Production of eta-mesons in collisions of nucleons and delta-resonances

Abstract

Abstract. We calculate the cross section for the production of q-mesons via AN---+NN~ in a relativistic OneBoson-Exchange-Model. Using this cross section we then determine the probability for the production of an qmeson by a A-resonance moving in nuclear matter. The result is compared to prescriptions in BUU-calculations in which q-production proceeds both through a direct channel and through the sequential process A-*Nn; nN ~ Nq. 13.60 cross sections used for the production processes involving resonances in the entrance channel; the BUU-calculations mentioned just use an ad-hoc recipe for the direct reaction channel AN ~ NN meson and contain an explicit treatment of the sequential channel A --* Nn; nN --* Nq. PACS:It is thus the aim of this study to investigate the elementary production process in more detail in order to put the results on the dominance of resonance channels on a firmer ground. For this study we chose the process AN ~ NNq because all the interaction vertices occurring there are known from other processes.

Phi meson production cross sections in pion-baryon and baryon-baryon interactions

“…A pole thus develops in the pion propagator at some region of the phase space, which then leads to a singular cross section. Similar singularities appear also in N∆ → NΛK [21] and N∆ → NNη [22]. In both Ref.…”

“…In this letter, we shall introduce a boson-exchange model to calculate these cross sections. Similar models have been used previously to study pion [18], kaon [19][20][21], eta meson [22], and dilepton [23] production in nucleon-nucleon interactions in the same energy region.…”

“…[21] and Ref. [22], a complex pion self-energy has been introduced to remove the singularity. Since the pion self-energy is density dependent, the resulting cross section becomes density dependent, and diverges when the density approaches zero.…”

Kaons in dense matter, kaon production in heavy-ion collisions, and kaon condensation in neutron stars

“…As a result the cross section becomes singular. This kind of singularity also appears in N ∆ → N N η [64], N ∆ → N N φ [65], and πρ → πρ [66], via pion exchange. The same kind of singularity occurs in the process µ + µ − → eνW + , in which the µ can decay to eνν µ and the exchanged neutrino goes on-shell in the diagram, leading to a singular cross section [67].…”

The reactionΔ+N→N+N+φin ion-ion collisions

“…(10), (11), (14), and (15) one can find the following formula for the ratio of the total threshold cross sections of the processes ∆ + N → N + N + φ and p + p → p + p + φ in terms of the coupling constants and of the ratio x = h 2 /h 1 of the two possible amplitudes for the π + N → N + φ process:…”