Measurement of neutral-meson masses in meson-nucleus interactions at a momentum of 7 GeV/c at the Hyperon-M setup

The π 0 , η , K 0 , ω , and f 2 (1270) masses were measured at the HYPERON-Msetup in meson-nucleus interactions at a momentum of 7 GeV/ c by using six nuclear targets: Be, C, Al, Cu, Sn, and Pb. The experiment in question proved to be insensitive to the expected effects of a modification to the omega-meson mass in nuclear matter. As for the f 2 (1270) meson, its mass and width values averaged over all experimental data, = 1275.8 ± 1.0(stat.) ± 0.4(syst.) MeV/ c 2 and = 190.3 ± 1.9(stat.) ± 1.8(syst.) MeV/ c 2 , agree well with the world-average values. At the same time, our experimental data do not rule out the possible effect of an in-medium modification to the f 2 (1270)-meson mass for heavy nuclei at a level better than 0.4%.