Meson production in nucleon?nucleon collisions close to the threshold

Hanhart, C.

doi:10.1016/j.physrep.2004.03.007

Cited by 233 publications

(230 citation statements)

References 276 publications

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“…The number is even larger for all s and p waves. General formulae are given by Hanhart [76], specific ones for the present reaction by Uzikov [77]. For completeness we give the relations between partial wave amplitudes and helicity amplitudes similar to the previous section.…”

Section: Pd → η 3 He Reactionmentioning

confidence: 90%

Search for quasi boundηmesons

Machner

2015

J. Phys. G: Nucl. Part. Phys.

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The search for a quasi bound η meson in atomic nuclei is reviewed. This tentative state is studied theoretically as well as experimentally. The theory starts from elastic η nucleon scattering which is derived from production data within some models. From this interaction the η nucleus interaction is derived. Model calculations predict binding energies and widths of the quasi bound state. Another method is to derive the η nucleus interaction from excitation functions of η production experiments. The s wave interaction is extracted from such data via final state interaction theorem. We give the derivation of s wave amplitudes in partial wave expansion and in helicity amplitudes and their relation to observables. Different experiments extracting the final state interaction are discussed as are production experiments. So far only three experiments give evidence for the existence of the quasi bound state: a pion double charge exchange experiment, an effective mass measurement, and a transfer reaction at recoil free kinematics with observation of the decay of the state.

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Section: Pd → η 3 He Reactionmentioning

confidence: 90%

Search for quasi boundηmesons

Machner

2015

J. Phys. G: Nucl. Part. Phys.

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“…Indeed, an enhancement and/or a strong energy dependence of nearthreshold cross sections has been seen in many other reactions involving hadrons and is commonly seen as to be caused by FSI effects, cf. [33][34][35][36][37][38][39]. Thus, it is plausible and it even has to be expected that FSI effects play a role in the decay J/Ψ→γpp as well.…”

Section: J/ψ Decay Rate and Fsi Effectsmentioning

confidence: 99%

Near threshold enhancement of thepp¯mass spectrum inJ/Ψdecay

et al. 2005

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We investigate the nature of the near-threshold enhancement in the pp invariant mass spectrum of the reaction J/Ψ→γpp reported recently by the BES Collaboration. Using the Jülich NN model we show that the mass dependence of the pp spectrum close to the threshold can be reproduced by the S-wave pp final state interaction in the isospin I=1 state within the Watson-Migdal approach. However, because of our poor knowledge of the NN interaction near threshold and of the J/Ψ→γpp reaction mechanism and in view of the controversal situation in the decay J/Ψ→π 0 pp, where no obvious signs of a pp final state interaction are seen, explanations other than final state interactions cannot be ruled out at the present stage.

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“…3) [22]. This means that the traditional models still fail to describe the π 0 -production in pp-collisions (especially for the spin observables).…”

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confidence: 99%

“…Comparison of the model predictions (see the Ref. [22]) to the data (pp → ppπ 0 ) taken from Ref. [21], (pp → dπ + ) Ref.…”

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confidence: 99%