相关论文: The dd -> 4He eta Reaction Near Threshold
The cross section for the dd -> 4He pi pi reaction is estimated near threshold in a two-step model where a pion created in a first interaction produces a second pion in a subsequent interaction. This approach, which describes well the rates…
The total cross section of the p d -> p d eta reaction has been measured at two energies near threshold by detecting the final proton and deuteron in a magneti spectrometer. The values are somewhat larger than expected on the basis of two…
A microscopic calculation of near-threshold eta-meson production in the reaction NN -> NNeta is presented. It is assumed that the eta meson is produced via direct emission and via elementary rescattering processes MN -> etaN of various…
Preliminary results of recent measurements of the near threshold eta meson production in the dp-->dp eta reaction are presented. The experiment was performed at the COSY-Juelich accelerator with the use of the COSY-11 detection system. Data…
The differential cross sections of $pD\to ^3He X$ reactions, where $X=\eta, \ \eta'\ ,\omega, \ \phi $, are calculated on the basis of a two-step mechanism involving the subprocesses $pp\to d\pi ^+$ and $\pi^+n\to Xp $. It is shown that…
The production rate for \eta' in pp ->pp \eta' at rest is calculated in a covariant one boson exchange model, previously applied to study pi^0 and \eta production in NN collisions. The transition amplitudes for the elementary BN -> eta' N…
The contributions of three different types of driving terms are included in the estimation of the pd -> pd eta reaction at low energies. Near threshold, it is predicted that a two-step model involving an intermediate pion should be the most…
Very recent data for the reaction gamma{d} --> eta{np} are analyzed within a model that includes contributions from the impulse approximation and next order corrections due to the np and eta{N} interactions in the final state. Comparison…
The production of $\eta'$ mesons in the reactions $pp\to pp\eta'$ and $pn\to pn\eta' $ at threshold-near energies is analyzed within a covariant effective meson-nucleon theory. The description of cross section and angular distributions of…
We study the inclusive near-threshold production of $\eta^\prime$ mesons in $\pi^-$ meson-nucleus reactions on the basis of the first-collision model relying on the nuclear spectral function and including incoherent processes of…
Total cross sections for the quasi-free pn --> pn eta reaction in the range from the kinematical threshold up to 20 MeV excess energy have been determined. At threshold they exceed corresponding cross sections for the pp --> pp eta reaction…
The two-step model with pi-, rho- and omega- exchanges taken into account is applied to investigate the reactions pn -> d eta and pn -> d eta-prime. The existing experimental data on the reaction pn -> d eta are analysed and predictions for…
In June 2008 we performed a search for the 4He-eta bound state by measuring the excitation function of the dd to 3He p pi- reaction near the eta production threshold using the WASA-at-COSY detector. During the experimental run the momentum…
We evaluate the threshold matrix-element for the reaction $pp \to pp\pi^0$ in a fully relativistic Feynman diagrammatic approach. We employ a simple effective range approximation to take care of the S-wave $pp$ final-state interaction. The…
The total cross section for the near threshold eta production in proton-proton collisions has been investigated with the assumption that the production mechanism is due to the emission of a meson x (pi, eta, sigma) from one of the nucleons…
It is shown that the striking energy variation in the $p\, d \rightarrow \mbox{$^{\, 3}{\rm He}$}\, \eta$ cross section near threshold is probably due to a final state interaction associated with a large (complex) $\eta -\mbox{$^{3}{\rm…
Measurements of the analysing power for the p(pol)p --> ppeta reaction have been performed in the close-to-threshold energy region at beam momenta of p_{beam}=2.010 and 2.085 GeV/c, corresponding to excess energies of Q=10 and 36 MeV,…
The $\pi$, $\eta$ and $\rho$ exchange contributions to the cross-section for the reaction $pp\to pp\eta$ near threshold are calculated with a phenomenological description of the intermediate S11 (N(1535)) resonance for all exchange…
We consider the reaction g+d -> pi+d in a wide energy range around and above the eta-meson photoproduction threshold at backward CM angles of the outgoing pion. Our theoretical analysis is essentially motivated by the recent measurements of…
It is argued that the strong energy dependence of the $p\, d \rightarrow \,^{3\!}H\!e\, \eta$ cross section near threshold is due to a final state interaction between the $\eta$ meson and the $^3$He nucleus. The large scattering length that…