Shailesh Chandrasekharan

Journal Article Physical Review D · November 1, 2024 We introduce a simple lattice spin model that is written in terms of the well-known four-dimensional γ-matrix representation of the Clifford algebra. The local spins with a four-dimensional Hilbert space transform in a spinorial (1/2,0) (0,1/2) representat ... Full text Cite

Worldline Monte Carlo method for few-body nuclear physics

Journal Article Physical Review C · August 1, 2024 In this work we introduce a worldline-based fermion Monte Carlo algorithm for studying few body quantum mechanics of self-interacting fermions in the Hamiltonian lattice formulation. Our motivation to construct the method comes from our interest in studyin ... Full text Cite

Asymptotic Freedom at the Berezinskii-Kosterlitz-Thouless Transition without Fine-Tuning Using a Qubit Regularization.

Journal Article Physical review letters · January 2024 We propose a two-dimensional hard-core loop-gas model as a way to regularize the asymptotically free massive continuum quantum field theory that emerges at the Berezinskii-Kosterlitz-Thouless transition. Without fine-tuning, our model can reproduce the uni ... Full text Cite

Phases of 2d massless QCD with qubit regularization

Preprint Physical Review D: Particles, Fields, Gravitation and Cosmology · December 29, 2023 Full text Cite

Topological terms with qubit regularization and relativistic quantum circuits

Preprint · October 10, 2023 Full text Link to item Cite

Erratum: Quantum Criticality of Antiferromagnetism and Superconductivity with Relativity [Phys. Rev. Lett. 128, 117202 (2022)].

Journal Article Physical review letters · September 2023 This corrects the article DOI: 10.1103/PhysRevLett.128.117202. ... Full text Cite

A qubit regularization of asymptotic freedom at the BKT transition without fine-tuning

Preprint Physical Review Letters · July 8, 2023 Full text Cite

Vacuum Entanglement Harvesting in the Ising Model

Other · February 24, 2023 Full text Link to item Cite

Three-dimensional Gross-Neveu model with two flavors of staggered fermions

Conference Proceedings of Science · July 8, 2022 We introduce a strongly interacting lattice field theory model containing two flavors of massless staggered fermions with two kind of interactions: (1) a lattice current-current interaction, and (2) an on-site four-fermion interaction. At weak couplings, w ... Cite

Spacetime symmetric qubit regularization of the asymptotically free two-dimensional O(4) model

Journal Article Physical Review D: Particles, Fields, Gravitation and Cosmology · March 21, 2022 Full text Cite

Quantum Criticality of Antiferromagnetism and Superconductivity with Relativity.

Journal Article Physical review letters · March 2022 Featured Publication We study a quantum phase transition from a massless to massive Dirac fermion phase in a new two-dimensional bipartite lattice model of electrons that is amenable to sign-free quantum Monte Carlo simulations. Importantly, interactions in our model are not o ... Full text Cite

Qubit Regularization and Qubit Embedding Algebras

Journal Article Symmetry · February 1, 2022 Featured Publication Qubit regularization is a procedure to regularize the infinite dimensional local Hilbert space of bosonic fields to a finite dimensional one, which is a crucial step when trying to simulate lattice quantum field theories on a quantum computer. When the qub ... Full text Cite

Subleading conformal dimensions at the O(4) Wilson-Fisher fixed point

Journal Article Physical Review D · February 1, 2022 In this work we focus on computing the conformal dimensions D(jL,jR) of local fields that transform in an irreducible representation of SU(2)×SU(2) labeled with (jL,jR) at the O(4) Wilson-Fisher fixed point using the Monte Carlo method. In the large charge ... Full text Cite

Qubit regularization of asymptotic freedom

Journal Article Physical Review Letters · December 3, 2020 Featured Publication We provide strong evidence that the asymptotically free (1+1)-dimensional non-linear O(3) sigma model can be regularized using a quantum lattice Hamiltonian, referred to as the "Heisenberg-comb", that acts on a Hilbert space with only two qubits per spatia ... Full text Link to item Cite

Hamiltonian models of lattice fermions solvable by the meron-cluster algorithm

Journal Article Physical Review D: Particles, Fields, Gravitation and Cosmology · November 30, 2020 We introduce a half-filled Hamiltonian of spin-half lattice fermions that can be studied with the efficient meron-cluster algorithm in any dimension. As with the usual bipartite half-filled Hubbard models, the naïve U(2) symmetry is enhanced to SO(4). On t ... Link to item Cite

Baryon bag simulation of QCD in the strong coupling limit

Conference PoS LATTICE2019 (2019) 117 · August 27, 2020 We explore the possibility of a simulation of strong coupling QCD in terms of so-called baryon bags. In this form the known representation in terms of monomers, dimers and baryon loops is reorganized such that the baryon contributions are collected in spac ... Open Access Cite

Quantum Critical Phenomena in an O(4) Fermion Chain

Conference PoS LATTICE2019 (2019) 222 · August 27, 2020 We construct a fermionic lattice model containing interacting spin-half fermions with an O(4) symmetry. In addition the model contains a Z2 chiral symmetry which prevents a fermion mass term. Our model is motivated by the ability to study its physics usin ... Cite

