HEP Lattice·hep-lat

Tue·Dec 14, 2021Tuesday·December 14, 2021

16 papers—11 primary·5 cross-listed·reconstructed*

01*
Duals of lattice Abelian models with static determinant at finite density
O. Borisenko🇺🇦 · V. Chelnokov🇩🇪 · S. Voloshyn🇺🇦 · P. Yefanov🇺🇦
Dual formulations of Abelian U(1) and Z(N) LGT with a static fermion determinant are constructed at finite temperatures and non-zero chemical potential. The dual form is valid for a broad class of lattice gauge actions, for arbitrary number of fermion flavors and in any dimension. The distinguished feature of the dual formulation is that the dual Boltzmann weight is strictly positive. This allows to gain reliable results at finite density via the Monte Carlo simulations. As a byproduct of the dual representation we outline an exact solution for the partition function of the (1 + 1)-dimensional theory and reveal an existence of a phase with oscillating correlations.
hep-latPLB(2022)·3 citations
02*
Excitations of static isolated fermions in the Higgs phase of gauge Higgs theory
Kazue Matsuyama🇺🇸 · Jeff Greensite🇺🇸
A spectrum of localized excitations of isolated static fermions has been discovered in several different gauge Higgs theories. In lattice numerical simulations, we show that the charged elementary particles can have the spectrum of excitations in the Higgs phase of SU(3) gauge Higgs theory, $q = 2$ Abelian Higgs theory, Landau-Ginzburg theory, and in chiral U(1) gauge Higgs theory. Possibly these excited states of the isolated fermions can be observed in ARPES studies of conventional superconductors. Also, we consider that similar kinds of excitations could exist in other gauge Higgs theories, such as the electroweak sector of the Standard Model.
hep-latcond-mat.supr-conhep-phSciPost Phys.Proc.(2022)·0 citations
03*
Scope and convergence of the hopping parameter expansion in finite temperature QCD with heavy quarks around the critical point
Naoki Wakabayashi🇯🇵 · Shinji Ejiri🇯🇵 · Kazuyuki Kanaya🇯🇵 · Masakiyo Kitazawa🇯🇵
Hopping parameter expansion is a useful tool to investigate heavy dynamical quarks in lattice QCD, while the range of its applicability has been sometimes questioned. We study the convergence and the valid range of the hopping parameter expansion in the determination of the critical point (critical quark mass) of QCD with heavy quarks at finite temperature and density. On lattices with sufficiently large spatial extent, the terms in the hopping parameter expansion are classified into Wilson loop terms and Polyakov-type loop terms. We first study the case of the worst convergence in which all the gauge link variables are unit matrices and thus the Wilson loops and the Polyakov-type loops get their maximum values. We perform explicit calculation up to more than 100th order of the hopping parameter expansion. We show that the hopping parameter expansion is convergent up to the chiral limit of free Wilson quarks. We then perform a Monte-Carlo simulation to measure correlation among Polyakov-type loop terms up to the 20th order of the hopping parameter expansion. In previous studies, strong correlation between the leading order Polyakov loop term and the next-to-leading order bent Polyakov loop terms was reported and used to construct an effective theory to incorporate the next-to-leading order effect by a shift of the leading order coupling parameter. We establish that the strong correlation among Polyakov-type loop terms holds also at higher orders of the hopping parameter expansion, and extend the effective theory to incorporate higher-order effects up to high orders. Using the effective theory, we study the truncation error of the hopping parameter expansion. We find that the previous next-to-leading order result of the critical point for $N_{t} = 4$ are well reliable. For $N_{t} \geq 6$ , we need to incorporate higher-order effects in the effective theory.
