We compute dilepton production from the deconfined phase of the quark-gluon plasma using leading-order (3+1)-dimensional anisotropic hydrodynamics. The anisotropic hydrodynamics equa- tions employed describe the full spatiotemporal evolution of the transverse temperature, spheroidal momentum-space anisotropy parameter, and the associated three-dimensional collective flow of the matter. The momentum-space anisotropy is also taken into account in the computation of the dilepton production rate, allowing for a self-consistent description of dilepton production from the quark-gluon plasma. For our final results, we present predictions for high-energy dilepton yields as a function of invariant mass, transverse momentum, and pair rapidity. We demonstrate that high- energy dilepton production is extremely sensitive to the assumed level of initial momentum-space anisotropy of the quark-gluon plasma. As a result, it may be possible to experimentally constrain the early-time momentum-space anisotropy of the quark-gluon plasma generated in relativistic heavy ion collisions using high-energy dilepton yields.
We calculate the yield and elliptic flow of mid-rapidity dileptons emitted from the quark-gluon plasma generated in Pb-Pb collisions at LHC. We use relativistic anisotropic hydrodynamics for the 3+1 dimensional evolution of the quark-gluon plasma and convolve this with the momentum-anisotropic local rest frame production rate for dileptons. The effects of momentum anisotropy of the quark distribution functions, viscosity to entropy density ratio, centrality of the collisions, and initial momentum anisotropy on the results are investigated and discussed.
Comment on: "Transverse-Mass $M_\perp$ Dependence of Dilepton Emission from Preequilibrium and Quark-Gluon Plasma in High Energy Nucleus-Nucleus Collisions"
Using the Landau-level representation for the imaginary part of the photon polarization tensor, we derive an explicit expression for the dilepton production rate from a hot quark-gluon plasma in a quantizing background magnetic field. We study in detail the dependence of the production rate on the dilepton invariant mass and the transverse momentum at mid-rapidity. We also investigate the angular dependence and ellipticity of dilepton emission. By comparing the result with the zero-field Born approximation, we find that the magnetic field leads to a strong enhancement of the dilepton rate at s…
Dilepton production by dynamical quasiparticles in the strongly interacting quark gluon plasma
讨论了强相互作用夸克胶子等离子体（sQGP）组分产生双轻子的问题。为了在较低的等离子体温度（O（T_c））、较低的双轻子质量（O（1GeV））和较强的耦合（α S =0.5-1）下进行定量预测，我们不仅考虑了高阶pQCD反应机制，而且考虑了夸克、反夸克和胶子的非微扰谱函数（离壳）和自能，从而超出了主导扭转。为此，我们的计算利用了匹配的动力学准粒子模型（DQPM）提供的夸克和胶子非微扰传播子的参数化来重现晶格数据。DQPM用单粒子格林函数描述QCD性质（在两粒子不可约方法的意义上），并导致sQGP的成分是有效准粒子的概念，这些准粒子是大质量的，具有宽谱函数（由于大的相互作用速率）。本文导出了反应q+qbar->l^+l^-中双轻子产生的离壳层截面。（Drell-Yan机理），q+qbar->g+l^+l^-（夸克湮灭与末态的胶子韧致辐射），q（qbar）+g->q（qbar）+l^+l^-通过用夸克和胶子的DQPM传播子修饰微扰图中的夸克和胶子线，得到了sQGP中g->q+qbar+l ^+l^-和q（qbar）->q（qbar）+g+l^+l^-（虚胶子衰变，虚夸克衰变）的关系.
In this paper, we propose an observable counting a weighted difference between right-handed and left-handed lepton pairs, which is coined dilepton helical rate. The weight is the momentum difference of the lepton pairs projected onto an auxiliary vector. We derive the helical rate in a quark-gluon plasma with a vorticity in the limit when the quark and lepton masses are ignored. We find the helical rate is maximized when the auxiliary vector is parallel to the vorticity, in which case it has a nearly spherical oblate ellipsoidal distribution. We propose that it can be used as a vortical-meter …
Fluid dynamic considerations are used to determine the electric current spectral density in the regime of small energies and momenta. The spectral density in this regime is parameterized by the electric conductivity, the charge susceptibility, and the relaxation time for the electric current, which is needed for relativistic causality. Experimentally, the spectral function can be accessed through the production rates of photons and dileptons in the expanding quark-gluon plasma. We use fluid dynamic simulations of high energy nuclear collisions, together with the transport limit of the spectral…
Dissipative spin hydrodynamics in Bjorken flow and thermal dilepton production
Birla Institute of Technology and Science Pilani（比拉理工学院皮拉尼分校）；National Institute of Science Education and Research（国家科学教育与研究机构）；Institute of Physics（物理研究所）
The spectrum of dileptons produced by the quark-gluon plasma in an ultrarelativistic nucleus-nucleus collision depends only, to a good approximation, on the transverse mass M_t of the dilepton. This scaling is exact as long as transverse flow is negligible, and the system is in local thermal equilibrium. We implement a state-of-the-art modelization of kinetic and chemical equilibration in the early stages of the evolution to study the modifications of the spectrum. Violations of M_t scaling resulting from these effects are evaluated as a function of the shear viscosity to entropy ratio (eta/s)…
We study the effect of vorticity present in heavy ion collisions (HICs) on the temperature evolution of hot quark-gluon plasma in the presence of spin-vorticity coupling. The initial global rotation entails a nontrivial dependence of the longitudinal flow velocity on the transverse coordinates and also develops a transverse velocity component that depends upon the longitudinal coordinate. Both of these velocities lead to a 2+1 dimensional expansion of the fireball. It is observed that with finite vorticity and spin-polarization the fireball cools faster as compared to the case without vorticit…
