Search results for "scattering [WIMP nucleon]"
showing 10 items of 187 documents
Electroproduction of hyperons
1997
Abstract We present some estimates for the reaction ep → e ′ Σ + . At small scattering angles, the differential cross section is completely determined by the experimental data for the radiative decay Σ + → pγ . For kinematical values typical of the proposed parity experiment at MAMI, we find a suppression factor of about 5 · 10 −15 as compared to elastic electron scattering. On the basis of conservative models for the transition form factors, this ratio might increase by about a factor of 20 at backward angles. Even higher values could be expected if the presently unknown convection currents should turn out to be large. Due to the parity violation involved in this process, we also expect a …
Threshold Electroproduction of Charged Pions from Light Nuclei
1977
Double-differential cross sections for the electroproduction of pions of both charges have been measured. We compare the data obtained for production near threshold from $^{12}\mathrm{C}$ and $^{16}\mathrm{O}$ with theoretical treatments employing both shell-model and sum-rule nuclear descriptions with full inclusion of the final-state interaction.
Measurement of ϕ -meson production at forward rapidity in p+p collisions at s=510 GeV and its energy dependence from s=200 GeV to 7 TeV
2018
The PHENIX experiment at the Relativistic Heavy Ion Collider has measured the differential cross section of φ(1020)-meson production at forward rapidity in p+p collisions at s=510 GeV via the dimuon decay channel. The partial cross section in the rapidity and pT ranges 1.2
Reggeized model forηandη′photoproduction
2003
A Reggeized model for $\ensuremath{\eta}$ and ${\ensuremath{\eta}}^{\ensuremath{'}}$ photoproduction on the nucleon is presented. In this model, $t$-channel vector meson exchanges are described in terms of Regge trajectories to comply with the correct high energy behavior. We compare this Reggeized model with an isobar model ($\ensuremath{\eta}$-MAID), where the $t$-channel exchanges are described by $\ensuremath{\rho}$ and $\ensuremath{\omega}$ poles. Both models contain the same resonance contributions, and describe current $\ensuremath{\gamma}p\ensuremath{\rightarrow}\ensuremath{\eta}p$ data up to ${E}_{\ensuremath{\gamma}}^{\text{lab}}=2\phantom{\rule{0.3em}{0ex}}\text{GeV}$ quite well,…
First measurement of the helicity-dependent γ p↦pη differential cross-section
2003
The helicity dependence of the (γ) over right arrow(p) over right arrow -+ peta reaction has been measured for the first time at a center-of-mass angle theta(eta)*= 70degrees in the photon energy range from 780 MeV to 790 MeV. The experiment, performed at the Mainz microtron MAMI, used a 4pi-detector system, a circularly polarized, tagged photon beam. and a longitudinally polarized frozen-spin target. The helicity 3/2 cross-section is found to be small and the results for helicity 1/2 agree with predictions from the MAID analysis.
Testing electromagnetic proton form factors in the annihilation process p+p¯→π0+e−+e+
2011
We study the annihilation channel in proton antiproton collisions with production of a single neutral pion and an electron-positron pair. It is shown that this reaction allows access to the proton electromagnetic form factors in the ‘unphysical’ region and to the difference between complex phases of the Dirac and Pauli proton form factors. The differential cross section is given in the laboratory frame in an experimental setup where all outgoing particles are fully detected.
Role of pion exchange inηmeson photoproduction on the deuteron
2015
Incoherent $\ensuremath{\eta}$ photoproduction on the deuteron is studied, with the main emphasis on the role of final-state interactions. In addition to the previously studied mechanisms of $NN$ and $\ensuremath{\eta}N$ rescatterings, the role of an intermediate pion exchange is considered in detail, where first a pion is photoproduced on one nucleon and then rescatters into an $\ensuremath{\eta}$ meson on the other, the spectator nucleon. It is found that the role of this pion-mediated contribution is comparable in size to that of $\ensuremath{\eta}N$ rescattering. Results for total and semi-inclusive differential cross sections and associated polarization observables are presented. In pa…
Neutrino induced weak pion production off the nucleon and coherent pion production in nuclei at low energies
2009
We present a microscopic model for neutrino induced one-pion production off the nucleon and its implementation for the purpose of calculating coherent pion production in nuclei. We further criticize the use of the Rein--Sehgal model for coherent pion production by low energy neutrinos. In particular, we show how the approximations in that model give rise to a much flatter differential cross section in the $\eta=E_\pi(1-\cos\theta_\pi)$ variable. We discuss the limitations intrinsic to any approach based on the partial conservation of the axial current hypothesis and the inability of such models to properly determine the angular distribution of the outgoing pion with respect to the direction…
Photoproduction of η and η′ mesons with EtaMAID
2016
The unitary isobar model EtaMAID has been updated with an extended list of nucleon resonances, fitted to recent and new data for differential cross sections and polarization observables. The nonresonant background is described by Regge trajectories of ω,ρ and a 1 , b 1 mesons and in addition Regge cuts, where vector and axial vector mesons are exchanged together with Pomeron and f 2 mesons.
Photo-production of tensor mesons
2016
Assuming that the f 2 (1270), f ′2 (1525), a 2 (1320), and K * 2 (1430) resonances are dynamically generated states from the vector meson-vector meson interactions in L = 0 and spin 2, we study the γp → f 2 (1270)[f ′2 (1525)]p , γp → a 0 2 (1320)p , and γp → K * 2 (1430)Λ(Σ) reactions. For the γp → f 2 (1270)p reaction, we find that the theoretical results for the differential cross sections are in good agreement with the experimental measurements and provide support for the molecular picture of the f 2 (1270) in the first baryonic reaction where it has been tested. Furthermore, we predict also the total and differential cross sections for other reactions. The results can be tested in futu…