Determination of the real part of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mi>η</mml:mi><mml:mo>′</mml:mo></mml:msup></mml:math>-Nb optical potential

Nanova, M.; Friedrich, Stefan; Metag, V.; Paryev, É. Ya.; Afzal, F.; Bayadilov, D.; Beck, R.; Becker, M.; Böse, S.; Brinkmann, Kai-Thomas; Credé, V.; Elsner, D.; Frommberger, F.; Grüner, M.; Gutz, E.; Hammann, Ch.; Hannappel, J.; Hartmann, J.; Hillert, W.; Hoffmeister, P.; Honisch, Christiane; Jude, T. C.; Kalischewski, F.; Keshelashvili, I.; Клейн, Ф.; Koop, K.; Krusche, B.; Lang, Μ.; Makónyi, K.; Messi, F.; Müller, J.; Müllers, J.; Piontek, D.; Rostomyan, T.; Schaab, D.; Schmidt, Ch.; Schmieden, H.; Schmitz, R.; Seifen, T.; Sowa, C.; Spieker, K.; Thiel, A.; Thoma, U.; Triffterer, T.; Urban, M.; Pee, H. van; Walther, Dirk; Wendel, Ch.; Werthmüller, D.; Wiedner, U.; Wilson, A.; Witthauer, L.; Wunderlich, Y.; Zaunick, Hans-Georg

doi:10.1103/physrevc.94.025205

Cited by 30 publications

(34 citation statements)

References 60 publications

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“…larger by about two orders of magnitude than the total cross section σ γN →η N for η photoproduction off the nucleon at incident photon energies around 2 GeV [3,22,23], studied in the CBELSA/TAPS η photoproduction experiments [3][4][5]. Therefore, the collected statistics in pion-induced η meson production experiment at beam momentum of 1.7 GeV/c is expected to be essentially higher than in the above experiments.…”

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confidence: 99%

“…Therefore, the collected statistics in pion-induced η meson production experiment at beam momentum of 1.7 GeV/c is expected to be essentially higher than in the above experiments. This offers the possibility to investigate the η effective scalar potential depth at substantially lower η momenta (∼ 200-300 MeV/c) compared to those, studied in the experiments [3][4][5], via the measurements of the η momentum distributions in π − A reactions at modern experimental facilities such as the GSI pion beam facility and J-PARC. In Eqs.…”

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confidence: 99%

“…where E η is the η total energy in vacuum. As indicated above, the potential depth V 0 of about -40 MeV was deduced in semi-exclusive [5] and inclusive [3,4] η photoproduction experiments for average η momenta of 0.6 and 1.1 GeV/c, respectively. Therefore, in this work it is natural to use the value V 0 = −40 MeV for the η mass shift V 0 at density ρ 0 for all studied η momenta.…”

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“…[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.…”

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

Paryev

2019

Nuclear Physics A

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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...

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Section: )mentioning

confidence: 99%

Section: )mentioning

confidence: 99%

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

Paryev

2019

Nuclear Physics A

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“…Then, another experiment called E16 experiment is planned at J-PARC. Besides, the η mesic nuclei experiments at GSI [18][19][20] and at the University of Bonn [21][22][23][24], and pp → ppη reaction experiment at the COSY accelerator complex [25] have been operated, regarding the investigation of the change of U (1) A axial anomaly in nuclear matter. Another η mesic nuclei experiments is ongoing at SPring-8 [26] (see Ref.…”

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Mass Modifications of Light Mesons in Nuclear Matter with the Three Flavor Extended Linear Sigma Model

Suenaga

Lakaschus

2019

Proceedings of the 8th International Conference on Quarks and Nuclear Physics (QNP2018)

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We study mass modifications of scalar, pseudo-scalar, vector, and axial-vector mesons in nuclear matter comprehensively using the three-flavor extended Linear Sigma Model (eLSM) and the twoflavor Parity Doublet Model (PDM). Nuclear matter is constructed by the one-loop approximation of the nucleon together with the meson mean fields. Correspondingly, we include one-loop corrections by the nucleons as well as the meson mean fields to define the meson masses in medium. As a result, we find all spin-0 meson masses except the pion, kaon, and the lightest scalar-isoscalar ones decrease at finite baryon density. The mass reduction of the η meson in nuclear matter supports the possibility of the formation of η mesic nuclei. For spin-1 mesons, masses of all axial-vector mesons decrease in medium, whereas density dependences of ρ and ω meson masses sufficiently depend on the value of chiral invariant mass (M0). Also, our results suggest M0 ≈ 0.8 GeV is preferable.1 Other extensions of the Linear Sigma Model can be possible by including tetraquark states [35][36][37], for example.

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