text
stringlengths
89
2.49k
category
stringclasses
19 values
The Lefschetz thimble and the sign problem: In this talk I review the proposal to formulate quantum field theories (QFTs) on a Lefschetz thimble, which was put forward to enable Monte Carlo simulations of lattice QFTs affected by sign problem. First I will review the theoretical justification of the approach, and comme...
hep-lat
Correlation functions and critical behaviour on fluctuating geometries: We study the two-point correlation function in the model of branched polymers and its relation to the critical behaviour of the model. We show that the correlation function has a universal scaling form in the generic phase with the only scale given...
hep-lat
Two topics from lattice NRQCD at non-zero temperature: heavy quark mass dependence and S-wave bottomonium states moving in a thermal bath: Using Non-Relativistic QCD (NRQCD), we study heavy quark mass dependence of S-wave and P-wave bottomonium correlators for 0.42Tc <= T <= 2.09Tc and study spectral functions of S-w...
hep-lat
On the possibility of the critical behavior of LGT in the area of asymptotically large β: Coupling dependence on lattice spacing and size is estimated analytically at \beta -> \infty region where for a->0 the critical area is shifted in accordance with Callan-Symanzik relation. In considered approximation no trace of...
hep-lat
Impact of stout-link smearing in lattice fermion actions: The impact of stout-link smearing in lattice fermion actions is examined through the consideration of the mass and renormalization functions of the overlap quark propagator over a variety of smeared configurations. Up to six sweeps of stout-link smearing are inv...
hep-lat
Charmonium Potentials at Finite Temperature: The charmonium states at non-zero temperature are studied on anisotropic lattices with 2 dynamical quark flavours. Non-local operators are used to determine the Nambu-Bethe-Salpeter (NBS) wavefunctions via both conventional fitting methods and the Maximum Entropy Method. The...
hep-lat
Quark Propagation in the Instantons of Lattice QCD: We quantitatively examine the extent to which instanton degress of freedom, contained within standard Monte-carlo generated gauge-field configurations, can maintain the characteristic features of the mass and renormalisation functions of the non-perturbative quark pro...
hep-lat
Bottomonium above deconfinement in lattice nonrelativistic QCD: We study the temperature dependence of bottomonium for temperatures in the range $0.4 T_c < T < 2.1 T_c$, using nonrelativistic dynamics for the bottom quark and full relativistic lattice QCD simulations for $N_f=2$ light flavors on a highly anisotropic la...
hep-lat
SU(3) Lattice Gauge Theory in the Fundamental--Adjoint Plane and Scaling Along the Wilson Axis: We present further evidence for the bulk nature of the phase transition line in the fundamental--adjoint action plane of SU(3) lattice gauge theory. Computing the string tension and some glueball masses along the thermal p...
hep-lat
Calculation of the running coupling in non-Abelian gauge theories from Jarzynski's equality: We discuss the theoretical foundations of non-equilibrium Monte Carlo simulations based on Jarzynski's equality and present, as an example of application, the determination of the running coupling in the Schr\"odinger-functio...
hep-lat
P-wave nucleon-pion scattering amplitude in the $Δ(1232)$ channel from lattice QCD: We determine the $\Delta(1232)$ resonance parameters using lattice QCD and the L\"uscher method. The resonance occurs in elastic pion-nucleon scattering with $J^P=3/2^+$ in the isospin $I = 3/2$, $P$-wave channel. Our calculation is p...
hep-lat
Running Gluon Mass from Landau Gauge Lattice QCD Propagator: The interpretation of the Landau gauge lattice gluon propagator as a massive type bosonic propagator is investigated. Three different scenarios are discussed: i) an infrared constant gluon mass; ii) an ultraviolet constant gluon mass; iii) a momentum dependen...
hep-lat
The S, U and Δρparameters in the Zaragoza proposal for lattice chiral gauge fermions: Using the Zaragoza proposal for lattice chiral gauge fermions, the S, U and \Delta\rho parameters have been calculated at one loop. It is shown that the continuum values for these quantities can be reproduced without requiring expli...
hep-lat
The chromomagnetic operator on the lattice: We present our study of the renormalization of the chromomagnetic operator,O(CM), which appears in the effective Hamiltonian describing Delta S = 1 transitions in and beyond the Standard Model. We have computed, perturbatively to one-loop, the relevant Green's functions with ...