Emergence of Gauss' law in a Z2 lattice gauge theory in 1 + 1 dimensions

Journal Article Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics · July 10, 2020 We explore a Z2 Hamiltonian lattice gauge theory in one spatial dimension with a coupling h, without imposing any Gauss' law constraint. We show that in our model h=0 is a free deconfined quantum critical point containing massless fermions where all Gauss' ... Full text Cite

Fermion-bag inspired Hamiltonian lattice field theory for fermionic quantum criticality

Journal Article Physical Review D: Particles, Fields, Gravitation and Cosmology · April 2, 2020 Motivated by the fermion bag approach we construct a new class of Hamiltonian lattice field theories that can help us to study fermionic quantum critical points. As a test of our method we construct the partition function of a simple lattice Hamiltonian in ... Full text Link to item Cite

Qubit regularization of the O (3) sigma model

Journal Article Physical Review D · September 17, 2019 We construct a qubit regularization of the O(3) nonlinear sigma model in two and three spatial dimensions using a quantum Hamiltonian with two qubits per lattice site. Using a worldline formulation and worm algorithms, we show that in two spatial dimension ... Full text Cite

Conformal Dimensions in the Large Charge Sectors at the O(4) Wilson-Fisher Fixed Point.

Journal Article Physical review letters · August 2019 Featured Publication We study the O(4) Wilson-Fisher fixed point in 2+1 dimensions in fixed large-charge sectors identified by products of two spin-j representations (j_{L},j_{R}). Using effective field theory we derive a formula for the conformal dimensions D(j_{L},j_{R}) of ... Full text Cite

Few-body physics on a spacetime lattice in the worldline approach

Journal Article Physical Review D · April 1, 2019 We formulate the physics of two species of nonrelativistic hard-core bosons with attractive or repulsive delta function interactions on a spacetime lattice in the worldline approach. We show that worm algorithms can efficiently sample the worldline configu ... Full text Cite

Baryon bag simulation of QCD in the strong coupling limit

Journal Article Proceedings of Science · January 1, 2019 We explore the possibility of a simulation of strong coupling QCD in terms of so-called baryon bags. In this form the known representation in terms of monomers, dimers and baryon loops is reorganized such that the baryon contributions are collected in spac ... Cite

Generating a mass gap using Feynman diagrams in an asymptotically free theory

Conference EPJ Web of Conferences · March 26, 2018 Using the example of a two dimensional four-fermion lattice field theory, we show that Feynman diagrams can generate a mass gap in a theory with massless fermions that interact via a marginally relevant coupling. We show this by introducing an infrared cut ... Full text Cite

Acknowledgement to Reviewers of Condensed Matter in 2017

Journal Article Condensed Matter · January 12, 2018 Peer review is an essential part in the publication process, ensuring that Condensed Matter maintains high quality standards for its published papers[...] ... Full text Cite

Worldline approach to few-body physics on the Lattice

Conference Proceedings of Science · January 1, 2018 We study the physics of two species of non-relativistic hard-core bosons with attractive or repulsive delta function interactions on a spacetime lattice using the worldline formulation. By tuning the chemical potential carefully we show that worm algorithm ... Cite

Generating a nonperturbative mass gap using Feynman diagrams in an asymptotically free theory

Journal Article Physical Review D - Particles, Fields, Gravitation and Cosmology · December 8, 2017 Full text Cite

Solution to the sign problem in a frustrated quantum impurity model

Journal Article Annals of Physics · January 1, 2017 In this work we solve the sign problem of a frustrated quantum impurity model consisting of three quantum spin-half chains interacting through an anti-ferromagnetic Heisenberg interaction at one end. We first map the model into a repulsive Hubbard model of ... Full text Cite

Solution to sign problems in models of interacting fermions and quantum spins.

Journal Article Physical review. E · October 2016 We show that solutions to fermion sign problems that are found in the formulation where the path integral is expanded in powers of the interaction in continuous time can be extended to systems involving fermions interacting with dynamical quantum spins. Wh ... Full text Cite

Fermion masses through four-fermion condensates

Journal Article Journal of High Energy Physics · October 1, 2016 Fermion masses can be generated through four-fermion condensates when symmetries prevent fermion bilinear condensates from forming. This less explored mechanism of fermion mass generation is responsible for making four reduced staggered lattice fermions ma ... Full text Cite

Real-time evolution of strongly coupled fermions driven by dissipation

Journal Article Annals of Physics · September 1, 2016 We consider the real-time evolution of a strongly coupled system of lattice fermions whose dynamics is driven entirely by dissipative Lindblad processes, with linear or quadratic quantum jump operators. The fermion 2-point functions obey a closed set of di ... Full text Cite

Origin of fermion masses without spontaneous symmetry breaking

Journal Article Physical Review D · April 20, 2016 Using large scale Monte Carlo calculations in a simple three dimensional lattice fermion model, we establish the existence of a second order quantum phase transition between a massless fermion phase and a massive one, both of which have the same symmetries ... Full text Cite

