id large_stringlengths 9 16 | title large_stringlengths 1 382 | abstract large_stringlengths 3 6.09k | publish_date date32 | update_date date32 | categories large listlengths 1 13 | authors large_stringlengths 3 62.8k |
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alg-geom/9210001 | Arrangements of Hyperplanes and Vector Bundles on $P^n$ | Any arrangement of hyperplanes in general position in $P^n$ can be regarded
as a divisor with normal crossing. We study the bundles of logarithmic 1-forms
corresponding to such divisors` from the point of view of classification of
vector bundles on $P^n$. It turns out that all such bundles are stable. The
study of jump... | 1992-10-06 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | I.Dolgachev and M.Kapranov |
alg-geom/9209001 | On the $(-1)$-curve conjecture of Friedman and Morgan | Main difference with previous version: we prove that every differentiably
embedded sphere with self intersection $-1$ in a simply connected algebraic
surface with $p_g >0$ is homologous to a $(-1)$-curve if $|K_{\min}|$ contains
a smooth irreducible curve of genus at least 2 and $p_g$ is even or $K_{\min}^2
\not\equiv ... | 1992-09-12 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Rogier Brussee |
alg-geom/9208004 | Torsion Sections of Semistable Elliptic Surfaces | Let S be a torsion section of an elliptic surface with only I_n fibers. This
article addresses the question: which components of singular fibers can S pass
through? We give necessary criteria for the "component numbers", and show an
equidistribution result for torsion sections of prime order. | 1992-08-21 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Rick Miranda |
alg-geom/9208003 | Weierstrass weight of Gorenstein singularities with one or two branches | Let $X$ denote an integral, projective Gorenstein curve over an algebraically
closed field $k$. In the case when $k$ is of characteristic zero, C. Widland
and the second author have defined Weierstrass points of a line bundle on $X$.
In the first section, this definition is extended to linear systems in
arbitrary chara... | 1992-08-20 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | A. Garcia and R.F. Lax |
alg-geom/9208002 | Abelian varieties over Q and modular forms | This paper gives a conjectural characterization of those elliptic curves over
the field of complex numbers which "should" be covered by standard modular
curves. The elliptic curves in question all have algebraic j-invariant, so they
can be viewed as curves over Q-bar, the field of algebraic numbers. The
condition that ... | 1992-08-06 | 2015-06-30 | [
"alg-geom",
"math.AG"
] | Kenneth A. Ribet |
alg-geom/9208001 | Open String Diagrams I: Topological Type | An arbitrary Feynman graph for string field theory interactions is analysed
and the homeomorphism type of the corresponding world sheet surface is
completely determined even in the non-orientable cases. Algorithms are found to
mechanically compute the topological characteristics of the resulting surface
from the struct... | 1992-08-03 | 2009-10-22 | [
"alg-geom",
"hep-th",
"math.AG"
] | Subhashis Nag and Parameswaran Sankaran (The Institute of Mathematical
Sciences C.I.T.Campus Madras) |
alg-geom/9207001 | Completions of mapping class groups and the cycle $C - C^-$ | In this paper we study the proalgebraic completion of mapping class relative
to their maps to the symplectic group. The main result is that the natural map
from the unipotent (a.k.a. Malcev) completion of the Torelli group to the
prounipotent radical of the Sp_g completion of the mapping class group is a non
trivial ce... | 1992-07-23 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Richard Hain (Duke Univeristy) |
alg-geom/9206009 | The complex separation and extensions of Rokhlin congruence for curves
on surfaces | The subject of this paper is the problem of arrangement of real algebraic
curves on real algebraic surfaces. In this paper we extend Rokhlin,
Kharlamov-Gudkov-Krakhnov and Kharlamov-Marin congruences for curves on
surfaces and give some applications of this extension.
For some pairs consisting of a surface and a curv... | 1992-06-24 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | G.Mikhalkin |
alg-geom/9206008 | The fibers of the Prym map | In this work we use the bigonal, trigonal and tetragonal constructions to
describe the fibers of the Prym map P : R_{g} ---->A_{g-1} inthe cases when it
is dominant, i.e. for g < 7. The most interesting cases are g = 5, where the
fiber is a double cover of the Fano surface of lines on a cubic threefold, and
g=6, where ... | 1992-06-17 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Ron Donagi |
alg-geom/9206007 | Rang de courbes elliptiques d'invariant donne | We prove that there exist infinitely many elliptic curves over \Q with given
modular invariant, and rank >=2. Furthermore, there exist infinitely many
elliptic curves over $\Q$ with invariant equal at 0 (resp. 1728) and rank >=6
(resp. >=4). | 1992-06-16 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Jean-Francois Mestre |
alg-geom/9206006 | Corps quadratiques dont le 5-rang du groupe des classes est >=3 | We prove the existence of infinitely many real and imaginary fields whose
5-rank of the class group is >=3. | 1992-06-16 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Jean-Francois Mestre |
alg-geom/9206005 | Two Two-dimensional Terminations | Varieties with log terminal and log canonical singularities are considered in
the Minimal Model Program, see \cite{...} for introduction. In
\cite{shokurov:hyp} it was conjectured that many of the interesting sets,
associated with these varieties have something in common: they satisfy the
ascending chain condition, whi... | 1992-06-12 | 2015-06-30 | [
"alg-geom",
"math.AG"
] | Valery Alexeev |
alg-geom/9206004 | Extremal Rays and Null Geodesics on a Complex Conformal Manifold | This is a revised version of the paper submitted before. | 1992-06-11 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Yun-Gang Ye |
alg-geom/9206003 | Affine like Surfaces | We classify smooth surfaces whose higher cohomologies of i-forms for all i
vanish. We show that if such a surface is not affine, then it has essentially
two possibilities. | 1992-06-04 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | N. Mohan Kumar |
alg-geom/9206002 | String Branchings on Complex Tori and Algebraic Representations of
Generalized Krichever-Novikov Algebras | The propagation differential for bosonic strings on a complex torus with
three symmetric punctures is investigated. We study deformation aspects between
two point and three point differentials as well as the behaviour of the
corresponding Krichever-Novikov algebras. The structure constants are
