Dimuon transverse momentum spectra as a tool to characterize the emission region in heavy-ion collisions

Journal Article · Fri Feb 15 04:00:00 EST 2008 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.77.024907· OSTI ID:21068143

Renk, Thorsten; Ruppert, Joerg ^[1]

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1. Department of Physics, Post Office Box 35, University of Jyvaeskylae, FIN-40014 (Finland) and Helsinki Institute of Physics, Post Office Box 64, University of Helsinki, FIN-00014 (Finland)

Previous dilepton measurements in heavy-ion collisions have mainly focused on invariant mass spectra to clarify in-medium changes of vector meson properties. However, a dimuon is characterized by two quantities - invariant mass M and transverse momentum p{sub T}. Like transverse momentum spectra of hadrons, p{sub T} spectra of dileptons arise from an interplay between emission temperature and collective transverse flow, whereas the invariant mass is insensitive to flow. Having two control parameters of which only one is sensitive to flow allows one at a given M to characterize the emission region in terms of average temperature and flow. Thus, one can study what phases of the fireball evolution radiate into a given mass window. We demonstrate this technique using the dimuon transverse momentum spectra measured by the NA60 Collaboration and present strong arguments that a thermalized evolution phase with T>170MeV leaves an imprint in the spectra.

• OSTI ID: 21068143
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 2 Vol. 77; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
EMISSION
FIREBALL MODEL
HEAVY ION REACTIONS
MASS SPECTRA
MUONS
PARTICLE IDENTIFICATION
REST MASS
TRANSVERSE MOMENTUM
VECTOR MESONS