in other words , the cardinality of a -field can be either finite or equal to ( uncountable ) ( billingsley ( 1995 ) , p. 34 ) . our focus is on the cardinality of a -field , generated by a finite class of sets , and to show that it assumes only particular values within a fixed range . to the best of our knowledge , this problem has been addressed only for some special cases ( ash and doleans - dade ( 2000 ) , p. 11 ) . several typical examples are discussed to bring out the nature of the finitely generated -fields . an algor

We study the cardinality of a finite class of sets generated by a given partition and then look at the -field generated by this partition. In this way, we obtain the cardinality of the partition induced by a set of natural numbers. The cardinateness of the generated - field is obtained by where is the cardineality of the set of real numbers, which is, a known result in the literature.

in this note , we first discuss some properties of generated -fields and a simple approach to the construction of finite -fields . it is shown that the -field generated by a finite class of -distinct sets which are also atoms , is the same as the one generated by the partition induced by them . the range of the cardinality of such a generated -field is explicitly obtained . some typical examples and their complete forms are discussed . we discuss also a simple algorithm to find the exact cardina


We present a publicly - available spectral model for thermal x - ray emission from a baryonic jet...

launching of relativistic outflows from inner regions of an accretion disc is one the basic predictions of the standard theory of disc accretion for specific regimes when radiation alone is not efficient enough to carry away all the liberated potential energy of the in - falling matter . although there are numerous indications of such outflows both in x - ray binary systems ( xrb ) and active galactic nuclei ( agn ) , their actual composition ( leptonic or baryonic ) as well as the corresponding launching mechanisms ( magnetic field vs. radiation pressure driven ) still remain unclear ( ; see also and for recent reviews in the context of xrbs and agn , respectively ) . while leptonic models are typically successful in describing the observed emission as having a primarily synchrotron origin , the existence of some baryonic loading is also frequently invoked to explain the high jet kinetic power required to produce and maintain large - scale cavities or cocoons associated with xrbs and agns . the main evidence for the existence of baryonic jets comes , however , from the outstanding galactic x - ray binary system ss 433 , whose x - ray emission is marked by pairs of oppositely doppler - shifted ( ) lines of highly ionised heavy elements on top of the thermal bremsstrahlung continuum with kev , while its optical emission also bears similar signatures of doppler - shifted lines of hydrogen and helium ( e.g. ) . these peculiar properties are attributed to a pair of strongly collimated ( the half - opening angle ) , mildly - relativistic ( the bulk velocity ) precessing jets of ordinary highly ionised plasma with almost solar abundance of elements ( see for a review ) . according to the standard multi - temperature model , the x - ray jets first become visible when their temperature is kev and then cool below kev as a result of adiabatic expansion , which allows a number of ionization stages of various elements to contribute to the net observed spectrum . by now , ss 433

We present a new model for the launching of relativistic outflows from inner regions of an accretion disc. This model is based on a combination of two different models, which are characterized by a pair of strongly collimated ( half - opening angle ) jets with almost solar abundance of elements. The jets are accompanied by ionisation stages of various elements and their mass distributions. We show that the jet kinetic power required to produce large cavities or cocoons associated with x - ray binary systems is largely due.

we present a publicly - available spectral model for thermal x - ray emission from a baryonic jet in an x - ray binary system , inspired by the microquasar ss 433 . the jet is assumed to be strongly collimated ( half - opening angle ) and mildly relativistic ( bulk velocity ) . its x - ray spectrum is found by integrating over thin slices of constant temperature , radiating in optically thin coronal regime . the temperature profile along the jet and corresponding differential emission measure di


Disc accretion to a rotating star with a non - dipole magnetic field is investigated for the first...

many accreting stars have a strong magnetic field which disrupts the accretion disc and channels accreting matter to the star s surface . for such stars many spectral and photometric properties are determined by the magnetic field . examples include young solar - type stars ( classical t tauri stars , hereafter ctts , e.g. , hartmann 1994 ) , neutron stars in binary systems ( x - ray pulsars and millisecond pulsars , e.g. ghosh & lamb 1978 ; chakrabarty et al . 2003 ) , white dwarfs in the binary systems ( cataclysmic variables , e.g. wickramasinghe et al . 1991 ; warner 1995 , 2000 ) , and also brown dwarfs ( e.g. , scholz & ray 2006 ) . the properties of such accretion will depend on the structure of the magnetic field of the star . in early models it was assumed that the star s intrinsic magnetic field was a pure _ dipole _ ( ghosh & lamb 1979a , b ; camenzind 1990 ; knigl 1991 ) . recently , 2d and full 3d mhd numerical simulations of magnetospheric accretion were performed which confirmed many predicted features and revealed many new details of accretion to a star with a dipole field ( romanova et al . 2002 , 2003 , 2004 ; long et al . 2005 ; kulkarni & romanova 2005 ) . different aspects of the disc - magnetosphere interaction were also investigated numerically ( hayashi et al . 1996 ; hirose et al . 1997 ; miller , & stone 1997 ; goodson , winglee & bhm 1997 , 1999 ; von rekowski & brandenburg 2004 , 2006 ) and theoretically ( e.g. , lovelace , romanova & bisnovatyi - kogan 1995 ; uzdensky , knigl & litwin 2002 ; matt & pudritz 2004 , 2005 ) . however , the actual configuration of the magnetic field of strongly magnetized stars may depart from the dipole one . for example , safier ( 1998 ) presented a number of arguments pointing to a non - dipolar magnetic fields in some cttss . the zeeman measurements of the magnetic field of a number of cttss based on the photospheric lines show that the magnetic field at the surface of cttss is strong ( 1 - 3 kgs ) but no

We present a numerical simulation of the magnetic field of a young solar - type star with a dipole field. The model is based on the _ accretion disc _ and the accrescence disc. In this paper we investigate the magnetic fields of the stars, their structure and their photometric properties. We find that the magnetic - field interaction between the disk and the magnetosphere is strongly dependent on the magnetic energy of the star.

