Studies on the $K^{\ast }\Sigma$ bound-state via $K^{+}p\to K^{+}\varphi p$

Abstract

In the present work, we investigate the hidden-strangeness production process in the $S=+1$ channel via $K^{+}p\to K^{+}\varphi p$, focussing on the exotic \textit{pentaquark} molecular $K^{\ast }\Sigma$ bound state, assigned by $P_s^{+}(2071,3/2^{-})$. For this purpose, we employ the effective Lagrangian approach in the tree-level Born approximation. Using the experimental and theoretical inputs for the exotic state and for the ground-state hadron interactions, the numerical results show a small but obvious peak structure from $P_s^{+}$ with the signal-to-background ratio $\approx 1.7\%$, and it is enhanced in the backward-scattering region of the outgoing $K^{+}$ in the center-of-mass frame. We also find that the contribution from the $K^{\ast }(1680,1^{-})$ meson plays an important role to reproduce the data. The proton-spin polarizations are taken into account to find a way to reduce the background. The effects of the possible $27$-plet pentaquark ${\Theta }_{27}^{++}$ is discussed as well.

Comments: 10 pages, 15 figures, accepted for publication via PRD