HEP Lattice·hep-lat

Fri·Dec 3, 2021Friday·December 3, 2021

12 papers—10 primary·2 cross-listed·reconstructed*

01*
Chromo-electric screening length in 2+1 flavor QCD
Peter Petreczky🇺🇸 · Sebastian Steinbeißer🇩🇪 · Johannes Heinrich Weber🇩🇪
We study Polyakov loop as well as correlators of real and imaginary parts of the Polyakov loop in 2+1 flavor QCD at finite temperature. We use hypercubic (HYP) smearing to improve the signal in the lattice calculations and to obtain reliable results for the correlators at large distances. From the large distance behavior of the correlators we estimate the chromo-electric screening length to be (0.38-44)/T. Furthermore, we show that the short distance distortions due to HYP smearing do not affect the physics of interest
hep-lathep-phPoS(2022)·6 citations
02*
Leading isospin breaking effects in the HVP contribution to $a_{μ}$ and to the running of $α$
Andreas Risch🇩🇪 · Hartmut Wittig🇩🇪
The anomalous magnetic moment of the muon $a_{μ}$ and the running of the electromagnetic coupling $α$ play a fundamental role in beyond Standard Model (SM) physics searches. Non-perturbative hadronic contributions to both quantities, which are related to the hadronic vacuum polarization (HVP) function consisting of two electromagnetic currents, are a main source of uncertainty in the SM prediction. We compute the HVP function in lattice QCD+QED applying the time-momentum representation method. We expand the relevant correlation functions around the isosymmetric limit. In particular, we focus on leading isospin breaking effects taking quark-connected contributions into account, which we evaluate on isosymmetric $N_{f} = 2 + 1$ QCD gauge ensembles generated by the CLS initiative with non-perturbatively $O (a)$ -improved Wilson fermions.
hep-latPoS(2022)·18 citations
03*
Scalar fields on fluctuating hyperbolic geometries
Muhammad Asaduzzaman🇺🇸 · Simon Catterall🇺🇸
We present results on the behavior of the boundary-boundary correlation function of scalar fields propagating on discrete two-dimensional random triangulations representing manifolds with the topology of a disk. We use a gravitational action that includes a curvature squared operator, which favors a regular tessellation of hyperbolic space for large values of its coupling. We probe the resultant geometry by analyzing the propagator of a massive scalar field and show that the conformal behavior seen in the uniform hyperbolic space survives as the coupling approaches zero. The analysis of the boundary correlator suggests that holographic predictions survive, at least, weak quantum gravity corrections. We then show how such an $R^{2}$ operator might be induced as a result of integrating out massive lattice fermions and show preliminary result for boundary correlation functions that include the effects of this fermionic backreaction on the geometry.
hep-latPoS(2022)·4 citations
04*
HAL QCD potentials with non-zero total momentum and an application to the $I = 2$ $π π$ scattering
Sinya Aoki🇯🇵 · Yutaro Akahoshi🇯🇵
We consider the HAL QCD method in the system with non-zero total momentum (laboratory frame). We derive a relation between the NBS wave function in the laboratory frame and the energy-independent non-local potential (HAL QCD potential), and propose the time-dependent method to extract the potential from correlation functions in the laboratory frame. We then apply this formulation to the $I = 2$ $π π$ system to calculate the corresponding potential in the laboratory frame, employing the 2+1 flavor gauge configuration on a $3 2^{3} \times 64$ lattice at the lattice spacing $a ≃ 0.091$ fm and $m_{π} ≃ 700$ MeV. While statistical errors are larger, the effective leading order (LO) potentials and corresponding phase shift agree with those from the HAL QCD potential in the center of mass (CM) frame. We also demonstrate the consistency in scattering phase shifts between the HAL QCD method in several frames and the finite volume method. The HAL QCD method in the laboratory frame enlarges applicabilities of the method to investigate hadron interaction including mesonic resonances such as $ρ$ and $σ$ .
