Baryon Chiral Perturbation Theory in Partially Quenched Large - N c QCD 1

Baryons of lower spin in partially quenched large-Nc QCD are studied with particular emphasis to interpolation between fully unquenched and fully quenched limits. In large Nc limit of partially quenched QCD, we calculate ∆m, the chiral one-loop correction to baryon masses. We find that leading order contribution to ∆m is independent of number of ghost quarks introduced. For finite Nc, ∆m does satisfy the Bernard–Golterman’s third theorem and has no infared quenching singularity except for fully quenched limit. At large Nc limit, however, we show that the third theorem is bypassed and non-trivial quenched chiral corrections do arise. In unquenched limit, we also show that standard chiral perturbation theory results are reproduced in which η′ loop contributions are explicitly taken into account. 1 Work supported in part by NSF Grant, NSF-KOSEF Bilateral Grant, KOSEF SRC-Program, Ministry of Education Grant BSRI 97-2418, and the Korea Foundation for Advanced Studies Faculty Fellowship.