disc accretion to a rotating star with a non - dipole magnetic field is investigated for the first time in full three - dimensional ( 3d ) magnetohydrodynamic ( mhd ) simulations . we investigated the cases of ( 1 ) pure dipole , ( 2 ) pure quadrupole , and ( 3 ) dipole plus quadrupole fields . the quadrupole magnetic moment is taken to be parallel to the dipole magnetic moment , and both are inclined relative to the spin axis of the star at an angle . simulations have shown that in each case th


We present experimental and theoretical results of a detailed study of laser - induced continuum...

the properties of the continuum of quantum states observed in the photoionization of an atom or the dissociation of a molecule have attracted interest since the first formulations of quantum theory . until the widespread use of lasers , the continuum was regarded as a dissipative system , to be treated by means of rate equations ( typically using the approximation of the fermi golden rule to calculate the transition rate into the continuum ) . contemporary views no longer regard continuum states as an irreversible drain of probability . an electron acted upon by a laser field of sufficiently high frequency to produce ionization does not move irreversibly away from the binding region . laser interactions with a continuum have been shown to exhibit rabi - type oscillations ( if the laser field is sufficiently strong ) and to enable nearly complete population transfer into a continuum ( i.e. photoionization or photodissociation ) or from a continuum ( i.e. photorecombination ) . both theoretical and experimental work has shown that the wavefunction of an electron in a laser field may often maintain coherence during the course of photoionization , and that photodissociation can also maintain coherence . consequences of continuum coherence are to be found in the well - studied phenomena of autoionization , which is revealed as a resonance in plots of photoionization cross - sections versus frequency . such resonances display the effect of interference between two ionization channels whose destructive interference can lead to complete suppression of photoionization at a specific wavelength . one of the more interesting coherent phenomena involving the continuum is the use of a laser field to embed an autoionization resonance into an otherwise featureless photoionization continuum . this dressing of a continuum by a bound state by means of a laser field is termed a laser induced continuum structure " ( lics ) . as with other types of resonances described by scattering theo

We study the properties of a laser field in photoionization and photodissociation by means of lics. We show that the wavefunction of an electron in a Laser field is maintained by the presence of rabi - type oscillations ( if the laser field is sufficiently strong ) and that photodisorption can also be observed.

we present experimental and theoretical results of a detailed study of laser - induced continuum structures ( lics ) in the photoionization continuum of helium out of the metastable state . the continuum dressing with a 1064 nm laser , couples the same region of the continuum to the 4s s state . the experimental data , presented for a range of intensities , show pronounced ionization suppression ( by as much as 70% with respect to the far - from - resonance value ) as well as enhancement , in a


We propose a new structural model for the si(111)-(5)-au reconstruction

forty years ago bishop and riviere first observed the ( 111 ) surface of silicon to reconstruct , with fivefold periodicity , in the presence of gold . since that time the si(111)-(5)-au reconstruction has been widely studied , in several hundred publications , as a prototype linear metallic chain system in which the physics of one - dimensional metals is approximately realized. these investigations have provided very substantial insights into many aspects of si(111)-(5)-au. less successful have been the many attempts to use the clues provided by experiment to construct a complete structural model for this complicated reconstruction . beginning with the early work of lelay over a dozen different models have been proposed. all were eventually found to be inconsistent with the results of scanning tunneling microscopy ( stm ) , angle - resolved photoemission spectroscopy ( arpes ) , or both . 2)-au with gold coverage equal to 0.6 monolayer . large yellow circles are gold , small circles are silicon . the surface layer consists of a gold single row ( s ) , gold double row ( d ) , and silicon honeycomb chain ( hc ) . the surface energy is minimized when this surface is decorated by silicon adatoms ( dark blue ) with 5 periodicity , as shown . in the presence of adatoms the 5 periodicity of the underlying substrate spontaneously doubles to 5 ( gray outline ) due to dimerization within the gold double row . [ model],width=302 ] in this paper we propose a new structural model for si(111)-(5)-au that is fully consistent with all experimental data to which we have compared . the model is similar to one proposed by erwin in 2003, but is modified to be consistent with a recently revised value of the gold coverage. the modifications , although seemingly minor , for the first time bring the predictions of the model for stm and arpes as well as other phenomena into excellent agreement with experiment . more importantly , the new model opens the door to a more fundamental physical

We propose a new structural model for si(111)-(5)-au that is fully consistent with all experimental data to which we have compared. The model is similar to one proposed by erwin in 2003, but is modified to be consistent with a recently revised value of the gold coverage.

we propose a new structural model for the si(111)-(5)-au reconstruction . the model incorporates a new experimental value of 0.6 monolayer for the coverage of gold atoms , equivalent to six gold atoms per 5 cell . five main theoretical results , obtained from first - principles total - energy calculations , support the model . ( 1 ) in the presence of silicon adatoms the periodicity of the gold rows spontaneously doubles , in agreement with experiment . ( 2 ) the dependence of the surface energy


Keldysh nonequilibrium green s function method is utilized to study theoretically the spin...

laser fields have been demonstrated to be a powerful tool for the exploration and modification of the materials properties . for example , in conventional semiconducting nanostructures a variety of applications have been established such as the various forms of the photo electronic devices ( e.g. , the radiation - controlled field - effect transistors , photodiodes , and the light - emitting diodes ) . on the other hand , graphene with its many unusual physical properties ( to mention but a few , the half integer quantum hall effect , the klein tunneling and the conductance properties ) offers a new platform to explore radiation effects . the influence of electromagnetic fields on graphene has been recently a subject of intense research . particularly interesting examples are the linear response to and the frequency dependence of the conductivity , the photon - assisted transport , the microwave and far - infrared response , the plasmon spectrum , as well as the nonlinear response to the electromagnetic radiation . the potential applications of graphene in terahertz electronics were pointed out in refs. . the resonant interaction between graphene and an electromagnetic field may open a dynamical gap in the quasiparticle spectrum of graphene , which leads to a strong suppression of the quasiparticle transmission through a graphene p - n junction . however , a directed current without applying any dc bias voltage can be generated in certain conditions as a result of inelastic quasiparticle tunneling assisted by one- or two - photon absorptions . another way to generate a direct current is to use shaped , timely tuned electromagnetic pulses which also may generate a valley current . therefore , it seems possible to control the transport properties of diverse graphene tunneling structures by the variation of the strength and the frequency of the external radiation fields . on the other hand , the potential of graphene for spin - dependent transport ( spintronic ) applic

