Speaker
Description
Direct photons produced in heavy ion collisions are penetrating probes
and as such encode the entire space-time history of the collision, from
the initial hard scattering till the final kinetic freeze-out. For the
very same reason theoretical models are challenged to connect and balance
many different production mechanisms. Simultaneous observation of large
yields and large azimuthal asymmetries (elliptic flow) by PHENIX could so
far not been reproduced quantitatively, a situation dubbed "direct photon
puzzle". Using the 2014 200 GeV Au+Au data, which have ten times the
statistics of earlier published results, and deploying the same analysis
technique over the wide 0.8 - 10 GeV/c transverse momentum range, PHENIX
re-measured both the direct and nonprompt photon yields and the direct
photon elliptic flow in finer centrality bins than before. In this
presentation we will discuss the results and their bearing on the
"direct photon puzzle".
| session | G. Heavy Ion Physics |
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