Leptonic and charged kaon decay modes of the $\varphi$ meson measured in heavy-ion collisions at the CERN SPS

We report a measurement of $\varphi$ meson production in central Pb+Au collisions at E${}_{lab}$/A=158 GeV. For the first time in heavy-ion collisions, $\varphi$ mesons were reconstructed in the same experiment both in the K${}^{+}$K${}^{-}$ and the dilepton decay channel. Near mid-rapidity, this yields rapidity densities, corrected for production at the same rapidity value, of 2.05 ± 0.14(stat) ± 0.25(syst) and 2.04 ± 0.49(stat)±{0.32}(syst), respectively. The shape of the measured transverse momentum spectra is also in close agreement in both decay channels. The data rule out a possible enhancement of the $\varphi$ yield in the leptonic over the hadronic channel by a factor larger than 1.6 at 95% CL.