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

• Main Authors: Xiu-Lei Ren, L. Alvarez-Ruso, Li-Sheng Geng, Tim Ledwig, Jie Meng, M.J. Vicente Vacas
• Format: Article
• Language: English
• Published: Elsevier 2017-03-01
• Series: Physics Letters B
• Subjects: Baryon chiral perturbation theory; Lattice QCD; Nucleon mass and sigma term
• Online Access: http://www.sciencedirect.com/science/article/pii/S037026931730031X

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 [1] is supported by comparing the effective parameters (the combinations of the 19 couplings) with the corresponding low-energy constants in the SU(2) sector [2]. 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. [2] that the SU(2) baryon chiral perturbation theory can be applied to study nf=2+1 lattice QCD simulations as long as the strange quark mass is close to its physical value.