2006/12/10 by Thorsten Renk, Jörg Ruppert, Jorg Ruppert · 5 citations
Physics and Astronomy · #Atomic physics #Hadron #Heavy ion #High-Energy Particle Collisions Research #Invariant mass #Ion #Mass spectrum #Meson #Momentum (technical analysis) #Nuclear physics #Particle physics #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #Rapidity #Spectral line #Transverse mass #Transverse plane #hep-ph
paper · pdf · doi:10.1103/physrevc.77.024907
published as Phys.Rev.C77:024907,2008
arxiv created 2006/12/10 · openalex publication_date 2008/02/26 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
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 pT. Like transverse momentum spectra of hadrons, pT 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.