The $\varphi$ meson width in the medium from proton induced $\varphi$ production in nuclei

We perform calculations for the production of $\varphi$ mesons in nuclei at energies just above threshold and study the $A$ dependence of the cross section. We use results for the $\varphi$ selfenergy in the medium obtained within a chiral unitary approach. We find a strong $A$ dependence which is tied to the distortion of the incident proton and to the absorption of the $\varphi$ in its way out of the nucleus. The effect of this latter process reduces the cross section in about a factor two in heavy nuclei proving that the $A$ dependence of the cross section bears valuable information on the $\varphi$ width in the nuclear medium. Calculations are done for energies which are accessible in an experimental facility like COSY.