We present a new method to control the spin - dependent transport of graphene tunneling structures by using an external electromagnetic field. The proposed method is based on the resonant interaction between graphen and an electromagnetic field and the variation of the strength and frequency of the external radiation fields. We show that the direct current generated by the induced voltage can be controlled by the variation in the strength of the electromagnetic field or the frequency of a pulse.

keldysh nonequilibrium green s function method is utilized to study theoretically the spin polarized transport through a graphene spin valve irradiated by a monochromatic laser field . it is found that the bias dependence of the differential conductance exhibits successive peaks corresponding to the resonant tunneling through the photon - assisted sidebands . the multi photon processes originate from the combined effects of the radiation field and the graphene tunneling properties , and are show


We study the distant red galaxy ( drg , ) neighbour population of quasi stellar objects ( qsos )...

studies of large samples of distant galaxies are fundamental to provide a deeper insight in the formation and evolution of galaxies and systems of galaxies , such as clusters and groups . using measurements of galaxy clustering at one can test the predictions of cosmological models of structure formation and evolution . in the last years diverse photometric selection techniques have been developed in order to select high redshift galaxies . in particular the lyman break technique is an ideal method for selecting a large number of distant galaxies and for studying the large - scale distribution and properties of star - forming systems at high redshifts from multicolour optical data . this technique requires a high rest - frame far ultraviolet luminosity , and so will preferentially select galaxies with recent or unobscured active star - formation . a new near - infrared selection technique has been developed in recent years to select samples of galaxies at high redshifts . the distant red galaxies ( drgs , hereafter ) colour cut criterion ( , vega system ) is expected to select galaxies with prominent rest frame optical breaks , caused by the 3625 balmer - break or the 4000 ca ii h+k break . the balmer discontinuity at 3625 is strongest in a - type stars and the 4000 break is characteristic of coolers stars with types later than g0 and strong in giant and supergiant stars . van dokkum et al . ( 2003 ) found that the drg criterion selects galaxies with rest - frame optical colours similar to those of normal nearby galaxies . using deep mid - infrared observations with irac on the spitzer space telescope , found that 70% of the drgs are best described by dust - reddened star forming models and 30% are very well fit with old stellar population , passive star evolution galaxy models . by comparison of the stellar populations of dgrs to those obtain in lyman - break galaxies ( lbgs ) , found that the average mass - to light ratios ( ) of the drgs are about three times hig

We present a new near - infrared selection technique for the distant red galaxies ( drgs ) at high redshifts. This technique is designed to select large samples of galaxii with recently or unobscured active star - formation. Using deep mid - irac observations on the spitzer space telescope, we find that 70% of the ddrGs are best described by dust - reddened star forming models and 30% are very well fit with old stellar population, passive star evolution galaxy models.

we study the distant red galaxy ( drg , ) neighbour population of quasi stellar objects ( qsos ) selected from the sloan digital sky survey ( sdss ) in the redshift range . we perform a similar analysis for optically obscured agns ( i.e. with a limiting magnitude ) detected in the mid - infrared ( 24 m ) with the spitzer space telescope and a mean redshift in the flamingos extragalactic survey ( flamex ) . both qsos and obscured agn target samples cover 4.7 deg in the same region of the sky . we


We are investigating the sn 1987a remnant by modeling the circumstellar environment of the...

observations of the sn 1987a nebula give us the clues that we will need to model its structure . figure [ fig : hst87a ] shows an hst image of the nebula ( burrows et al . 1995 ) and a schematic diagram of the nebular structure . the hst image shows two of the salient features of the nebula : the inner and outer rings . the diagram shows a slice containing the symmetry axis . the inner ring lies in the equatorial plane at a radius of about lt yr and is expanding with a velocity of 10.3 km s ( crotts & heathcote 1991 ) , while the outer rings are at an angle of about 55 from the equatorial plane and an axial radius of about lt yr . a tenuous shell connects the inner and outer rings ( crotts , kunkel , & heathcote . 1995 ) , but the shell does not extend past the outer rings ; that is , the nebula is open along the symmetry axis . in an interacting winds model for the nebula , a fast , hot wind ejected during a blue supergiant phase overtakes a slow , dense wind ejected from a previous red supergiant phase . in order to produce the equatorial ring the rsg wind must be asymmetrical , with higher density at the equator and lower density at the symmetry axis . blondin & lundqvist ( 1993 ) performed numerical simulations of this interacting winds scenario for adiabatic and radiatively cooling gas . these simulations showed that the interacting winds model could produce the inner ring and the overall shape of the nebula . however , the blondin and lundqvist models did not produce the outer rings , and the shell in these models is complete all the way to the symmetry axis . therefore , the interacting wind models need some refinement if they are to describe the sn 1987a nebula . radio and x - ray observations of the nebula since 1990 provide additional information . these observations indicate that the supernova blast has encountered a region of density intermediate to the inner and outer winds ( gorenstein , hughes , & tucker 1994 ; beuermann , brandt , & pietsch 1994 ; st

We present a numerical simulation of the sn 1987a nebula using a interacting winds model for adiabatic and radiatively cooling gas. The interacting wind is asymmetrical with higher density at the equator and lower density at symmetry axis. In this scenario, the rsg wind must be asymmetryal, with higher densities at the.

