XXVIII International Workshop on Deep Inelastic Scattering and Related Subjects

Low pT direct photon measurements at PHENIX experiment

25 Mar 2020, 09:00

22m

Brooklyn, NY

Contributed Talk QCD with Heavy Flavors and Hadronic Final States QCD with Heavy Flavors and Hadronic Final States

Speaker

Dr Veronica Canoa Roman (Stony Brook University)

Description

PHENIX has made a comprehensive measurement of low p${}_{\mathrm{T}}$ direct photon yield in Au+Au collisions at 200 GeV that show both a large yield and a large azimuthal anisotropy produced. The mechanism for such simultaneous large production is not well understood yet.
  Recently the PHENIX collaboration has improved on those measurements by using the Au+Au data collected in 2014 which provides a 10-fold increase in statistics. Furthermore, PHENIX has found that the low p${}_{\mathrm{T}}$  direct photon yield dN${}_{\gamma }$/d$\eta$ is proportional to (dN${}_{\mathrm{ch}}$/d$\eta$)${}^{\alpha }$. This scaling holds for beam energies both at RHIC and at the LHC in large-on-large systems. An extrapolation to smaller systems suggests an onset of QGP formation at low dN${}_{\mathrm{ch}}$/d$\eta$.
  In this talk I will show the most recent results on direct photon measurements from large and small systems.