hep-lat
General properties of logarithmically divergent one-loop lattice Feynman integrals: We prove that logarithmically divergent one-loop lattice Feynman integrals have the general form I(p,a) = f(p)log(aM)+g(p,M) up to terms which vanish for lattice spacing a -> 0. Here p denotes collectively the external momenta and M i...
hep-lat
Hadronic Coupling Constants in Lattice QCD: We calculate the hadronic coupling constants $g_{NN\pi}$ and $g_{\rho\pi\pi}$ in QCD, including dynamical quarks in the framework of staggered fermions in the lattice approach. For the nucleon--pion coupling we obtain $g_{NN\pi} = 13.8 \pm 5.8$, to be compared with the experi...
hep-lat
Solution to new sign problems with Hamiltonian Lattice Fermions: We present a solution to the sign problem in a class of particle-hole symmetric Hamiltonian lattice fermion models on bipartite lattices using the idea of fermion bags. The solution remains valid when the particle-hole symmetry is broken through a stagger...
hep-lat
Convergence of chiral effective field theory: We formulate the expansion for the mass of the nucleon as a function of pion mass within chiral perturbation theory using a number of different ultra-violet regularisation schemes; including dimensional regularisation and various finite-ranged regulators. Leading and next-t...
hep-lat
Two-Baryon Systems with Twisted Boundary Conditions: We explore the use of twisted boundary conditions in extracting the nucleon mass and the binding energy of two-baryon systems, such as the deuteron, from Lattice QCD calculations. Averaging the results of calculations performed with periodic and anti-periodic boundar...
hep-lat
Chiral Determinant as an Overlap of Two Vacua: The effective action induced by chiral fermions can be written, formally, as an overlap of two states. These states are the Fock ground states of Hamiltonians for fermions in even dimensional space with opposite sign mass terms coupled to identical static vector potentials...
hep-lat
Effects of non-perturbatively improved dynamical fermions in UKQCD simulations: We present results for QCD with 2 degenerate flavours of quark using a non-perturbatively improved action on a lattice volume of $16^3\times32$ where the bare gauge coupling and bare dynamical quark mass have been chosen to maintain a fix...
hep-lat
Solving the left-hand cut problem in lattice QCD: $T_{cc}(3875)^+$ from finite volume energy levels: A novel effective-field-theory-based approach is implemented for extracting two-body scattering information from finite volume energies, serving as an alternative to L\"uscher's method. By explicitly incorporating one...
hep-lat
Schwinger-Keldysh on the lattice: a faster algorithm and its application to field theory: A new algorithm is developed allowing the Monte Carlo study of a 1 + 1 dimensional theory in real time. The main algorithmic development is to avoid the explicit calculation of the Jacobian matrix and its determinant in the upda...
hep-lat
Test for a universal behavior of Dirac eigenvalues in the complex Langevin method: We apply the complex Langevin (CL) method to a chiral random matrix theory (ChRMT) at non-zero chemical potential and study the nearest neighbor spacing (NNS) distribution of the Dirac eigenvalues. The NNS distribution is extracted usi...
hep-lat
Polyakov loop effects on the phase diagram in strong-coupling lattice QCD: We investigate the Polyakov loop effects on the QCD phase diagram by using the strong-coupling (1/g^2) expansion of the lattice QCD (SC-LQCD) with one species of unrooted staggered quark, including O}(1/g^4) effects. We take account of the eff...
hep-lat
A lattice regularization of Weyl fermions in a gravitational background: We report on a lattice fermion formulation with a curved domain-wall mass term to nonperturbatively describe fermions in a gravitational background. In our previous work in 2022, we showed under the time-reversal symmetry that the edge-localized m...
hep-lat
Lattice real-time simulations with learned optimal kernels: We present a simulation strategy for the real-time dynamics of quantum fields, inspired by reinforcement learning. It builds on the complex Langevin approach, which it amends with system specific prior information, a necessary prerequisite to overcome this exc...
hep-lat
Double parton distributions in the nucleon from lattice QCD: We evaluate nucleon four-point functions in the framework of lattice QCD in order to extract the first Mellin moment of double parton distributions (DPDs) in the unpolarized proton. In this first study, we employ an nf = 2 + 1 ensemble with pseudoscalar masse...