we are investigating the sn 1987a remnant by modeling the circumstellar environment of the progenitor star . interacting stellar winds models have been reasonably successful at reproducing the gross features of the nebula , but some details , such as the early rise of the radio and x - ray emission from the supernova blast and the presence of the outer rings , are not explained in a pure wind model . in this paper we describe preliminary results from 2-d models that incorporate the effects of ph


The behavior of small samples in very short and intense hard x - ray pulses is studied by molecular...

today s most important tool for structure determination is x - ray crystallography . this method works only on samples having spatial periodicity . however , there is a growing need for the determination of the atomic order of small non - periodic entities such as biomolecules , individual nanoparticles , atomic clusters etc . since in these systems the radiation damage is not distributed randomly among a huge number of identical units ( elementary cells in crystals ) , the average structure significantly changes with any single damage event . therefore the structure determination of these particles requires a different approach then that of crystalline substances . a solution , which avoids geometrical distortion was suggested by solem et al . and later it was extended to biomolecules by neutze et al . their idea was catalyzed by the construction of future x - ray free - electron lasers ( xfels ) , which will provide extremely bright hard x - ray beam with very short pulses . according to their reasoning elastically scattered photons should be collected during the very short and intense pulse of xfel s . although in long term the radiation damage is fatal ( the sample explodes ) , in extremely short times , the atoms of the sample do not move appreciately . limiting the collection of elastically scattered photons to this period we could obtain useful data for the original structure of the sample . the key question in this case is the dynamics of the sample explosion : how much time do we have for imaging ? various models have been worked out to describe the behavior of the sample in the beam . although the explosion dynamics predicted by these models slightly differ in details , but they all arrive at the same general conclusion : to do successful imaging with atomic resolution one needs shorter pulses then the pulse length of the presently constructed sources . since the realization of shorter pulses is not simple , there is a search for methods by which the usefu

We present a new method for the structure determination of non - periodic particles in x - ray crystallography. It is based on the usefu method, which allows to obtain very short pulses and a high energy density. The method is compared with the current method.

the behavior of small samples in very short and intense hard x - ray pulses is studied by molecular dynamics type calculations . the main emphasis is put on the effect of various tamper layers about the sample . this is discussed from the point of view of structural imaging of single particles , including not only the distortion of the structure but also the background conditions . a detailed picture is given about the coulomb explosion , with explanation of the tampering mechanism . it is shown


Single crystal nematic elastomers undergo a transition from a strongly ordered phase to an ``...

nematic rubbers were first constructed in a single domain form by h. finkelmann and coworkers . they show a spectacular change in shape when they are switched from low temperatures ( ) to high temperatures ( ) . many properties resulting from the coupling between nematic order and elastic deformations have been analyzed by m. warner , e. m. terentjev and coworkers . we are concerned here mainly by the transition from the nematic phase , to the high temperature phase . two striking facts should be mentioned here : ( a ) the transition is expected to be first order , but the plots of birefringence versus temperature are continuous . ( b ) the transition is very slow ( minutes ) . our aim here is to discuss some effects of the nematic / elastic coupling on the phase transition . first , we discuss the anisotropy induced by the preparation method . we show that this preparation imposes a fixed _ external field _ coupled to the order parameter : under this field the plots of order versus temperature are expected to be continuous . second , we analyze -jumps : for a cooling jump we find a traditional spinodal transition . but for a heating jump we show that the elastic couplings tend to suppress the spinodal instability . finally , we discuss the nucleation of an phase inside a nematic single crystal , and show that it should take place in the form of platelets , with well defined geometrical conditions . in the finkelmann scheme , a very weak network is prepared first , and is put under a prescribed deformation along one axis . then a second reaction is started and the final nematic rubber is generated . the basic energy for this situation is of the form where summation over the repeated indices is implied . for simplicity , we restrict our attention to small deformations . is the standard landau free energy of the nematic order , describes the coupling between deformation and order , and the last term is the shear elastic energy ( we consider only incompressible systems

We discuss the effects of nematic / elastic couplings on the phase transition from the nascent to the high temperature phase. In this paper we study the anisotropy induced by the preparation method, and show that it is expected to be first order, but the plots of birefringence versus temperature are continuous.

single crystal nematic elastomers undergo a transition from a strongly ordered phase to an `` isotropic '' phase . we show that : ( a ) samples produced under tension by the finkelmann procedure are intrinsically anisotropic and should show a small ( temperature dependent ) birefringence in the high temperature phase . ( b ) for the transition _ via _ cooling there is a spinodal limit but for the transition _ via _ heating there is no soft mode at the standard spinodal temperature . ( c ) the tr


The _ theory unifying spin and charges and predicting families _ , proposed by n

the _ theory unifying spin and charges and predicting families _ ( hereafter named the _ spin - charge - family - theory _ ) , proposed by n.s . manko bortnik , seems promising to show the right way beyond the _ standard model _ of fermions and bosons . the reader is kindly asked to learn more about this theory in the refs . and in the references therein . following analyses of the ref . , we here repeat the parts which are necessary for understanding the starting assumptions and the conclusions to which one loop corrections beyond the tree level lead . we look at the two loop corrections and present for the case that each group of four families would decouple into two times two families numerical results with two loop corrections as well . some of this results can be found in . the _ spin - charge - family - theory _ predicts eight massless families of quarks and leptons before the two successive breaks first from to and then from to . mass matrices originate in a simple starting action : they are determined on the tree level by nonzero vacuum expectation values of scalar ( with respect to ) fields , to which vielbeins and two kinds of spin connection fields contribute . one kind of the spin connection fields includes fields gauging , which are determined by the dirac gammas ( s ) , another kind gauges , determined by the second kind of gammas s , used in the _ spin - charge - family - theory _ to generate families . each of the two breaks is triggered by different ( orthogonal ) superposition of scalar fields . to the first break , besides vielbeins , only the spin connections of one kind contribute . to the second break all the scalar fields contribute . the mass matrices for eight families appear to be four times four by diagonal matrices , with no mixing matrix elements among the upper four and the lower four families ( not in comparison with the life of the universe ) also after the two breaks : the upper four families are namely doublets with respect to two i