calculated and from this ... | 1992-06-03 | 2009-10-22 | [
"alg-geom",
"math.AG"
] | Andreas Ruffing, Thomas Deck, Martin Schlichenmaier |
alg-geom/9206001 | Linear orbits of smooth plane curves | The group PGL(3) of linear transformations of the projective plane acts
naturally on the projective space parametrizing curves of a given degree. In
this note we begin the study of the orbits of smooth curves under this action:
we construct a resolution of the closure of the orbit of a given curve, and we
use it to com... | 1992-06-02 | 2012-04-10 | [
"alg-geom",
"math.AG"
] | Paolo Aluffi, Carel Faber |
alg-geom/9205007 | On the Tangent Space to the Universal Teichmuller Space | We find a remarkably simple relationship between the following two models of
the tangent space to the Universal Teichm\"uller Space: (1) The real-analytic
model consisting of Zygmund class vector fields on the unit circle; (2) The
complex-analytic model comprising 1-parameter families of schlicht functions on
the exter... | 1992-05-22 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Subhashis Nag |
alg-geom/9205006 | Upper Bounds for the Betti Numbers of a given Hilbert Function | From a Macaulay's paper it follows that a lex-segment ideal has the greatest
number of generators (the 0-th Betti number $\b_0$) among all the homogeneous
ideals with the same Hilbert function. In this paper we prove that this fact
extends to every Betti number, in the sense that all the Betti numbers of a
minimal free... | 1992-05-19 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Anna Maria Bigatti |
alg-geom/9205005 | Linear orbits of d-tuples of points in P^1 | The group PGL(2) of linear transformations of the projective line acts
naturally on the d-dimensional projective space P^d parametrizing
configurations (`d-tuples') of points on the line. In this note we are
concerned with the orbits of this action of PGL(2) on P^d. The closure of each
orbit is a projective subvariety ... | 1992-05-12 | 2012-04-10 | [
"alg-geom",
"math.AG"
] | Paolo Aluffi, Carel Faber |
alg-geom/9205004 | Notes on Kodaira energies of polarized varieties | The Kodaira energy of a polarized manifold (M,L) is defined by
\kappa\epsilon(M,L)=-Inf{t\in Q|\kappa(K+tL)\ge 0}. Here we propose a couple of
conjectures and announce several partial results. 3-dimensional cases are
mainly considered. A hard copy is available on request to the author. | 1992-05-08 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Takao Fujita |
alg-geom/9205003 | Chern classes and degenerations of hypersurfaces and their lines | We study limiting lines on degenerations of generic hypersurfaces in $P^n$. | 1992-05-07 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Xian Wu |
alg-geom/9205002 | Cohomology, Symmetry, and Perfection | One of the aims of this paper is to better explain the philosophy behind the
computations in [E.Bifet, C.De Concini,C.Procesi Cohomology of Regular
Embeddings ] and to place them in a wider conceptual setting. Another aim of
the paper is to outline in the last section an ``equivariant'' approach to some
key results in ... | 1992-05-04 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Emili Bifet |
alg-geom/9205001 | Report on the Torsion of the Differential Module of an algebraic Curve | There is a conjecture, that the torsionfreeness of the module of
differentials in a point of an algebraic or algebroid curve should imply that
the curve is non singular at that point. A report on the main results is given. | 1992-05-03 | 2008-02-03 | [
"alg-geom",
"math.AC",
"math.AG"
] | Robert W. Berger |
alg-geom/9204001 | Weierstrass Gap Sequence at Total Inflection Points of Nodal Plane
Curves | Let $\Gamma$ be a plane curve of degree $d$ with $\delta$ ordinary nodes and
no other singularities. If $P$ is a smooth point on $\Gamma$ then the
Weierstrass gap sequence at $P$ is considered as that at the corresponding
point on the normalization of $\Gamma$. A smooth point $P\in\Gamma$ is called a
total inflection p... | 1992-04-02 | 2015-06-30 | [
"alg-geom",
"math.AG"
] | Marc Coppens and Takao Kato |
alg-geom/9203005 | Homotopy groups of the complements to singular hypersurfaces,II | The homotopy group $\pi_{n-k} ({\bf C}^{n+1}-V)$ where $V$ is a hypersurface
with a singular locus of dimension $k$ and good behavior at infinity is
described using generic pencils. This is analogous to the van Kampen procedure
for finding a fundamental group of a plane curve. In addition we use a certain
representatio... | 1992-03-24 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | A.Libgober |
alg-geom/9203002 | Prym Varieties and Integrable Systems | A new relation between Prym varieties of arbitrary morphisms of algebraic
curves and integrable systems is discovered. The action of maximal commutative
subalgebras of the formal loop algebra of GL(n) defined on certain
infinite-dimensional Grassmannians is studied. It is proved that every
finite-dimensional orbit of t... | 1992-03-20 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Yingchen Li and Motohico Mulase |
alg-geom/9203004 | On the Abel-Jacobi Map for Divisors of Higher Rank on a Curve | The aim of this paper is to present an algebro-geometric approach to the
study of the geometry of the moduli space of stable bundles on a smooth
projective curve defined over an algebraically closed field $k$, of arbitrary
characteristic. This establishes a bridge between the arithmetic approach of
Harder, Narasimhan e... | 1992-03-19 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Emili Bifet, Franco Ghione and Maurizio Letizia |
alg-geom/9203003 | Computing the Cohomological Brauer Group of a Toric Variety | The purpose of this article is to show how one might compute the \'etale
cohomology groups $H^p_{\acute{e}t}(X,G_m)$ in degrees $p=0$, $1$ and $2$ of a
toric variety $X$ with coefficients in the sheaf of units. The method is to
reduce the computation down to the problem of diagonalizing a matrix with
integral coefficie... | 1992-03-18 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Timothy J. Ford |
alg-geom/9203001 | Exceptional linear systems on curves on Enriques surfaces | The main purpose in this paper is to study the gonality, the Clifford index
and the Clifford dimension on linearly equivalent smooth curves on Enriques
surfaces. The method is similar to techniques of M.Green $\&$ R.Lazarsfeld and
G.Pareschi. | 1992-03-05 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Severinas Zube |
alg-geom/9202028 | Complex Divisors on Algebraic Curves and Some Applications to String
Theory | These are notes of a talk to the International Conference on Algebra in honor
of A. I. Mal'tsev, Novosibirsk, USSR, 1989 (to appear in Contemporary
