The reaction $\Delta +N\to N+N+\varphi$ in ion-ion collisions

Abstract

We study the threshold $\varphi$-meson production in the process $\Delta +N\to N+N+\varphi$, which appears as a possible important mechanism in high energy nuclei-nuclei collisions. The isotopic invariance of the strong interaction and the selection rules due to P-parity and total angular momentum result in a general and model independent parametrization of the spin structure of the matrix element in terms of three partial amplitudes. In the framework of one-pion exchange model these amplitudes can be derived in terms of the two threshold partial amplitudes for the process $\pi +N\to N+\varphi$. We predict the ratio of cross sections for $\varphi -$meson production in $pp$- and $\Delta N$-collisions and the polarization properties of the $\varphi$-meson, in $\Delta +N\to N+N+\varphi$, as a function of a single parameter, which characterizes the relative role of transversal and longitudinal $\varphi$-meson polarizations in the process $\pi +N\to N+\varphi$.

Comments: 10 pages 3 figures