相关论文: Higher excitations of $\omega$ and $\phi$ in dilep…
We study the net dielectron production rates from an ensemble of thermal mesons, using an effective Lagrangian to model their interaction. The coupling between the electromagnetic and the hadronic sectors is done through the vector meson…
In this work, we investigate a novel production mechanism of vector mesons, exemplified by the production of a neutral vector meson associated with a lepton pair in $e^+e^-$ annihilation, i.e., $e^+e^-\to V l^+l^-$ ($V=J/\psi, \rho^0,…
We consider the reaction (gamma p) to (pi+ pi- p) at high energies. Our description includes dipion production via the resonances rho, omega, rho-prime and f2, and via non-resonant mechanisms. The calculation is based on a model of high…
We estimate the numbers and mass spectra of observed lepton and kaon pairs produced from $\phi$ meson decays in the central rapidity region of an Au+Au collision at lab energy 11.6 GeV/nucleon. The following effects are considered: possible…
Production of lepton pairs in gamma p -> e-e+ p reaction is studied at photon energies up to 1 GeV. We show that even if lepton charge is not measured there are extensive kinematical regimes where the nuclear process dominates over the…
Dilepton production from resonance scattering in hot hadronic matter is studied. Including the widths of these resonances, which enhance the phase space for dilepton production, we find that the production rate is significantly increased if…
Dielectron production in reactions $\pi^- p \rightarrow n e^+e^-$ and $\pi^- p \rightarrow n e^+e^- \gamma$ at energies less than 1 GeV is studied assuming electron-positron pair production to occur in the virtual time-like photon splitting…
We compute the production rate of lepton pair by static photons at finite temperature at two-loop order. We treat the infrared region of the gluon phase space carefully by using a hard thermal loop gluon propagator. The result is free of…
We present a model of electron-positron pair production in pion-nucleon collisions in the exclusive reaction \pi N -> Ne^+e^-. The model is based on an effective field theory approach, incorporating 16 baryon resonances below 2 GeV.…
We discuss two processes, the $\pi N \to e^+e^- N$ and the $\gamma N \to e^+e^- N$ reactions, below and close to the vector meson production threshold ($1.40<\sqrt s <1.75$ GeV). The aim is to gain understanding of the coupling of vector…
We present a unified description of the vector meson and dilepton production in elementary and in heavy ion reactions. The production of vector mesons ($\rho,\omega,\phi$) is described via the excitation of nucleon resonances ($R$). The…
We study the production of $K^+, \rho, \omega$ and $\phi$ mesons in $p + ^{12}C$ reactions on the basis of empirical spectral functions. The high momentum, high removal energy part of the spectral function is found to be negligible in all…
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 pion electromagnetic form factor at finite temperature is studied using an effective chiral lagrangian that includes explicitly vector mesons. We find that in the time-like region around the rho meson resonance it decreases with…
We study finite temperature effects on dilepton production from pion-pion annihilation in hot hadronic matter. The softening of the pion dispersion relation in a medium is found to enhance the production rate of dileptons with invariant…
We present a dynamical study of $e^+e^-$ production in $\pi^-$A reactions at 1.3 and 1.7 GeV on the basis of the Coupled-Channel-BUU approach. The contributions from vector mesons ($\rho,\omega$) are calculated taking into account the…
The invariant mass spectrum of the $e^{+}e^{-}$ and $\mu ^{+}\mu ^{-}$ pairs from decays of light unflavored mesons with masses below the $\phi (1020)$-meson mass to final states containing along with a dilepton pair one photon, one meson,…
We report on a search in $e^+e^-$ annihilations for new $\pi^0$-like particles produced in association with a $\tau$-lepton pair. These objects, with a similar mass and similar decay modes to $\pi^0$ mesons, could provide an explanation for…
We point out that formation time of pions produced in heavy ion collisions modifies the mass spectrum of dileptons produced via pipi -> ee annihilation. Increasing formation time enhances the production of dileptons with lower masses. The…
The $\pi^-p \to e^+e^- n$ and $\pi^+n \to e^+e^- p$ reaction cross sections are calculated below and in the vicinity of the vector meson ($\rho^0$, $\omega$) production threshold. These processes are largely responsible for the emission of…