Mathematics). The concept of a divisor with complex coefficients on an
algebraic curve is introduced. We consider families of complex divisors, or,
equivalently, families o... | 1992-02-27 | 2008-02-03 | [
"alg-geom",
"hep-th",
"math.AG"
] | A. A. Voronov |
alg-geom/9202027 | Cohomological and Cycle-theoretic connectivity | One of the themes in algebraic geometry is the study of the relation between
the ``topology'' of a smooth projective variety and a (``general'') hyperplane
section. Recent results of Nori produce cohomological evidence for a conjecture
that a general hypersurface of sufficently large degree should have no
``interesting... | 1992-02-26 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Kapil H. Paranjape |
alg-geom/9202026 | Picard-Fuchs equations and mirror maps for hypersurfaces | We describe a strategy for computing Yukawa couplings and the mirror map,
based on the Picard-Fuchs equation. (Our strategy is a variant of the method
used by Candelas, de la Ossa, Green, and Parkes in the case of quintic
hypersurfaces.) We then explain a technique of Griffiths which can be used to
compute the Picard-F... | 1992-02-26 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | David R. Morrison |
alg-geom/9202024 | Sur la cohomologie de certains espaces de modules de fibr\'es vectoriels | Let M be a moduli space of stable vector bundles on a curve with rank and
degree fixed and coprime. We give a simple proof that the rational cohomology
of M is generated by the Kunneth components of the Chern classes of the
universal bundle. The proof applies also to some moduli spaces of vector
bundles over higher-dim... | 1992-02-21 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | A. Beauville |
alg-geom/9202025 | The Singularities of the parameter surface of a minimal elliptic
threefold | Let f : X -> S be any elliptic fibration. If X has dimension 3 and is not
uniruled, then X has a minimal model (with terminal singularities) [Mori]. In
earlier work we have shown that there exists a birationally equivalent elliptic
fibration p: Y -> T such that Y is minimal and a multiple of K_Y can be
expressed as the... | 1992-02-21 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | A. Grassi |
alg-geom/9202021 | Grobner bases and extension of scalars | This paper studies the behavior of Grobner bases with respect to extensions
of scalars. We prove that an extension of scalars commutes with taking Grobner
bases iff the extension is flat. We consider what information can be deduced
about fibers of a family, from the Grobner basis of the defining ideal of the
family its... | 1992-02-20 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Dave Bayer, Andre Galligo, Mike Stillman |
alg-geom/9202022 | Classical Polylogarithms | This paper is an introduction to classical polylogarithms and is an expanded
version of a talk given by the author at the Motives conference. Topics covered
include, monodromy; the polylogarithm local systems; Bloch's constructions of
regulators using the dilogarithm; polylog locals systems as variations of mixed
Hodge... | 1992-02-20 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Richard Hain |
alg-geom/9202020 | Disproving Hibi's Conjecture with CoCoA or Projective Curves with bad
Hilbert Functions | In this paper we show how to combine different techniques from Commutative
Algebra and a systematic use of a Computer Algebra System (in our case mainly
CoCoA) in order to explicitly construct Cohen-Macaulay domains, which are
standard $k$-algebras and whose Hilbert function is ``bad". In particular we
disprove a well-... | 1992-02-20 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | G. Niesi, L. Robbiano |
alg-geom/9202023 | Regulators and characteristic classes of flat bundles | This is a substantial revision of the older version of this paper. The main
result of the old version (the equality, up to a factor of 2 of the Beilinson
and Borel regulators) is now a conjecture. The main results give equality of
Beilinson chern classes and Cheeger-Simons-Chern classes in various situations
such as fo... | 1992-02-20 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Johan Dupont, Richard Hain and Steven Zucker |
alg-geom/9202018 | Arithmetically Cohen-Macaulay Curves cut out by Quadrics | Addressing a question of M. Stillman, it had been shown by Ein, Eisenbud, and
the author that in a projective space of dimension at most 5, every
arithmetically Cohen-Macaulay curve which is cut out by quadrics scheme-
theoretically also has its homogeneous ideal generated by quadrics. In this
note it is shown that thi... | 1992-02-19 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Sheldon Katz |
alg-geom/9202019 | The cohomological Brauer group of a toric variety | Toric varieties are a special class of rational varieties defined by
equations of the form {\it monomial = monomial}. For a good brief survey of the
history and role of toric varieties see [10]. Any toric variety $X$ contains a
cover by affine open sets described in terms of arrangements (called fans) of
convex bodies ... | 1992-02-19 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Frank DeMeyer, Tim Ford, and Rick Miranda |
alg-geom/9202016 | Congruences for real algebraic curves on an ellipsoid | The problem of arrangement of a real algebraic curve on a real algebraic
surface is related to the 16th Hilbert problem. We prove in this paper new
restrictions on arrangement of nonsingular real algebraic curves on an
ellipsoid. These restrictions are analogues of Gudkov-Rokhlin,
Gudkov-Krakhnov-Kharlamov, Kharlamov-M... | 1992-02-18 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | G.Mikhalkin |
alg-geom/9202017 | Extensions of Rokhlin congruence for curves on surfaces | The subject of this paper is the problem of arrangement of a real nonsingular
algebraic curve on a real non-singular algebraic surface. This paper contains
new restrictions on this arrangement extending Rokhlin and
Kharlamov-Gudkov-Krakhnov congruences for curves on surfaces. | 1992-02-18 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | G.Mikhalkin |
alg-geom/9202015 | Note on curves in a Jacobian | For a curve C, viewed as a cycle in its Jacobian, we study its image n_*C
under multiplication by n on JC. We prove that the subgroup generated by these
cycles, in the Chow group modulo algebraic equivalence, has rank at most d-1,
where d is the gonality of C. We also discuss some general facts on the action
of n_* on ... | 1992-02-17 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Elisabetta Colombo and Bert van Geemen |
alg-geom/9202014 | Degenerations of generalized KNN algebras on tori | Degenerations of Lie algebras of meromorphic vector fields on elliptic curves
