NN→NNπ reaction near threshold in a covariant one-boson-exchange model

Shyam, Radhey; Mosel, U.

doi:10.1016/s0370-2693(98)00297-4

Cited by 33 publications

(37 citation statements)

References 30 publications

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“…1 indeed turned out to give the correct energy dependence of the total cross-section [3]. Several authors [4][5][6][7][8][9] concluded from this observation that it is appropriate to calculate the transition NN → NNx to lowest order in perturbation theory and just include the final state interaction (FSI) by using a formula of the type in eq. 1; they implement the FSI by use of just the on-shell NN T -matrix, not only to get the right energy dependence of the cross-section, but also to get the strength of the matrix elements.…”

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confidence: 95%

“…9 must depend on the regularization scheme in such a way to compensate for the regularization dependence of P(E, p ′ ). At this stage one has to conclude that the procedure of just evaluating M in the on-shell tree level approximation and simply multiplying it with the on-shell NN T -matrix without consistency between the NN scattering and production amplitudes (as it was done in [4][5][6][7][8][9]) is not acceptable in order to obtain quantitative predictions. In the appendix we develop a simple model in order to gain more insight on this issue.…”

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confidence: 99%

“…It should be clear, however, that this does not fully disregard the results of refs. [4][5][6][7][8][9]: For the purpose of investigating the relative importance of different contributions to the production process the approach used there is still justified. Our criticism is not to the result of ref.…”

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confidence: 99%

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On the treatment of NN interaction effects in meson production in NN collisions

Hanhart

Nakayama

1999

Physics Letters B

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We clarify under what circumstances the nucleon-nucleon final state interaction fixes the energy dependence of the total cross-section for the reaction N N → N N x close to production threshold, where x can be any meson whose interaction with the nucleon is not too strong. We strongly criticize the procedure used recently by several authors to include the final state interaction in the reactions under discussion. In addition, we give a formula that allows one to estimate the effect of the initial state interaction for the production of heavy mesons. In the above equation q ′ is the momentum of the outgoing meson and A(E, p ′ ) is the NN → NNx transition amplitude, which, for future convenience, is

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On the treatment of NN interaction effects in meson production in NN collisions

Hanhart

Nakayama

1999

Physics Letters B

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“…The dotted line corresponds to the inverse of the squared Jost function, calculated using the formulas of references [29,30], also corrected for the Coulomb force. The presented prescriptions evidently differ significantly, especially for k larger than ≈ 50 MeV/c.…”

Section: Introductionmentioning

confidence: 99%

“…In this case |M pp→pp | 2 is a dimensionless factor which approaches zero as the relative proton momentum k→0, peaks sharply at k ≈ 25 MeV/c, and asymptotically approaches unity for large relative proton-proton momentum. The solid and dashed lines agree quite well for small relative protons momentum.The dotted line corresponds to the inverse of the squared Jost function, calculated using the formulas of references [29,30], also corrected for the Coulomb force. The presented prescriptions evidently differ significantly, especially for k larger than ≈ 50 MeV/c.…”

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S-wave η′-proton FSI; phenomenological analysis of near-threshold production of π0, η, and η′ mesons in proton-proton collisions

et al. 2000

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We describe a novel technique for comparing total cross sections for the reactions pp → ppπ 0 , pp → ppη, and pp → ppη ′ close to threshold. The initial and final state proton-proton interactions are factored out of the total cross section, and the dependence of this reduced cross section on the volume of phase space is discussed. Different models of the proton-proton interaction are compared. We argue that the scattering length of the S-wave η ′ -proton 1 interaction is of the order of 0.1 fm. PACS: 13.60. Le, 13.85.Lg, 29.20.Dh Typeset using REVT E X 2 New results on η and η ′ meson production in the reaction pp → ppX, measured very recently at the COSY-11 facility [1,2], together with previous data [3,4,5,6,7,8], determine the energy dependence of the near-threshold total cross section with a precision comparable to the measurements of the reaction pp → ppπ 0 [9,10]. These new data encouraged us to perform a phenomenological analysis similar to those of references [11,12,13]. Here we concentrate on π 0 , η, and η ′ meson production, and complete the analysis of these references by taking into account the interaction between the incident protons, and by introducing a new representation of the data. The production rates of π 0 , η, and η ′ mesons will be compared as a function of the available phase space. We will study the phase-space dependence of the quantity |M 0 | which is derived from the total cross section with the ISI and pp-FSI factored out. Consideration of the dependence of |M 0 | on phase space allows us to infer the η-proton and η ′ -proton interactions. To avoid large ambiguities due to differences in pp-FSI models, we normalize the |M 0 | for η and η ′ mesons to the one for the π 0 meson and show that the resulting η ′ -proton interaction is comparable to the π 0 -proton one.In general, the total cross section is presented as a function of the dimensionless parameter η M [9,10,12] 1 , which is defined as the maximum meson momentum in units of meson mass (η M = q max M ), or as a function of the center-of-mass excess energy Q [3,6,8], where nonrelativistically these variables are related by:with m p and M denoting the proton and meson mass, respectively. The above equationshows that the proportionality factor between the variables Q and η 2 M changes for different mesons, since the masses of the π 0 , η, and η ′ are distinct. Hence, depending which variable is selected, the relation between the cross section values changes for different mesons. For example, as shown in reference [4] the η meson production-cross-section exceeds the π 0 cross 1 In order to avoid ambiguities with the abbreviation for the eta-meson, we introduce an additional suffix M for this parameter, which usually is called η.3 section by about a factor of five using η M , whereas the π 0 meson cross section is always larger when employing the Q scale.The total cross section for pp → ppX is in general an integral over phase space, weighted by the square of the transition matrix element and normalized to the incoming fl...

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Strangeness production in proton—proton and proton—nucleus collisions

Shyam

2006

Pramana - J Phys

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In these lectures we discuss the investigation of the strange meson production in protonproton (pp) and in proton-nucleus (pA) reactions within an effective Lagrangian model. The kaon production proceeds mainly via the excitations of N * (1650), N * (1710), and N * (1720) resonant intermediate nucleonic states, in the collision of two initial state nucleons. Therefore, the strangeness production is expected to provide information about the resonances lying at higher excitation energies. For beam energies very close to the kaon production threshold the hyperon-proton final state interaction effects are quite important. Thus, these studies provide a check on the models of hyperon-nucleon interactions. The inmedium production of kaons show strong sensitivity to the self energies of the intermediate mesons.

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NN→NNπ reaction near threshold in a covariant one-boson-exchange model

Cited by 33 publications

References 30 publications

On the treatment of NN interaction effects in meson production in NN collisions

On the treatment of NN interaction effects in meson production in NN collisions

S-wave η′-proton FSI; phenomenological analysis of near-threshold production of π0, η, and η′ mesons in proton-proton collisions

Strangeness production in proton—proton and proton—nucleus collisions

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