Measurement of differential cross sections for $\hat{I}{\pounds }^{+}p$ elastic scattering in the momentum range 0.44-0.80 GeV/c

Abstract

We performed a novel $\hat{I}{\pounds }^{+}p$ scattering experiment at the J-PARC Hadron Experimental Facility. Approximately 2400 $\hat{I}{\pounds }^{+}p$ elastic scattering events were identified from $4.9\times 10^7$ tagged $\hat{I}{\pounds }^{+}$ particles in the $\hat{I}{\pounds }^{+}$ momentum range 0.44 -- 0.80 GeV/$c$. The differential cross sections of the $\hat{I}{\pounds }^{+}p$ elastic scattering were derived with much better precision than in previous experiments. The obtained differential cross sections were approximately 2 mb/sr or less, which were not as large as those predicted by the fss2 and FSS models based on the quark cluster model in the short-range region. By performing phase-shift analyses for the obtained differential cross sections, we experimentally derived the phase shifts of the ${}^3{S}_1$ and ${}^1{P}_1$ channels for the first time. The phase shift of the ${}^3{S}_1$ channel, where a large repulsive core was predicted owing to the Pauli effect between quarks, was evaluated as $20^{\circ }<|\hat{I}{´}_{{}^3{S}_1}|<35^{\circ }$. If the sign of $\hat{I}{´}_{{}^3{S}_1}$ is assumed to be negative, the interaction in this channel is moderately repulsive, as the Nijmegen extended-sort-core models predicted.