(i.e. complex tori) which are holomorphic outside a certain set of points
(markings) are studied. By an algebraic geometric degeneration process certain
subalgebras of Lie algebras of meromorphic vector fields on P^1 the Riemann
sphere are ob... | 1992-02-17 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Martin Schlichenmaier |
alg-geom/9202013 | Deformations of Semi-Euler Characteristics | (Generalizes theorem of Atiyah and Mumford.) | 1992-02-14 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | George R. Kempf |
alg-geom/9202012 | Cohomology of coherent sheaves on a proper scheme | (Makes a Gamma-acylic coherent resolution of a coherent sheaf on a projection
scheme.) | 1992-02-14 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | George R. Kempf |
alg-geom/9202011 | The Geometry and Arithmetic of Elliptic Surfaces | We survey some aspects of the theory of elliptic surfaces and give some
results aimed at determining the Picard number of such a surface. For the
surfaces considered, this will be equivalent to determining the Mordell-Weil
rank of an elliptic curve defined over a function field in one variable. An
interesting conjectur... | 1992-02-14 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Peter F. Stiller |
alg-geom/9202010 | Another Relation Between Approaches to the Schottky Problem | The recent extensive work on different approaches to the Schottky problem has
produced marked progress on several fronts. At the same time, it has become
apparent that there exist very close connections between the various
characterizations of Jacobian varieties described in Mumford's classic lectures
{\it Curves and T... | 1992-02-13 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | John B. Little |
alg-geom/9202009 | On a Grauert-Riemenschneider vanishing theorem for Frobenius split
varieties in characteristic p | This paper is about sheaf cohomology for varieties (schemes) in
characteristic $p>0$. We assume the presence of a Frobenius splitting. (See
V.B. Mehta and A. Ramanathan, Frobenius splitting and cohomology vanishing for
Schubert varieties, Annals of Math. 122 (1985), 27--40). The main result is
that a non-zero higher di... | 1992-02-13 | 2009-10-22 | [
"alg-geom",
"math.AG"
] | V. B. Mehta and Wilberd van der Kallen |
alg-geom/9202007 | The algebraic de Rham theorem for toric varieties | On an arbitrary toric variety, we introduce the logarithmic double complex,
which is essentially the same as the algebraic de Rham complex in the
nonsingular case, but which behaves much better in the singular case. Over the
field of complex numbers, we prove the toric analog of the algebraic de Rham
theorem which Grot... | 1992-02-12 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Tadao Oda |
alg-geom/9202008 | On irregular links at infinity of algebraic plane curves | We give two proofs of a conjecture of the first author (Inv. Math. 98, 1989)
that a reduced algebraic plane curve is regular at infinity if and only if its
link at infinity is a regular toral link. This conjecture has also been proved
by Ha H.~V. using Lojasiewicz numbers at infinity. Our first proof uses the
polar inv... | 1992-02-12 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Walter D. Neumann and Le Van Thanh |
alg-geom/9202005 | On the difference between real and complex arrangements | Let $B$ be an arrangement of linear complex hyperplanes in $C^d$. Then a
classical result by Orlik \& Solomon asserts that the cohomology algebra of the
complement can be constructed from the combinatorial data that are given by the
intersection lattice.
If $B'$ is, more generally, a $2$-arrangement in $R^{2d}$ (an a... | 1992-02-11 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | G\"unter M. Ziegler |
alg-geom/9202006 | Twistors, Kaehler Manifolds, and Bimeromorphic Geometry II | Using examples of compact complex 3-manifolds which arise as twistor spaces,
we show that the class of compact complex manifolds bimeromorphic to K\"ahler
manifolds is not stable under small deformations of complex structure. | 1992-02-11 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Claude LeBrun and Yat-Sun Poon |
alg-geom/9202004 | Mirror symmetry and rational curves on quintic threefolds: a guide for
mathematicians | We give a mathematical account of a recent string theory calculation which
predicts the number of rational curves on the generic quintic threefold. Our
account involves the interpretation of Yukawa couplings in terms of variations
of Hodge structure, a new $q$-expansion principle for functions on the moduli
space of Ca... | 1992-02-10 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | David R. Morrison |
alg-geom/9202003 | Complex Contact Threefolds and Their Contact Curves | A complex contact threefold is a threefold with a two-dimensional
non-integrable holomorphic distribution. A contact curve on a contact threefold
is an integrable curve of the distribution. This work was inspired by two
papers of Bryant, in which he used complex contact geometry to study
superminimal surfaces in four-s... | 1992-02-07 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Yun-Gang Ye |
alg-geom/9202001 | Rational Curves on Calabi-Yau Threefolds | The point is to compare the mathematical meaning of the ``number of rational
curves on a Calabi-Yau threefold'' to the meaning ascribed to the same notion
by string theorists. | 1992-02-05 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Sheldon Katz |
alg-geom/9202002 | Gorenstein Threefold Singularities with Small Resolutions via Invariant
Theory for Weyl Groups | We classify simple flops on smooth threefolds, or equivalently, Gorenstein
threefold singularities with irreducible small resolution. There are only six
families of such singularities, distinguished by Koll{\'a}r's {\em length}
invariant. The method is to apply invariant theory to Pinkham's construction of
small resolu... | 1992-02-05 | 2008-02-03 | [
"alg-geom",
"math.AG"
] | Sheldon Katz and David R. Morrison |
astro-ph/9212006 | Two Populations and Models of Gamma Ray Bursts | Gamma-ray burst statistics are best explained by a source population at
cosmological distances, while spectroscopy and intensity histories of some
individual bursts imply an origin on Galactic neutron stars. To resolve this
inconsistency I suggest the presence of two populations, one at cosmological
distances and the o... | 1992-12-31 | 2015-06-24 | [
"astro-ph"
] | J. I. Katz |
astro-ph/9212005 | The Escape of Gravitational Radiation from the Field of Massive Bodies | We consider a compact source of gravitational waves of frequency $\omega$, in
or near a massive spherically symmetric distribution of matter or a black hole.