Fermion bags, topology and index theorems

Conference Proceedings of Science · January 1, 2016 The fermion bag formulation helps to extend the concepts of topology and index theorem associated with non-Abelian gauge theories to simple lattice fermion field theories. Using this extension we can argue that fermion masses can arise either through the t ... Cite

Massive fermions without fermion bilinear condensates

Journal Article Physical Review D - Particles, Fields, Gravitation and Cosmology · March 30, 2015 We study a lattice field theory model containing two flavors of massless staggered fermions with an onsite four-fermion interaction. The model contains an SU(4) symmetry which forbids nonzero fermion bilinear mass terms, due to which there is a massless fe ... Full text Cite

Progress towards quantum simulating the classical O(2) model

Journal Article Physical Review A - Atomic, Molecular, and Optical Physics · December 1, 2014 We connect explicitly the classical O(2) model in 1+1 dimensions, a model sharing important features with U(1) lattice gauge theory, to physical models potentially implementable on optical lattices and evolving at physical time. Using the tensor renormaliz ... Full text Cite

Solution to new sign problems with Hamiltonian Lattice Fermions

Journal Article PoS (LATTICE 2014) 058 · November 26, 2014 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 staggere ... Open Access Link to item Cite

Solution to sign problems in half-filled spin-polarized electronic systems

Journal Article Physical Review B - Condensed Matter and Materials Physics · March 12, 2014 We solve the sign problem in a particle-hole symmetric spin-polarized fermion model on bipartite lattices using the idea of fermion bags. The solution can be extended to a class of models at half filling but without particle-hole symmetry. Attractive Hubba ... Full text Cite

Fermion bags and a new origin for a fermion mass

Journal Article Proceedings of Science · January 1, 2014 The fermion bag is a powerful idea that helps to solve fermion lattice field theories using Monte Carlo methods. Some sign problems that had remained unsolved earlier can be solved within this framework. In this work we argue that the fermion bag also give ... Open Access Cite

Quantum critical behavior in three dimensional lattice Gross-Neveu models

Journal Article Physical Review D - Particles, Fields, Gravitation and Cosmology · July 31, 2013 We study quantum critical behavior in three dimensional lattice Gross-Neveu models containing two four-component massless Dirac fermions. We focus on two models with SU(2) flavor symmetry and either a Z2 or a U(1) chiral symmetry. Both models could not be ... Full text Cite

Fermion bag approach to fermion sign problems

Journal Article The European Physical Journal A · July 2013 Full text Cite

Quantum critical behavior with massless staggered fermions in three dimensions

Conference Proceedings of Science · January 1, 2013 We report on studies of quantum critical behavior in three dimensional lattice Gross-Neveu models with one flavor of staggered fermions. We focus on two models, one with SU(2)×Z2 symmetry and the other with an SU(2)×U(1) symmetry. Both these models could n ... Cite

Fermion Bag Solutions to Sign Problems

Journal Article Proceedings of Science · December 2012 Cite

Solutions to sign problems in lattice Yukawa models

Journal Article Phys. Rev. D · July 2012 Full text Link to item Cite

Fermion bag solutions to some sign problems in four-fermion field theories

Journal Article Phys. Rev. D · May 2012 Full text Link to item Cite

Fermion Bags, Duality, and the Three Dimensional Massless Lattice Thirring Model

Journal Article Phys. Rev. Lett. · April 2012 Full text Link to item Cite

The generalized fermion bag approach

Journal Article Proceedings of Science · December 2011 Cite

Partition Functions of Strongly Correlated Electron Systems as "Fermionants"

Journal Article · August 11, 2011 We introduce a new mathematical object, the "fermionant"

{Ferm}_{N} (G)

, of type

N

of an

n \times n

matrix

G

. It represents certain

n

-point functions involving

N

species of free fermions. When N=1, the fermionant reduces to the determinan ... Link to item Cite

Fermion bag approach to the sign problem in strongly coupled lattice QED with Wilson fermions

Journal Article Journal of High Energy Physics · 2011 We explore the sign problem in strongly coupled lattice QED with one flavor of Wilson fermions in four dimensions using the fermion bag formulation. We construct rules to compute the weight of a fermion bag and show that even though the fermions are confin ... Link to item Cite

Finite size effects in the presence of a chemical potential: A study in the classical non-linear O(2) sigma-model

Journal Article Physical Review D · 2010 Open Access Link to item Cite

Fermion bag approach to lattice field theories

Journal Article Physical Review D · 2010 Open Access Cite

Anomaly and a QCD-like phase diagram with massive bosonic baryons

Journal Article Journal of High Energy Physics · 2010 Full text Link to item Cite

Conductance of quantum impurity models from quantum Monte Carlo

Journal Article Physical Review B · 2010 Open Access Link to item Cite

Quantum Phase Transition and Dynamically Enhanced Symmetry in Quadruple Quantum Dot System

Journal Article Physical Review Letters · 2010 Link to item Cite

Ground state and excitations of quantum dots with magnetic impurities

Journal Article Phys. Rev. B · 2009 We consider an “impurity” with a spin degree of freedom coupled to a finite reservoir of non-interacting electrons, a system which may be realized by either a true impurity in a metallic nano-particle or a small quantum dot coupled to a large one. We show ... Link to item Cite

