A Search for $\phi $ Meson Nucleus Bound State Using Antiproton Annihilation on Nucleus

Abstract

Data on the production of η mesons on light nuclei near threshold are surveyed. The photoproduction of η 3 He and elastic scattering from this nucleus are modelled in a multiple scattering scheme and the positions of the poles both here and in the scattering from neighbouring light nuclei are studied in an optical potential approach. The production of η 7 Li is compared to that of η 3 He within a cluster model. The decay of light η-mesic nuclei through pion or nucleon emission is also considered.

$\phi$ meson in nuclear matter and nuclei

“…Furthermore, since the so-called dispersive effect of the absorptive potential is repulsive, the bound states disappear completely in some cases, even though they were found when the absorptive part was set to zero. This feature is obvious for the 4 He nucleus, making it especially relevant to the future experiments, planned at J-PARC and JLab using light and medium-heavy nuclei [5,6]. -4.0 (-5.9) 12.3 -8.9 (-10.0) 12.5 -12.6 (-13.4) 12.4 1p n (n) n n (n) n n (-1.5) n 208 φ Pb 1s -15.0 (-15.5) 17.…”

“…A large in-medium broadening of its decay width has been reported by most of the experiments performed, while only a few of them find evidence for a substantial mass shift [4]. The study of the φ -nucleus bound states [5,6] is complementary to the invariant mass measurements, where only a small fraction of the produced φ decay inside the nucleus, and may be expected to provide extra information on the φ properties at finite baryon density, since a downward mass shift of the φ in a nucleus is directly connected with the existence of an attractive potential between the φ and the nucleus where it has been produced. This new experimental approach will produce a slowly moving φ such that the maximum nuclear matter effect can be probed.…”

Partial restoration of chiral symmetry in cold nuclear matter: theϕ-meson case

“…This has been in part due to their potential to carry information on the partial restoration of chiral symmetry, and the possible role of QCD of van der Waals forces in the binding of quarkonia to nuclei. In particular, there is special interest on the φ-meson, the main reasons being: i) despite its nearly pure ss content, the φ-meson does interact strongly with a nucleus, composed predominantly of light u and d quarks, through the excitation of below-threshold virtual kaon and anti-kaon states that might have their properties changed in medium [6,7,8,9,10]; (ii) the φN interaction in vacuum [11,12,13,14]and a possible in-medium mass shift of the φ are related to the strangeness content of the nucleon [15], which may have implications beyond the physics of the strong interaction [16,17,18]; (iii) medium modifications of φ-meson properties have been proposed [19] as a possible source for the anomalous nuclear mass number A-dependence observed in φ-meson production from nuclear targets [20]; (iv) furthermore, as the φ-meson is a nearly pure ss state and gluonic interactions are flavor blind, studying it serves to test theories of the multiple-gluon exchange interactions, including long range QCD van der Waals forces [21], which are believed to play a role in the binding of the J/Ψ and other exotic heavy-quarkonia to matter [22,23,24,25,26,27,28,29,30,31,32,33]. Heavy-ion collisions and photon-or proton-induced reactions on nuclear targets have been used to extract information on the in-medium properties of hadrons.…”

“…[34], where only a small fraction of the produced φ-mesons decay inside the nucleus and may be expected to provide extra information on the φ-meson properties at finite baryon density. Along these lines, and motivated by the 3.4% mass reduction reported by the KEK-E325 experiment [34], the E29 collaboration at J-PARC has recently put forward a proposal [40,41] to study the in-medium mass modification of the φ-meson via the possible formation of φ-meson-nucleus bound states [31,42]. Furthermore, there is also a proposal at JLab, following the 12 GeV upgrade, to study the binding of φ and η mesons to 4 He [43].…”

“…Furthermore, there is also a proposal at JLab, following the 12 GeV upgrade, to study the binding of φ and η mesons to 4 He [43]. This new experimental approach [31,32,42,43] for the measurement of the φ-meson mass shift in nuclei, will produce a slowly moving φ-meson [31,32,42,43], where the maximum nuclear matter effect can be probed. In this way, one may indeed anticipate the formation of a φ-meson-nucleus bound state, where the φ-meson is trapped inside the nucleus.…”