Recent calculations have led to apparently contradictory results for the
influence of the massive body on the propagation of the waves. We show here
that the resu... | 1992-12-23 | 2010-11-30 | [
"astro-ph",
"gr-qc"
] | Richard H. Price, Jorge Pullin and Prasun Kundu |
astro-ph/9212004 | Recent advances in extended inflationary cosmology | Extended inflation is a promising new approach to implementing the
inflationary universe scenario. This paper reviews recent advances including a
new, more robust mechanism for ending extended inflation, a new prediction for
the density fluctuation spectrum generated by extended inflation, and the
discovery that extend... | 1992-12-16 | 2010-04-06 | [
"astro-ph"
] | Paul J. Steinhardt |
astro-ph/9212003 | Gravity's rainbow | Could COBE DMR be detecting the imprint from a spectrum of gravitational
waves generated during inflation? The conventional inflationary prediction had
been that the cosmic microwave anisotropy is dominated by energy density
fluctuations generated during inflation and that the gravitational waves
contribute negligibly.... | 1992-12-16 | 2009-09-15 | [
"astro-ph"
] | George F. Smoot and Paul J. Steinhardt |
astro-ph/9212002 | Structure in a Loitering Universe | We study the formation of structure for a universe that undergoes a recent
loitering phase. We compare the nonlinear mass distribution to that in a
standard, matter dominated cosmology. The statistical aspects of the clustered
matter are found to be robust to changes in the expansion law, an exception
being that the pe... | 1992-12-10 | 2009-10-22 | [
"astro-ph",
"hep-ph"
] | Hume A. Feldman and August E. Evrard |
astro-ph/9212001 | A rotating black hole in the Galactic Center | Recent observations of Sgr A* give strong constraints for possible models of
the physical nature of Sgr A* and suggest the presence of a massive black~hole
with M<2 10^6 M_sun surrounded by an accretion disk which we estimate to
radiate at a luminosity of <7 10^5 L_sun. We therefore calculate the appearance
of a standa... | 1992-12-07 | 2011-05-23 | [
"astro-ph"
] | Heino Falcke, Peter L. Biermann, Wolfgang J. Duschl and Peter G.
Mezger |
astro-ph/9211014 | On the General Properties of Matter | By means of a general classification of the different kinds of matter of
nature form a chain from the world of the subatomic particles to the large
bodies of the universe, the galaxies. Then, it proposes a new baryonic force
for the universe that is the fifth force which has been proposed in the
literature. It explains... | 1992-11-30 | 2007-05-23 | [
"astro-ph"
] | Mario Everaldo de Souza (Departamento de Fisica, Universidade Federal
de Sergipe, Aracaju, Brazil) |
astro-ph/9211013 | Particle Astrophysics after COBE: Blois92 Summary Talk | The IV Rencontres de Blois, on Particle Astrophysics, held at the Ch\^ateau
de Blois, June 15-20, 1992, was a meeting well-timed for a reconsideration of
the issues in particle astrophysics in the light of the COBE discovery of the
cosmic microwave background (CMB) fluctuations. This is a summary of what I
thought were... | 1992-11-20 | 2007-05-23 | [
"astro-ph",
"hep-ph"
] | Joel R. Primack |
astro-ph/9211010 | Gamma-Ray Bursts and Neutron Star Mergers - Possibly the Strongest
Explosions in the Universe | $\gamma$-ray bursts have baffled theorists ever since their accidental
discovery at the sixties. We suggest that these bursts originate in merger of
neutron star binaries, taking place at cosmological distances. These mergers
release $\approx 10^{54}ergs$, in what are possibly the strongest explosions in
the Universe. ... | 1992-11-17 | 2009-10-22 | [
"astro-ph"
] | Tsvi Piran |
astro-ph/9211011 | A Possible Solution to the Horizon Problem: The Mad Era for Massless
Scalar Theories of Gravity | Extensions of Einstein gravity which allow the gravitational constant $G$ to
change with time as the universe evolves may provide a resolution to the
horizon problem without invoking a period of vacuum domination and without the
subsequent entropy violation. In a cosmology for which the gravitational
constant is not in... | 1992-11-17 | 2009-10-22 | [
"astro-ph",
"gr-qc",
"hep-ph"
] | Janna J Levin and Katherine Freese |
astro-ph/9211012 | On the rotation of polarization by a gravitational lens | It is proved that the field of a gravitational lens induces no rotation in
the polarization vector of electromagnetic radiation, in agreement with the
previous literature, but with a different approach. The result is generalized
to the case of less conventional gravitational lenses (static cosmic strings
and gravitatio... | 1992-11-17 | 2007-05-23 | [
"astro-ph"
] | Valerio Faraoni |
astro-ph/9211009 | Fireballs in the Galactic Halo and $\gamma$-Ray Bursts | If gamma ray burst sources are in the galactic halo they inevitably involve a
creation of an opaque pair plasma fireball, just like in cosmological sources.