-Resonance and convergence of chiral perturbation theory

Conference Proceedings of Science · January 1, 2008 The dimensionless parameter′ = M2/(16π2F2), where F is the pion decay constant in the chiral limit and M is the pion mass at leading order in the quark mass, is expected to control the convergence of chiral perturbation theory applicable to QCD. Here we de ... Cite

Sigma-resonance and convergence of chiral perturbation theory

Journal Article PoS · 2008 http://arxiv.org/abs/0810.2423 ... Link to item Cite

{A new computational approach to lattice quantum field theories}

Journal Article PoS · 2008 http://arxiv.org/abs/0810.2419 ... Link to item Cite

From an Antiferromagnet to a Valence Bond Solid: Evidence for a First Order Phase Transition

Journal Article J. Stat. Mech. · 2008 Using a loop-cluster algorithm we investigate the spin 1/2 Heisenberg antiferromagnet on a square lattice with exchange coupling

J

and an additional four-spin interaction of strength

Q

. We confirm the existence of a phase transition separating antiferr ... Link to item Cite

{Rotor spectra, Berry phases, and monopole fields: From antiferromagnets to QCD}

Journal Article Phys. Rev. · 2008 http://arxiv.org/abs/cond-mat/0612252 ... Link to item Cite

Role of the sigma-resonance in determining the convergence of chiral perturbation theory

Journal Article Phys. Rev. D (Rapid Communications) · 2008 The dimensionless parameter

ξ = M_{π}^{2} / (16 π^{2} F_{π}^{2})

, where

F_{π}

is the pion decay constant and

M_{π}

is the pion mass, is expected to control the convergence of chiral perturbation theory applicable to QCD. Here we demonstrate that a strong ... Link to item Cite

Absence of vortex condensation in a two dimensional fermionic XY model

Journal Article Phys. Rev. D · 2008 Motivated by a puzzle in the study of two dimensional lattice Quantum Electrodynamics with staggered fermions, we construct a two dimensional fermionic model with a global

U (1)

symmetry. Our model can be mapped into a model of closed packed dimers and pl ... Link to item Cite

Novel transitions in S=1 spinor condensates and XY Ashkin-Teller universality

Journal Article arXiv:0707.0695 [cond-mat.stat-mech] · 2007 We study spin-1 polar spinor condensates with magnetic anisotropy, in two spatial dimensions at finite temperatures. The topological binding of vorticity to nematic disclinations leads to a rich phase diagram, which is captured by a U(1) version of the Ash ... Cite

Disorder-Induced Superfluidity in Hardcore Bosons in Two Dimensions

Journal Article Phys. Rev. B · 2007 Link to item Cite

Modeling pion physics in the epsilon-regime of two-flavor QCD using strong coupling lattice QED

Journal Article Phys. Rev. D · 2007 In order to model pions of two-flavor QCD we consider a lattice field theory involving two flavors of staggered quarks interacting strongly with U(1) gauge fields. For massless quarks, this theory has an

S U_{L} (2) \times S U_{R} (2) \times U_{A} (1)

symmetry. By a ... Link to item Cite

Effects of the anomaly on the two-flavor QCD chiral phase transition

Journal Article Physical Review Letters · 2007 We use strongly coupled lattice QED with two flavors of massless staggered fermions to model the chiral phase transition in two-flavor massless QCD. Our model allows us to vary the QCD anomaly and thus study its effects on the transition. Our study confirm ... Link to item Cite

Phase Transitions of S=1 Spinor Condensates in an Optical Lattice

Journal Article Phys. Rev. B. (accepted) · 2007 http://arxiv.org/abs/arXiv:0707.0695 [cond-mat] ... Open Access Link to item Cite

Effects of the anomaly on the QCD chiral phase transition

Journal Article Proceedings of Science · 2006 Link to item Cite

Quantum Phase Transitions of Hard-Core Bosons in Background Potentials

Journal Article Phys. Rev. Lett. · 2006 Link to item Cite

Anomalous Superconductivity in 2+1 dimensional two-color lattice QCD

Journal Article Phys. Rev. Lett. · 2006 We study thermodynamics of strongly coupled lattice QCD with two colors of staggered fermions in 2+1 dimensions. The partition function of this model can be written elegantly as a statistical mechanics of dimers and baryon loops. The model is invariant und ... Link to item Cite

New approaches to strong coupling lattice QCD

Journal Article Int. J. Mod. Phys. · 2006 Cite

Chiral limit of 2-color QCD at strong couplings

Journal Article PoS · 2006 http://arxiv.org/abs/hep-lat/0509117 ... Link to item Cite

Spectroscopy of the Kondo Problem in a Box

Journal Article Phys.Rev.Lett. · 2006 Motivated by experiments on double quantum dots, we study the problem of a single magnetic impurity confined in a finite metallic host. We prove an exact theorem for the ground state spin, and use analytic and numerical arguments to map out the spin struct ... Link to item Cite

