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Electromagnetic radiation from nuclear collisions at RHIC energies  [PDF]
Simon Turbide,Charles Gale,Evan Frodermann,Ulrich Heinz
Physics , 2007, DOI: 10.1103/PhysRevC.77.024909
Abstract: The hot and dense strongly interacting matter created in collisions of heavy nuclei at RHIC energies is modeled with relativistic hydrodynamics, and the spectra of real and virtual photons produced at mid-rapidity in these events are calculated. Several different sources are considered, and their relative importance is compared. Specifically, we include jet fragmentation, jet-plasma interactions, the emission of radiation from the thermal medium and from primordial hard collisions. Our calculations consistently take into account jet energy loss, as evaluated in the AMY formalism. We obtain results for the spectra, the nuclear modification factor (R_AA), and the azimuthal anisotropy (v_2) that agree with the photon measurements performed by the PHENIX collaboration at RHIC.
Electromagnetic Radiation from Broken Symmetries in Relativistic Nuclear Collisions
Qin, Guang-You;Majumder, Abhijit;Gale, Charles
High Energy Physics - Phenomenology , 2007, DOI: 10.1142/S0218301307007921
Abstract: A new channel of direct photon production from a quark gluon plasma (QGP) is explored in the framework of high-temperature QCD. This process appears at next-to-leading order, in the presence of a charge asymmetry in the excited matter. The photon production rate from this new mechanism is suppressed compared to the QCD annihilation and Compton scattering at low baryon density but assumes importance in baryon-rich matter.
Electromagnetic Radiation from Broken Symmetries in Relativistic Nuclear Collisions  [PDF]
Guang-You Qin,Abhijit Majumder,Charles Gale
Physics , 2007, DOI: 10.1142/S0218301307007921
Abstract: A new channel of direct photon production from a quark gluon plasma (QGP) is explored in the framework of high-temperature QCD. This process appears at next-to-leading order, in the presence of a charge asymmetry in the excited matter. The photon production rate from this new mechanism is suppressed compared to the QCD annihilation and Compton scattering at low baryon density but assumes importance in baryon-rich matter.
Yang-Mills Radiation in Ultra-relativistic Nuclear Collisions  [PDF]
Miklos Gyulassy,Larry McLerran
Physics , 1997, DOI: 10.1103/PhysRevC.56.2219
Abstract: The classical Yang-Mills radiation computed in the McLerran-Venugopalan model is shown to be equivalent to the gluon bremsstrahlung distribution to lowest order in pQCD. The classical distribution is also shown to match smoothly onto the conventional pQCD mini-jet distribution at a scale characteristic of the initial parton transverse density of the system. The atomic number and energy dependence of that scale is computed from available structure function information. The limits of applicability of the classical Yang-Mills description of nuclear collisions at RHIC and LHC energies are discussed.
Probing the early-time dynamics of relativistic heavy-ion collisions with electromagnetic radiation  [PDF]
Gojko Vujanovic,Jean-Francois Paquet,Gabriel S. Denicol,Matthew Luzum,Bjoern Schenke,Sangyong Jeon,Charles Gale
Physics , 2014, DOI: 10.1016/j.nuclphysa.2014.08.053
Abstract: Using 3+1D viscous relativistic fluid dynamics, we show that electromagnetic probes are sensitive to the initial conditions and to the out-of-equilibrium features of relativistic heavy-ion collisions. Within the same approach, we find that hadronic observables show a much lesser sensitivity to these aspects. We conclude that electromagnetic observables allow access to dynamical regions that are beyond the reach of soft hadronic probes.
Electromagnetic radiation from collisions at almost the speed of light: an extremely relativistic charged particle falling into a Schwarzschild black hole  [PDF]
Vitor Cardoso,Jose' P. S. Lemos,Shijun Yoshida
Physics , 2003, DOI: 10.1103/PhysRevD.68.084011
Abstract: We investigate the electromagnetic radiation released during the high energy collision of a charged point particle with a four-dimensional Schwarzschild black hole. We show that the spectra is flat, and well described by a classical calculation. We also compare the total electromagnetic and gravitational energies emitted, and find that the former is supressed in relation to the latter for very high energies. These results could apply to the astrophysical world in the case charged stars and small charged black holes are out there colliding into large black holes, and to a very high energy collision experiment in a four-dimensional world. In this latter scenario the calculation is to be used for the moments just after the black hole formation, when the collision of charged debris with the newly formed black hole is certainly expected. Since the calculation is four-dimensional, it does not directly apply to Tev-scale gravity black holes, as these inhabit a world of six to eleven dimensions, although our results should qualitatively hold when extrapolated with some care to higher dimensions.
Electromagnetic radiation in heavy ion collisions: Progress and puzzles  [PDF]
Charles Gale
Physics , 2012,
Abstract: We review the current state of photon and dilepton measurements at RHIC, emphasizing that of the theoretical work seeking to interpret them. We highlight the progress made recently in the modelling of relativistic nuclear collisions, and explore the effect on electromagnetic observables. Some outstanding puzzles are presented.
Relativistic Nuclear Collisions  [PDF]
Reinhard Stock
Physics , 2009,
Abstract: A comprehensive introduction is given to the field of relativistic nuclear collisions, and the phase diagram of strongly interacting matter. The content of this complex of reviews is shown.
In-medium effects on electromagnetic probes  [PDF]
Charles Gale
Physics , 2005, DOI: 10.1140/epjc/s2005-02331-9
Abstract: We discuss some of the aspects of the physics of relativistic nuclear collisions, in particular those having to do with the observation of electromagnetic radiation. We concentrate on what such measurements tell us about the local, in-medium properties of the environment from which they emerge. The contribution from different sources are considered: that from the partonic sector of QCD, and that from the confined hadronic phase. Specifically, we discuss the observation of real photons and of lepton pairs at the SPS and at RHIC, and make predictions for the LHC. The role of jets is discussed.
Fluid Dynamics for Relativistic Nuclear Collisions  [PDF]
D. H. Rischke
Physics , 1998, DOI: 10.1007/BFb0107310
Abstract: I give an introduction to the basic concepts of fluid dynamics as applied to the dynamical description of relativistic nuclear collisions.
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