Monopole Catalysis of Nucleon Decay in Old Pulsars

The measured x-ray fluxes of old, nearby pulsars are used to constrain the monopole flux times the cross section for monopole-catalyzed nucleon decay. Observations of PSR 1929 + 10 provide the best limit: $F×{}{{σ}v}{(3×{}{10}^{{-}18} {cm}³ {s}^{{-}1})}<~2×{}{10}^{{-}22}$ ${cm}^{{-}2}$ ${sr}^{{-}1}$ ${s}^{{-}1}$. When the monopoles captured by the progenitor star while it was on the main sequence are taken into account, the limit becomes $F×{}{{σ}v}{(3×{}{10}^{{-}18} {cm}³ {s}^{{-}1})}<~2×{}{10}^{{-}28}$ ${cm}^{{-}2}$ ${sr}^{{-}1}$ ${s}^{{-}1}$.