38 research outputs found
Diagrammatic and Kinetic Equation Analysis of Ultrasoft Fermionic Sector in Quark-Gluon Plasma
No full texta
Dilepton and photon production in the presence of a nontrivial Polyakov loop
No full textWe calculate the production of dileptons and photons in the presence of a nontrivial Polyakov loop in QCD. This is applicable to the semi-Quark Gluon Plasma (QGP), at temperatures above but near the critical temperature for deconfinement. The Polyakov loop is small in the semi-QGP, and near unity in the perturbative QGP. Working to leading order in the coupling constant of QCD, we find that there is a mild enhancement, ~ 20%, for dilepton production in the semi-QGP over that in the perturbative QGP. In contrast, we find that photon production is strongly suppressed in the semi-QGP, by about an order of
magnitude, relative to the perturbative QGP. In the perturbative QGP photon production contains contributions from 2->2 scattering and collinear emission with the Landau- Pomeranchuk-Migdal (LPM) effect. In the semi-QGP we show that the two contributions are modified differently. The rate for 2->2 scattering is suppressed by a factor which depends upon the Polyakov loop. In contrast, in an SU(N) gauge theory the collinear rate is suppressed by 1/N, so that the LPM effect vanishes at infinite N. To leading order in the semi-QGP at large N, we compute the rate from 2->2 scattering to the leading logarithmic order and the collinear rate to leading order
クォーク・グルーオンプラズマ中のウルトラソフトフェルミオンセクターにおけるダイアグラムおよび運動論的方程式を用いた解析
No full text京都大学0048新制・課程博士博士(理学)甲第17349号理博第3846号新制||理||1555(附属図書館)30115京都大学大学院理学研究科物理学・宇宙物理学専攻(主査)教授 國廣 悌二, 教授 大西 明, 教授 青山 秀明学位規則第4条第1項該当Doctor of ScienceKyoto UniversityDA
Exact sum rules for vector channel at finite temperature and their application to lattice QCD analysis
No full textWe derive three exact sum rules for the spectral function of the electromagnetic current with zero spatial momentum at finite temperature. Possible applications of the three sum rules to lattice computations of the spectral function and transport coefficients are also discussed: We propose an ansatz for the spectral function that can be applied to all three sum rules and fit it to available lattice data of the Euclidean vector correlator above the critical temperature. As a result, we obtain estimates for both the electrical conductivity σ and the second order transport coefficient τJ
Exact sum rules for vector channel at finite temperature and their application to lattice QCD analysis
No full textWe derive three exact sum rules for the spectral function of the electromagnetic current with zero spatial momentum at finite temperature. Possible applications of the three sum rules to lattice computations of the spectral function and transport coefficients are also discussed: We propose an ansatz for the spectral function that can be applied to all three sum rules and fit it to available lattice data of the Euclidean vector correlator above the critical temperature. As a result, we obtain estimates for both the electrical conductivity σ and the second order transport coefficient τJ
Chiral Magnetic Effect at Weak Coupling with Relaxation Dynamics
No full textWe provide a resolution of an old issue in weak coupling computation of the Chiral Magnetic Effect (CME) current, where a free chiral fermion theory gives two different results depending on the order of the two limits, ω → 0 (frequency) and k → 0 (spatial momentum). We first argue based on hydrodynamics that in any reasonable interacting theory of chiral fermions the non-commutativity between the two limits should be absent, and we demonstrate this at weak coupling regime in two different frameworks: kinetic theory in the relaxation time approximation, and diagrammatic computation with resummation of damping rate. In the latter computation, we also show that the “pinch ” singularity, which would make the summation of ladder diagrams necessary as in the P-even correlation function, is absent in the relevant P-odd correlation function. The correct value of CME current is reproduced even in the presence of relaxation dynamics in both computations
