$\phi$ meson in nuclear matter and nuclei

Abstract

The mass and decay width of the φ meson in cold nuclear matter are computed in an effective Lagrangian approach, with the medium dependence of these properties obtained by evaluating kaon-antikaon loop contributions to the φ self-energy. At normal nuclear matter density, we find a downward shift of the φ mass by a few percent, while the decay width is enhanced by an order of magnitude. We also present φ -nucleus bound state energies and absorption widths for some selected nuclei, using complex optical potentials obtained in the local density approximation. Our results suggest that the φ should form bound states with all the nuclei considered. However, the identification of the signal for these predicted bound states will need careful investigation because of their sizable absorption widths.

$Υ$ and $η_b$ nuclear bound states

“…with cutoff parameter Λ B [21][22][23][24][56][57][58][59][60], for each ΥBB vertex. In a later section we will discuss the nonneglegible role played by this form factor and the cutoff parameter Λ B .…”

$η_{c}$-nucleus bound states

“…We now discuss the situation where the η c -meson is produced inside a nucleus A with baryon density distribution ρ A B (r). The nuclei we consider here are 4 He, 12 C, 16 O, 40 Ca, 48 Ca, 90 Zr, 197 Au, and 208 Pb. Their nuclear density distribution are also calculated within the QMC model, except for 4 He, whose parametrization was obtained in Ref.…”

“…It is worth stressing that compared to the situation for the lighter φ meson [40,41,42,43,44,45,46,47,48,49], which couples strongly to abovethreshold K K states, the charmonium states are expected to have a small width in medium. Moreover, since charmonia are heavier than the φ meson, they are expected to move slower than the φ meson once produced near threshold inside a nucleus.…”

“…We use the effective interaction Lagrangians in Eqs. ( 1)-(2) to compute the η c and J/Ψ self energies in vacuum and symmetric nuclear matter, following our previous works [17,18,19,20,45,46,47,48,49]. In this section we focus on the η c meson.…”