Charmed baryon spectroscopy and light flavour symmetry from lattice QCD

TL;DR

This study uses lattice QCD to compute the masses of various charmed baryons and mesons, examining their spectrum, flavor symmetry, and comparing results with experimental data to improve understanding of heavy-light hadron structures.

Contribution

The paper provides the first comprehensive lattice QCD calculation of both ground and excited states of singly and doubly charmed baryons with detailed analysis of flavor symmetry and discretisation effects.

Findings

Most baryons fit SU(3) multiplets with constrained extrapolations

Agreement with experimental masses and splittings for singly charmed baryons

Discretisation errors cause 10-20 MeV deviations in hyperfine splittings

Abstract

We determine the ground state and first excited state masses of singly and doubly charmed spin 1/2 and 3/2 baryons with positive and negative parity. Configurations with $N_f=2+1$ non-perturbatively improved Wilson-clover fermions were employed, with the same quark action also being used for the valence quarks, including the charm. The spectrum is calculated for pion masses in the range $M_\pi \sim 259-460$ MeV at a lattice spacing $a\sim 0.075$ fm. Finite volume effects are studied comparing lattices with two different linear spatial extents ($1.8\,{\rm fm}$ and $2.4\,{\rm fm}$). The physical point is approached from the SU(3) limit keeping the flavour averaged light quark mass fixed. The baryon masses are extrapolated using expansions in the strange-light quark mass difference. Most particles fall into the expected SU(3) multiplets with well constrained extrapolations, the exceptions having a possibly more complex internal structure. Overall agreement is found with experiment for the masses and splittings of the singly charmed baryons. As part of the calculation an analysis of the lower lying charmonium, $D$ and $D_s$ spectra was performed in order to assess discretisation errors. The gross spectra are reproduced, including the $D^*_{s0}$, $D_{s1}$ and $D_1$ mesons, while at this single lattice spacing hyperfine splittings come out $10-20$ MeV too low.