hep-latPoS(2022)·3 citations
05*
Equation of State of dense QCD in external magnetic field
N. Yu. Astrakhantsev🇨🇭 · V. V. Braguta🇷🇺 · N. V. Kolomoyets🇷🇺 · A. Yu. Kotov🇩🇪 · A. A. Roenko🇷🇺
In this proceeding we present our first results of the study of the QCD Equation of State at non-zero baryon density and in external magnetic field. We focused on the first three non-vanishing expansion coefficients of pressure in chemical potential and their dependence on magnetic field. The study is carried out within lattice simulations with $N_{f} = 2 + 1$ dynamical quarks with physical quark masses. To overcome the sign problem, the simulations are carried out at imaginary baryon chemical potential. Our results suggest that external magnetic field considerably enhances the expansion coefficients and modifies their dependence on temperature.
hep-latPoS(2022)·4 citations
06*
Magnetic monopole dominance for the Wilson loops in higher representations
Akihiro Shibata🇯🇵 · Seikou Kato🇯🇵 · Kei-Ichi Kondo🇯🇵
The dual superconductor picture is one of the most promising scenarios for quark confinement. To investigate this picture in a gauge-invariant manner, we have proposed a new formulation of Yang-Mills theory, named the decomposition method, on the lattice. The so-called restricted field obtained from the gauge-covariant decomposition plays the dominant role in quark confinement. It has been known by preceding works that the restricted-field dominance is not observed for the Wilson loop in higher representations if the restricted part of the Wilson loop is obtained by adopting the Abelian projection or the field decomposition naively in the same way as done in the fundamental representation. Recently, through the non-Abelian Stokes theorem (NAST) for the Wilson loop operator, we have proposed suitable gauge-invariant operators constructed from the restricted field to reproduce the correct behavior of the original Wilson loop averages for higher representations. We have demonstrated the numerical evidence for the restricted-field dominance in the string tension. In this talk, we focus on the magnetic monopole. According to this picture, magnetic monopoles causing the dual superconductivity are the dominant degrees of freedom responsible for confinement. With the help of the NAST, we define the magnetic monopole and the string tension extracted from the magnetic-monopole part of the Wilson loop in a gauge-invariant manner. We will further perform lattice simulations to measure the static potential for quarks in higher representations using the proposed operators and examine the magnetic monopole dominance in the string tension, which means that the string tension extracted from the magnetic-monopole part of the Wilson loop reproduces the proper string tension obtained from the original Wilson loop.
hep-latPoS(2022)·0 citations
07*
Lattice determination of the pion mass difference $M_{π^{+}} - M_{π^{0}}$ at order $O (α_{e m})$ and $O ((m_{d} - m_{u})^{2})$ including disconnected diagrams
R. Frezzotti🇮🇹 · G. Gagliardi🇮🇹 · V. Lubicz🇮🇹 · G. Martinelli🇮🇹 · F. Sanfilippo🇮🇹 · S. Simula🇮🇹
We present our preliminary results concerning the charged/neutral pion mass difference $M_{π^{+}} - M_{π^{0}}$ at order $O (α_{e m})$ in the QED interactions, and for $M_{π^{+}} - M_{π^{0}}$ at order $O ((m_{d} - m_{u})^{2})$ in the strong isospin-breaking term. The latter contribution provides a determination of the $SU (2)$ chiral perturbation theory low-energy constant $ℓ_{7}$ , whose present estimate is affected by a rather large uncertainty. The disconnected contributions appearing in the diagrammatic expansion of $M_{π^{+}} - M_{π^{0}}$ , being very noisy, are notoriously difficult to evaluate and have been neglected in our previous calculations. By making use of twisted mass Lattice QCD simulations and adopting the RM123 method, we will show that taking profit from our recently proposed rotated twisted-mass (RTM) scheme, tailored to improve the signal on these kinds of observables, it is possible to evaluate the disconnected diagrams with good precision. For the QED induced pion mass difference, we obtain, after performing the extrapolation towards the continuum and thermodynamic limit and at the physical point, the preliminary value $M_{π^{+}} - M_{π^{0}} = 4.622 (95) MeV$ , that is in good agreement with the experimental result. For the determination of the low-energy constant $ℓ_{7}$ , our result $ℓ_{7} = 2.5 (1.4) \times 1 0^{- 3}$ , which is limited so far to a single lattice spacing, is in agreement and improves phenomenological estimates.