We find that the typical physical conditions in a galactic halo fireball are:
optical depth $\ap 10^8$, thermal energy $\ap 100 KeV$, maximal relativstic
expansion... | 1992-11-13 | 2009-10-22 | [
"astro-ph"
] | Tsvi Piran and Amotz Shemi |
astro-ph/9211008 | The Mad Era: A Possible New Resolution to the Horizon, Flatness, and
Monopole Problems | A cosmology with a dynamical Planck mass $m_{pl}$ is shown to solve the
horizon and monopole problems (and possibly flatness) if there is an early MAD
(modified aging) era where the universe becomes older than in the standard
model as a result of a large $m_{pl}$: the causality condition is $m_{pl}(T_c)/
m_{pl}(T_o) \g... | 1992-11-10 | 2007-05-23 | [
"astro-ph",
"gr-qc",
"hep-ph"
] | Katherine Freese and Janna J Levin |
astro-ph/9211007 | Generalized Einstein Theory on Solar and Galactic Scales | We study a generalized Einstein theory with the following two criteria:{\it
i}) on the solar scale, it must be consistent with the classical tests of
general relativity, {\it ii}) on the galactic scale, the gravitational
potential is a sum of Newtonian and Yukawa potentials so that it may explain
the flat rotation curv... | 1992-11-09 | 2010-11-01 | [
"astro-ph",
"gr-qc"
] | Masakatsu Kenmoku, Yuko Okamoto and Kazuyasu Shigemoto |
astro-ph/9211006 | The ($\log R_e$, $\mu_e$) Plane of Hot Stellar Systems | Two families of hot stellar systems, named {\it `ordinary'\/} and {\it
'bright'\/}, are identified in the ($\log R_e, \mu_e$) plane built with a
luminosity--limited sample of ellipticals and bulges of S0s and spirals of the
Virgo and Fornax clusters. This finding, based on {\it ad hoc\/} new
observations, is confirmed ... | 1992-11-09 | 2007-05-23 | [
"astro-ph"
] | Massimo Capaccioli, Nicola Caon and Mauro D'Onofrio |
astro-ph/9211005 | Centri`fugal' Force around a Black Hole | Besides having some very interesting perturbatively unstable orbits, it seems
that for a Schwarzschild black hole, below $r=3M$, the force always increases
inward with increasing angular momentum. Here this previously known result is
derived with greater simplicity, and a similar analysis is performed for black
holes w... | 1992-11-08 | 2008-02-03 | [
"astro-ph"
] | A.Y.Shiekh |
astro-ph/9211004 | Gravitational Radiation from Colliding Vacuum Bubbles: Envelope
Approximation to Many-Bubble Collisions | We introduce an approximation to calculate the gravitational radiation
produced by the collision of true-vacuum bubbles that is simple enough to allow
the simulation of a phase transition by the collision of hundreds of bubbles.
This ``envelope approximation'' neglects the complicated ``overlap'' regions of
colliding b... | 1992-11-07 | 2008-11-26 | [
"astro-ph",
"hep-ph"
] | Arthur Kosowsky and Michael S. Turner |
astro-ph/9211003 | Evolution of Elliptical Galaxies: The Multiphase Model | We present a multiphase model for the evolution of elliptical galaxies.
Diffuse gas, molecular clouds, stars and remnants are taken into account.
Cloud--cloud collisions and stimulated processes are the main causes of star
formation. The occurrence of winds driven by Supernovae is considered, and the
evolution of the s... | 1992-11-07 | 2009-10-22 | [
"astro-ph"
] | Federico Ferrini, Bianca Maria Poggianti |
astro-ph/9211002 | Detection of brown dwarfs by the micro-lensing of unresolved stars | The presence of brown dwarfs in the dark galactic halo could be detected
through their gravitational lensing effect and experiments under way monitor
about one million stars to observe a few lensing events per year. We show that
if the photon flux from a galaxy is measured with a good precision, it is not
necessary to ... | 1992-11-04 | 2007-05-23 | [
"astro-ph"
] | Paul Baillon, Alain Bouquet, Yannick Giraud-H\'eraud and Jean Kaplan |
astro-ph/9211001 | A Burst of Speculation | Self-consistent models of gamma-ray burst source regions at 100 Kpc distance
are possible if the radiating plasma is confined to very thin sheets, and I
estimate parameters. Energy sources might be elastic (by starquakes) or
magnetic (by reconnection), but mechanisms remain obscure. I discuss a very
speculative model i... | 1992-11-03 | 2015-06-24 | [
"astro-ph"
] | J. I. Katz |
astro-ph/9210007 | Effect of Neutrino Heating on Primordial Nucleosynthesis | We have modified the standard code for primordial nucleosynthesis to include
the effect of the slight heating of neutrinos by $e^\pm$ annihilations. There
is a small, systematic change in the $^4$He yield, $\Delta Y \simeq +1.5\times
10^{-4}$, which is insensitive to the value of the baryon-to-photon ratio
$\eta$ for $... | 1992-10-31 | 2009-10-22 | [
"astro-ph",
"hep-ph"
] | B. Fields, S. Dodelson, M.S. Turner (U. Chicago/Fermilab) |
astro-ph/9210006 | On the Origin of the Galactic Magnetic Field | The galactic magnetic field is commonly supposed to be due to a dynamo acting
on some large scale seed field. A major difficulty with this idea is that
estimates of reasonable seed field strengths tend to be quite low, on the order
of $\sim10^{-20}$ gauss. Here we examine the contribution due to the flux
entrained in w... | 1992-10-30 | 2007-05-23 | [
"astro-ph"
] | Ethan T. Vishniac |
astro-ph/9210004 | Dynamics of the Young Binary LMC Cluster NGC 1850 | In this paper we have examined the age and internal dynamics of the young