hep-lathep-phPTEP(2022)·16 citations
04*
Advances in lattice hadron physics calculations using the gradient flow
K.U. Can🇦🇺 · R. Horsley🇬🇧 · Y. Nakamura🇯🇵 · H. Perlt🇩🇪 · P.E.L. Rakow🇬🇧 · G. Schierholz🇩🇪 · H. Stüben · R.D. Young🇦🇺 · J.M. Zanotti🇦🇺
Lattice calculations of hadronic observables are aggravated by short-distance fluctuations. The gradient flow, which can be viewed as a particular realisation of the coarse-graining step of momentum space RG transformations, proves a powerful tool for evolving the lattice gauge field to successively longer length scales for any initial coupling. Already at small flow times we find the signal-to-noise ratio of two- and three-point functions significantly enhanced and the projection onto the ground state largely improved, while the effect on the hadronic observables considered here to be negligible. A further benefit is that far fewer conjugate gradient iterations are needed for the Wilson-Dirac inverter to converge. Additionally, we find the renormalisation constants of quark bilinears to be significantly closer to unity.
hep-lathep-phhep-thPoS(2022)·2 citations
05*
Symmetry, Confinement, and the Higgs Phase
Jeff Greensite🇺🇸 · Kazue Matsuyama🇺🇸
We show that the Higgs and confinement phases of a gauge Higgs theory, with the Higgs field in the fundamental representation of the gauge group, are distinguished both by a broken or unbroken realization of the global center subgroup of the gauge group, and by the type of confinement in each phase. This is color confinement in the Higgs phase, and a stronger property, which we call "separation-of-charge" confinement, in the confining phase.
hep-lathep-thSymmetry(2022)·18 citations
06*
Deconfinement critical point of heavy quark effective lattice theories
Jangho Kim🇩🇪 · Anh Quang Pham🇩🇪 · Owe Philipsen🇩🇪
Effective three-dimensional Polyakov loop theories derived from QCD by strong coupling and hopping expansions are valid for heavy quarks and can also be applied to finite chemical potential $μ$ , due to their considerably milder sign problem. We apply the Monte-Carlo method to the $N_{f} = 1, 2$ effective theories up to $O (κ^{4})$ in the hopping parameter at $μ = 0$ to determine the critical quark mass, at which the first-order deconfinement phase transition terminates. The critical end point obtained from the effective theory to order $O (κ^{2})$ agrees well with 4-dimensional QCD simulations with a hopping expanded determinant by the WHOT-QCD collaboration. We also compare with full QCD simulations and thus obtain a measure for the validity of both the strong coupling and the hopping expansion in this regime.
hep-latPoS(2022)·4 citations
07*
Computation of QCD meson screening masses at high temperature
Davide Laudicina🇮🇹 · Mattia Dalla Brida🇨🇭 · Leonardo Giusti🇮🇹 · Tim Harris🇬🇧 · Michele Pepe🇮🇹
We compute flavor non-singlet meson screening masses in the chiral limit of QCD with $N_{f} = 3$ quarks. The calculation is carried out at 12 temperatures from $T \approx 1$ GeV up to the electroweak scale. For each temperature we simulated several lattice spacings, so as to be able to perform the continuum limit extrapolation with confidence at a few permille accuracy. In the entire range of temperatures explored, the meson screening masses deviate from the free theory result $2 π T$ by at most a few percent. Their values, however, cannot be explained by one-loop perturbation theory up to the electroweak scale, where the pseudoscalar and the vector screening masses are still significantly different within our precision. Chiral symmetry restoration manifests itself through the degeneracy of the pseudoscalar and the scalar channels and of the vector and the axial ones.
hep-lathep-exhep-phnucl-thPoS(2022)·4 citations
08*
Scale Setting for CLS 2+1 Simulations
Ben Straßberger🇩🇪 · Marco Cè🇨🇭 · Sara Collins🇩🇪 · Antoine Gérardin🇫🇷 · Georg von Hippel🇩🇪 · Piotr Korcyl🇵🇱 · Tomasz Korzec🇩🇪 · Daniel Mohler🇩🇪 · Andreas Risch🇩🇪 · Stefan Schaefer🇩🇪 · Wolfgang Söldner🇩🇪 · Rainer Sommer🇩🇪
We present an update of the scale setting for $N_{f} = 2 + 1$ flavor QCD using gradient flow scales and pseudo-scalar decay constants. We analyze the latest ensembles with $2 + 1$ flavors of non-perturbatively improved Wilson fermions generated by CLS for improved precision. Special care is taken to correct for mistuning by measuring directly the mass derivatives of the various observables. We determine $t_{0}$ with input taken from a combination of leptonic decay rates of the Pion and the Kaon.
