Modification of the $\varphi$-meson spectrum in nuclear matter

Abstract

The vacuum spectrum of the $\varphi$-meson is characterized by its decay into $K\bar{K}$. Modifications of the $K\bar{K}$-loops in baryonic matter change this spectrum. We calculate these in-medium modifications taking both s- and p-wave kaon-nucleon interactions into account. We use results of the in-medium $K$ and $\bar{K}$ spectra determined previously from a coupled channel approach based on a chiral effective Lagrangian. Altogether we find a very small shift of the $\varphi$ meson mass, by less than 10 MeV at normal nuclear matter density ${\rho }_0$. The in-medium decay width of the $\varphi$ meson increases such that its life time at $\rho ={\rho }_0$ is reduced to less than 5 fm/c. It should therefore be possible to observe medium effects in reactions such as ${\pi }^{-}p\to \varphi n$ in heavy nuclei, where the $\varphi$ meson can be produced with small momentum.

Comments: 10 pages, Latex 2.E ,3 figures in ps, submitted Physics Letters B