hep-lat
Non-relativistic bound states in a finite volume: We derive general results for the mass shift of bound states with angular momentum l >= 1 in a periodic cubic box in two and three spatial dimensions. Our results have applications to lattice simulations of hadronic molecules, halo nuclei, and Feshbach molecules. The si...
hep-lat
Lattice QCD Calculation of Electroweak Box Contributions to Superallowed Nuclear and Neutron Beta Decays: We present the first lattice QCD calculation of the universal axial $\gamma W$-box contribution $\square_{\gamma W}^{VA}$ to both superallowed nuclear and neutron beta decays. This contribution emerges as a signi...
hep-lat
Phase structure of four flavor QCD in the T μplane from a new method for simulations of lattice gauge theories at non zero baryon density: We review a method for numerical simulations of lattice gauge theories at non-zero baryonic chemical potential we recently proposed. We first report on a test of the method using ...
hep-lat
Light Quark Masses with Dynamical Wilson Fermions: We determine the masses of the light and the strange quarks in the $\bar{MS}$-scheme using our high-statistics lattice simulation of QCD with dynamical Wilson fermions. For the light quark mass we find $m^{light}_{\bar{MS}}(2 GeV) = 2.7(2) MeV$, which is lower than in ...
hep-lat
Core -- a New Method for Solving Hamiltonian Lattice Systems: The COntractor REnormalization group (CORE) approximation, a new method for solving Hamiltonian lattice systems, is introduced. The approach combines variational and contraction techniques with the real-space renormalization group approach and is systematica...
hep-lat
Phases at finite winding number of an Abelian lattice gauge theory: Pure gauge theories are rather different from theories with pure scalar and fermionic matter, especially in terms of the nature of excitations. For example, in scalar and fermionic theories, one can create ultra-local excitations. For a gauge theory, s...
hep-lat
Quantum tunneling in the real-time path integral by the Lefschetz thimble method: Quantum tunneling is mostly discussed in the Euclidean path integral formalism using instantons. On the other hand, it is difficult to understand quantum tunneling based on the real-time path integral due to its oscillatory nature, whic...
hep-lat
Cutoff effects in twisted mass lattice QCD: We present a first numerical study of lattice QCD with O(a) improved Wilson quarks and a chirally twisted mass term. Renormalized correlation functions are derived from the Schroedinger functional and evaluated in an intermediate space-time volume of size 0.75^3 x 1.5 fm^4. I...
hep-lat
Excited state baryon spectroscopy from lattice QCD with spin identification: Lattice QCD calculations are presented for the spectra of N* excited states with spins up to J = 7/2. Ambiguities of the standard method of spin identification are shown to be overcome by the use of lattice operators that transform according...
hep-lat
Three-particle finite-volume formalism for $π^+π^+ K^+$ and related systems: We consider three-particle systems consisting of two identical particles and a third that is different, with all being spinless. Examples include $\pi^+\pi^+ K^+$ and $K^+K^+\pi^+$. We derive the formalism necessary to extract two- and three...
hep-lat
Interplay between sign problem and Z_3 symmetry in three-dimensional Potts model: We construct four kinds of Z3-symmetric three-dimentional (3-d) Potts models, each with different number of states at each site on a 3-d lattice, by extending the 3-d three-state Potts model. Comparing the ordinary Potts model with the ...
hep-lat
K^0--\bar{K}^0 mixing in full lattice QCD: There are at least two methods to calculate $ B_K $ with staggered fermions: one is the two spin trace formalism and the other is the one spin trace formalism. We have performed numerical simulations on a $ 16^3 \times 40 $ lattice in full QCD with $ \beta = 5.7 $ and a dynami...
hep-lat
Remarks on the quantum gravity interpretation of 4D dynamical triangulation: We review some of the phenomenology in 4D dynamical triangulation and explore its interpretation in terms of a euclidean effective action of the continuum form $\intx \sqrt{g} [\mu -\frac{1}{16\pi G} R + \cdots]$.
hep-lat
Phase Quenched Lattice QCD at Finite Density and Temperature: We simulate 3-flavour lattice QCD at finite quark-number chemical potential mu in the phase-quenched approximation, close to the finite temperature transition. Working close to the critical quark mass, we find no evidence for the expected critical endpoint a...
hep-lat
Light hadron spectroscopy with O(a) improved dynamical fermions: We present the first results for the static quark potential and the light hadron spectrum using dynamical fermions at $\beta=5.2$ using an O(a) improved Wilson fermion action together with the standard Wilson plaquette action for the gauge part. Sea quark...
