Theoretical description of the pd → pdη reaction near threshold

Tengblad, Ulla; Fäldt, Göran; Wilkin, C.

doi:10.1140/epja/i2005-10112-5

Cited by 11 publications

(26 citation statements)

References 14 publications

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“…However, due to the fact that there are three particles in the final state, the incorporation of the FSI is much more complicated in this reaction. One theoretical effort to understand these data is made in [126] where the authors essentially explore the role of different reaction mechanisms in the production amplitude, but do not include the FSI. In what follows we shall discuss Ref.…”

Section: 22mentioning

confidence: 99%

Interaction of eta mesons with nuclei

et al. 2013

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Back in the mid-1980s, a new branch of investigation related to the interaction of eta mesons with nuclei came into existence. It started with the theoretical prediction of possible exotic states of eta mesons and nuclei bound by the strong interaction and later developed into an extensive experimental program to search for such unstable states as well as understand the underlying interaction via eta-meson producing reactions. The vast literature of experimental as well as theoretical works that studied various aspects of eta-producing reactions such as the π(+)n → ηp, pd → (3)Heη, p (6)Li → (7)Be η and γ (3)He → η X, to name a few, had but one objective in mind: to understand the eta-nucleon (ηN) and hence the η-nucleus interaction which could explain the production data and confirm the existence of some η-mesic nuclei. In spite of these efforts, there remain uncertainties in the knowledge of the ηN and hence the η-nucleus interaction. Therefore, this review is an attempt to bind together the findings in these works and draw some global and specific conclusions which can be useful for future explorations.The ηN scattering length (which represents the strength of the η-nucleon interaction) using different theoretical models and analyzing the data on η production in pion, photon and proton induced reactions was found to be spread out in a wide range, namely, 0.18 ≤ Re aηN ≤ 1.03 fm and 0.16 ≤ Rm aηN ≤ 0.49 fm. Theoretical searches of heavy η-mesic nuclei based on η-nucleus optical potentials and lighter ones based on Faddeev type few-body approaches predict the existence of several quasibound and resonant states. Although some hints of η-mesic states such as (3)(η)He and (25)(η)Mg do exist from previous experiments, the promise of clearer signals for the existence of η-mesic nuclei lies in the experiments to be performed at the J-PARC, MAMI and COSY facilities in the near future. This review is aimed at giving an overall status of these efforts.

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Section: 22mentioning

confidence: 99%

Interaction of eta mesons with nuclei

et al. 2013

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“…A theoretical effort to understand the Uppsala data [3] was made earlier by Tengblad, Fäldt, and Wilkin [17]. In Ref.…”

Section: Introductionmentioning

confidence: 99%

“…In Ref. [17] the contribution of three different diagrams, namely, the pickup (a direct one-step mechanism of η production), the impulse approximation, and the two-step mechanism (here the η meson is produced in two steps via the pp → π + d and π + N → ηN reactions) to the cross section for the pd → pdη reaction is determined. The authors in Ref.…”

Section: Introductionmentioning

confidence: 99%

“…The authors in Ref. [17] conclude that the impulse approximation is in general negligible as compared to the other two diagrams, the two-step mechanism is dominant in the near threshold region and the contribution of the pickup diagram (referred to as the direct mechanism in the present work) increases with energy and matches the two-step contribution at an excess energy of Q = 95 MeV. The latter conclusions regarding the contributions of the two-step and pickup diagrams are in contrast to the findings of the present work as well as to existing literature on similar kind of reactions.…”

Section: Introductionmentioning

confidence: 99%

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Study of thepd→pdηreaction

et al. 2007

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A study of the pd → pdη reaction in the energy range where the recent data from Uppsala are available is done in the two-step model of η production including the final state interaction. The η−d final state interaction is incorporated through the solution of the Lippmann Schwinger equation using an elastic scattering matrix element, T ηd→ηd , which is required to be half off-shell. It is written in a factorized form, with an off-shell form factor multiplying an on-shell part given by an effective range expansion up to the fourth power in momentum. The parameters of this expansion have been taken from an existing recent relativistic Faddeev equation solution for the ηNN system corresponding to different η−N scattering amplitudes. Calculations have also been done using few body equations within a finite rank approximation to generate T ηd→ηd. The p−d final state interaction is included in the spirit of the Watson-Migdal prescription by multiplying the matrix element by the inverse of the Jost function. The η−d interaction is found to be dominant in the region of small invariant η−d mass, M ηd. The p−d interaction enhances the cross section in the whole region of M ηd , but is larger for large M ηd. We find nearly isotropic angular distributions of the proton and the deuteron in the final state. All the above observations are in agreement with the data. The production mechanism for the entire range of the existing data on the pd → pdη reaction seems to be dominated by the two-step model of η production.

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“…41. Near threshold it is predicted [262] that the two-step model, similar to that used to explain the threshold pd → 3 He η reaction, should dominate but, as Q approaches the threshold in nucleon-nucleon collisions, then the quasi-free pn → dη (pick-up) contribution becomes larger. In all cases the impulse approximation (triangle graph) is negligible.…”

Section: The Pd → Pdη Reactionmentioning

confidence: 99%

Production of η and η′ mesons on nucleons and nuclei

Krusche¹,

Wilkin²

2015

Progress in Particle and Nuclear Physics

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The production of η and η mesons in photon-and hadron-induced reactions on free and quasifree nucleons and on nuclei is reviewed. The extensive database on γN → ηN , for both proton and neutron targets, is described in detail and its implications for the search for N resonances much heavier than the dominant S 11 (1535) discussed. Though less is currently known about the production of the η or of ηπ pairs, these also offer tantalizing prospects in the search for the missing isobars. The more limited data available on pion-induced production are still necessary ingredients in the partial wave analysis discussed.The production of the η-meson in pp and pn collisions shows once again the strong influence of the S 11 (1535) isobar, which is in contrast to the relatively weak behaviour seen near threshold for η production. This difference is reflected in the important final state interaction effects of the η in nuclei that may even lead to this meson being "bound" in some systems. The evidence for this is reviewed for both γA and pA collisions. The inclusive photoproduction of η, η , and ηπ pairs from nuclei provides further information regarding the production mechanism and the interaction of the η and η with nuclei and the ηπ pairs may even allow access to low mass ηA systems that are forbidden in direct single-meson photoproduction.

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Theoretical description of the pd → pdη reaction near threshold

Cited by 11 publications

References 14 publications

Interaction of eta mesons with nuclei

Interaction of eta mesons with nuclei

Study of thepd→pdηreaction

Production of η and η′ mesons on nucleons and nuclei

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