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HK: Fachverband Physik der Hadronen und Kerne
HK 26: Heavy-Ion Collisions and QCD Phases V
HK 26.2: Vortrag
Dienstag, 19. März 2019, 17:00–17:15, HS 15
Considering the Effects of Radial Flow in Decay Photon Calculations in Ultrarelativistic Nucleus-Nucleus Collisions — •Ilya Fokin — Physikalisches Institut, Heidelberg, Germany
For decay-photon calculations, it is crucial to accurately describe the spectra of particles that decay into photons. These include particle species for which there are either no measurements available or only measurements with large uncertainties such as the η, ω and η′. Since collective radial flow is expected in heavy-ion collisions, it must be taken into account when predicting particle spectra. A cocktail from transverse mass scaling, which does not include radial flow, serves as a baseline. In a two-component model, the momentum distributions are split into one component that incorporates all radial flow using a blast-wave description and one component for hard scatterings without radial flow. The parameters for extrapolating to other particles are obtained in a simultaneous fit with π± and K± data from ALICE. The model predicts an enhancement in the η, ω and η′ to π0 ratios at intermediate transverse momenta which results in a 5% increase in decay-photons in this range. Because the direct photon signal is already small compared to the background of decay photons, this relatively small increase can have a significant effect on the double ratio Rγ which determines the direct photon yield.