The _ spin - charge - family - theory _ predicts eight massless families of quarks and leptons before the two successive breaks first from to and then from to. The mass matrices for eight families are four times four by diagonal matrics, with no mixing matrix elements among the upper four and the lower four families.

the _ theory unifying spin and charges and predicting families _ , proposed by n.s.m.b . , predicts at the low energy regime two ( in the mixing matrix elements decoupled ) groups of four families . there are two kinds of contributions to mass matrices in this theory . one kind distinguishes on the tree level only among the members of one family , that is among the -quark , -quark , neutrino and electron , the left and right handed , while the other kind distinguishes only among the families . m


The effect of plasma environment on the atomic energy levels of he - like and li - like mg and fe...

the emission spectra of helium - like ( he - like ) and lithium - like ( li - like ) ions have been observed in recent years both in astrophysical and laboratory plasmas . the x - ray spectra from these ions are observed from a large variety of astrophysical sources and laser plasma interactions . they are used to determine the primordial abundances of elements that are of immense interest for testing the big bang cosmology . detection of these lines using astronomy telescopes reveal many x - ray sources . also , the earth s atmosphere absorbs most of the radiation at the x - ray wavelengths , so its behavior and dynamics can be investigated by knowing these lines accurately . accurate determination of these lines have become very demanding in recent years with the advent of increasingly powerful x - ray satellite telescopes . the two most powerful telescopes to date are the chandra x - ray observatory , launched by nasa , in 1999 , and the x - ray multi - mirror ( xmm ) newton telescope , launched by the european space agency , recently . the astrosat satellite , launched last year by indian space research organization ( isro ) is also aiming at exploring the possible x - ray sources in the space . the international x - ray observatory is being planned to be launched in 2021 jointly by nasa , european space agency ( esa ) and japan aerospace exploration agency ( jaxa ) which can cover a large effective area to probe for the x - ray sources . this is why x - ray astronomy remains to be an active research area today . due to high spectral resolution and sensitivity of the current generation x - ray satellites chandra and xmm - newton , it is possible to resolve the he - like ion lines distinctly and use them in the diagnostics for extra - solar objects . indeed , the he - like ion line ratios are valuable tools in the analysis of high - resolution spectra of a variety of plasmas such as collisional ionization equilibrium ( cie ) plasmas or also called coronal plasmas

We present a new method to analyze the emission spectra of helium - like ( he -like ) and lithium - Like ( li - nice ) ions in the atmosphere using the x - ray multi - mirror ( xmm ) newton telescope. The he and l - similar lines are found to be very sensitive to the radiation at the spectral resolution of the current generation xMM - newtonal telescopes chandra and xm - neuenton, which is expected.

the effect of plasma environment on the atomic energy levels of he - like and li - like mg and fe ions have been studied using debye model . the equation - of - motion coupled - cluster ( eomcc ) and fock - space coupled - cluster ( fscc ) formalisms in the relativistic frame work have been adopted to describe the atomic states and the energy levels of the above plasma embedded ions . salient features of these methods have been described to account the two electron screening effects through the


Our aim in this paper is to establish some strong stability properties of a solution of a...

consider a fractional brownian motion ( fbm ) , a self - similar gaussian process with stationary increments . it was introduced by kolmogorov and studied by mandelbrot and van ness . the fbm with hurst parameter is a centered gaussian process with covariance function if , then the process is a standard brownian motion . when , is neither a semimartingale nor a markov process , so that many of the techniques employed in stochastic analysis are not available for an fbm . the self - similarity and stationarity of increments make the fbm an appropriate model for many applications in diverse fields from biology to finance . we refer to for details on these notions . consider the following stochastic differential equation ( sde ) where ^d ^d $ ] is a measurable function , and is a -dimensional fbm with hurst parameter whose components are one - dimensional independent fbms defined on a probability space } , p)$ ] , where the filtration }$ ] is generated by , $ ] , augmented by the -null sets . it has been proved in that if satisfies the assumption ; l^1 (^{d}) l^(^d)),\ ] ] for , then eq . ( [ sde1 ] ) has a unique strong solution , which will be assumed throughout this paper . notice that if the drift coefficient is lipschitz continuous , then eq . ( [ sde1 ] ) has a unique strong solution , which is continuous with respect to the initial condition . moreover , the solution can be constructed using various numerical schemes . our purpose in this paper is to establish some stability results under the pathwise uniqueness of solutions and under weak regularity conditions on the drift coefficient . we mention that a considerable result in this direction has been established in when an fbm is replaced by a standard brownian motion . the paper is organized as follows . in section 2 , we introduce some properties , notation , definitions , and preliminary results . section 3 is devoted to the study of the variation of solution with respect to the initial data . in the last sec

We consider a fractional brownian motion ( fbm ) with hurst parameter. The self - similarity and stationarity of increments make the fcm an appropriate model for many applications in diverse fields from biology to finance. We consider the following stochastic differential equation ( sde ) where l, l =, is a measurable function, and is -dimensional fdm with a stationary increase. It has been proved that if satisfies the assumption; l is l.

our aim in this paper is to establish some strong stability properties of a solution of a stochastic differential equation driven by a fractional brownian motion for which the pathwise uniqueness holds . the results are obtained using skorokhod s selection theorem . ./style / arxiv - vmsta.cfg fractional brownian motion , stochastic differential equations 60g15,60g22


Gamma ray bursts ( grbs ) have recently attracted much attention as a possible way to extend the...

