Photoproduction of $ \eta{^\prime}$ -mesons off the deuteron

“…To date, although there are ongoing efforts to measure the beam asymmetry [13] and the beam-target asymmetry [14], experimental data for spin observables are not available yet for η production reactions. However, as we shall show in this work, the simultaneous consideration of the high-precision cross-section data in free γp → η p [4] that have only become available recently, together with the cross-section data on quasifree γ n → η n [6] and the invariant-mass-distribution data in pp → ppη [7], impose sufficient constraints to remove the ambiguity among various sets of possible spin-1 2 and - 3 2 resonances.…”

Section: Introductionmentioning

confidence: 98%

“…[1]. However, the situation has changed in the past few years, especially in η photoproduction, where high-precision data for both nucleon and deuteron targets have become available [3][4][5][6]. Also, the pp and pη invariant-mass distribution data in the pp → ppη reaction are now available [7], in addition to the cross-section data [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Combined analysis ofη′production reactions:γN→η′N,

2013

Self Cite

View full text Add to dashboard Cite

The production of η mesons in photon-and hadron-induced reactions has been revisited in view of the recent additions of high-precision data to the world data base. Based on an effective Lagrangian approach, we performed a combined analysis of the free and quasifree γ N → η N , NN → NNη , and πN → η N reactions. Considering spin-1 2 and -3 2 resonances, we found that a set of above-threshold resonances {S 11 , P 11 , P 13 }, with fitted mass values of about M R = 1925, 2130, and 2050 MeV, respectively, and the four-star subthreshold P 13 (1720) resonance reproduce best all existing data for the η production processes in the resonance-energy region considered in this work. All three above-threshold resonances found in the present analysis are essential and indispensable for the good quality of the present fits.

show abstract

Near-threshold η′ meson production in π−A reactions

Paryev

2019

Nuclear Physics A

View full text Add to dashboard Cite

We study the inclusive near-threshold production of η mesons in π − meson-nucleus reactions on the basis of the first-collision model relying on the nuclear spectral function and including incoherent processes of η production in π − meson-proton collisions. The model accounts for the absorption of initial π − and final η mesons, the binding of intranuclear protons and their Fermi motion, as well as the effect of the scalar η -nucleus potential (or the in-medium shift of the η meson mass) on these processes. We calculate the differential and total cross sections for η production off carbon and tungsten nuclei at laboratory angles of 0 • -10 • and 10 • -45 • by π − mesons with momentum of 1.7 GeV/c, which is close to the threshold momentum for η creation on a free target proton at rest. We show that the calculated η production cross sections are larger than those, studied earlier in the η photoproduction reactions, by about two orders of magnitude. We also demonstrate that the high absolute values of the present differential and total η production cross sections in the momentum ranges of 0.2-0.3 GeV/c and 0.1-0.6 GeV/c, respectively, possess a high sensitivity to changes in the in-medium shift of the η mass. This offers the possibility of evaluating the above shift at these momenta from the respective data, which could be taken in future experiments at the GSI pion beam facility or at J-PARC. arXiv:1906.02185v1 [nucl-th] 5 Jun 2019Studies of the η meson mass and its interaction in finite nuclei have received considerable interest in recent years due to the hope to extract valuable information on the partial restoration of chiral symmetry at finite density, on gluon dynamics in low-energy QCD, and on the possible formation of η bound states inside the nuclei (see, for example, Refs. [1,2]). Recent measurements of inclusive η photoproduction from carbon [3] and niobium [4] nuclear targets by the CBELSA/TAPS Collaboration in Bonn gave for the real part V 0 of the η -nucleus potential at saturation density ρ 0 (which is equal to the η meson mass shift in the medium) the combined value of V 0 = −(39 ± 7 stat ± 15 syst ) MeV [1,4] for average momentum of the produced η of ≈ 1.1 GeV/c. A new determination of the η -nucleus potential V 0 with lower average η momentum of 600 MeV/c was performed also by the CBELSA/TAPS Collaboration [5] by measuring the production of η mesons in coincidence with forward-going protons in photon-induced reactions on 12 C for initial photon energies of 1.3-2.6 GeV at the electron accelerator ELSA with the result V 0 = −(44 ± 16 stat ± 15 syst ) MeV, consistent with the above value for the potential V 0 , deduced from inclusive measurements for average η momentum of ≈ 1.1 GeV/c. The imaginary part W 0 of the η -nucleus optical potential was determined in [6] to be W 0 = −(13 ± 3 stat ± 3 syst ) MeV near-threshold from an extrapolation of the transparency ratio measurements on Nb at various η momenta well above threshold to near-threshold momenta. These numbers, with a small modulus of the imagin...

show abstract

Photoproduction of $ \eta{^\prime}$ -mesons off the deuteron

Cited by 51 publications

References 52 publications

Formation of $\eta{^\prime}$ (958) meson bound states by the 6Li( $\gamma$ ,d) reaction

Formation of $\eta{^\prime}$ (958) meson bound states by the 6Li( $\gamma$ ,d) reaction

Combined analysis ofη′production reactions:γN→η′N,

Near-threshold η′ meson production in π−A reactions

Contact Info

Product

Resources

About