Related papers: e^+e^- Pair Production from $\gamma$ A Reactions
The invariant-mass spectrum of $e^+ e^-$ pairs produced in $^{12}$C+$^{12}$C collisions at an incident energy of 2 GeV per nucleon has been measured for the first time. The measured pair production probabilities span over five orders of…
Dilepton production has been measured with HADES, the "High Acceptance DiElectron Spectrometer". In pp collisions at 2.2GeV kinetic beam energy, exclusive eta production and the Dalitz decay eta -> gamma e+e- has been reconstructed. The…
Motivated by the ongoing analysis by the BESIII Collaboration on the single-tagged $e^+e^-\to e^+e^- \eta \pi^+\pi^-$ reaction, we present a phenomenological study of the diphoton fusion to $\eta \pi^+ \pi^-$, focusing on the production…
We present a study of the dijet invariant mass distribution for the reaction $\pbp \to 2 $jets$+\gamma+X$, at a center of mass energy of 1.8 TeV, using data collected by the CDF experiment. We compare the data to predictions for the…
Dilepton production in $pp$ and $Au+Au$ nucleus-nucleus collisions at $\sqrt{s}$ = 200 GeV as well as in $In+In$ and $Pb+Au$ at 158 A$\cdot$GeV is studied within the microscopic HSD transport approach. A comparison to the data from the…
The $\omega$-, $\rho$- and $\phi$-resonance production and their dileptonic decay in $\pi^- A$ reactions at 1.1 - 1.7 GeV/c are calculated within the intranuclear cascade (INC) approach. The invariant mass distribution of the dilepton pair…
We calculate the gauge-boson pairs $W^-Z$, $W^-\gamma$, $W^+W^-$, $ZZ$ productions in the $e^- \gamma$ collisions, where the photon beam is realized by the laser back-scattering method. These processes are important tests for the…
Positive pion and kaon production from Au+Au reactions have been measured as a function of beam energy over the range 2.0-10.7~AGeV. Both the kaon and the pion production cross-sections at mid-rapidity are observed to increase steadily with…
We calculate the cross sections for the single production of doubly-charged dileptons, both scalar and vector, at $e^+e^-$, $e\gamma$ and $\gamma\gamma$ colliders at $\sqrt{s}=500$ GeV and 1 TeV. The $e\gamma$ mode is by far the most…
Dilepton production in intermediate energy nucleus-nucleus collisions as well as in elementary proton-proton reactions is analysed within the UrQMD transport model. For C+C collisions at 1 AGeV and 2 AGeV the resulting invariant mass…
We study the reaction e+e- --> e+e-pi0 and measure the gamma gamma* --> pi0 transition form factor in the momentum transfer range from 4 to 40 GeV^2. The analysis is based on 442 fb^-1 of integrated luminosity collected at PEP-II with the…
Along with $\pi^0$ and $\eta$ mesons, a resonance structure in the invariant mass spectrum of two photons at $M_{\gamma\gamma}= 360 \pm 7 \pm 9$ MeV is observed in the reaction $d C\to\gamma + \gamma +X$ at momentum 2.75 GeV/c per nucleon.…
The production and decay of vector mesons ($\rho, \omega$) in pA and AA reactions is studied with particular emphasis on their in-medium spectral functions. It is explored within transport calculations if hadronic in-medium decays like…
We investigate the production of $e^+e^-$ pairs from $p + Be$ and nucleus-nucleus collisions from 2 GeV/A to 200 GeV/A within a covariant transport approach and focus on the dilepton angular anisotropies as a function of the dilepton…
We consider lepton pair production via two-hadron annihilation through various isoscalar vector mesons within hot, baryon-free matter. This is tantamount to constructing effective form factors which we model using a vector-meson-dominance…
Dilepton production provides a unique probe of the strong electromagnetic field produced in heavy-ion collisions. To map out the behavior of its transverse momentum broadening, we present a theoretical model based on the equivalent photon…
The inclusive reactions $pp \rightarrow e^+ e^- X$ and $np \rightarrow e^+ e^- X$ at the laboratory kinetic energy of 1.25 GeV are investigated in a model of dominance of nucleon and $\Delta$ resonances. Experimental data for these…
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,…
Dilepton invariant-mass spectra for heavy-ion collisions at SIS 18 and BEVALAC energies are calculated using a coarse-grained time evolution from the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model. The coarse-graining of the…
We investigate the discovery potential of the $a_1(1260)$ photoproduction in the $\gamma p \to a_1(1260)^+ n$ and $\gamma p \to \pi^+\pi^+\pi^- n$ reactions via the $\pi$-exchange mechanism. For the $\gamma p \to \pi^+\pi^+\pi^- n$…