Related papers: Lepton pairs from thermal mesons
The production of high invariant mass opposite sign lepton pairs in proton-proton collisions at the LHC is dominated by the Drell-Yan process. In addition to this photon or Z exchange mediated mechanism, gamma-gamma collisions, where…
By introducing electromagnetic formfactors in the spacelike region we extend an effective, gauge invariant Lagrangian model considering Born terms, baryon resonances up to 1.7 GeV and vector meson contributions (Rho, Omega) to calculate…
The measurements of hadron and lepton-pair production cross sections and leptonic forward-backward asymmetries performed with the L3 detector at centre-of-mass energies between 130 GeV and 189 GeV are used to search for new physics…
We calculate the differential cross section and single-polarization observables for the reaction $\gamma p \to \Phi p$ within perturbative QCD, treating the proton as a quark-diquark system. The phenomenological couplings of gauge bosons to…
Recently, significant enhancements of $e^{+} e^{-}$ pair production at very low transverse momentum ($p_{T} < 0.15$ GeV/c) were observed by the STAR collaboration in peripheral hadronic A+A collisions. This excesses can not be described by…
Through the analysis of HELIOS-3 data on dilepton spectra, we demonstrate the importance of secondary processes for the dilepton production in heavy-ion collisions in the intermediate mass region. We find that, while the dilepton spectra in…
A simple schematic model anchored on the notion of hadronic freedom inferred from hidden local symmetry in the vector manifestation, the infinite tower of vector mesons in holographic QCD and "stickiness" of $\pi\pi$ interactions inferred…
The key results on lepton-pair production in ultra-relativistic nuclear collisions are shortly reviewed, starting at the roots of pp collisions in the seventies, and ending at the perspectives of the colliders RHIC and LHC. The presence is…
In this review we discuss the observable consequences of in-medium changes of hadronic properties in reactions with elementary probes, and in particular photons, on nuclei. After an outline of the theoretical method used we focus on a…
In this paper, we propose an observable counting a weighted difference between right-handed and left-handed lepton pairs, which is coined dilepton helical rate. The weight is the momentum difference of the lepton pairs projected onto an…
Electron-positron pairs can be produced via the Schwinger mechanism in the presence of strong electric fields. In particular, the fields involved in $\alpha$ decay and nuclear fission are strong enough to produce them. The energy of the…
We present a study of $\tau^+ \tau^-$ lepton pair production in Pb + Pb collisions at $\sqrt{s_{NN}}$ = 5.5 TeV. The larger mass of tau lepton compared to electron and muon leads to considerably small hadronic contribution to the $\tau^+…
The reaction e+ e- -> e+ e- gamma* gamma* -> e+ e- hadrons is analysed for quasi-real virtual photons using data collected by the L3 detector during the LEP high energy runs at sqrt(s) = 183 and 189 GeV. Preliminary results on the cross…
Based on a Lagrangian with a coupling of two gluons to J^pi=0^+ (the quantum numbers of the vacuum) which decay to q-qbar pairs, a model is presented, in which hadrons couple directly to the absolute vacuum of fluctuating gluon fields. By…
The properties of electromagnetic radiation from hot fireballs as created in ultra-relativistic heavy-ion collisions are reviewed. We first outline how the medium effects in the electromagnetic spectral function, which governs thermal…
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…
We study the double-charged vector-bilepton pair production and double-charged scalar-bilepton pair production {\it via} $p + p \longrightarrow Y^{++} + Y^{--} + X$ and $p + p \longrightarrow S_1^{++} + S_1^{--} + X$, where $Y$ and $S_1$…
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…
Chiral Lagrangians are used to compute the production rate of photons from the hadronic phase of relativistic nuclear collisions. Special attention is paid to the role of the pseudovector a_1 meson. Calculations that include reactions with…
We present a description of the production of a di-lepton pair (through Z boson and virtual photon) in association with at least two jets. This calculation adds to the fixed-order accuracy the dominant logarithms in the limit of large…