phi-Meson Mass Modification in Heavy-Ion Collisions

We recently presented a method of analyzing invariant-mass spectra of kaon pairs resulting from decay of $\varphi$ mesons produced in high-energy heavy-ion collisions. It can be used to extract the shifts in the mass and the width ($\mathrm{\Delta }M$ and $\mathrm{\Delta }\mathrm{\Gamma }$) of the $\varphi$ mesons when they are inside the dense matter formed in these collisions. We have now performed a Monte-Carlo simulation of this process. We illustrate our method with the help of available preliminary data. Extracted value of $\mathrm{\Delta }M$ is significantly larger than that obtained with an earlier method. Our results are consistent with the experimentally observed $p_T$ dependence of the mass shift.