hep-lat
High-loop perturbative renormalization constants for Lattice QCD (II): three-loop quark currents for tree-level Symanzik improved gauge action and n_f=2 Wilson fermions: Numerical Stochastic Perturbation Theory was able to get three- (and even four-) loop results for finite Lattice QCD renormalization constants. Mo...
hep-lat
Renormalization constants for $N_{\rm f}=2+1+1$ twisted mass QCD: We summarize recent non-perturbative results obtained for the renormalization constants computed in the RI'-MOM scheme for $N_{\rm f}=2+1+1$ twisted mass QCD. Our implementation employs the Iwasaki gauge action and four dynamical degenerate twisted mass ...
hep-lat
Rigidity and percolation of center vortices: Effective action of center vortices in SU(2) lattice gauge theory is investigated by studying the correlation between the action density on their worldsheets and their geometric properties. It turns out that center vortices are rigid, however, their dynamics is more complica...
hep-lat
Unpolarized gluon distribution in the nucleon from lattice quantum chromodynamics: In this study, we present a determination of the unpolarized gluon Ioffe-time distribution in the nucleon from a first principles lattice quantum chromodynamics calculation. We carry out the lattice calculation on a $32^3\times 64$ ens...
hep-lat
Lattice QCD constraints on the parton distribution functions of ${}^3\text{He}$: The fraction of the longitudinal momentum of ${}^3\text{He}$ that is carried by the isovector combination of $u$ and $d$ quarks is determined using lattice QCD for the first time. The ratio of this combination to that in the constituent ...
hep-lat
SO(2N) and SU(N) gauge theories: We present our preliminary results of SO(2N) gauge theories, approaching the large-N limit. SO(2N) theories may help us to understand QCD at finite chemical potential since there is an orbifold equivalence between SO(2N) and SU(N) gauge theories at large-N and SO(2N) theories do not hav...
hep-lat
Multi-hadron interactions from lattice QCD: First-principles calculations of multi-hadron dynamics are a crucial goal in lattice QCD. Significant progress has been achieved in developing, implementing, and applying theoretical tools that connect finite-volume quantities to their infinite-volume counterparts. Here, I re...
hep-lat
Lattice diffeomorphism invariance: We propose a lattice counterpart of diffeomorphism symmetry in the continuum. A functional integral for quantum gravity is regularized on a discrete set of space-time points, with fermionic or bosonic lattice fields. When the space-time points are positioned as discrete points of a co...
hep-lat
Thermal monopole condensation in QCD with physical quark masses: Thermal monopoles, identified after Abelian projection as magnetic currents wrapping non-trivially around the thermal circle, are studied in $N_f = 2+1$ QCD at the physical point. The distribution in the number of wrappings, which in pure gauge theories p...
hep-lat
A non-perturbative calculation of the mass of the Bc: We present a calculation of the mass of the 1S0 pseudoscalar anti-b c (Bc) state using a non-perturbative measurement from quenched lattice QCD. We find M_Bc = 6.386(9)(98)(15) GeV where the first error is statistical, the second systematic due to the quark mass amb...
hep-lat
An estimate for the thermal photon rate from lattice QCD: We estimate the production rate of photons by the quark-gluon plasma in lattice QCD. We propose a new correlation function which provides better control over the systematic uncertainty in estimating the photon production rate at photon momenta in the range {\pi}...
hep-lat
Quark contribution to the proton spin from 2+1+1-flavor lattice QCD: We present the first chiral-continuum extrapolated up, down and strange quark spin contribution to the proton spin using lattice QCD. For the connected contributions, we use eleven ensembles of 2+1+1-flavor of Highly Improved Staggered Quarks (HISQ) g...
hep-lat
Large N: I review some of the things we have learned about large N gauge theories (and QCD at N=oo) from lattice calculations in recent years. I point to some open problems.
hep-lat
Gauge-fixing approach to lattice chiral gauge theories: We review the status of our recent work on the gauge-fixing approach to lattice chiral gauge theories. New numerical results in the reduced version of a model with a U(1) gauge symmetry are presented which strongly indicate that the factorization of the correlatio...
hep-lat
Nucleon Structure in Lattice QCD using twisted mass fermions: We present results on the nucleon form factors and moments of generalized parton distributions obtained within the twisted mass formulation of lattice QCD. We include a discussion of lattice artifacts by examining results at different volumes and lattice spa...
