Speaker
Prof.
Rainer Fries
(Texas A&M University)
Description
We investigate the correlations of photons produced by back scattering of fast partons in quark gluon plasma
with their away‐side jets. Back scattering with photon emission, or jet‐photon conversion,
was originally proposed as a novel source of photons in Phys. Rev. Lett. 90, 132301 (2003).
The unique appeal of this photon source lies in the fact that its photons carry information about both
the medium via a T^2 log 1/T dependence of the yield and about the energy loss of partons before
the back scattering occurs. Attempts to identify this source in experiment through inclusive
direct photon spectra or direct photon v_2 at intermediate PT at RHIC have been inconclusive so.
We show that the capability to measure jets in coincidence with photons at the upgraded STAR or
SPHENIX experiment, or at one of the LHC experiments, offers a unique opportunity to identify
back scattering photons at large photon momenta. Jet‐triggered back‐scattering photons
can be distinguished from bremsstrahlung through their strong correlation with the given trigger ET,
and from prompt hard photons through the energy loss of their parent parton.
We demonstrate with leading and next‐to-leading order calculations that jet‐triggered
direct photon spectra and nuclear modification factors in nuclear collisions as a function of photon
PT show a distinct feature around the trigger ET due to back‐scattering photons.
The height and width of this structure are correlated with the medium temperature
and parton energy loss spectrum, respectively.
Author
Prof.
Rainer Fries
(Texas A&M University)
Co-authors
Dinesh Srivastava
(Variable Energy Cyclotron Centre, Kolkata)
Somnath De
(Variable Energy Cyclotron Centre, Kolkata)
Peer reviewing
Paper
Paper files:
