Apparent and Actual Shifts in Mass and Width of ϕ Mesons Produced in Heavy-Ion Collisions

Abstract

We present a method of analyzing invariant-mass spectra of kaon pairs resulting from decay of φ mesons produced in high-energy heavy-ion collisions.It can be used to extract the shifts in the mass and the width (∆M and ∆Γ) of the φ mesons when they are inside the dense matter formed in these collisions. We illustrate our method with the help of available preliminary data.Extracted values of ∆M and ∆Γ are significantly larger than those obtained with an earlier method. Our results are consistent with the experimentally observed p T dependence of the mass shift. Finally, we present a phenomenological relation between ∆M and ∆Γ. It provides a useful constraint on theories which predict the values of these two quantities.1

Mass dependence of inclusive nuclear φ photoproduction

“…Several proposals to test the φ properties in a nuclear medium have been done, for instance, regarding the detection of its decay products in A−A and p−A collisions [24,11]. Particularly a method to analyse the invariant mass spectra of the emitted charged kaon pairs was studied in [25]. Having into account that the calculations in [3,7,20,23] were done for a φ at rest in the nucleus, it has been suggested to determine this large width using reactions like π − p → φn in nuclei [7] and φ photoproduction in nuclei [26], assuming the φ to emerge with a small momentum.…”

Chiral unitary theory: Application to nuclear problems

“…The total width of the φ that we obtain is about 22 MeV at ρ = ρ 0 , about a factor two smaller than the one obtained in [51,52], yet, the important message is the nearly one order of magnitude increase of the width with respect to the free one. We are hopeful that in the near future one can measure the width of the φ in the medium, from heavy ion reactions or particle nucleus interactions, although it will require careful analyses as shown in [54] for the case of K K production in heavy ion collisions, where consideration of the possibility that the observed kaons come from φ decay outside the nucleus leads to nuclear φ widths considerably larger than the directly observed ones.…”

Collision broadening of the φ meson in baryon rich hadronic matter

“…The topic of this paper, the width of the φ, has also been studied previously. These studies, however, have focused on effects resulting from a φ mass dropping scenario due to chiral symmetry restoration, or similarly, through kaon mass dropping effects [11,13,[15][16][17][18][19]. This work presents a systematic study of φ dynamics by calculating the change in the width of the φ through scattering with other particles in the medium.…”