Measurement of the in-medium ϕ-meson width in proton–nucleus collisions

Polyanskiy, A.; Hartmann, Michael; Kiselev, Yu.T.; Paryev, É. Ya.; Büscher, M.; Chiladze, D.; Dymov, S.; Dzyuba, A.; Gebel, R.; Hejny, V.; Kämpfer, B.; Keshelashvili, I.; Koptev, V.; Lorentz, B.; Maeda, Yoshikazu; Merzliakov, S.; Mikirtytchiants, S.; Nekipelov, M.; Ohm, H.; Schade, H.; Serdyuk, V.; Sibirtsev, A.; Sinitsyna, V. Y.; Stein, H. J.; Ströher, H.; Trusov, S.; Valdau, Yu.; Wilkin, C.; Wüstner, P.

doi:10.1016/j.physletb.2010.10.050

Cited by 63 publications

(72 citation statements)

References 29 publications

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“…The screening of the φ production in the deuteron is found to be very small. This could be consistent with moderate changes of the screening of the φ production seen in nuclei [19,38,39]. This conclusion is in agreement with the recent experiment at Jefferson Lab.…”

Section: Discussionsupporting

confidence: 92%

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Theoretical study of incoherent φ photoproduction on a deuteron target

2012

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Abstract. We study the photoproduction of φ mesons in deuteron, paying attention to the modification of the cross section from bound protons to the free ones. For this purpose we take into account Fermi motion in single scattering and rescattering of φ to account for φ absorption on a second nucleon as well as the rescattering of the proton on the neutron. We find that the contribution of the double scattering for φ is much smaller than the typical cross section of γp → φp in free space, which implies a very small screening of the φ production in deuteron. The contribution from the proton rescattering, on the other hand, is found to be not negligible compared to the cross section of γp → φp in free space, and leads to a moderate reduction of the φ photoproduction cross section on a deuteron at forward angles if the LEPS set up is taken into account. The Fermi motion allows contribution of the single scattering in regions forbidden by phase space in the free case. In particular, we find that for momentum transferred squared close to the maximum value, the Fermi motion changes drastically the shape of dσ/dt, to the point that the ratio of this cross section to the free one becomes very sensitive to the precise value of t chosen, or the size of the bin used in an experimental analysis. Hence, this particular region of t does not seem the most indicated to find effects of a possible φ absorption in the deuteron. This reaction is studied theoretically as a function of t and the results are contrasted with recent experiments at LEPS and Jefferson Lab. The effect of the experimental angular cuts at LEPS is also discussed, providing guidelines for future experimental analyses of the reaction.

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Section: Discussionsupporting

confidence: 92%

“…Yet, sinceφ(p) is very sensitive to the momentum, we do not take q ex = p φ in the argument ofφ(p) in Eq. (39). This approximation allows us to factorize T For the φ meson propagator, we take its imaginary part, keeping the φ on-shell, as in Glauber theory, hence,…”

Section: Scattering Amplitudementioning

confidence: 99%

Theoretical study of incoherent φ photoproduction on a deuteron target

2012

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“…To do so we have compiled in Fig. 6 the excess yields integrated over the mass region M ee = 0.15 − 0.5 GeV/c 2 from all available reaction systems [6,8,9]. For comparison, inclusive π 0 and η multiplicities measured in photon calorimetry with the TAPS detector [10,11] are plotted as well.…”

Section: Results From A-a Collisionsmentioning

confidence: 99%

“…Results from p(γ) − A experiments are somehow controversial: while the E325 experiment at KEK claims [4] the observation of a mass drop of the ρ meson in the e + e − invariant mass spectrum according to the Brown-Rho scaling [5], investigations at JLAB (CLAS) [6] does not corroborate such a conclusion showing only slight broadening of the ρ. Transparency measurements for the ω at ELSA/MAMI (CBELSA-TAPS) [8] and JLAB [7], and φ at COSY (ANKE) [9], LEPS at Spring8 [10] indicate large absorption of both mesons. However, the extraction of the in-medium widths from the measured nuclear transparency is not straightforward and even model dependant (for a review see T. Rodrigez's contribution to this conference).…”

Section: Introductionmentioning

confidence: 99%

Hades Experiments: Investigation of Hadron In-medium Properties

Salabura¹,

Przygoda²

2014

Acta Phys. Pol. B

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Abstract.Hadron modifications in nuclear matter are discussed in connection to chiral symmetry restoration and/or hadronic many body effects. Experiments with photon, proton and heavy ion beams are used to probe properties of hadrons embedded in nuclear matter at different temperatures and densities. Most of the information has been gathered for the light vector mesons ρ, ω and φ. HADES is a second generation experiment operating at GSI with the main aim to study in-medium modifications by means of dielectron production at the SIS18/Bevelac energy range. Large acceptance and excellent particle identification capabilities allows also for measurements of strangeness production. These abilities combined with the variety of beams provided by the SIS18 allow for a characterization of properties of the dense baryonic matter properties created in heavy ion collisions at these energies. A review of recent experimental results obtained by HADES is presented, with main emphasis on hadron properties in nuclear matter.

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“…Results from p(γ) + A experiments have not yet produced a consistent picture: while the E325 experiment at KEK claims [5] the observation of a mass drop of the ρ meson in the e + e − invariant mass spectrum according to the Brown-Rho scaling [4], investigations at JLab (CLAS) [6,7] does not corroborate such a conclusion showing only a slight broadening of the ρ. Transparency measurements for the ω at ELSA/MAMI (CBELSA-TAPS) [8] and JLab [6,7], and φ at COSY (ANKE) [9], LEPS at SPring-8 [10] indicate large absorption of both mesons. However, the extraction of the in-medium widths from the measured nuclear transparency is not straightforward and remains model dependent.…”

Section: Introductionmentioning

confidence: 99%

In-medium hadron properties measured with HADES

Gumberidze¹

2014

Proceedings of XV International Conference on Hadron Spectroscopy — PoS(Hadron 2013)

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The High Acceptance DiElectron Spectrometer HADES is installed at the Helmholtzzentrum Für Schwerionenforschung (GSI) accelerator facility in Darmstadt (Germany). It investigates dielectron emission and strangeness production in the 1-3A GeV regime. In this energy regime HADES has measured hadrons and dielectron signals in C+C, Ar+KCl, p+p, d+p and p+Nb collisions. For the first time, e + e − pairs were reconstructed from quasi-free n+p sub-reactions by detecting the proton spectator from the deuteron breakup. Also for the first time dielectrons radiated from cold nuclear matter in a kinematic regime (low momenta) where strong medium effects are expected have been detected. In contrast to other experiments, the high acceptance of the HADES allows for a detailed analysis of electron pairs with low momenta relative to nuclear matter where modifications of the spectral functions of the vector mesons are predicted to be most prominent. An experimentally constrained N+N(nucleon-nucleon collision) reference spectrum was established. A direct comparison of the latter with the e + e − invariant mass distribution measured in the heavier system Ar+KCl at 1.76 AGeV shows an excess yield above the reference. This observation can be interpreted as the onset of an actual medium effect.

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Measurement of the in-medium ϕ-meson width in proton–nucleus collisions

Cited by 63 publications

References 29 publications

Theoretical study of incoherent φ photoproduction on a deuteron target

Theoretical study of incoherent φ photoproduction on a deuteron target

Hades Experiments: Investigation of Hadron In-medium Properties

In-medium hadron properties measured with HADES

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