arXiv subjects

Ruben Flores-Mendieta

Publications and source records attributed to Ruben Flores-Mendieta.

38 records · Page 3Linked to original sources

arXiv2000

On the structure of large N cancellations in baryon chiral perturbation theory

We show how to compute loop graphs in heavy baryon chiral perturbation theory including the full functional dependence on the ratio of the Delta--nucleon mass difference to the pion mass, while at the same time automatically incorporating the 1/N cancellations that follow from the large-N spin-flavor symmetry of baryons in QCD. The one-loop renormalization of the baryon axial vector current is studied to demonstrate the procedure. A new cancellation is identified in the one-loop contribution to the baryon axial vector current. We show that loop corrections to the axial vector currents are exceptionally sensitive to deviations of the ratios of baryon-pion axial couplings from SU(6) values.

hep-ph↗

arXiv1998

SU(3) symmetry breaking in hyperon semileptonic decays

Flavor SU(3) symmetry breaking in the hyperon semileptonic decay form-factors is analyzed using the 1/N expansion. A detailed comparison with experimental data shows that corrections to f_1 are approximately 10%, which agrees with theoretical expectations. Corrections to g_1 are compatible with first-order symmetry breaking. A fit to the experimental data allows one to predict the g_1 form factor for Xi^0 -> Sigma^+ decay. The proton matrix element of the T^8 component of the axial current (which is equal to 3F-D in the SU(3) symmetry limit) is found to be approximately 0.34.

hep-ph↗