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Single photon spectra in heavy-ion collisions at SPS energies are studied in the relativistic transport model that incorporates self-consistently the change of hadron masses in dense matter. We separate the total photon spectrum into…

Nuclear Theory · Physics 2009-10-30 G. Q. Li , G. E. Brown

Dilepton production in proton- and nucleus-induced reactions at SPS energies is studied in the relativistic transport model using initial conditions determined by the string dynamics from RQMD. It is found that both the CERES and HELIOS-3…

Nuclear Theory · Physics 2009-10-30 C. M. Ko , G. Q. Li , G. E. Brown , H. Sorge

Recently the NA60 collaboration has presented high precision measurements of dimuon spectra double differential in invariant mass $M$ and transverse pair momentum $p_T$ in In-In collisions at $158 {\rm AGeV}$. While the $M$-dependence is…

High Energy Physics - Phenomenology · Physics 2008-11-26 Jorg Ruppert , Thorsten Renk

The formulation of the real and virtual photon production rate from strongly interacting matter is presented in the framework of finite temperature field theory. The changes in the hadronic spectral function induced by temperature are…

High Energy Physics - Phenomenology · Physics 2009-10-31 Jan-e Alam , Sourav Sarkar , Pradip Roy , T. Hatsuda , Bikash Sinha

We analyze the dilepton and photon emission rates from a hadronic gas using chiral reduction formulas and a virial expansion. The emission rates are reduced to pertinent vacuum correlation functions, most of which can be assessed from…

High Energy Physics - Phenomenology · Physics 2009-10-28 James V. Steele , Hidenaga Yamagishi , Ismail Zahed

We compute the rates of real and virtual photon (dilepton) emission from dense QCD matter in the color-flavor locked (CFL) phase, focusing on results at moderate densities (3-5 times the nuclear saturation density) and temperatures…

High Energy Physics - Phenomenology · Physics 2009-11-07 Prashanth Jaikumar , Ralf Rapp , Ismail Zahed

The electromagnetic emissivity from QCD media away from equilibrium is studied in the framework of closed time path thermal field theory. For the dilepton rate a nonequilibrium mesonic medium is considered applying finite temperature…

High Energy Physics - Phenomenology · Physics 2011-04-15 R. Baier , M. Dirks , K. Redlich

Two-particle correlation functions of negative hadrons over wide phase space, and transverse mass spectra of negative hadrons and deuterons near mid-rapidity have been measured in central Pb+Pb collisions at 158 GeV per nucleon by the NA49…

High Energy Physics - Experiment · Physics 2012-08-27 NA49 Collaboration

Recent developments in the evaluation of vector-meson spectral functions in hot and dense matter are discussed with emphasis on connections to the chiral phase transition in QCD. Model independent approaches including chiral low-density…

High Energy Physics - Phenomenology · Physics 2015-05-13 R. Rapp , J. Wambach , H. van Hees

The effects of the variation of vector meson masses and decay widths on photon production from hot strongly interacting matter formed after Pb + Pb and S + Au collisions at CERN SPS energies are considered. It has been shown that the…

Nuclear Theory · Physics 2009-10-31 Sourav Sarkar , Pradip Roy , Jan-e Alam , Bikash Sinha

Theoretical calculation of transverse momentum($p_T$) distribution of thermal photons and dileptons originating from ultra-relativistic heavy ion collisions suffer from several uncertainties since the evaluation of these spectra needs…

Nuclear Theory · Physics 2008-11-26 Jajati K. Nayak , Jan-e Alam , Sourav Sarkar , Bikash Sinha

The structure of the one loop self-energy graphs of the $\rho$ meson is analyzed in the real time formulation of thermal field theory. The modified spectral function of the $\rho$ meson in hot hadronic matter leads to a large enhancement of…

Nuclear Theory · Physics 2015-05-27 Sabyasachi Ghosh , Sourav Sarkar , Jan-e Alam

We reinterpret the dilepton emission rate from a hadronic gas expected to be produced in heavy ion collisions in terms of the spectral functions available from the $e^+e^-$ annihilation and the $\tau$ lepton decays experiments. We take into…

High Energy Physics - Phenomenology · Physics 2015-06-25 Zheng Huang

Clear signs of excess dileptons above the known sources were found at the SPS since long. However, a real clarification of these observations was only recently achieved by NA60, measuring dimuons with unprecedented precision in 158A GeV…

Nuclear Experiment · Physics 2015-05-13 Sanja Damjanovic

A realistic model for the free rho meson with coupling to two-pion states is employed to calculate the rho propagator in a hot and dense hadron gas. The medium modifications are based on hadronic rescattering processes: intermediate…

High Energy Physics - Phenomenology · Physics 2009-10-30 R. Rapp , G. Chanfray , J. Wambach

Spectra for the emission of charged leptons from evaporating hot-spots of preconfining phase in SU(2) Yang-Mills thermodynamics are computed. Specifically, we consider charged single and dileptons with their spectra being functions of…

High Energy Physics - Phenomenology · Physics 2012-03-07 Julian Moosmann , Ralf Hofmann

We study photon production from the hidden local symmetry approach that includes pions, rho and a1 mesons and compute the corresponding photon emission rates from a hadronic gas in thermal equilibrium. Together with experimental radiative…

Nuclear Theory · Physics 2008-11-26 M. A. Halasz , J. V. Steele , G. Q. Li , G. E. Brown

A unique parametrization of secondary (thermal) dilepton yields in heavy-ion experiments at CERN-SPS is proposed. This parametrization resembles a thermal $q \bar q$ annihilation rate. This is inspired by the observation that lepton pair…

High Energy Physics - Phenomenology · Physics 2009-09-25 K. Gallmeister , B. Kämpfer , O. P. Pavlenko , C. Gale

Dilepton spectra are calculated within the microscopic transport model UrQMD and compared to data from the CERES experiment. The invariant mass spectra in the region 300 MeV < M < 600 MeV depend strongly on the mass dependence of the $\rho$…

Nuclear Theory · Physics 2007-05-23 C. Ernst , S. A. Bass , S. Soff , H. Stöcker , W. Greiner

We study the effect of in-medium hadronic properties in photon nucleus interactions in the context of shadowing as well as the dilepton spectrum for incident photon energies in the range 1.1- 3 GeV. A reasonable agreement with the…

Nuclear Theory · Physics 2009-11-10 Jan-e Alam , Sanjay K. Ghosh , Pradip Roy , Sourav sarkar