Hadron Spectrum in a Two-Colour Baryon-Rich Medium

TL;DR

This study investigates the hadron spectrum in SU(2) lattice gauge theory with two flavors, revealing how diquark and meson states respond to increasing chemical potential, including superfluidity effects and possible bound states.

Contribution

It provides new insights into the behavior of hadron states under baryon-rich conditions, especially the emergence of superfluidity and meson-baryon degeneracies.

Findings

Diquark states respond to chemical potential as expected.

Onset of non-zero baryon density occurs at mu=m_pi/2.

Evidence suggests possible kaon-like bound states in the medium.

Abstract

The hadron spectrum of SU(2) lattice gauge theory with two flavours of Wilson quark is studied on an 8^3x16 lattice using all-to-all propagators, with particular emphasis on the dependence on quark chemical potential mu. As mu is increased from zero the diquark states with non-zero baryon number B respond as expected, while states with B=0 remain unaffected until the onset of non-zero baryon density at mu=m_pi/2. Post onset the pi-meson mass increases in accordance with chiral perturbation theory while the rho becomes lighter. In the diquark sector a Goldstone state associated with a superfluid ground state can be identified. A further consequence of superfluidity is an approximate degeneracy between mesons and baryons with the same spacetime and isospin quantum numbers. Finally we find tentative evidence for the binding of states with kaon quantum numbers within the baryonic medium.