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A: Fachverband Atomphysik

A 33: Interaction with VUV and X-Ray Light II

A 33.2: Fachvortrag

Thursday, March 5, 2009, 17:00–17:30, VMP 8 R208

Time evolution of photon emission from the quark-gluon plasma — •Andreas Ipp, Jörg Evers, and Christoph H. Keitel — Max Planck Institut für Kernphysik, Heidelberg

Photons emitted from the quark gluon plasma (QGP) carry information directly from the interior of the strongly interacting plasma, since they are likely to leave the QGP without further interaction. They can for example provide information about a global quark polarization that can be created in non-central heavy ion collisions. Such a global quark polarization is transferred efficiently to the circular polarization of photons for various emission energies and momentum anisotropies [1].

In this work, we analyze the time evolution of the photon production in the QGP. For this, we fold the photon production with a model of the time evolution of temperature and momentum anisotropy [2]. The evolution is based on Bjorken’s one-dimensional expansion model [3]. The photon production rate locally depends on the temperature and the momentum anisotropy. It is boosted from the expanding frame into the laboratory frame to obtain the time-dependent signal in the detector. We find that a strongly varying momentum anisotropy could lead to particular emission envelopes, like a double-peak structure on the zepto-second scale. A detection of the emission shape could lead to experimental insight into the isotropization process within the QGP.

[1] A. Ipp, A. Di Piazza, J. Evers, and C. H. Keitel, Phys. Lett. B 666, 315 (2008).

[2] M. Martinez, M. Strickland, Phys. Rev. C 78, 034917 (2008).

[3] J. D. Bjorken, Phys. Rev., D 27, 140 (1983).