Fri·Oct 8, 2021Friday·October 8, 2021

1. 01*

   Measuring charged particle polarizabilities on the lattice without background fields

   Walter Wilcox🇺🇸 · Frank X. Lee🇺🇸

   We show how to compute electromagnetic polarizabilities of charged hadrons without the use of background fields in lattice QCD. The low-energy behavior of the Compton scattering amplitude is matched to matrix elements of current-current correlation functions on the lattice. Working in momentum space, formulas for electric polarizability (${\alpha }_E$) and magnetic polarizability (${\beta }_M$) are derived for both charged pion and proton. Lattice four-point correlation functions are constructed from quark and gluon fields to be used in Monte-Carlo simulations. We also draw attention to the potential of four-point functions as a multi-purpose tool for hadron structure.

   hep-latPoS(2022)·0 citations
2. 02*

   The muon $g-2$ with four flavors of staggered quarks

   Christopher Aubin🇺🇸 · Thomas Blum🇺🇸 · Maarten Golterman🇺🇸 · Santiago Peris🇪🇸

   We present updated results for the light-quark connected part of the leading hadronic contribution to the muon $g-2$ from configurations with 2+1+1 flavors of HISQ quarks using the time-momentum representation of the electromagnetic current correlator. We have added statistics on two ensembles as well as a fourth lattice spacing using configurations that have been generated by the MILC collaboration at the physical pion mass. Additionally we account for the leading finite-volume and taste-breaking effects using Staggered Chiral Perturbation Theory at NNLO.

   hep-latPoS(2022)·2 citations
3. 03*

   Update on (2+1+1)-flavor QCD equation of state

   Johannes Heinrich Weber🇩🇪 · Alexei Bazavov🇺🇸 · Peter Petreczky🇺🇸

   We report on preliminary results from the calculations of the QCD equation of state for 2+1+1 flavors using HISQ action. The calculations are performed on lattices with temporal extents $N_{\tau }=6,8,10$, and $12$ and aspect ratio $N_{\sigma }/N_{\tau }=4$. We find that there is a significant contribution to the pressure from charm quarks at temperatures $T>300$ MeV.

   hep-lathep-phnucl-thPoS(2022)·5 citations
4. 04*

   A Parallel Computing Method for the Higher Order Tensor Renormalization Group

   Takumi Yamashita🇯🇵 · Tetsuya Sakurai🇯🇵

   In this paper, we propose a parallel computing method for the Higher Order Tensor Renormalization Group (HOTRG) applied to a $d$-dimensional $(d\ge 2)$ simple lattice model. Sequential computation of the HOTRG requires $O({\chi }^{4d-1})$ computational cost, where $\chi$ is bond dimension, in a step to contract indices of tensors. When we simply distribute elements of a local tensor to each process in parallel computing of the HOTRG, frequent communication between processes occurs. The simplest way to avoid such communication is to hold all the tensor elements in each process, however, it requires $O({\chi }^{2d})$ memory space. In the presented method, placement of a local tensor element to more than one process is accepted and sufficient local tensor elements are distributed to each process to avoid communication between processes during considering computation step. For the bottleneck part of computational cost, such distribution is achieved by distributing elements of two local tensors to ${\chi }^2$ processes according to one of the indices of each local tensor which are not contracted during considering computation. In the case of $d\ge 3$, computational cost in each process is reduced to $O({\chi }^{4d-3})$ and memory space requirement in each process is kept to be $O({\chi }^{2d-1})$.

   hep-latComput.Phys.Commun.(2022)·6 citations
5. 05*

   Universal microscopic spectrum of the unquenched QCD Dirac operator at finite temperature

   Gernot Akemann🇩🇪 · Tim R. Würfel🇬🇧

   In the $\epsilon$-regime of chiral perturbation theory the spectral correlations of the Euclidean QCD Dirac operator close to the origin can be computed using random matrix theory. To incorporate the effect of temperature, a random matrix ensemble has been proposed, where a constant, deterministic matrix is added to the Dirac operator. Its eigenvalue correlation functions can be written as the determinant of a kernel that depends on temperature. Due to recent progress in this specific class of random matrix ensembles, featuring a deterministic, additive shift, we can determine the limiting kernel and correlation functions in this class, which is the class of polynomial ensembles. We prove the equivalence between this new determinantal representation of the microscopic eigenvalue correlation functions and existing results in terms of determinants of different sizes, for an arbitrary number of quark flavours, with and without temperature, and extend them to non-zero topology. These results all agree and are thus universal when measured in units of the temperature dependent chiral condensate, as long as we stay below the chiral phase transition.

   ↳ math-phhep-lathep-thmath.MPJHEP(2021)·1 citation

* 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.