hep-latPoS(2022)·47 citations
09*
Nucleon form factors from $N_{f}$ =2+1+1 twisted mass QCD at the physical point
Constantia Alexandrou🇨🇾 · Simone Bacchio🇨🇾 · Martha Constantinou🇺🇸 · Jacob Finkenrath🇨🇾 · Kyriakos Hadjiyiannakou🇨🇾 · Karl Jansen🇩🇪 · Giannis Koutsou🇨🇾 · Alejandro Vaquero🇺🇸
We present the nucleon axial and electromagnetic form factors using \Nf{2}{1}{1} ensembles of twisted mass fermions with clover improvement and with masses tuned to their physical values. Excited state effects are studied using several sink-source time separations in the range 0.8 fm - 1.6 fm, exponentially increasing statistics with the separation such that statistical errors remain approximately constant. In addition, quark loop disconnected diagrams are included in order to extract the isoscalar axial form factors and the proton and neutron electromagnetic form factors, as well as their strange-quark contributions. The radii and moments are extracted by modelling the $Q^{2}$ dependence, including using the so-called $z$ -expansion. A preliminary assessment of lattice cut-off effects is presented using two lattice spacings directly at the physical point.
hep-latPoS(2022)·8 citations
10*
Mass estimates of the SU(2) $0^{++}$ glueball from spectral methods
David Dudal🇧🇪 · Orlando Oliveira🇵🇹 · Martin Roelfs🇧🇪
The estimation of the Källén-Lehmann spectral density from gauge invariant lattice QCD two point correlation functions is proposed, and explored via an inversion strategy based on Tikhonov regularisation. We test the method on a mesonic toy model, showing that our methodology is competitive with the traditional Maximum Entropy Method. As proof of concept the SU(2) glueball spectrum for the quantum numbers $J^{P C} = 0^{++}$ is investigated, for various values of the lattice spacing, using the published data of arXiv:1910.07756. Our estimates for the ground state mass are in good agreement with the traditional approach, which is based on the large time exponential behaviour of the correlation functions. Furthermore, the spectral density also contains hints of excites states in the spectrum. Spectroscopic analysis of glueball two-point functions therefore provides a straightforward and insightful alternative to the traditional method based on the large time exponential behaviour of the correlation functions.
hep-lathep-phPoS(2022)·0 citations
11*
Chiralspin symmetry and confinement
Marco Catillo🇨🇭
Interesting lattice QCD simulations at high temperature in QCD and particular truncated studies have shown the emergence of an unexpected group symmetry, so called \textit{chiralspin}. However this is not a symmetry of the QCD action for free quarks, which makes unclear the transition to deconfinement at high temperature in QCD. Therefore we try to redefine this group so that is a symmetry of free quark action and it is consistent with the presence of deconfinement in QCD.
hep-latSciPost Phys.Proc.(2022)·0 citations
12*
Fermion sign bounds theory in quantum Monte Carlo simulation
Xu Zhang🇨🇳 · Gaopei Pan🇨🇳 · Xiao Yan Xu🇺🇸 · Zi Yang Meng🇨🇳
Sign problem in fermion quantum Monte Carlo (QMC) simulation appears to be an extremely hard problem. Traditional lore passing around for years tells people that when there is a sign problem, the average sign in QMC simulation approaches zero exponentially fast with the space-time volume of the configurational space. We, however, analytically show this is not always the case and manage to find physical bounds for the average sign. Our understanding is based on a direct connection between the sign bounds and a well-defined partition function of reference system and could distinguish when the bounds have the usual exponential scaling, and when they are bestowed on an algebraic scaling at low temperature limit. We analytically explain such algebraic sign problems found in flat band moiré lattice models at low temperature limit. At finite temperature, a domain size argument based on sign bounds also explains the connection between sign behavior and finite temperature phase transition. Sign bounds, as a well-defined observable, may have ability to ease or even make use of the sign problem.