the hubble diagram of type ia supernovae ( sneia ) provided the first evidence of the cosmic speed up opening the way to a flood of theoretical and observational efforts devoted to investigate the nature and the nurture of such a phenomenon . the astrophysical data coming from later sneia samples , baryonic acoustic oscillations , the anisotropy spectrum of cosmic microwave background radiation and the large scale structure data from large galaxy redshift surveys have strenghtened the then surprising result . as a consequence , there is nowadays little doubt that the universe is spatially flat , has a low matter content ( ) and is undergoing a phase of accelerated expansion . to close the energy budget and drive the cosmic speed up , a new fluid with negative pressure dubbed dark energy has been invoked as the only viable solution . understanding what dark energy really is stands out as one of the most fascinating problems of modern cosmology . roughly speaking , we can divide the different proposals in two broad categories . in the first class , one can include all models considering dark energy as a true fluid with unusual properties with proposals ranging from the classical cosmological constant to scalar fields running down their self interaction potential . on the other hand , one may give off general relativity resorting to modified gravity theories such as models ( see , e.g. , capozziello et al . 2008 , sotiriou & faraoni 2008 and references therein ) and braneworld cosmologies manifesting themselves as a fictitious dark energy - like fluid . notwithstanding their radically different inspiring phylosophies , all the viable theories share the same ability to be in satisfactory agreement with the available data . such a confusing situation is a clear evidence that present dataset are unable to discriminate among different models . such a problem comes out as a consequence of the still low redshift range probed . the sneia hubble diagram is an illuminating exam

We present a new study of the dark energy in type ia supernovae ( sneia ). We consider the scalar field as a model with a low redshift range and show that it is not a fictitious dark energy like fluid. The results are consistent with the data from the astrophysical surveys of the universe.

gamma ray bursts ( grbs ) have recently attracted much attention as a possible way to extend the hubble diagram to very high redshift . to this aim , the luminosity ( or isotropic emitted energy ) of a grb at redshift must be evaluated from a correlation with a distance independent quantity so that one can then solve for the luminosity distance and hence the distance modulus . averaging over five different two parameters correlations and using a fiducial cosmological model to calibrate them , sc


There has been a long - lasting debate on the question of whether or not electric currents in solar...

the energy required to power solar flares and cmes is stored in current - carrying magnetic fields in the corona . active regions ( ars ) , the main source regions of eruptions , carry a total electric current of 1ta ( e.g. , * ? ? ? * ) , which is commonly inferred from applying ampre s law , , to photospheric vector magnetograms . since such data are hampered by limited resolution and various uncertainties ( e.g , * ? ? ? * ) , it is not yet well understood how ar currents are distributed . the observations indicate that the currents in magnetically well - isolated ars are _ balanced _ to a very good approximation , i.e. , the total current , , calculated by integrating the vertical current density , , over the _ whole _ photospheric ar extension vanishes , as expected from ( e.g. , * ? ? ? what remains controversial is to which extent the currents are _ neutralized _ , meaning that calculated over a _ single _ ar polarity vanishes as well . full neutralization requires the main ( or direct ) currents which connect the ar polarities to be surrounded by shielding ( or return ) currents of equal total strength and opposite direction ( see , e.g. , figure1 in * ? ? ? both observations and theoretical considerations are not yet fully conclusive regarding the existence or amount of return currents in ars , which has led to an ongoing debate ( e.g. , * ? ? ? * ; * ? ? ? * ; * ? ? ? ar currents are believed to be formed by two main mechanisms : ( i ) the stressing of the coronal magnetic field by photospheric and sub - surface flows ( e.g. , * ? ? ? * ) and ( ii ) the emergence of current - carrying flux from the solar interior into the corona ( e.g. , * ? ? ? * ) . at first glance , mechanism ( i ) is expected to produce neutralized currents . to illustrate this , we show in fig.[fig : fg1](a , b ) a simple ar model created from a bipolar potential field by photospheric vortex flows . such an isolated , symmetric system must be current - balanced . to see if it is also

We present a new method for the analysis of magnetically well - isolated active regions ( ars ) in the corona. We use the _ irradiated _ photometric data to investigate the distribution of the currents in the active region, and find that the total current is balanced over the whole ar extension, as expected from ( e. G., *?? * ). The total electric current is calculated by integrating the vertical current density over the entire ar extension vanishes, i. E. _ the.

there has been a long - lasting debate on the question of whether or not electric currents in solar active regions are neutralized . that is , whether or not the main ( or direct ) coronal currents connecting the active region polarities are surrounded by shielding ( or return ) currents of equal total value and opposite direction . both theory and observations are not yet fully conclusive regarding this question , and numerical simulations have , surprisingly , barely been used to address it .


We propose a means to discriminate between the two basic variants of little higgs models , the...

little higgs models have been proposed as a solution to the hierarchy problem , the vast difference between the scales of electroweak symmetry breaking and the scale where quantum effects of gravity can no longer be neglected . the higgs boson emerges as a pseudo - goldstone boson of spontaneously broken chiral symmetries of a strongly interacting theory in the multi - tev regime . the quadratically divergent contributions to the higgs mass are canceled unlike in supersymmetry by particles of like statistics , chiral multiplet partners of the standard model ( sm ) fermions . the collective breaking of these symmetries generates a quadratically - divergent correction to the higgs mass only at two - loop order , such that the models remain weakly interacting at the tev scale , thereby satisfying electroweak precision data constraints . ideas about possible uv completions exist , but we ignore them in this paper and take little higgs models as low - energy effective theories . various realizations of the little higgs symmetry structure have been proposed , grouped quite generally into two classes ( cf . e.g. ) . the original models are mostly product group models , where the electroweak gauge group is extended to a product gauge group that contains subgroups in at least two distinct factors . the physical and bosons are mixtures of the gauge bosons from both factors . the global symmetry group is a simple group that includes the full gauge structure [ e.g. , , and the higgs is part of an irreducible multiplet of pseudo - goldstone bosons . in simple group models , the electroweak gauge group is embedded in a simple ( e.g. , ) gauge group , while the global symmetry group has a product structure , and the higgs is a mixture of the components of several ( at least two ) independent irreducible representations of the factor groups . although these models remain weakly interacting at the tev scale , nevertheless electroweak precision observables pose constraints on their p

We present a new class of little higgs models that are based on the electroweak gauge group and the global symmetry group. The model is a combination of two different types of product group models, where the electro weak gauge groups are embedded in a simple gauge group, while the global weak Gauge group has a product structure. We show that these models can be used as low - energy effective theories, which satisfy the constraints on their p.

