J. Magnin

Three and two hadron correlations in sq.rt.(S(NN))=200 GeV proton-proton and nucleus-nucleus collisions.

We compare the azimuthal correlations arising from three and two hadron production in p+p and Au+Au collisions at sq.rt.(S(NN))=200 GeV. We show that in Au+Au, the two away side partons in two-to-three processes have in average a smaller and a greater path length than the average path length of the away-side parton in two-to-two processes. Since in average the particle with the shortest path length in two-to-three processes loses less energy, with respect to the away-side particle in two-to-two processes, this effect leads to a relative enhancement of the ratio of two-to-three to two-to-two processes in Au+Au compared to p+p collisions. We argue that this phenomenon may be responsible for the shape of the away side in azimuthal correlations at the Relativistic Heavy-Ion Collider.

Monte Carlo approach for hadron azimuthal correlations in high energy proton and nuclear collisions

We use a Monte Carlo approach to study hadron azimuthal angular correlations in high energy proton-proton and central nucleus-nucleus collisions at the BNL Relativistic Heavy Ion Collider (RHIC) energies at mid-rapidity. We build a hadron event generator that incorporates the production of

Three-hadron angular correlations in high-energy proton-proton and nucleus-nucleus collisions from perturbative QCD

2\to 2

Collisional parton energy loss in a finite size QCD medium reexamined: Off-mass-shell effects

and

Nuclear modification factor for heavy flavors: An energy loss effect or more baryons than mesons?

2\to 3

Spin alignment of vector mesons in heavy ion and proton–proton collisions

parton processes and their evolution into hadron states. For nucleus-nucleus collisions we include the effect of parton energy loss in the Quark-Gluon Plasma using a modified fragmentation function approach. In the presence of the medium, for the case when three partons are produced in the hard scattering, we analyze the Monte Carlo sample in parton and hadron momentum bins to reconstruct the angular correlations. We characterize this sample by the number of partons that are able to hadronize by fragmentation within the selected bins. In the nuclear environment the model allows hadronization by fragmentation only for partons with momentum above a threshold

Finite size effects on pion spectra in relativistic heavy-ion collisions

p_T^{{\tiny{thresh}}}=2.4

Proton and pion transverse spectra at the BNL Relativistic Heavy Ion Collider from radial flow and finite size effects

GeV. We argue that one should treat properly the effect of those partons with momentum below the threshold, since their interaction with the medium may lead to showers of low momentum hadrons along the direction of motion of the original partons as the medium becomes diluted.

ρpropagation and dilepton production at finite pion density and temperature

Alejandro Ayala, Jamal Jalilian-Marian, Antonio Ortiz, Guy Paić, J. Magnin and Maria Elena Tejeda-Yeomans Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Apartado Postal 70-543, México Distrito Federal 04510, Mexico. Department of Natural Sciences, Baruch College, New York, New York 10010, USA and CUNY Graduate Center, 365 Fifth Avenue, New York, New York 10016, USA. Centro Brasileiro de Pesquisas F́ısicas, CBPF, Rua Dr. Xavier Sigaud 150, 22290-180, Rio de Janeiro, Brazil. Departamento de F́ısica, Universidad de Sonora, Boulevard Luis Encinas J. y Rosales, Colonia Centro, Hermosillo, Sonora 83000, Mexico.

Three-hadron angular correlations from perturbative QCD at the Relativistic Heavy Ion Collider and at the Large Hadron Collider

We study the collisional energy loss mechanism for particles produced off mass shell in a finite size QCD medium. The off-mass-shell effects introduced consider particles produced in wave packets instead of plane waves and a length scale associated with an in-medium particle lifetime. We show that these effects reduce the energy loss as compared to the case when the particles are described as freely propagating from the source. The reduction in energy loss is stronger as the scale becomes of the order of or smaller than the medium size. We discuss possible consequences of the result on the description of the energy loss process in the parton recombination scenario.