Orbifold equivalence and the sign problem at finite baryon density

TL;DR

This paper demonstrates that SO(2N_c) gauge theory lacks a sign problem at finite baryon density, enabling lattice simulations that can provide insights into QCD at finite chemical potential through orbifold equivalence.

Contribution

It shows the absence of a sign problem in SO(2N_c) gauge theory at finite density and establishes conditions for orbifold equivalence to QCD, facilitating lattice studies of dense matter.

Findings

SO(2N_c) theory has no sign problem at finite mu_B.

Orbifold equivalence relates observables in SO(2N_c) theory to QCD.

Potential to study QCD at finite density via lattice simulations of SO(2N_c).

Abstract

We point out that SO(2N_{c}) gauge theory with N_{f} fundamental Dirac fermions does not have a sign problem at finite baryon number chemical potential \mu_{B}. One can thus use lattice Monte Carlo simulations to study this theory at finite density. The absence of a sign problem in the SO(2N_{c}) theory is particularly interesting because a wide class of observables in the SO(2N_{c}) theory coincide with observables in QCD in the large N_{c} limit, as we show using the technique of large N_{c} orbifold equivalence. We argue that the orbifold equivalence between the two theories continues to hold at \mu_{B} \neq 0 provided one adds appropriate deformation terms to the SO(2N_{c}) theory. This opens up the prospect of learning about QCD at \mu_{B} \neq 0 using lattice studies of the SO(2N_{c}) theory.