Phenomenology of collinear photon emission from quark–gluon plasma in AA collisions

Abstract

We study the role of running coupling and the effect of variation of the thermal quark mass on contribution of the collinear bremsstrahlung and annihilation to photon emission in AA collisions in a scheme similar to that used in our previous jet quenching analyses. We find that for a scenario with the thermal quark mass mq ∼ 50 − 100 MeV contribution of the higher order collinear processes summed with the 2 → 2 processes can explain a considerable part (∼ 50%) of the experimental photon spectrum at kT ∼ 2 − 3 GeV for Au+Au collisions at √ s = 0.2 TeV. But for mq = 300MeV and for the thermal quark mass predicted by the HTL scheme the theoretical predictions underestimate considerably the experimental spectrum.

On solutions for some class of integrable difference equations

“…The Volterra lattice (1.10), at one time was noted by physicists and used by them as a simplified model in some processes of plasma physics [14], [25]. In [14], the method of the inverse scattering problem was applied to this equation.…”

Probing confinement by direct photons and dileptons

“…Up to now theoretical calculations still underestimate these challenging measurements [2,3]. This tension known as "direct photon flow puzzle" remains rather intriguing and exciting although several phenomenological suggestions (see, for example, [2,3,[8][9][10][11][12][13][14][15][16][17][18][19][20] and Refs. therein) have been done to understand an origin of this interesting observation.…”

Anisotropy of thermal dileptons

“…Recent interesting suggestions for photon and dilepton sources [11] (thermal photons may have elliptic flow), [12] (thermal radiation from semi-QGP), and [13] (forming a gluon condensate that radiates the photons at the early stage of collisions) which are idealogically close to the scinario we develop in this letter declare pretty small photon azimuthal anisotropy [14] and insufficient to explain the experimental data mentioned. There are many other phenomenological models under discussion (see, for example, [15,16,17,18,19,20,21]) which are in different extent fairly successful at treating the experimental data quantitatively but sometimes with noticeable uncertainties. In our previous work [22] we have suggested significantly alternative mechanism that contributes to the observed anisotropy of direct photons.…”