Proton Decay with a Light Gravitino or Axino

Abstract

We consider the 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 U^c_i D^c_j D^c_k as $\lambda {"}_{112}<10^{-15}(m_{3/2}/eV)$ for a light gravitino, and $\lambda {"}_{112}<10^{-15}(F_a/10^{10}GeV)$ for a light DFSZ axino. For hadronic axino, the constraint is weakened by the factor of 10^{3}.

Comments: 8 pages, RevTex