arXiv subjects

J. N. Guenther

Publications and source records attributed to J. N. Guenther.

4 recordsLinked to original sources

arXiv2026

Equation of state of dense magnetized QCD matter via a robust analytic continuation

We compute the equation of state of dense and magnetized strongly interacting matter using lattice QCD at a non-zero value of the lattice spacing. Our simulations employ $2+1+1$ dynamical flavors of rooted staggered quarks with masses tuned to the physical point. To conform with experimental constraints, we impose strangeness neutrality and isospin asymmetry on our observables. We circumvent the sign problem by simulating imaginary values of the chemical potential and applying the $T'$-expansion scheme to carry out the analytic continuation of our observables to the real chemical potential axis. This novel scheme, adapted to the setup with nonzero magnetic fields, is demonstrated to produce significantly smaller systematic errors in the final observables, compared to the standard analytical continuation at fixed temperature, allowing for better-controlled extrapolations. Our results for the pressure, the entropy density and the interaction measure are tabulated for direct use in heavy-ion phenomenology applications.

hep-lat↗

arXiv2022

QED and strong isospin corrections in the hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon

Recently, the Budapest-Marseille-Wuppertal collaboration achieved sub-percent precision in the evaluation of the lowest-order hadronic vacuum polarization contribution to the muon $g_μ-2$ (arXiv:hep-lat/2002.12347v3). At this level of precision, isospin-symmetric QCD is not sufficient. In this contribution we review how QED and strong-isospin-breaking effects have been included in our work. Isospin breaking is implemented by expanding the relevant correlation functions to second order in the electric charge $e$ and to first order in $m_u-m_d$. The correction terms are then computed using isospin-symmetric configurations. The choice of this approach allows us to better distribute the available computing resources among the various contributions.

hep-lat↗

arXiv2021

Leading hadronic contribution to the muon magnetic moment from lattice QCD

We compute the leading order hadronic vacuum polarization (LO-HVP) contribution to the anomalous magnetic moment of the muon, $(g_μ-2)$, using lattice QCD. Calculations are performed with four flavors of 4-stout-improved staggered quarks, at physical quark masses and at six values of the lattice spacing down to 0.064~fm. All strong isospin breaking and electromagnetic effects are accounted for to leading order. The infinite-volume limit is taken thanks to simulations performed in volumes of sizes up to 11~fm. Our result for the LO-HVP contribution to $(g_μ-2)$ has a total uncertainty of 0.8\%. Compared to the result of the dispersive approach for this contribution, ours significantly reduces the tension between the standard model prediction for $(g_μ-2)$ and its measurement.

hep-lat↗

arXiv2021

Lattice QCD equation of state at finite chemical potential from an alternative expansion scheme

Taylor expansion of the equation of state of QCD suffers from shortcomings at chemical potentials $μ_B \geq (2-2.5)T$. First, one faces difficulties inherent in performing such an expansion with a limited number of coefficients; second, higher order coefficients determined from lattice calculations suffer from a poor signal-to-noise ratio. In this work, we present a novel scheme for extrapolating the equation of state of QCD to finite, real chemical potential that can extend its reach further than previous methods. We present continuum extrapolated lattice results for the new expansion coefficients and show the thermodynamic observables up to $μ_B/T\le3.5$.

hep-lat↗