Related papers: Production of soft $e^+e^-$ Pairs in Heavy Ion Col…
This report presents double helicity asymmetry in inclusive $\pi^0$ production in polarized proton-proton collisions at a center-of-mass energy ($\sqrt{s}$) of 200 GeV. The data were collected with the PHENIX detector at the Relativistic…
We investigate different methods to incorporate the effect of photons in hard processes. We compare two different approaches used for calculating cross sections for two-photon $p p \to l^+ l^- X$ process. In one of the approaches photon is…
The cross section for exclusive heavy quark and heavy antiquark pair ($Q \bar Q$) production in peripheral ultrarelativistic heavy ion collisions is calculated for the LHC energy $\sqrt{s_{NN}}$ = 5.5 TeV. Here we consider only processes…
Superposition of jets of different flavors as well as superposition of jets of different topologies describe well observed structures (shoulder, H_q oscillations) in e+e- annihilation. The analysis of similar effects seen in experimental…
A new model of QCD parton shower is proposed which is dedicated to two-photon process in $e^+ e^-$ scattering. When hadron jets are produced, the photon may resolve into quark-antiquark pairs so that the structure functions of the photon…
PHENIX reports on electromagnetic and hadronic observables in large data sets of p+p, d+Au and Au+Au collisions at various cms energies. Initial state effects in cold nuclear matter are quantified by centrality dependent $\pi^0$, $\eta$,…
We present a detailed phenomenological study of direct photon production in association with a heavy-quark jet in pA collisions at the Relativistic Heavy Ion Collider (RHIC) and at the Large Hadron Collider (LHC) at next-to-leading order in…
We report on a measurement of hard photons (Eg>30 MeV) in the reaction Ar+Ca at 180A MeV at an energy in which photons from the decay of pi0 mesons are dominating. Simultaneous measurement with the TAPS spectrometer of the photon spectrum…
The planed HERA upgrade will increase the integrated luminosity by two orders of magnitude.A new program of electron-nucleus collisions at HERA is under discussion now.In this connection we present prospects for the study of a light neutral…
The strong electromagnetic fields of short duration associated with relativistic heavy ions make a heavy-ion collider a unique tool to study two-photon and photonuclear collisions. In this talk, we introduce the principles of…
In ultra-peripheral relativistic heavy ion collisions the beam ions scatter at impact parameters larger than the sum of their radii, so that they interact via long range electromagnetic forces. Due to the Lorentz-boost of the beam…
The multiplicity of charged particles produced in Au+Au collisions as a function of energy, centrality, rapidity and azimuthal angle has been measured with the PHOBOS detector at RHIC. These results contribute to our understanding of the…
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…
Thermal photons can provide information on the temperature of the new state of matter created at RHIC. In the p_T region of 1--3 GeV/c thermal photons are expected to be the dominant direct photon source. Therefore, a possible excess…
The baryon production mechanism at the intermediate $p_T$ (2 - 5 GeV/$c$) at RHIC is still not well understood. The beam energy scan data in Cu+Cu and Au+Au systems at RHIC may provide us a further insight on the origin of the baryon…
We confront the generally small cross sections for gluino pair production in e^+e^- annihilation with the much larger ones in photon-photon scattering at a multi-TeV linear collider like CERN CLIC. The larger rates and the steeper rise of…
In this letter we study the photoproduction of heavy quarks and vector mesons in the coherent proton-nucleus (pA) interactions for RHIC and LHC energies and analyze if these processes can be used to determine the QCD dynamics at high…
The production of electron pairs with transverse momentum between 1 and 5 GeV/c and m< 300 MeV has been measured at mid-rapidity in 200 GeV p+p and Au+Au collisions by the PHENIX experiment at RHIC. A significant excess above the hadronic…
At high collision energies as achieved at the LHC there are increasing contributions from hard processes, which can be computed with perturbative QCD. Nevertheless, particle production is still dominated by soft QCD with transferred…
The production of electron-positron pairs with the capture of the electron in an atomic orbital is investigated for the conditions of the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider LHC). Dirac wave functions for…