Phase diagram of two-color lattice QCD in the chiral limit

Journal Article Phys. Rev. D · 2006 We study thermodynamics of strongly coupled lattice QCD with two colors of massless staggered fermions as a function of the baryon chemical potential μ in 3+1 dimensions using a new cluster algorithm. We find evidence that the model undergoes a weak first ... Link to item Cite

On the Sign Problem in the Hirsch-Fye Algorithm for Impurity Problems

Journal Article J. Phys. A: Math. and General · 2005 Link to item Cite

Failure of Mean Field Theory at Large N

Journal Article Physical Review Letters · 2005 We study strongly coupled lattice QCD with N colors of staggered fermions in 3+1 dimensions. While mean field theory describes the low temperature behavior of this theory at large N, it fails in the scaling region close to the finite temperature second ord ... Link to item Cite

Cluster Algorithms for Quantum Impurity Models and Mesoscopic Kondo Physics

Journal Article Phys. Rev. B · 2005 Link to item Cite

Mesoscopic Kondo Problem

Journal Article Europhys. Lett. · 2005 Link to item Cite

Quantum Monte Carlo Study of Disordered Fermions

Journal Article Phys. Rev. B · 2005 Link to item Cite

A Multi-level Algorithm for Quantum-impurity Models

Journal Article Phys. Rev. E · 2005 Link to item Cite

Lattice theories with nonlinearly realized chiral symmetry

Journal Article Nucl. Phys. Proc. Suppl. · 2004 http://arxiv.org/abs/hep-lat/0309093 ... Link to item Cite

Chiral and critical behavior in strong coupling QCD

Journal Article Nucl. Phys. Proc. Suppl. · 2004 http://arxiv.org/abs/hep-lat/0309098 ... Link to item Cite

CONNECTING LATTICE QCD WITH CHIRAL PERTURBATION THEORY AT STRONG COUPLING

Journal Article Physical Review (Rapid Communications) · 2004 Cite

D THEORY: FIELD QUANTIZATION BY DIMENSIONAL REDUCTION OF DISCRETE VARIABLES

Journal Article Nucl. Phys. B · 2004 Cite

An introduction to chiral symmetry on the lattice

Journal Article Prog. Part. Nucl. Phys. · 2004 http://arxiv.org/abs/hep-lat/0405024 ... Link to item Cite

LATTICE QCD AT FIXED TOPOLOGY

Journal Article Phys. Lett. B · 2003 Since present Monte Carlo algorithms for lattice QCD may become trapped in a fixed topological charge sector, it is important to understand the effect of calculating at fixed topology. In this work, we show that although the restriction to a fixed topologi ... Cite

MERON CLUSTER APPROACH TO SYSTEMS OF STRONGLY CORRELATED ELECTRONS

Journal Article Nucl. Phys. B · 2003 Numerical simulations of strongly correlated electron systems suffer from the notorious fermion sign problem which has prevented progress in understanding if systems like the Hubbard model display high-temperature superconductivity. Here we show how the fe ... Cite

CHIRAL LIMIT OF STRONGLY COUPLED LATTICE QCD AT FINITE TEMPERATURES

Journal Article Physical Reviews D (Rapid Communications) · 2003 Cite

Chiral limit of staggered fermions at strong couplings: A loop representation

Journal Article Nucl. Phys. Proc. Suppl. · 2003 http://arxiv.org/abs/hep-lat/0208071 ... Link to item Cite

CONNECTIONS BETWEEN QUANTUM CHROMODYNAMICS AND CONDENSED MATTER PHYSICS

Journal Article Pramana · 2003 Cite

QCD at fixed topology

Journal Article Phys. Lett. B · 2003 http://arxiv.org/abs/hep-lat/0302005 ... Link to item Cite

CHIRAL LIMIT OF STRONGLY COUPLED LATTICE GAUGE THEORIES

Journal Article Nucl. Phys. B · 2003 We construct a new and efficient cluster algorithm for updating strongly coupled U(N) lattice gauge theories with staggered fermions in the chiral limit. The algorithm uses the constrained monomer-dimer representation of the theory and should also be of in ... Cite

NON-LINEAR REALIZATION OF CHIRAL SYMMETRY ON THE LATTICE

Journal Article JHEP · 2003 Cite

KOSTERLITZ-THOULESS UNIVERSALITY IN DIMER MODELS

Journal Article Physical Reviews D (Rapid Communications) arXiv:hep-lat/0306034 · 2003 Cite

Nonlinear realization of chiral symmetry on the lattice

Journal Article Journal of High Energy Physics · 2003 We formulate lattice theories in which chiral symmetry is realized nonlinearly on the fermion fields. In this framework the fermion mass term does not break chiral symmetry. This property allows us to use the Wilson term to remove the doubler fermions whil ... Cite

PHYSICAL OBSERVABLES FROM LATTICE QCD AT FIXED TOPOLOGY

Journal Article Nucl. Phys. B (Proc. Suppl.) · 2002 Cite

FROM SPIN LADDERS TO THE 2-D O(3) MODEL AT NONZERO DENSITY

Journal Article Comput. Phys. Commun. · 2002 The numerical simulation of various field theories at non-zero chemical potential suffers from severe complex action problems. In particular, QCD at non-zero quark density can presently not be simulated for that reason. A similar complex action problem ari ... Cite