hep-lat
N=1 super Yang-Mills on a (3+1) dimensional transverse lattice with one exact supersymmetry: We formulate ${\cal N}$=1 super Yang-Mills theory in 3+1 dimensions on a two dimensional transverse lattice using supersymmetric discrete light cone quantization in the large-$N_c$ limit. This formulation is free of fermion s...
hep-lat
The Chiral Condensate of One-Flavor QCD and the Dirac Spectrum at θ=0: In a sector of fixed topological charge, the chiral condensate has a discontinuity given by the Banks-Casher formula also in the case of one-flavor QCD. However, at fixed \theta-angle, the chiral condensate remains constant when the quark mass cro...
hep-lat
The strange quark contribution to the spin of the nucleon: Quark line disconnected matrix elements of an operator, such as the axial current, are difficult to compute on the lattice. The standard method uses a stochastic estimator of the operator, which is generally very noisy. We discuss and develop further our altern...
hep-lat
Spectrum of the open QCD flux tube and its effective string description: I perform a high precision measurement of the static quark-antiquark potential in three-dimensional ${\rm SU}(N)$ gauge theory with $N=2$ to 6. The results are compared to the effective string theory for the QCD flux tube and I obtain continuum li...
hep-lat
Nuclear force in Lattice QCD: We perform the quenched lattice QCD analysis on the nuclear force (baryon-baryon interactions). We employ $20^3\times 24$ lattice at $\beta=5.7$ ($a\simeq 0.19$ fm) with the standard gauge action and the Wilson quark action with the hopping parameters $\kappa=0.1600, 0.1625, 0.1650$, and g...
hep-lat
Two dimensional SU(N)xSU(N) Chiral Models on the Lattice (II): the Green's Function: Analytical and numerical methods are applied to principal chiral models on a two-dimensional lattice and their predictions are tested and compared. New techniques for the strong coupling expansion of SU(N) models are developed and ap...
hep-lat
Effects of the anomaly on the QCD chiral phase transition: We study a lattice field theory described by two flavors of massless staggered fermions interacting with U(1) gauge fields in the strong coupling limit. We show that the lattice model has a $SU(2)\times SU(2)\times U(1)$ chiral symmetry and can be used to model...
hep-lat
Running Coupling and the Lambda-Parameter from SU(3) Lattice Simulations: We present new results on the static qq-potential from high statistics simulations on 32^4 and smaller lattices, using the standard Wilson beta = 6.0, 6.4, and 6.8. Within our statistical errors we do not observe any finite size effects affecting...
hep-lat
Domain Decomposition method on GPU cluster: Pallalel GPGPU computing for lattice QCD simulations has a bottleneck on the GPU to GPU data communication due to the lack of the direct data exchanging facility. In this work we investigate the performance of quark solver using the restricted additive Schwarz (RAS) precondit...
hep-lat
Deflated BiCGStab for linear equations in QCD problems: The large systems of complex linear equations that are generated in QCD problems often have multiple right-hand sides (for multiple sources) and multiple shifts (for multiple masses). Deflated GMRES methods have previously been developed for solving multiple right...
hep-lat
Electroweak three-body decays in the presence of two- and three-body bound states: Recently, formalism has been derived for studying electroweak transition amplitudes for three-body systems both in infinite and finite volumes. The formalism provides exact relations that the infinite-volume amplitudes must satisfy, as...
hep-lat
One dimensional supersymmetric Yang-Mills theory with 16 supercharges: We report on numerical simulations of one dimensional maximally supersymmetric SU(N) Yang-Mills theory, by using the lattice action with two exact supercharges. Based on the gauge/gravity duality, the gauge theory corresponds to N D0-branes system i...
hep-lat
Confined Charged Particles in C-periodic Volumes: Charged particles in an Abelian Coulomb phase are non-local infraparticles that are surrounded by a cloud of soft photons which extends to infinity. Gauss' law prevents the existence of charged particles in a periodic volume. In a $C$-periodic volume, which is periodic ...
hep-lat
Toward solving the sign problem with path optimization method: We propose a new approach to circumvent the sign problem in which the integration path is optimized to control the sign problem. We give a trial function specifying the integration path in the complex plane and tune it to optimize the cost function which re...