binary LMC cluster NGC 1850 using BV CCD images and echelle spectra of 52
supergiants. Isochrone fits to a BV color-magnitude diagram revealed that the
primary cluster has an age of $\tau = 90 \pm 30$ Myr while the secondary member
has $\tau = 6 ... | 1992-10-20 | 2009-10-22 | [
"astro-ph"
] | P. Fischer, D. L. Welch, and M. Mateo |
astro-ph/9210005 | Evidence for a Very Broad Line Region in PG 1138+222 | We present a high S/N spectrum for the quasar PG 1138+222. We detect a very
broad HeII$\lambda$4686 emission line component with twice the FWHM of the
conventional broad line region (BLR) as evidenced by the Balmer lines. The
profile shape and centroid redshift also distinguish this HeII component from
the BLR features... | 1992-10-20 | 2009-10-22 | [
"astro-ph"
] | Paolo Marziani and Jack W. Sulentic |
astro-ph/9210003 | Cosmic Rays, Gamma Rays and Neutrinos from Point Sources | The suggestion has been made that the energy spectrum from point sources such
as AGN (Active Galactic Nuclei) and GBHC (Galactic Black Hole Candidates) is
universal, irrespective of the nature of the emitted particles. A comparison of
the energy spectrum for cosmic rays at the source and $\gamma$-rays from
quasars obta... | 1992-10-19 | 2009-10-22 | [
"astro-ph"
] | Yukio Tomozawa |
astro-ph/9210002 | Coordinated UV-optical observations of quasars: the evolution of the
Lyman absorption | The average flux decrement shortward the Ly$_{\alpha}$ emission, due to the
well-known ``forest'' of absorptions, has been measured in the spectra of 8
quasars. Quasi-simultaneous optical and IUE observations of the two low
redshift quasars PKS 0637--75 (z=0.654) and MC 1104+16 (z=0.632) have been
carried out, obtainin... | 1992-10-14 | 2007-05-23 | [
"astro-ph"
] | S. Cristiani, E. Giallongo, L. M. Buson, C. Gouiffes, F. La Franca |
astro-ph/9210001 | The Edge of the Galactic Disc | As part of a stellar population sampling program, a series of photometric
probes at various field sizes and depths have been obtained in a low extinction
window in the galactic anticentre direction. Such data set strong constraints
on the radial structure of the disc. At the forefront of this "drilling"
program, very d... | 1992-10-02 | 2009-10-22 | [
"astro-ph"
] | Annie C. Robin, Michel Creze, Vijay Mohan |
astro-ph/9209006 | Inflation at the Electroweak Scale | We present a simple model for slow-rollover inflation where the vacuum energy
that drives inflation is of the order of $G_F^{-2}$; unlike most models, the
conversion of vacuum energy to radiation (``reheating'') is moderately
efficient. The scalar field responsible for inflation is a standard-model
singlet, develops a ... | 1992-09-30 | 2009-10-22 | [
"astro-ph",
"hep-ph"
] | L. Knox and M.S. Turner (U. of Chicago/Fermilab) |
astro-ph/9209005 | Neutrino Flavor Conversion in a Supernova Core | If $\nu_\mu$ or $\nu_\tau$ mix with $\nu_e$, neutrino oscillations and
collisions in a supernova (SN) core allow these flavors effectively to
participate in $\beta$ equilibrium and thus to obtain a large chemical
potential. If a sterile species mixes with $\nu_e$, these effects lead to an
anomalous loss of energy and l... | 1992-09-24 | 2009-10-22 | [
"astro-ph",
"hep-ph"
] | G. Raffelt and G. Sigl |
astro-ph/9209004 | On the Tail Problem in Cosmology | The tail problem for the propagation of a scalar field is considered in a
cosmological background, taking a Robertson-Walker spacetime as a specific
example. The explicit radial dependence of the general solution of the
Klein-Gordon equation with nonminimal coupling is derived, and the
inapplicability of the standard c... | 1992-09-23 | 2009-10-22 | [
"astro-ph"
] | Valerio Faraoni and Sebastiano Sonego |
astro-ph/9209003 | The Spectral Index in the CDM Cosmogony | In a recent paper, we suggested that the density fluctuation spectra arising
from power-law (or extended) inflation, which are tilted with respect to the
Harrison--Zel'dovich spectrum, may provide an explanation for the excess large
scale clustering seen in galaxy surveys such as the APM survey. In the light of
the new... | 1992-09-13 | 2007-05-23 | [
"astro-ph",
"gr-qc",
"hep-ph"
] | David H Lyth and Andrew A Liddle |
astro-ph/9209002 | Extended Hot Gas Halos Around Starburst Galaxies | Reanalysis of Einstein IPC data and new observations from the GINGA
LAC indicate the presence of extended X-ray emission (10-50 kpc) around the
starburst galaxy M82. Here we model this emission by calculating numerical
hydrodynamic simulations of the starburst event to much later times and larger
scales than previous... | 1992-09-12 | 2007-05-23 | [
"astro-ph"
] | Kohji Tomisaka and Joel N. Bregman |
astro-ph/9209001 | The Radial Structure of the Galactic Disc | Three colour photometry on CCD frames in the Special Area SpA23 provides a
deep probe of the galactic disc in a low absorption window towards the
anticenter. Magnitudes to better than 10% at V = 25 and B-V colour down to V =
23 have been obtained. These new data, used in combination with lower magnitude
photographic da... | 1992-09-04 | 2011-05-23 | [
"astro-ph"
] | Annie C. Robin, Michel Creze, Vijay Mohan |
astro-ph/9208006 | Binary Black Holes in Stationary Orbits | We show that under certain astrophysical conditions a binary system
consisting of two compact objects can be stabilized against indefinite