we propose a means to discriminate between the two basic variants of little higgs models , the product group and simple group models , at the next generation of colliders . it relies on a special coupling of light pseudoscalar particles present in little higgs models , the pseudo - axions , to the and the higgs boson , which is present only in simple group models . we discuss the collider phenomenology of the pseudo - axion in the presence of such a coupling at the lhc , where resonant productio


To accurately predict the space weather effects of coronal mass ejection ( cme ) impacts at earth...

coronal mass ejections ( cmes ) are one of the key drivers of space weather at earth . to account for their effects , one must be able to forecast if a cme will hit earth , as well as the timing and the cme parameters upon impact . recent efforts have focused on predicting the arrival time of cmes . typically , a cme is observed in a coronagraph field - of - view , and the interplanetary motion is simulated based upon the interaction of the cme with the background solar wind . these models tend to yield errors of 6 - 12 hours . cmes frequently show significant deflections from a purely radial trajectory ( e.g. and ) . deflection can cause a high latitude cme to move toward the equator and impact earth or potentially cause a cme to miss the earth when impact was expected . cmes tend to deflect toward the heliospheric current sheet ( hcs ) and away from coronal holes ( chs , ) . accordingly , magnetic forces have become a popular explanation for the cause of cme deflections . in the low corona these forces will `` channel '' cmes towards local null points and deflect cmes toward the hcs on global scales . cmes have also been observed to rotate in both observations and simulations . the rotation changes the orientations of the cme s magnetic field . knowing the direction of the magnetic field is crucial for space weather forecasting as the strength of geomagnetic storms , as measured by , tends to increase with increasing southward magnetic field . to begin addressing the questions about cmes relevant to space weather predictions , developed forecasting a cme s altered trajectory ( forecat ) . forecat initially addressed cme deflections due to magnetic forces . with recent advancements forecat is capable of simulating cme rotation as well . forecat reproduces the general trends in cme deflections - cmes tend to deflect toward the hcs on global scales , although the magnetic structure in the low corona can also affect the direction of deflection . the magnetic forces re

We present a model for the arrival of coronal mass ejections ( cmes ) in the low corona. We use the spherical magnetic field to simulate the rotation of cme s magnetic field. The model is based on a radial trajectory and the magnetic field is simulated using the cdm - trm, ccm / tcm model. Our model reproduces the general trends in cme deflections due to magnetic forces.

to accurately predict the space weather effects of coronal mass ejection ( cme ) impacts at earth one must know if and when a cme will impact earth , and the cme parameters upon impact . presents forecasting a cme s altered trajectory ( forecat ) , a model for cme deflections based on the magnetic forces from the background solar magnetic field . knowing the deflection and rotation of a cme enables prediction of earth impacts , and the cme orientation upon impact . we first reconstruct the posit


Electron beams provide important probes and constraints for nuclear astrophysics

chiral eft is based on the symmetries of quantum chromodynamics ( qcd ) and is applicable at momentum scales of the order of the pion mass , where pions are included as explicit degrees of freedom and build up the long - range parts of strong interactions . in chiral eft , nucleons interact via pion exchanges and shorter - range contact interactions . the resulting nuclear forces and consistent electroweak operators are organized in a systematic expansion in powers of , where denotes the breakdown scale , leading to a typical expansion parameter for nuclei . as shown in fig . [ chiraleft ] , at a given order this includes contributions from one- or multi - pion exchanges and from contact interactions , with short - range couplings that are fit to data and thus capture all short - range effects relevant at low energies . the eft enables one to estimate theoretical uncertainties and chiral eft connects nuclear forces to the underlying theory through lattice qcd ( see talk by w. detmold ) . chiraleft.pdf chiral eft opens up a systematic path to investigate many - body forces and their impact on few- and many - body systems . this results from the consistency of nn and 3n interactions , which predicts the two - pion - exchange parts of 3n forces at nlo , leaving only two low - energy couplings that encode pion interactions with short - range nn pairs and short - range three - body physics . the leading nlo 3n forces improve few - body scattering , but interesting open problems remain . this makes the application of 3n and 4n forces at the next order ( nlo ) very exciting , in particular because they are predicted parameter - free with many new structures . because of gauge symmetries , the same eft expansion is used to derive consistent electroweak operators . therefore , the couplings in nuclear forces determine also electroweak processes . this provides an important consistency test and an exciting opportunity for electron beams . a prime example in chiral eft are axi

We present chiral eft at the momentum scales of the order of the pion mass, where nucleons are included as explicit degrees of freedom and build up the long - range parts of strong interactions. This allows one to estimate theoretical uncertainties and chiraleft connects nuclear forces to the underlying theory through lattice qcd.

electron beams provide important probes and constraints for nuclear astrophysics . this is especially exciting at energies within the regime of chiral effective field theory ( eft ) , which provides a systematic expansion for nuclear forces and electroweak operators based on quantum chromodynamics . this talk discusses some recent highlights and future directions based on chiral eft , including nuclear structure and reactions for astrophysics , the neutron skin and constraints for the properties


This paper is focused on the structure of the kauffman bracket skein algebra of a punctured surface...

in this paper we study the structure of the kauffman bracket skein algebra of an oriented punctured surface at a -th root of unity where is odd . these algebras play a crucial role in constructions of quantum invariants of -manifolds and in investigating quantum hyperbolic geometry . given an orientable surface its kauffman bracket skein algebra is formed by taking linear combinations of framed links in a cylinder over the surface , , with complex coefficients , and modding out by the relations that define the kauffman bracket link invariant . the multiplication comes from stacking one link above the other , with the up and down direction given by the interval . the kauffman bracket skein relation involves a complex parameter . we assume that is a -th root of unity for odd , and use the notation to indicate the level . it was shown by bullock , and przytycki - sikora that when , so that , this algebra is isomorphic to the character ring of the representations of the fundamental group of the surface . bonahon and wong constructed an embedding of into the center of via the so - called threading map , showing that the algebra is a central extension of the -characters of . abdiel and frohman proved that this is a finite extension . they localized the algebra over the non - zero characters of and showed that the localized algebra is finite dimensional over the function field of the -character variety of . in this paper we work with surfaces of negative euler characteristic that have at least one puncture . the kauffman bracket skein algebra has no zero divisors , and is finite rank over its center . the center of is the coordinate ring of an algebraic variety that is a finite sheeted branched cover of the character variety of the surface . in algebraic geometry , localization corresponds to restricting to an open subset of the underlying space . the localizations in this paper come from restricting to zariski open subsets of the variety related to the center of . we defi