KOSTERLITZ-THOULESS UNIVERSALITY IN A FERMIONIC SYSTEM

Journal Article Physical Review B · 2002 A new extension of the attractive Hubbard model is constructed to study the critical behavior near a finite temperature superconducting phase transition in two dimensions using the recently developed meron-cluster algorithm. Unlike previous calculations in ... Cite

UNEXPECTED RESULTS IN THE CHIRAL LIMIT WITH STAGGERED FERMIONS

Journal Article Physics Letters B · January 2002 A cluster algorithm is constructed and applied to study the chiral limit of the strongly coupled lattice Schwinger model involving staggered fermions. The algorithm is based on a novel loop representation of the model. Finite size scaling of the chiral sus ... Cite

Superconductivity and chiral symmetry breaking with fermion clusters

Journal Article Nucl. Phys. Proc. Suppl. · 2002 http://arxiv.org/abs/hep-lat/0110125 ... Link to item Cite

Kosterlitz-Thouless universality in a fermionic system

Journal Article Physical Review B - Condensed Matter and Materials Physics · 2002 An extension of the attractive Hubbard model is constructed to study the critical behavior near a finite-temperature superconducting phase transition in two dimensions using the recently developed meron-cluster algorithm. Unlike previous calculations in th ... Cite

Novel Quantum Monte Carlo Algorithms for Fermions

Journal Article · October 8, 2001 Recent research shows that the partition function for a class of models involving fermions can be written as a statistical mechanics of clusters with positive definite weights. This new representation of the model allows one to construct novel algorithms. ... Link to item Cite

SOLUTION OF THE COMPLEX ACTION PROBLEM IN THE POTTS MODEL FOR DENSE QCD.

Journal Article Nucl. Phys. B · 2001 Monte Carlo simulations of lattice QCD at non-zero baryon chemical potential

μ

suffer from the notorious complex action problem. We consider QCD with static quarks coupled to a large chemical potential. This leaves us with an SU(3) Yang-Mills theory wi ... Cite

FLOP TRANSITIONS IN CUPRATE AND COLOR SUPERCONDUTORS From SO(5) to SO(10) unification?

Journal Article Nucl. Phys. B (Proc. Suppl.) · 2001 The phase diagrams of cuprate superconductors and of QCD at non-zero baryon chemical potential are qualitatively similar. The Neel phase of the cuprates corresponds to the chirally broken phase of QCD, and the high-temperature superconducting phase corresp ... Cite

QCD AT A FINITE DENSITY OF STATIC QUARKS.

Journal Article Nucl. Phys. B (Proc. Suppl.) · 2001 Recently, cluster methods have been used to solve a variety of sign problems including those that arise in the presence of fermions. In all cases an analytic partial re-summation over a class of configurations in the path integral was necessary. Here the n ... Cite

SO(10) Unification of Color Superconductivity and Chiral Symmetry Breaking?

Journal Article · March 21, 2000 Motivated by the SO(5) theory of high-temperature superconductivity and antiferromagnetism, we ask if an SO(10) theory unifies color superconductivity and chiral symmetry breaking in QCD. The transition to the color superconducting phase would then be anal ... Link to item Cite

Solving Sign Problems with Meron Algorithms

Journal Article Springer Proc. Phys. · 2000 Cite

MERON CLUSTER SIMULATION OF A CHIRAL PHASE TRANSITION WITH STAGGERED FERMIONS.

Journal Article Nucl. Phys. B · 2000 Cite

A chiral phase transition using a fermion cluster algorithm

Journal Article Chin. J. Phys. · 2000 http://arxiv.org/abs/hep-lat/0001003 ... Link to item Cite

Fermion cluster algorithms

Journal Article Nucl. Phys. Proc. Suppl. · 2000 http://arxiv.org/abs/hep-lat/9909007 ... Link to item Cite

CRITICAL BEHAVIOR OF A CHIRAL CONDENSATE WITH A MERON CLUSTER ALGORITHM.

Journal Article Phys. Letts. B · 2000 A new meron cluster algorithm is constructed to study the finite temperature critical behavior of the chiral condensate in a

(3 + 1)

dimensional model of interacting staggered fermions. Using finite size scaling analysis the infinite volume condensate is s ... Cite

QCD as a quantum link model

Journal Article Physical Review D - Particles, Fields, Gravitation and Cosmology · November 1, 1999 QCD is constructed as a lattice gauge theory in which the elements of the link matrices are represented by non-commuting operators acting in a Hilbert space. The resulting quantum link model for QCD is formulated with a fifth Euclidean dimension, whose ext ... Cite

Meron-Cluster Simulation of Quantum Spin Ladders in a Magnetic Field

Journal Article · September 30, 1999 Numerical simulations of numerous quantum systems suffer from the notorious sign problem. Meron-cluster algorithms lead to an efficient solution of sign problems for both fermionic and bosonic models. Here we apply the meron concept to quantum spin systems ... Link to item Cite

