Björn Wellegehausen

The phase diagram of a gauge theory with fermionic baryons

The fermion-sign problem at finite density is a persisting challenge for Monte-Carlo simulations. Theories that do not have a sign problem can provide valuable guidance and insight for physically more relevant ones that do. Replacing the gauge group SU(3) of QCD by the exceptional group G2, for example, leads to such a theory. It has mesons as well as bosonic and fermionic baryons, and shares many features with QCD. This makes the G2 gauge theory ideally suited to study general properties of dense, strongly-interacting matter, including baryonic and nuclear Fermi pressure effects. Here we present the first-ever results from lattice simulations of G2 QCD with dynamical fermions, providing a first explorative look at the phase diagram of this QCD-like theory at finite temperature and baryon chemical potential.

Hadron masses and baryonic scales in

The QCD phase diagram at densities relevant to neutron stars remains elusive, mainly due to the fermion-sign problem. At the same time, a plethora of possible phases has been predicted in models. Meanwhile

G_2

G_2

-QCD at finite density

-QCD, for which the

Asymptotic safety on the lattice: The nonlinear O(N) sigma model

SU(3)

G2 gauge theories

gauge group of QCD is replaced by the exceptional Lie group

Spectroscopy of four-dimensional N = 1 supersymmetric SU(3) Yang-Mills theory

G_2

Two-dimensional N = 2 Super-Yang-Mills Theory

, does not have a sign problem and can be simulated at such densities using standard lattice techniques. It thus provides benchmarks to models and functional continuum methods, and it serves to unravel the nature of possible phases of strongly interacting matter at high densities. Instrumental in understanding these phases is that

Critical flavour number of the Thirring model in three dimensions

G_2

Four-Fermion Theories with Exact Chiral Symmetry in Three Dimensions

-QCD has fermionic baryons, and that it can therefore sustain a baryonic Fermi surface. Because the baryon spectrum of