Charge symmetry breaking inHe4

Abstract

Calculations for $^{4}\mathrm{He}(\ensuremath{\gamma}, \mathrm{p})^{3}\mathrm{H}$ and $^{4}\mathrm{He}(\ensuremath{\gamma}, \mathrm{n})^{3}\mathrm{He}$ have been performed with the recoil-corrected continuum shell model. A charge-symmetry breaking interaction has been introduced in an effort to explain the large value (\ensuremath{\sim}2) observed in recent experiments for the cross section ratio $R=\frac{\ensuremath{\sigma}(\ensuremath{\gamma}, \mathrm{p})}{\ensuremath{\sigma}(\ensuremath{\gamma}, \mathrm{n})}$. The calculations indicate that it is highly unlikely that such a large value of the cross section ratio can be obtained within standard theoretical assumptions.NUCLEAR REACTIONS $^{4}\mathrm{He}(\ensuremath{\gamma}, \mathrm{p})$, ($\ensuremath{\gamma}, \mathrm{n}$), ${E}_{x}=20\ensuremath{-}36$ MeV; calculated $\ensuremath{\sigma}(E)$, expansion coefficients ${a}_{k}(E)$, ${B}_{k}(E)$ for $\ensuremath{\sigma}(E, \ensuremath{\theta})$, $P(E, \ensuremath{\theta})$. $^{3}\mathrm{H}$(p,n); calculated $A(E)$, $P(E)$. Studied influence of charge symmetry breaking interaction.