hep-lat
Scaling studies of QCD with the dynamical HISQ action: We study the lattice spacing dependence, or scaling, of physical quantities using the highly improved staggered quark (HISQ) action introduced by the HPQCD/UKQCD collaboration, comparing our results to similar simulations with the asqtad fermion action. Results are...
hep-lat
Confinement-Deconfinement transition and $Z_2$ symmetry in $Z_2+$Higgs theory: We study the Polyakov loop and the $Z_2$ symmetry in the lattice $Z_2+$Higgs theory in 4D Euclidean space using Monte Carlo simulations. The results show that this symmetry is realised in the Higgs symmetric phase for large number of tempo...
hep-lat
Proton decay matrix element on the lattice with physical pion mass: Proton decay is one of possible signatures of baryon number violation, which has to exist to explain the baryon asymmetry and the existence of nuclear matter. Proton decays must be mediated through effective low-energy baryon number violating operators...
hep-lat
Deriving exact results for Ising-like models from the cluster variation method: The cluster variation method (CVM) is an approximation technique which generalizes the mean field approximation and has been widely applied in the last decades, mainly for finding accurate phase diagrams of Ising-like lattice models. Here...
hep-lat
Measurement of hybrid content of heavy quarkonia using lattice NRQCD: Using lowest-order lattice NRQCD to create heavy meson propagators and applying the spin-dependent interaction, $c_B^{} \frac{-g}{2m_q}\vec\sigma\cdot\vec{B}$, at varying intermediate time slices, we compute the off-diagonal matrix element of the Ham...
hep-lat
Pion form factor with twisted mass QCD: The pion form factor is calculated using quenched twisted mass QCD with beta=6.0 and maximal twisting angle omega=pi/2. Two pion masses and several values of momentum transfer are considered. The momentum averaging procedure of Frezzotti and Rossi is used to reduce lattice spacin...
hep-lat
Chiral Lattice Gauge Theories from Warped Domain Walls and Ginsparg-Wilson Fermions: We propose a construction of a 2-dimensional lattice chiral gauge theory. The construction may be viewed as a particular limit of an infinite warped 3-dimensional theory. We also present a "single-site'' construction using Ginsparg-W...
hep-lat
Logarithmic corrections to O($a$) and O($a^2$) effects in lattice QCD with Wilson or Ginsparg-Wilson quarks: We derive the asymptotic lattice spacing dependence $a^n[2b_0\bar{g}^2(1/a)]^{\hat{\Gamma}_i}$ relevant for spectral quantities of lattice QCD, when using Wilson, O$(a)$ improved Wilson or Ginsparg-Wilson quar...
hep-lat
Exact calculation of disconnected loops: We present an implementation of the disconnected diagram contributions to quantities such as the flavor-singlet pseudoscalar meson mass which are accelerated by GPGPU technology utilizing the NVIDIA CUDA platform. To enable the exact evaluation of the disconnected loops we use a...
hep-lat
Light hadronic physics using domain wall fermions in quenched lattice QCD: In the past year domain wall fermion simulations have moved from exploratory stages to the point where systematic effects can be studied with different gauge couplings, volumes, and lengths in the fifth dimension. Results are presented here fo...
hep-lat
Flux representation of an effective Polyakov loop model for QCD thermodynamics: We discuss an effective Polyakov loop model for QCD thermodynamics with a chemical potential. Using high temperature expansion techniques the partition sum is mapped exactly onto the partition sum of a flux model. In the flux representati...
hep-lat
The beta function and equation of state for QCD with two flavors of quarks: We measure the pressure and energy density of two flavor QCD in a wide range of quark masses and temperatures. The pressure is obtained from an integral over the average plaquette or psi-bar-psi. We measure the QCD beta function, including th...
hep-lat
A study of the (m,d,N)=(1,3,2) Lifshitz point and of the three- dimensional XY universality class by high-temperature bivariate series for the XY models with anisotropic competing interactions: High-temperature bivariate expansions have been derived for the two-spin correlation-function in a variety of classical la...
hep-lat
$ξ/ξ_{2nd}$ ratio as a tool to refine Effective Polyakov Loop models: Effective Polyakov line actions are a powerful tool to study the finite temperature behaviour of lattice gauge theories. They are much simpler to simulate than the original lattice model and are affected by a milder sign problem, but it is not clear ...