GINSPARG-WILSON FERMIONS: A STUDY IN THE SCHWINGER MODEL

Journal Article Phys. Rev. D · 1999 Qualitative features of Ginsparg-Wilson fermions, as formulated by Neuberger, coupled to two dimensional U(1) gauge theory are studied. The role of the Wilson mass parameter in changing the number of massless flavors in the theory and its connection with t ... Cite

LATTICE QCD WITH GINSPARG-WILSON FERMIONS

Journal Article Phys. Rev. D · 1999 Lattice QCD using fermions whose Dirac operator obeys the Ginsparg-Wilson relation, is perhaps the best known formulation of QCD with a finite cutoff. It reproduces all the low energy QCD phenomenology associated with chiral symmetry at finite lattice spac ... Cite

QCD AS A QUANTUM LINK MODEL

Journal Article Phys. Rev. D · 1999 QCD is constructed as a lattice gauge theory in which the elements of the link matrices are represented by non-commuting operators acting in a Hilbert space. The resulting quantum link model for QCD is formulated with a fifth Euclidean dimension, whose ext ... Cite

Non-perturbative renormalization constants using Ward identities

Journal Article Nucl. Phys. Proc. Suppl. · 1999 http://arxiv.org/abs/hep-lat/9810018 ... Link to item Cite

MERON CLUSTER SOLUTION OF A FERMION SIGN PROBLEM

Journal Article Phys. Rev. Letts. · January 1999 We present a general strategy to solve the notorious fermion sign problem using cluster algorithms. The method applies to various systems in the Hubbard model family as well as to relativistic fermions. Here it is illustrated for non-relativistic lattice f ... Cite

ANOMALOUS CHIRAL SYMMETRY BREAKING ABOVE THE QCD PHASE TRANSITION

Journal Article Phys. Rev. Lett. · 1999 We study the anomalous breaking of U_A(1) symmetry just above the QCD phase transition for zero and two flavors of quarks, using a staggered fermion, lattice discretization. The properties of the QCD phase transition are expected to depend on the degree of ... Cite

NONPERTURBATIVE RENORMALIZATION CONSTANTS USING WARD IDENTITIES.

Journal Article Phys. Letts. B · 1999 We extend the application of axial Ward identities to calculate

b_{A}, b_{P}

and

b_{T}

, coefficients that give the mass dependence of the renormalization constants of the corresponding bilinear operators in the quenched theory. The extension relies on using ... Cite

CONFINEMENT, CHIRAL SYMMETRY BREAKING AND CONTINUUM LIMITS IN QUANTUM LINK MODELS

Journal Article Nucl. Phys. B Proc. Suppl. · 1999 Cite

Lattice QCD with Ginsparg-Wilson fermions

Journal Article Physical Review D - Particles, Fields, Gravitation and Cosmology · 1999 Lattice QCD using fermions whose Dirac operator obeys the Ginsparg-Wilson relation is perhaps the best known formulation of QCD with a finite cutoff. It reproduces all the low energy QCD phenomenology associated with chiral symmetry at finite lattice spaci ... Cite

Ginsparg-Wilson fermions: A study in the Schwinger model

Journal Article Physical Review D - Particles, Fields, Gravitation and Cosmology · 1999 The qualitative features of Ginsparg-Wilson fermions, as formulated by Neuberger, coupled to two-dimensional U(1) gauge theory are studied. The role of the Wilson mass parameter in changing the number of massless flavors in the theory and its connection wi ... Cite

QCD as a quantum link model

Journal Article Physical Review D · 1999 QCD is constructed as a lattice gauge theory in which the elements of the link matrices are represented by non-commuting operators acting in a Hubert space. The resulting quantum link model for QCD is formulated with a fifth Euclidean dimension, whose exte ... Cite

Green’s functions from quantum cluster algorithms11This work is supported in part by funds provided by the US Department of Energy (DOE) under cooperative research agreement DE-FC02-94ER40818.

Journal Article · 1998 We show that cluster algorithms for quantum models have a meaning independent of the basis chosen to construct them. Using this idea, we propose a new method for measuring with little effort a whole class of Green’s functions, once a cluster algorithm for ... Cite

D-THEORY: FIELD THEORY VIA DIMENSIONAL REDUCTION OF DISCRETE VARIABLES

Journal Article Nucl. Phys. B (Proc. Suppl.) · 1998 A new non-perturbative approach to quantum field theory --- D-theory --- is proposed, in which continuous classical fields are replaced by discrete quantized variables which undergo dimensional reduction. The 2-d classical O(3) model emerges from the (2+1) ... Cite

GREEN'S FUNCTIONS FROM QUANTUM CLUSTER ALGORITHMS

Journal Article Physica A · 1998 We show that cluster algorithms for quantum models have a meaning independent of the basis chosen to construct them. Using this idea, we propose a new method for measuring with little effort a whole class of Green's functions, once a cluster algorithm for ... Cite

