Search for $\hat{I}{\cdot }^{\prime }$ bound nuclei in the ${}^{12}\mathrm{C}({\hat{I}}^3,p)$ reaction with simultaneous detection of decay products

Abstract

We measured missing mass spectrum of the ${}^{12}\mathrm{C}({\hat{I}}^3,p)$ reaction for the first time in coincidence with potential decay products from $\hat{I}{\cdot }^{\prime }$ bound nuclei. We tagged an ($\hat{I}\cdot +p$) pair associated with the $\hat{I}{\cdot }^{\prime }N\to \hat{I}\cdot N$ process in a nucleus. After applying kinematical selections to reduce backgrounds, no signal events were observed in the bound-state region. An upper limit of the signal cross section in the opening angle $\cos \hat{I}{¸}_{lab}^{\hat{I}\cdot p}<-0.9$ was obtained to be 2.2 nb/sr at the 90$\%$ confidence level. It is compared with theoretical cross sections, whose normalization ambiguity is suppressed by measuring a quasifree $\hat{I}{\cdot }^{\prime }$ production rate. Our results indicate a small branching fraction of the $\hat{I}{\cdot }^{\prime }N\to \hat{I}\cdot N$ process and/or a shallow $\hat{I}{\cdot }^{\prime }$-nucleus potential.

7 pages, 4 figures