Consistency between SU(3) and SU(2) covariant baryon chiral perturbation theory for the nucleon mass

摘要

Treating the strange quark mass as a heavy scale compared to the light quark mass, we perform a matching of the nucleon mass in the SU(3) sector to the two-flavor case in covariant baryon chiral perturbation theory. The validity of the 19 low-energy constants appearing in the octet baryon masses up to next-to-next-to-next-to-leading order is supported by comparing the effective parameters (the combinations of the 19 couplings) with the corresponding low-energy constants in the SU(2) sector . In addition, it is shown that the dependence of the effective parameters and the pion-nucleon sigma term on the strange quark mass is relatively weak around its physical value, thus providing support to the assumption made in Ref. that the SU(2) baryon chiral perturbation theory can be applied to study n f = 2 + 1 lattice QCD simulations as long as the strange quark mass is close to its physical value.