Low-lying baryon masses using twisted mass fermions ensembles at the physical pion mass

TL;DR

This study computes low-lying baryon masses using lattice QCD with twisted mass fermions at physical pion mass, providing results consistent with other recent findings and predicting masses for doubly and triply charmed baryons.

Contribution

First lattice QCD calculation of low-lying baryon spectrum at physical pion mass using twisted mass fermions with multiple ensembles and continuum extrapolation.

Findings

Baryon masses are consistent with experimental and other lattice results.

Isospin splitting is negligible at the lattice spacings used.

Predicted masses for doubly and triply charmed baryons.

Abstract

We investigate the low-lying baryon spectrum using three $N_f$=2+1+1 ensembles simulated with physical values of the quark masses and lattice spacings of 0.080, 0.069, and 0.057 fm. The ensembles are generated using twisted mass clover-improved fermions and the Iwasaki gauge action. The spatial length is kept approximately the same at about 5.1 fm to 5.5 fm fulfilling the condition $m_\pi L$> 3.6. We investigate isospin splitting within isospin multiples and verify that for most cases the isospin splitting for these lattice spacing is consistent with zero. In the couple of cases, for which there is a non-zero value, in the continuum limit, the mass splitting goes to zero. The baryon masses are extrapolated to the continuum limit using the three $N_f$=2+1+1 ensembles and are compared to other recent lattice QCD results. For the strange and charm quark masses, we find, respectively, $m_s$(2 GeV)=99.2(2.7) MeV and $m_c$(3 GeV)=1.015(39) GeV. The values predicted for the masses of the doubly charmed $\Xi_{cc}^\star$, $\Omega_{cc}$ and $\Omega_{cc}^\star$ baryons are 3.676(55) GeV, 3.703(51) GeV and 3.803(50) GeV, respectively, and for the triply charmed $\Omega_{ccc}$ baryon is 4.785(71) GeV.