shrinking of orbits due to the emission of gravitational radiation. In this
case, the lighter binary companion settles down to a stable orbit when the loss
of the angular momentum d... | 1992-08-27 | 2007-05-23 | [
"astro-ph",
"gr-qc"
] | Sandip K. Chakrabarti (Tata Institute of Fundamental Research, Bombay,
INDIA) |
astro-ph/9208007 | COBE, Gravitational Waves, Inflation and Extended Inflation | We analyse the implications for inflationary models of the cosmic microwave
background (cmb) anisotropy measured by COBE. Vacuum fluctuations during
inflation generate an adiabatic density perturbation, and also gravitational
waves. The ratio of these two contributions to the cmb anisotropy is given for
an arbitrary sl... | 1992-08-27 | 2009-10-22 | [
"astro-ph",
"gr-qc",
"hep-ph"
] | David H Lyth and Andrew R Liddle |
astro-ph/9208005 | The Last Three Minutes: Issues in Gravitational Wave Measurements of
Coalescing Compact Binaries | Gravitational-wave interferometers are expected to monitor the last three
minutes of inspiral and final coalescence of neutron star and black hole
binaries at distances approaching cosmological, where the event rate may be
many per year. Because the binary's accumulated orbital phase can be measured
to a fractional acc... | 1992-08-25 | 2009-07-09 | [
"astro-ph",
"gr-qc"
] | Curt Cutler, Theocharis A. Apostolatos, Lars Bildsten, Lee Samuel
Finn, Eanna E. Flanagan, Daniel Kennefick, Dragoljubov M. Markovic, Amos Ori,
Eric Poisson, Gerald Jay Sussman, and Kip S. Thorne |
astro-ph/9208004 | Constraints on radiative decay of the 17-keV neutrino from COBE
Measurements | It is shown that, for a nontrivial radiative decay channel of the 17-keV
neutrino, the photons would distort the microwave background radiation through
ionization of the universe. The constraint on the branching ratio of such
decays from COBE measurements is found to be more stringent than that from
other consideration... | 1992-08-12 | 2009-10-22 | [
"astro-ph",
"hep-ph"
] | Biman B. Nath |
astro-ph/9208003 | The Probability for Formation of Collapsing Textures and Texture Knots | Global textures are interesting because they are promising candidates for
seeds in the structure formation of the universe. The important configurations
are those who will be able to collapse. The type of configurations that I will
consider are half knots and true knots. I define a half knot as one that covers
more tha... | 1992-08-07 | 2011-07-19 | [
"astro-ph",
"hep-th"
] | Stefan {\AA}minneborg (Stockholm University) |
astro-ph/9208002 | Dependence of Density Perturbations on the Coupling Constant in a Simple
Model of Inflation | In the standard inflationary scenario with inflaton potential
$V(\Phi)=M^4-{1\over4}\lambda\Phi^4$, the resulting density perturbations
$\delta\rho/\rho$ are proportional to $\lambda^{1/2}$. Upper bounds on
$\delta\rho/\rho$ require $\lambda < 10^{-13}$. Ratra has shown that an
alternative treatment of reheating result... | 1992-08-04 | 2009-10-22 | [
"astro-ph"
] | Toby Falk, Raghavan Rangarajan, and Mark Srednicki |
astro-ph/9208001 | The Angular Dependence of the Three-Point Correlation Function of the
Cosmic Microwave Background Radiation as Predicted by Inflationary
Cosmologies | Inflationary models predict a definite, model independent, angular dependence
for the three-point correlation function of $\Delta T/T$ at large angles
(greater than $\sim 1^\circ$) which we calculate. The overall amplitude is
model dependent and generically unobservably small, but may be large in some
specific models. ... | 1992-08-04 | 2009-10-22 | [
"astro-ph",
"hep-ph"
] | Toby Falk, Raghavan Rangarajan, and Mark Srednicki |
astro-ph/9207001 | Cosmic Microwave Background Probes Models of Inflation | Inflation creates both scalar (density) and tensor (gravity wave) metric
perturbations. We find that the tensor mode contribution to the CMB anisotropy
on large-angular scales can only exceed that of the scalar mode in models where
the spectrum of perturbations deviates significantly from scale invariance
(e.g., extend... | 1992-07-13 | 2009-09-15 | [
"astro-ph",
"hep-ph"
] | R.L. Davis, H.M. Hodges, G.F. Smoot, P.J. Steinhardt, M.S. Turner |
astro-ph/9207002 | Graceful Exit in Extended Inflation and Implications for Density
Perturbations | Two qualitatively different modes of ending superluminal expansion are
possible in extended inflation. One mode, different from the one envoked in
most extended models to date, easily avoids making big bubbles that distort the
cosmic microwave background radiation (CMBR). In this mode, the spectrum of
density fluctuati... | 1992-07-13 | 2009-09-15 | [
"astro-ph",
"hep-ph"
] | R. Crittenden and Paul J. Steinhardt |
astro-ph/9206005 | Entropy of a Classical Stochastic Field and Cosmological Perturbation | We propose a general definition of nonequilibrium entropy of a classical
stochastic field. As an example of particular interest in cosmology we apply
this definition to compute the entropy of density perturbations in an
inflationary Universe. On the scales of structures in the Universe, the entropy
of density perturbat... | 1992-06-24 | 2009-10-22 | [
"astro-ph",
"hep-ph"
] | R. Brandenberger (Brown), V. Mukhanov (ETH Zuerich) and T. Prokopec
(Brown) |
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