Recently a peak structure was observed near the $K^{ -} p p$ threshold in the in-flight ${ }^{ 3} { \rm He} (K^{ -} , \, \Lambda p) n$ reaction of the E15 experiment at J-PARC, which could be a signal of a $\bar{ K} N N$ bound state. In order to investigate what is the origin of this peak, we calculate the cross section of this reaction, in particular based on the scenario that the $\bar{ K} N N$ bound state is indeed generated and decays into $\Lambda p$. We find that the numerical result of the $\Lambda p$ invariant-mass spectrum in the $\bar{ K} N N$ bound scenario is consistent with the J-PARC E15 data.
Categories: nucl-th hep-ph nucl-ex