We study the structure of the kauffman bracket skein algebra of an oriented punctured surface at a -th root of unity where is odd. This algebra is formed by taking linear combinations of framed links in a cylindrical over the surface, with complex coefficients, and modding out by the relations that define the Kauffman bracket link invariant. We assume that is a root of Einheit for odd,, using the notation to indicate the level. It was shown by bonahon and wong that when,.

this paper is focused on the structure of the kauffman bracket skein algebra of a punctured surface at roots of unity . a criterion that determines when a collection of skeins forms a basis of the skein algebra as an extension over the characters of the fundamental group of the surface , with appropriate localization is given . this is used to prove that when the algebra is localized so that every nonzero element of the center has a multiplicative inverse , that it is a division algebra . finall


We analyze zero modes of the dirac operator for su(2 ) lattice gauge theory

in the last few years the study of dirac eigenmodes was established as a powerful method for analyzing infrared structures of lattice gauge field configurations . after early work ( e.g. ) , the idea of probing the qcd vacuum with dirac eigenmodes picked up steam with the discussion of the local chirality of near - zero modes . in evidence was given , that the infrared structures which couple to the low lying dirac eigenmodes are self - dual , and in it was argued , that these structures could be low - dimensional objects . a new technique , the probing of the qcd vacuum with eigenmodes that are computed for different boundary conditions of the dirac operator , was introduced for the study of so - called kraan van baal ( kvb ) solutions . kvb solutions are solutions of the classical yang - mills equations on a euclidean cylinder . a kvb solution of topological charge can be seen to consist of constituents ( for su( ) ) , which locally resemble monopoles . for higher charges one finds constituents . the connection to the dirac eigenmodes was given in , where the zero mode for a charge 1 kvb solution was calculated . this eigenvalue problem was solved for a general boundary condition in the compactified ( time- ) direction , where is the extent of the compact direction of the euclidean cylinder . the boundary phase has values between 0 and 1 ( we stress that in all of our discussion the gauge fields obey periodic boundary conditions ) . it was shown , that the zero mode is not distributed over all of the constituents simultaneously , but instead is localized on only one of them . which of the constituents is chosen depends on the phase , relative to the phases determining the polyakov loop at spatial infinity . thus if one varies , the zero mode will become located on each of the constituents , one after the other . this property of the zero mode was confirmed in lattice studies and strong evidence for the appearance of kvb solutions in thermalized lattice gauge confi

We present a new method for probing the qcd vacuum with dirac eigenmodes that are computed for different boundary conditions of the dirac operator. This technique is used to study so - called kraan van baal ( kvb ) solutions. The zero mode is not distributed over all of the constituents simultaneously, but instead is localized on only one of them. In this paper, we show that the zero modes are not distributed on all of their constituents, and they are locally located on only a single constituent.

we analyze zero modes of the dirac operator for su(2 ) lattice gauge theory . we find that the zero modes are strongly localized in all 4 directions . the position of these lumps depends on the boundary conditions we use for the dirac operator . we compare periodic boundary conditions and anti - periodic boundary conditions and find that the position of the zero modes jumps for about one third of the configurations .


In this work we present an approach which can be systematically used to construct nonlinear systems...

the study of nonlinear systems is growing since the sixties of the last century . nowadays the nonlinearity is found in many areas of the physics , including condensed matter physics , field theory , cosmology and others - . particularly , whenever we have a potential with two or more degenerate minima , one can find different vacua at different portions of the space . thus , one can find domain walls connecting such regions , and this necessarily leads to the appearance of multi - kink configurations . some time ago , a. champney and collaborators made an analysis of the reasons for the appearance of multi - kinks in dispersive nonlinear systems . in part this was motivated by the discovery by peyrard and kruskal that a single kink becomes unstable when it moves in a discrete lattice at sufficiently large velocity , whereas multi - kinks are stable . the effect was shown to be associated with a resonant interaction between the kink and the radiation , and the resonances were already observed experimentally . in fact , in an earlier work by manton and merabet , it was discussed the mechanism of production of kinks from excitations of the internal mode , in a study of the dynamics of the interaction of two kinks and one anti - kink in a model . furthermore , in a recent work by m. a. garcia - ustes and j. a. gonzlez , it is shown that a pair of kinklike solitons is emitted during the process of kink breakup by internal mode instabilities in a sine - gordon model . the multi - kinks are responsible , for instance , for a mobility hysteresis in a damped driven commensurable chain of atoms . moreover in arrays of josephson junctions , instabilities of fast kinks generate bunched fluxon states presenting multi - kink profiles . in a different context , by working with space - time dependent field configurations , coleman and collaborators analyzed the fate of the false vacuum through a semiclassical analysis of an asymmetric -like model . there , they considered the deca

We study the dynamics of a single kink in a dispersive nonlinear system with two or more degenerate minima. The effect is found to be associated with a resonant interaction between the kinkte and the radiation, and the resonances are already observed experimentally.

in this work we present an approach which can be systematically used to construct nonlinear systems possessing analytical multi - kink profile configurations . in contrast with previous approaches to the problem , we are able to do it by using field potentials which are considerably smoother than the ones of doubly quadratic family of potentials . this is done without losing the capacity of writing exact analytical solutions . the resulting field configurations can be applied to the study of pro