Onset Transition to Cold Nuclear Matter from Lattice QCD with Heavy Quarks

TL;DR

This paper investigates the transition to cold nuclear matter using a three-dimensional effective lattice QCD theory with heavy quarks, revealing a first order phase transition at low temperatures.

Contribution

It introduces a new effective theory for heavy quarks with a mild sign problem, enabling the study of cold nuclear matter onset in lattice QCD.

Findings

First order phase transition at $_B  m_B$ as temperature approaches zero.

Agreement between Metropolis and complex Langevin algorithms.

Analytic strong coupling solution accurately describes the data.

Abstract

Lattice QCD at finite density suffers from a severe sign problem, which has so far prohibited simulations of the cold and dense regime. Here we study the onset of nuclear matter employing a three-dimensional effective theory derived by combined strong coupling and hopping expansions, which is valid for heavy but dynamical quarks and has a mild sign problem only. Its numerical evaluations agree between a standard Metropolis and complex Langevin algorithm, where the latter is free of the sign problem. Our continuum extrapolated data clearly show a first order phase transition building up at $\mu_B \approx m_B$ as the temperature approaches zero. An excellent description of the data is achieved by an analytic solution in the strong coupling limit.