Finite density lattice QCD without extrapolation: Bulk thermodynamics with physical quark masses from the canonical ensemble

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Main Authors: Adam, Alexander, Borsányi, Szabolcs, Fodor, Zoltán, Guenther, Jana N., Pirelli, Ludovica, Parotto, Paolo, Pásztor, Attila, Wong, Chik Him
Format: Preprint
Published: 2026
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author Adam, Alexander
Borsányi, Szabolcs
Fodor, Zoltán
Guenther, Jana N.
Pirelli, Ludovica
Parotto, Paolo
Pásztor, Attila
Wong, Chik Him
author_facet Adam, Alexander
Borsányi, Szabolcs
Fodor, Zoltán
Guenther, Jana N.
Pirelli, Ludovica
Parotto, Paolo
Pásztor, Attila
Wong, Chik Him
contents Quantum Chromodynamics (QCD) at finite density is most often formulated on the lattice as a grand canonical ensemble. Since lattice QCD has a complex action problem at finite baryo-chemical potential ($μ_B$), its results at finite density are indirect: e.g. in the form of a set of expansion coefficients. In contrast, the canonical formulation offers direct results for integer-valued net-baryon number. In this work we present for the first time results in the canonical formulation with physical quark masses. To this end we use a high statistics finite-volume lattice ($16^3\times8$) data set that we generated at $μ_B=0$ with our 4HEX staggered action. We extend the canonical ensemble to non-integer net-baryon number and connect the results back to the grand canonical ensemble. Unlike reweighing to real $μ_B$, this method can also be used with rooted staggered quarks. For densities where the sign problem can be overcome by brute force computing power, this scheme provides lattice QCD results (e.g. for pressure, baryon density) directly, without relying on any extrapolation in the baryo-chemical potential. In this work we chart the phase diagram by studying bulk thermodynamic observables, which we show to be feasible up to $μ_B\approx500$~MeV.
format Preprint
id arxiv_https___arxiv_org_abs_2604_14117
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Finite density lattice QCD without extrapolation: Bulk thermodynamics with physical quark masses from the canonical ensemble
Adam, Alexander
Borsányi, Szabolcs
Fodor, Zoltán
Guenther, Jana N.
Pirelli, Ludovica
Parotto, Paolo
Pásztor, Attila
Wong, Chik Him
High Energy Physics - Lattice
Quantum Chromodynamics (QCD) at finite density is most often formulated on the lattice as a grand canonical ensemble. Since lattice QCD has a complex action problem at finite baryo-chemical potential ($μ_B$), its results at finite density are indirect: e.g. in the form of a set of expansion coefficients. In contrast, the canonical formulation offers direct results for integer-valued net-baryon number. In this work we present for the first time results in the canonical formulation with physical quark masses. To this end we use a high statistics finite-volume lattice ($16^3\times8$) data set that we generated at $μ_B=0$ with our 4HEX staggered action. We extend the canonical ensemble to non-integer net-baryon number and connect the results back to the grand canonical ensemble. Unlike reweighing to real $μ_B$, this method can also be used with rooted staggered quarks. For densities where the sign problem can be overcome by brute force computing power, this scheme provides lattice QCD results (e.g. for pressure, baryon density) directly, without relying on any extrapolation in the baryo-chemical potential. In this work we chart the phase diagram by studying bulk thermodynamic observables, which we show to be feasible up to $μ_B\approx500$~MeV.
title Finite density lattice QCD without extrapolation: Bulk thermodynamics with physical quark masses from the canonical ensemble
topic High Energy Physics - Lattice
url https://arxiv.org/abs/2604.14117