Plasmons in anisotropic quark-gluon plasma (original) (raw)

Strongly and weakly unstable anisotropic quark-gluon plasma

Physical Review D, 2005

Using explicit solutions of the QCD transport equations, we derive an effective potential for an anisotropic quark-gluon plasma which under plausible assumptions holds beyond the Hard Loop approximation. The configurations, which are unstable in the linear response approach, are characterized by a negative quadratic term of the effective potential. The signs of higher order terms can be either negative or positive, depending on the parton momentum distribution. In the case of a Gaussian momentum distribution, the potential is negative and unbound from below. Therefore, the modes, which are unstable for gauge fields of small amplitude, remain unstable for arbitrary large amplitudes. We also present an example of a momentum distribution which gives a negative quadratic term of the effective potential but the whole potential has a minimum and it grows for sufficiently large gauge fields. Then, the system is weakly unstable. The character of the instability is important for the dynamical evolution of the plasma system. * Electronic address: cristina.manuel@ific.uv.es † Electronic address: mrow@fuw.edu.pl 1 The term 'parton' is used to denote a fermionic (quark) or bosonic (gluon) excitation of the quark-gluon plasma. 2 Although we consider anisotropic systems, the characteristic momentum in all directions is assumed to be of the same order.

Progress in Anisotropic Plasma Physics

In 1959 Weibel demonstrated that when a QED plasma has a temperature anisotropy there exist unstable transverse magnetic excitations which grow exponentially fast. In this paper we will review how to determine the growth rates for these unstable modes in the weak-coupling and ultrarelativistic limits in which the collective behavior is describable in terms are so-called "hard-loops". We will show that in this limit QCD is subject to instabilities which are analogous to the Weibel instability in QED. The presence of such instabilities dominates the early time evolution of a highly anisotropic plasma; however, at longer times it is expected that these instabilities will saturate (condense). We will discuss how the presence of non-linear interactions between the gluons complicates the determination of the saturated state. In order to discuss this we present the generalization of the Braaten-Pisarski isotropic hard-thermal-loop effective action to a system with a temperature anisotropy in the parton distribution functions. The resulting hard-loop effective action can be used to determine the time and energy scales associated with the possible saturation (condensation) of the gluonic modes. We will also discuss the effects of anisotropies on observables, in particular on the heavy quark energy loss.

Photons from anisotropic quark-gluon plasma

Physical Review C, 2008

We calculate medium photons due to Compton and annihilation processes in an anisotropic media. The effects of time-dependent momentum-space anisotropy of Quark-Gluon-Plasma (QGP) on the medium photon production are discussed. Such an anisotropy can results from the initial rapid longitudinal expansion of the matter, created in relativistic heavy ion collisions. A phenomenological model for the time-dependence of the parton hard momentum scale, p hard (τ), and anisotropy parameter, ξ(τ), has been used to describe the plasma space-time evolution. We find significant dependency of photon yield on the isotropization time (τ iso). It is shown that the introduction of early time momentum-space anisotropy can enhance the photon production by a factor of 10 (1.5) (in the central rapidity region) for free streaming (collisionally-broadened) interpolating model if we assume fixed initial condition. On the other hand, enforcing the fixed final multiplicity significantly reduces the enhancement of medium photon production.

Some Aspects of Anisotropic Quark-Gluon Plasma

Advances in High Energy Physics, 2013

We review the various aspects of anisotropic quark-gluon plasma (AQGP) that have recently been discussed by a number of authors. In particular, we focus on the electromagnetic probes of AQGP, inter quark potential, quarkonium states in AQGP, and the nuclear modifications factor of various bottomonium states using this potential. In this context, we will also discuss the radiative energy loss of partons and nuclear modification factor of light hadrons in the context of AQGP. The features of the wake potential and charge density due to the passage of jet in AQGP will also be demonstrated.

Plasmon Dispersion of a Weakly Degenerate Nonideal One-Component Plasma

Contributions to Plasma Physics, 2002

Classical Molecular Dynamics simulations (MD) for a one-component weakly degenerate plasma are presented. Using an effective quantum pair potential (Kelbg potential), the dynamic structure factor and the dispersion of Langmuir waves are computed. The influence of the coupling strength Γ and degree of degeneracy ρΛ 3 on these properties is discussed. The results are compared with predictions of mean-field theories.

Plasmon modes of a massive Dirac plasma, and their superlattices

Physical Review B

We explore the collective density oscillations of a collection of charged massive Dirac particles, in one, two and three dimensions and their one dimensional superlattice. We calculate the long wavelength limit of the dynamical polarization function analytically, and use the random phase approximation to obtain the plasmon dispersion. The density dependence of the long wavelength plasmon frequency in massive Dirac systems is found to be different as compared to systems with parabolic, and gapless Dirac dispersion. We also calculate the long wavelength plasmon dispersion of a 1d metamaterial made from 1d and 2d massive Dirac plasma. Our analytical results will be useful for exploring the use of massive Dirac materials as electrostatically tunable plasmonic metamaterials and can be experimentally verified by infrared spectroscopy as in the case of graphene [Nat. Nanotechnol. 6, 630 (2011)].

High-Energy Dileptons From An Anisotropic Quark-Gluon Plasma

Arxiv preprint arXiv:0904.2866, 2009

We calculate leading-order dilepton yields from a quark-gluon plasma which has a time-dependent anisotropy in momentum space. Such anisotropies can arise during the earliest stages of quark-gluon plasma evolution due to the rapid longitudinal expansion of the created ...

Non-Abelian excitations of the quark-gluon plasma

Physical Review Letters, 1994

We present new, non-abelian, solutions to the equations of motion which describe the collective excitations of a quark-gluon plasma at high temperature. These solutions correspond to spatially uniform color oscillations.