hep-lat
Numerical simulations with two flavours of twisted-mass Wilson quarks and DBW2 gauge action: Discretisation errors in two-flavour lattice QCD with Wilson-quarks and DBW2 gauge action are investigated by comparing numerical simulation data at two values of the bare gauge coupling. Both non-zero and zero twisted mass v...
hep-lat
4d Simplicial Quantum Gravity: Matter Fields and the Corresponding Effective Action: Four-dimensional simplicial quantum gravity is modified either by coupling it to U(1) gauge fields or by introducing a measure weighted by the orders of the triangles. Strong coupling expansion and Monte Carlo simulations are used. A...
hep-lat
Magnetic polarizability of hadrons from lattice QCD: We extract the magnetic polarizability from the quadratic response of a hadron's mass shift in progressively small static magnetic fields. The calculation is done on a 24x12x12x24 lattice at a = 0.17 fm with an improved gauge action and the clover quark action. The r...
hep-lat
Curvature of the pseudocritical line in (2+1)-flavor QCD with HISQ fermions: We study QCD with (2+1)-HISQ fermions at nonzero temperature and nonzero imaginary baryon chemical potential. Monte Carlo simulations are performed using the MILC code along the line of constant physics with a light to strange mass ratio of ...
hep-lat
Bosonic color-flavor transformation for the special unitary group: We extend Zirnbauer's color-flavor transformation in the bosonic sector to the color group SU(N_c). Because the flavor group U(N_b, N_b) is non-compact, the algebraic method by which the original color-flavor transformation was derived leads to a useful...
hep-lat
Charged Pion Polarizability from the Lattice: Direct evaluation of charged particle polarizabilities on the lattice is quite difficult. However, a short cut for charged pion polarizability - the Das, Mathur, Okubo Sum Rule - can readily be calculated using lattice techniques. A phenomenological model has been developed...
hep-lat
Chiral condensate from the Banks-Casher relation: We report on our ongoing project of determining the chiral condensate of two-flavor QCD from the Banks-Casher relation. We compute the mode number of the O(a)-improved Wilson-Dirac operator for several values of \Lambda, and we discuss different fitting strategies to ex...
hep-lat
Thermal Correlators in the ρ channel of two-flavor QCD: We present a lattice QCD calculation with two dynamical flavors of the isovector vector correlator in the high-temperature phase. We analyze the correlator in terms of the associated spectral function, for which we review the theoretical expectations. In our main ...
hep-lat
Power corrections from decoupling of the charm quark: Decoupling of heavy quarks at low energies can be described by means of an effective theory as shown by S. Weinberg in Ref. [1]. We study the decoupling of the charm quark by lattice simulations. We simulate a model, QCD with two degenerate charm quarks. In this cas...
hep-lat
$d^\ast (2380)$ dibaryon from lattice QCD: The $\Delta\Delta$ dibaryon resonance $d^\ast (2380)$ with $(J^P, I)=(3^+, 0)$ is studied theoretically on the basis of the 3-flavor lattice QCD simulation with heavy pion masses ($m_\pi =679, 841$ and $1018$ MeV). By using the HAL QCD method, the central $\Delta$-$\Delta$ pot...
hep-lat
Dilaton EFT from p-regime to RMT in the $ε$-regime: New results are reported from tests of a low-energy effective field theory (EFT) that includes a dilaton field to describe the emergent light scalar with ${ 0^{++} }$ quantum numbers in the strongly coupled near-conformal gauge theory with a massless fermion flavor do...
hep-lat
Quark propagator from an improved staggered action in Laplacian and Landau gauges: Studies of gauge dependent quantities are afflicted with Gribov copies, but Laplacian gauge fixing provides one possible solution to this problem. We present results for the lattice quark propagator in both Landau and Laplacian gauges ...
hep-lat
SPHERICALLY SYMMETRIC RANDOM WALKS III. POLYMER ADSORPTION AT A HYPERSPHERICAL BOUNDARY: A recently developed model of random walks on a $D$-dimensional hyperspherical lattice, where $D$ is {\sl not} restricted to integer values, is used to study polymer growth near a $D$-dimensional attractive hyperspherical boundar...
hep-lat
Some exact results on the QCD critical point: We show, in a model-independent manner, that the QCD critical point can appear only inside the pion condensation phase of the phase-quenched QCD as long as the contribution of flavor-disconnected diagrams is negligible. The sign problem is known to be maximally severe in th...
hep-lat