Searcharxiv⌕ Search

arXiv subjects

Kalman Szabo

Publications and source records attributed to Kalman Szabo.

6 recordsLinked to original sources
arXiv2025

Reconstruction of the vector meson propagator using a generalized eigenvalue problem

For long distances in the euclidean time the vector-vector correlator ($ρ$) has an exponentially decreasing signal-to-noise ratio. However, the vector correlator not only consists of the vector meson but also receives contributions from a two-pion system with the same quantum numbers. We measure all two-pion propagators with an energy lower than the mass of the resting vector meson and employ a generalized eigenvalue problem (GEVP) to resolve the different contributing energy states. Using those we can reconstruct the propagator with a much smaller noise at large euclidean time distances. In this work we present an efficient way to measure two-pion propagators and our results on reconstruction of the vector meson propagator with staggered fermions in a $(6^3\times 8.5)\,\textrm{fm}^4$ box.

hep-lat↗
arXiv2015

Finite-volume corrections to the leading-order hadronic contribution to $g_μ-2$

We present preliminary results of a 2+1-flavor study of finite-volume effects in the lattice QCD computation of the leading-order hadronic contribution to the muon anomalous magnetic moment. We also present methods for obtaining directly the invariant hadronic polarization function, $Π(Q^2)$, and the Adler function at all discrete lattice values of $Q^2$, including $Q^2=0$. Results are obtained with HEX-smeared clover fermions.

hep-lat↗
arXiv2013

Leading-order hadronic contributions to $g_μ-2$

We present preliminary lattice results for the leading-order hadronic contribution to the muon anomalous magnetic moment, calculated with HEX-smeared clover fermions. In our calculation we include 2+1-flavor ensembles with pions at the physical mass.

hep-lat↗
arXiv2013

Lattice QCD at the physical point meets SU(2) chiral perturbation theory

We perform a detailed, fully-correlated study of the chiral behavior of the pion mass and decay constant, based on 2+1 flavor lattice QCD simulations. These calculations are implemented using tree-level, O(a)-improved Wilson fermions, at four values of the lattice spacing down to 0.054 fm and all the way down to below the physical value of the pion mass. They allow a sharp comparison with the predictions of SU(2) chiral perturbation theory (χPT) and a determination of some of its low energy constants. In particular, we systematically explore the range of applicability of NLO SU(2) χPT in two different expansions: the first in quark mass (x-expansion), and the second in pion mass (ξ-expansion). We find that these expansions begin showing signs of failure around M_π=300 MeV for the typical percent-level precision of our N_f=2+1 lattice results. We further determine the LO low energy constants (LECs), F=88.0 \pm 1.3\pm 0.3 and B^\msbar(2 GeV)=2.58 \pm 0.07 \pm 0.02 GeV, and the related quark condensate, Σ^\msbar(2 GeV)=(271\pm 4\pm 1 MeV)^3, as well as the NLO ones, l_3=2.5 \pm 0.5 \pm 0.4 and l_4=3.8 \pm 0.4 \pm 0.2, with fully controlled uncertainties. We also explore the NNLO expansions and the values of NNLO LECs. In addition, we show that the lattice results favor the presence of chiral logarithms. We further demonstrate how the absence of lattice results with pion masses below 200 MeV can lead to misleading results and conclusions. Our calculations allow a fully controlled, ab initio determination of the pion decay constant with a total 1% error, which is in excellent agreement with experiment.

hep-lat↗
arXiv2011

Fluctuations of conserved charges at finite temperature from lattice QCD

We present the full results of the Wuppertal-Budapest lattice QCD collaboration on flavor diagonal and non-diagonal quark number susceptibilities with 2+1 staggered quark flavors, in a temperature range between 125 and 400 MeV. The light and strange quark masses are set to their physical values. Lattices with Nt=6, 8, 10, 12, 16 are used. We perform a continuum extrapolation of all observables under study. A Symanzik improved gauge and a stout-link improved staggered fermion action is utilized. All results are compared to the Hadron Resonance Gas model predictions: good agreement is found in the temperature region below the transition.

hep-lat↗