Proton decay with a light gravitino or axino

Abstract

We consider proton decay in supersymmetric models with a, gravitino or axino lighter than the proton, This consideration leads to a stringent limit on the R-parity and B-violating Yukawa coupling of the superpotential operator (UjDjDkc)-D-c-D-c as lambda(112)''less than or equal to 10(-15)(m(3/2)/eV) for a light gravitino, and lambda(112)''less than or equal to 10(-15)(F-a/10(10) GeV) for light Dine-Fischler-Srednicki-Zhitnitskii axino. For the hadronic axino, the constraint is weakened bg a factor of 10(3).