Related papers: Neutral pion photoproduction at high energies
Photoproduction of the $\Lambda^*(1520)$ resonance of spin-parity ${3\over2}^-$ off the proton target is investigated within the Regge framework where the $t$-channel reggeization is applied for the $K(494)+K^*(892)+K_2^*(1430)$ exchanges…
This paper presents results from partial-wave analyses of the photoproduction reactions $\gamma p \rightarrow \eta p$ and $\gamma n \rightarrow \eta n$. World data for the observables \DSG, $\Sigma$, $T$, $P$, $F$, and $E$ were analyzed as…
The long-distance electromagnetic radiative corrections to tau- -> pi- pi0 nu are re-evaluated. A meson dominance model is used to describe the emission of real photons in this decay. Results obtained for the hadronic spectrum and the decay…
A theoretical study of $\bar{p}p \to \bar{p}n \pi^+ $ reaction for anti-proton beam energy from 1 to 4 GeV is made by including contributions from various known $N^*$ and $\Delta^*$ resonances. It is found that for the beam energy around…
We report calculations for exclusive pion photoproduction on nuclei beyond the first resonance region in the distorted wave impulse approximation. The elementary operator contains contributions from the resonances $P_{33}(1232)$,…
The $\sigma$-exchange and $f_2$-exchange mechanisms for $\rho$ meson photoproduction are re-examined. Then the commonly employed $\sigma$-exchange amplitude is revised by using the recent information from the analyses on the $\rho \to…
S-wave photoproduction of pion and kaon pairs on hydrogen is studied. Coupled channel final state interactions between different pseudoscalar mesons are included. Effective mass and momentum transfer distributions as well as total cross…
We report on a high statistics measurement of the cross section of the process gamma gamma to pi^+ pi^- in the center-of-mass energy range 0.8 GeV/c^2 < W < 1.5 GeV/c^2 with 85.9 fb^-1 of data collected at sqrt(s)=10.58 GeV and 10.52 GeV…
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…
The quasi-free $\gamma d\to\pi^{-}p(p)$ differential cross section has been measured with CLAS at photon beam energies $E_\gamma$ from 0.445 GeV to 2.510 GeV (corresponding to $W$ from 1.311 GeV to 2.366 GeV) for pion center-of-mass angles…
We report the first inclusive photon measurements about mid-rapidity (|y|<0.5) from Au+Au collisions at sqrt(s_{NN}) = 130 GeV at RHIC. Photon pair conversions were reconstructed from electron and positron tracks measured with the Time…
[Background] Above the nucleon resonance region, the $N(e,e'\pi^\pm)N'$ data cannot be explained by conventional hadronic models. For example, the observed magnitude of the transverse cross section is significantly underestimated in a…
The two reactions $\gamma p\to K^+\Lambda$ and $\pi^-p\to K^0\Lambda$ are analyzed to determine the leading photoproduction multipoles and the pion-induced partial wave amplitudes in slices of the invariant mass. The multipoles and the…
Based on the field-theory-inspired approach, a new expression for the pion form factor F_pi is proposed. It takes into account the pseudoscalar meson loops $\pi^+\pi^-$ and $K\bar K$ and the mixing of $\rho(770)$ with heavier $\rho(1450)$…
We present a detailed quark-model study of pion photoproduction within the effective Lagrangian approach. Cross sections and single-polarization observables are investigated for the four charge channels, $\gamma p\to \pi^+ n$, $\gamma n\to…
The existence of non-strange partner of pentaquark, the J^p = 1/2^+ narrow resonance, has been investigated by utilizing kaon photoproduction off a proton. It is found that the corresponding mass is 1650 MeV and the appropriate observables…
We report on a study of the reaction, $\gamma p \to p \pi^+\pi^+\pi^-\pi^-\pi^0$, at an incident photon energy of 19.3 GeV. The most significant feature of this reaction is $\Delta^{++}$ production which occurs with a cross section of…
We present consistent theoretical descriptions of the $\pi N \to e^+e^- N$ and $\gamma N \to e^+e^- N$ reactions on proton and neutron targets for total center of mass energies $\sqrt s$ ranging between 1.50 GeV and 1.75 GeV. These…
The $^{12}$C$(\gamma,ppn)$ reaction has been measured for E$_{\gamma}$=150-800 MeV in the first study of this reaction in a target heavier than $^3$He. The experimental data are compared to a microscopic many body calculation. The model,…
An effective Lagrangian calculation of pion photoproduction including all nucleon resonances up to $\sqrt s = 1.7$ GeV is presented. We compare our results to recent calculations and show the influence of different width parametrizations…