hep-lathep-phPoS(2022)·4 citations
08*
Gauge-fixed Lattice QCD and the dispersion relation of Wilson fermions
G. Burgio🇩🇪 · H. Vogt🇩🇪
We show that, when investigating Wilson-fermions correlation functions on the lattice, one is bound to encounter major difficulties in defining their dispersion relation, even at tree level. The problem is indeed quite general and, although we stumbled upon it while studying Coulomb-gauge applications, it also affects gauge fixed studies in covariant gauges, including their most popular version, Landau gauge. In this paper we will discuss a solution to this problems based on a redefinition of the kinematic momentum of the fermion.
hep-latEPJ Web Conf.(2022)·0 citations
09*
Spectral reconstruction in SU(4) gauge theory with fermions in multiple representations
Luigi Del Debbio🇬🇧 · Alessandro Lupo🇬🇧 · Marco Panero🇮🇹 · Nazario Tantalo🇮🇹
The naturalness problem in the Higgs sector finds a popular solution in composite Higgs models. In such theories the Higgs boson emerges as the pseudo-Nambu-Goldstone boson associated with the breaking of a global symmetry realised in a new, strongly interacting sector. We address a model arising in this context, a SU(4) gauge theory with fermions in two distinct representations. We present a novel lattice study of this theory, in which we address the non-perturbative reconstruction of spectral densities from lattice correlators.
hep-latPoS(2022)·17 citations
10*
Tensor-network study of the 3d $O (2)$ model at non-zero chemical potential and temperature
Jacques Bloch🇩🇪 · Robert Lohmayer🇩🇪 · Maximilian Meister🇩🇪
We present results of tensor-network simulations of the three-dimensional $O (2)$ model at non-zero chemical potential and temperature, which were computed using the higher-order tensor-renormalization-group method (HOTRG). This necessitated enhancements to the HOTRG blocking procedure to reduce the truncation error in the case of anisotropic tensors. Moreover, the construction of the truncated vector spaces was adapted to strongly reduce the effect of systematic errors in the computation of observables using the finite-difference method. Our (improved) HOTRG results for the evolution of the number density with the chemical potential are in agreement with results obtained with the worm algorithm, and both the Silver Blaze phenomenon at zero temperature and the temperature dependence of the number density can be adequately reproduced.
hep-latcond-mat.stat-mechPoS(2022)·3 citations
11*
Ab initio nuclear thermodynamics from lattice effective field theory
Bing-Nan Lu🇨🇳 · Ning Li🇨🇳 · Serdar Elhatisari🇹🇷 · Dean Lee🇺🇸 · Joaquín E. Drut🇺🇸 · Timo A. Lähde🇩🇪 · Evgeny Epelbaum🇩🇪 · Ulf-G. Meißner🇩🇪
We show that the {\it ab initio} calculations of nuclear thermodynamics can be performed efficiently using lattice effective field theory. The simulations use a new approach called the pinhole trace algorithm to calculate thermodynamic observables for a fixed number of protons and neutrons enclosed in a finite box. In this framework, we calculate the equation of state, the liquid-vapor coexistence line and the critical point of neutral symmetric nuclear matter with high precision. Since the algorithm uses a canonical ensemble with a fixed number of particles, it provides a sizable computational advantage over grand canonical ensemble simulations that can be a factor of several thousands to as much as several millions for large volume simulations.
↳ nucl-thcond-mat.stat-mechhep-latnucl-exPoS(2022)·0 citations
12*
The force-force-correlator in hot QCD perturbatively and from the lattice
Jacopo Ghiglieri🇫🇷 · Guy D. Moore🇩🇪 · Philipp Schicho🇫🇮 · Niels Schlusser🇫🇮
High-energy particles traversing a medium experience modified dispersion. In the Quark-Gluon Plasma, such dispersion affects jet propagation and transport properties and should be determined better. Above $\sim 2 T_{c}$ we expect strongly coupled infrared behavior and perturbative ultraviolet behavior, allowing a perturbative matching to an effective theory called EQCD, which can be studied non-perturbatively. We study the relevant non-local operator in EQCD at next-to-leading order which allows for a complete EQCD-to-lattice match and prepares the groundwork for a matching between EQCD and full QCD. Our results in EQCD show remarkable agreement between perturbation theory and the lattice in the expected regime.
↳ hep-phhep-latJHEP(2022)·16 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.