Lifetime of bound states of negative pions and neutrons

Abstract

We estimate the lifetime of systems consisting of negative pions and neutrons (pineuts). We consider the direct decay of the pion as well as second-order diagrams involving the intermediate decay processes $n\ensuremath{\rightarrow}{p+e}^{\ensuremath{-}}+\overline{\ensuremath{\nu}}$ and ${\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{+e}^{\ensuremath{-}}+\overline{\ensuremath{\nu}}$ by assuming a simple single-particle model. We found that the dominant process is that with an intermediate neutron decay which leads to a lifetime of around ${10}^{\ensuremath{-}8}$ sec.