The role of $N^{\ast }(1535)$ in $pp\to pp\varphi$ and ${\pi }^{-}p\to n\varphi$ reactions

Abstract

The near threshold $\varphi$ meson production in proton-proton and ${\pi }^{-}p$ collisions is studied with the assumption that the production mechanism is due to the sub-$N\varphi$-threshold $N^{\ast }(1535)$ resonance. The ${\pi }^0$, $\eta$ and ${\rho }^0$-meson exchanges for proton-proton collisions are considered. It is shown that the contribution to the $pp\to pp\varphi$ reaction from the t-channel ${\pi }^0$ meson exchange is dominant. With a significant $N^{\ast }(1535)N\varphi$ coupling ($g_{N^{\ast }(1535)N\varphi }^2/4\pi$ = 0.13), both $pp\to pp\varphi$ and ${\pi }^{-}p\to n\varphi$ data are very well reproduced. The significant coupling of the $N^{\ast }(1535)$ resonance to $N\varphi$ is compatible with previous indications of a large $s\bar{s}$ component in the quark wave function of the $N^{\ast }(1535)$ resonance and may be the real origin of the significant enhancement of the $\varphi$ production over the naive OZI-rule predictions.

Comments: 15 pages, 6 figures