Masses of the conjectured H-dibaryon at different temperatures

TL;DR

This study uses lattice QCD to determine the masses of the H-dibaryon and other baryons across various temperatures, revealing potential bound states and spectral density changes indicative of thermal effects.

Contribution

First lattice QCD calculation of H-dibaryon mass at multiple temperatures, analyzing spectral densities and bound state properties in a thermal environment.

Findings

H-dibaryon likely forms a bound state at low temperature

Spectral densities show rich structures at low temperatures

Mass differences suggest stability of the H-dibaryon below T_c

Abstract

We present a lattice QCD determination of masses of the conjectured H-dibaryon $m_H$ at nine different temperatures $T/T_c =0.24, 0.63, 0.76, 0.84, 0.95, 1.09, 1.27, 1.52, 1.90$. In the meantime, the masses of baryon $N$, $\Sigma$, $\Xi$ and $\Lambda$ at different temperatures are also computed. The simulation is performed on anisotropic lattice with $N_f=2+1$ flavours of clover fermion at quark mass which corresponds to $m_\pi=384(4) {\rm MeV} $. The thermal ensembles were provided by the FASTSUM collaboration and the zero temperature ensembles by the Hadspec collaboration. We also calculate the spectral density of the correlation function of those particles. The spectral density distributions show rich peak structure at the lowest temperature, while at intermediate temperatures, the mass values of those particles obtained by extrapolation method reflect a two-peak structure. While the spectral density for octet baryon becomes smooth at $T/T_c = 1.27, 1.52, 1.90$, the spectral density for H-dibaryon becoms smooth at $T/T_c = 1.90$. At $T/T_c =0.24 $, the mass difference of H-dibaryon and $\Lambda$ pair $\Delta m = m_H - 2\,m_{\Lambda} $ is estimated to be $\Delta m = -14.6(6.2) {\rm MeV}$ which suggests there exists a bound H-dibaryon state.