相关论文: Direct photon production from viscous QGP
Direct photon production is an important process at hadron colliders, being relevant both for precision measurement of the gluon density, and as background to Higgs and other new physics searches. Here we explore the implications of…
Direct photon production in central Pb+Pb collisions at CERN-SPS energy is calculated within the relativistic microscopic transport model UrQMD, and within distinctly different versions of relativistic hydrodynamics. We find that in UrQMD…
We study the multiplicity and rapidity dependence of thermal and prompt photon production in p+Pb collisions at 5.02 TeV, using a (3+1)D viscous hydrodynamic framework. Direct photon anisotropic flow coefficients $v^\gamma_{2,3}$ and…
Based on the two-gluon-exchange dynamical mechanism for deeply inelastic scattering at low x ~= Q^2/W^2 <<1, we stress the intimate connection between the total virtual photoabsorption cross section, deeply virtual Compton scattering and…
The first results of a project in progress for the validation of the simulation of electron-positron pair production are presented. They concern the pair production cross section in a low energy range close to the production threshold. The…
Direct photon emission in heavy-ion collisions is calculated within a relativistic micro+macro hybrid model and compared to the microscopic transport model UrQMD. In the hybrid approach, the high-density part of the evolution is replaced by…
The recent status of hard thermal photon production in relativistic heavy ion collisions is reviewed and the current rates are presented with emphasis on corrected bremsstrahlung processes in the quark-gluon plasma (QGP) and quark-hadron…
Bright single photon emission from single quantum dots in suspended circular Bragg grating microcavities is demonstrated. This geometry has been designed to achieve efficient (> 50 %) single photon extraction into a near-Gaussian shaped…
We report a measurement of high-p_T inclusive pi^0, eta, and direct photon production in p+p and d+Au collisions at sqrt(s_NN) = 200 GeV at midrapidity (0 < eta < 1). Photons from the decay pi^0 -> gamma gamma were detected in the Barrel…
Using the extrapolation of existing data estimations of prompt photon production at FAIR energies have been made. At $y=y_{c.m.}$ the rapidity density of prompt photons with $p_{t}>$ 1.5 GeV/c per central Au+Au event at 25 AGeV is estimated…
The present theoretical knowledge about photons and hard photoproduction processes, i.e. the production of jets, light and heavy hadrons, quarkonia, and prompt photons in photon-photon and photon-hadron collisions, is reviewed. Virtual and…
We discuss the exclusive photoproduction of a photon-meson pair with large $ p_{T} $ as a channel to probe generalised parton distributions (GPDs). Like other $ 2\to3 $ exclusive processes, this channel allows us to better study the $ x…
Direct photon spectra measured at small $p_T$ in p+p, d+Au and Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV are presented. Several measurement techniques including statistical subtraction, tagging, and internal and external conversion were…
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…
Results on direct photon measurements from the PHENIX experiment at RHIC are presented. The direct photon yields for $p_T>$6 GeV/$c$ as a function of centrality in Au-Au collisions at $\sqrt{s_{NN}}$=200 GeV are found to be consistent with…
The DO and CDF experiments have measured prompt photon production using Run II data taken at a centre-of-mass energy sqrt(s) of 1.96 TeV. The results are compared to different types of perturbative QCD calculations.
Compton scattering of quasi-real virtual photons, gamma e+- -> gamma e+-, is studied with 0.6fb-1 of data collected by the L3 detector at the LEP e+e- collider at centre-of-mass energies root(s')=189-209GeV. About 4500 events produced by…
The near-threshold photo- and electroproduction of heavy vector quarkonia off the proton provides direct access to its gluonic structure. In particular, the cross section for $J/\Psi$ photoproduction near threshold is governed by the…
Direct photon production in association with a heavy quark can serve as an excellent tool for the study of the heavy quark distributions. Currently it is believed that heavy quarks are produced radiatively inside the nucleon, and so there…
We report on the results of the first measurement of exclusive $f_0(980)$ meson photoproduction on protons for $E_\gamma=3.0 - 3.8$ GeV and $-t = 0.4-1.0$ GeV$^2$. Data were collected with the CLAS detector at the Thomas Jefferson National…