THE PERFECT QUARK GLUON VERTEX FUNCTION

Journal Article Nucl. Phys. B (Proc. Suppl.) · 1998 We evaluate a perfect quark-gluon vertex function for QCD in coordinate space and truncate it to a short range. We present preliminary results for the charmonium spectrum using this quasi-perfect action. ... Cite

PERFECT LATTICE TOPOLOGY: THE QUANTUM ROTOR AS A TEST CASE

Journal Article Phys. Lett. B · 1997 Lattice actions and topological charges that are classically and quantum mechanically perfect (i.e. free of lattice artifacts) are constructed analytically for the quantum rotor. It is demonstrated that the Manton action is classically perfect while the Vi ... Cite

PERFECT LATTICE ACTIONS FOR STAGGERED FERMIONS

Journal Article Nucl. Phys. B · 1997 We construct a perfect lattice action for staggered fermions by blocking from the continuum. The locality, spectrum and pressure of such perfect staggered fermions are discussed. We also derive a consistent fixed point action for free gauge fields and disc ... Cite

QUANTUM LINK MODELS: A DISCRETE APPROACH TO GAUGE THEORIES

Journal Article Nucl. Phys. B · 1997 We construct lattice gauge theories in which the elements of the link matrices are represented by non-commuting operators acting in a Hilbert space. These quantum link models are related to ordinary lattice gauge theories in the same way as quantum spin mo ... Cite

PROGRESS ON PERFECT LATTICE ACTIONS FOR QCD

Journal Article Nucl. Phys. B (Proc. Suppl.) · 1997 We describe a number of aspects in our attempt to construct an approximately perfect lattice action for QCD. Free quarks are made optimally local on the whole renormalized trajectory and their couplings are then truncated by imposing 3-periodicity. The spe ... Cite

A LARGE N CHIRAL TRANSITION ON A PLAQUETTE

Journal Article Phys. Lett. B · 1997 We construct a model of a chiral transition using the well known large N transition in two dimensional U(N) lattice gauge theory. Restricting the model to a single plaquette, we introduce Grassmann variables on the corners of the plaquette with the natural ... Cite

DIRAC SPECTRUM, AXIAL ANOMALY AND THE QCD CHIRAL PHASE TRANSITION

Journal Article NUcl. Phys. B (Proc. Suppl.) · 1996 The QCD phase transition is studied on

16^{3}

and

32^{3} \times 4

lattices both with and without quark loops. We introduce a new zero-flavor or quenched species of quark

ζ

and study the resulting chiral condensate,

\azbz

as a function of the $\zeta ... Cite

Z(3) TWISTED CHIRAL CONDENSATES IN QCD AT FINITE TEMPERATURES

Journal Article Phys. Rev. D · 1996 It was recently observed in a lattice QCD measurement that the chiral condensate in the quenched approximation shows dramatically different behavior in the three

Z_{3}

-equivalent de-confined phases. We argue that this phenomenon can be understood qualitati ... Cite

Z₃ twisted chiral condensates in QCD at finite temperatures

Journal Article Physical Review D - Particles, Fields, Gravitation and Cosmology · 1996 It was recently observed in a lattice QCD measurement that the chiral condensate in the quenched approximation shows dramatically different behavior in the three Z3-equivalent deconfined phases. We argue that this phenomenon can be understood qualitatively ... Cite

CRITICAL BEHAVIOR OF THE CHIRAL CONDENSATE AT THE QCD PHASE TRANSITION

Journal Article Nucl. Phys. B (Proc. Suppl.) · 1995 We study the critical behavior of the chiral condensate near the QCD phase transition in the background of two fixed light dynamical (sea) quarks. We study the condensate for

5.245 \leq β \leq 5.3

and

10^{- 10} \leq m_{v a l} \leq 10

... Cite

ANOMALY CANCELLATION IN (2+1)-DIMENSIONS IN THE PRESENCE OF A DOMAIN WALL MASS

Journal Article Phys. Rev. D · 1994 A fermion in 2+1 dimensions, with a mass function which depends on one spatial coordinate and passes through a zero (a domain wall mass), in the background of an Abelian gauge field is considered. In this model, originally proposed in a non-Abelian version ... Cite

FERMIONS WITH A DOMAIN WALL MASS: EXPLICIT GREENS FUNCTION AND ANOMALY CANCELLATION

Journal Article Nucl. Phys. B (Proc. Suppl.) · 1994 Cite

Fermion bag approach to Hamiltonian lattice field theories in continuous time

Journal Article Physical Review D - Particles, Fields, Gravitation and Cosmology We extend the idea of fermion bags to Hamiltonian lattice field theories in the continuous time formulation. Using a class of models we argue that the temperature is a parameter that splits the fermion dynamics into small spatial regions that can be used t ... Link to item Cite

Conformal dimensions via large charge expansion

Journal Article We construct an efficient Monte Carlo algorithm that overcomes the severe signal-to-noise ratio problems and helps us to accurately compute the conformal dimensions of large-Q fields at the Wilson-Fisher fixed point in the O(2) universality class. Using it ... Link to item Cite

Benchmark results in the 2D lattice Thirring model with a chemical potential

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