Critical enhancement of thermal photons

19 May 2014, 15:20
20m
helium (darmstadtium)

helium

darmstadtium

Schlossgraben 1 64283 Darmstadt Germany
Contributed Talk Electromagnetic Probes Electromagnetic probes

Speaker

Prof. Ralf Rapp (Texas A&M University)

Description

A relatively small spectral slope and large elliptic flow of direct photons measured at RHIC and LHC has reignited the discussion of thermal photons as a probe of the quark-gluon plasma (QGP). We present a systematic discussion of the macro- and micro-physics that figures into calculating thermal emission spectra. For the bulk medium we compare the temperature and flow evolution in fireball [1] and hydrodynamic approaches [2], and study how different tunes of initial conditions, compatible with bulk hadron observables, affect the photon spectra. We deduce evidence for an enhancement of currently available hadronic and QGP emission rates around Tc, and a potential suppression of early QGP radiation (indicative for a gluon-rich early QGP). We then present an updated (more complete) assessment of hadronic emission channels involving meson exchange reactions in baryon-meson scattering which have not been considered thus far [3]. We also investigate consequences for thermal dilepton v2. [1] H. van Hees, C. Gale and R. Rapp, Phys. Rev. C 84 (2011) 054906 [2] H. van Hees, M. He and R. Rapp, in preparation. [3] N. Holt and R. Rapp, work in progress.
On behalf of collaboration: None

Primary author

Prof. Ralf Rapp (Texas A&M University)

Co-authors

Hendrik van Hees (Goethe University Frankfurt) Min He (Nanjing University of Science and Technology)

Presentation Materials