22–27 Sept 2016
East Lake International Conference Center
Asia/Chongqing timezone
<a href="http://hp2016.ccnu.edu.cn">http://hp2016.ccnu.edu.cn</a>

Holographic photon production and flow in strongly coupled quark gluon plasmas

24 Sept 2016, 11:20
20m
Jing-Zhou Hall (East Lake International Convention Center)

Jing-Zhou Hall

East Lake International Convention Center

Speaker

Di-Lun Yang (RIKEN)

Description

We investigate the thermal-photon emission from strongly coupled gauge theories at finite temperature via the bottom-up models in holographic QCD in the deconfined phase. Particularly, we apply a model encoding flavor degrees of freedom in the Veneziano limit of a large number of colors $N_c$ and flavors $N_f$ but fixed $x=N_f=N_c$ (VQCD). In this model, the normalization and gauge-field couplings pertinent to photon production have been chosen to approximately reproduce the electric conductivity obtained from lattice simulations for the quark gluon plasma (QGP). The emission rates are then embedded in hydrodynamic simulations combined with prompt photons from hard scattering and the thermal photons from hadron gas to analyze the spectra and anisotropic flow of direct photons in RHIC and LHC. We compare the results for different sources responsible for the thermal photons in QGP including the weakly coupled QGP (wQGP) with hard-thermal-loop resummation, strongly coupled $\mathcal{N}=4$ super Yang-Mills (SYM) plasma (as a benchmark for reference), and Gubser’s phenomenological model in holography. In general, the direct-photon spectra are enhanced in the strongly coupled scenario compared with the ones in the wQGP especially in high momenta. Moreover, by using IP-glassma initial states, both the elliptic flow and triangular flow of direct photons are amplified in high momenta for VQCD and the SYM plasma as comparable with those for the wQCD, while the flow for VQCD is suppressed in low momenta, which is associated with the increase of electric conductivity with temperature. We further compare our results with experimental observations.

Presentation type Oral

Presentation materials