↳ cond-mat.str-elcond-mat.stat-mechhep-lathep-thPRB(2022)·26 citations
13*
Automatic differentiation approach for reconstructing spectral functions with neural networks
Lingxiao Wang🇩🇪 · Shuzhe Shi🇺🇸 · Kai Zhou🇩🇪
Reconstructing spectral functions from Euclidean Green's functions is an important inverse problem in physics. The prior knowledge for specific physical systems routinely offers essential regularization schemes for solving the ill-posed problem approximately. Aiming at this point, we propose an automatic differentiation framework as a generic tool for the reconstruction from observable data. We represent the spectra by neural networks and set chi-square as loss function to optimize the parameters with backward automatic differentiation unsupervisedly. In the training process, there is no explicit physical prior embedding into neural networks except the positive-definite form. The reconstruction accuracy is assessed through Kullback-Leibler(KL) divergence and mean square error(MSE) at multiple noise levels. It should be noted that the automatic differential framework and the freedom of introducing regularization are inherent advantages of the present approach and may lead to improvements of solving inverse problem in the future.
↳ physics.comp-phcs.LGhep-lat12 citations
14*
3+1 Dimension Schwinger Pair Production with Quantum Computers
Bin Xu🇺🇸 · Wei Xue🇺🇸
Real-time quantum simulation of quantum field theory in (3+1)D requires large quantum computing resources. With a few-qubit quantum computer, we develop a novel algorithm and experimentally study the Schwinger effect, the electron-positron pair production in a strong electric field, in (3+1)D. The resource reduction is achieved by treating the electric field as a background field, working in Fourier space transverse to the electric field direction, and considering parity symmetry, such that we successfully map the three spatial dimension problems into one spatial dimension problems. We observe that the rate of pair production of electrons and positrons is consistent with the theoretical predication of the Schwinger effect. Our work paves the way towards exploring quantum simulation of quantum field theory beyond one spatial dimension.
↳ quant-phhep-lathep-phPRD(2022)·8 citations
15*
Mixed leptonic and hadronic corrections to the anomalous magnetic moment of the muon
Martin Hoferichter🇨🇭 · Thomas Teubner🇬🇧
Higher-order hadronic corrections to the anomalous magnetic moment of the muon have been evaluated including next-to-next-to-leading-order insertions of hadronic vacuum polarization and next-to-leading-order corrections to hadronic light-by-light scattering. This leaves a set of mixed leptonic and hadronic corrections in the form of double-bubble topologies as the only remaining hadronic effect at $O (α^{4})$ . Here, we estimate these contributions by analyzing the respective cuts of the diagrams, suggesting that the impact is limited to $≲ 1 \times 1 0^{- 11}$ and thus negligible at the level of the final precision of the Fermilab $g - 2$ experiment.
↳ hep-phhep-exhep-latnucl-thPRL(2022)·36 citations
16*
Index theorems, generalized Hall currents and topology for gapless defect fermions
David B. Kaplan🇺🇸 · Srimoyee Sen🇺🇸
We show how the index of the fermion operator from the Euclidean action can be used to uncover the existence of gapless modes living on defects (such as edges and vortices) in topological insulators and superconductors. The 1-loop Feynman diagram that computes the index reveals an analog of the Quantum Hall current flowing on and off the defect -- even in systems without conserved currents or chiral anomalies -- and makes explicit the interplay between topology in momentum and coordinate space. We provide several explicit examples.
↳ cond-mat.mes-hallcond-mat.str-elhep-lathep-thPRL(2022)·9 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.