Moving quark in a viscous fluid

Abstract:We use holographic duality to analyze the drag force on, and consequent energy loss of, a heavy quark moving through a strongly coupled conformal fluid with non-vanishing gradients in its velocity and temperature. We derive the general expression for the drag force to first order in the fluid gradients. Using this general expression, we show that a quark that is instantaneously at rest, relative to the fluid, in a fluid whose velocity is changing with time feels a nonzero force. And, we show that for a quark that is moving ultra-relativistically, the first order gradient "corrections" become larger than the zeroth order drag force, suggesting that the gradient expansion may be unreliable in this regime. We illustrate the importance of the fluid gradients for heavy quark energy loss by considering a fluid with one-dimensional boost invariant Bjorken expansion as well as the strongly coupled plasma created by colliding sheets of energy.

“…And, indeed our results for the drag force that we shall present in section 3 do differ from those in refs. [39,40].…”

Section: Jhep02(2014)068mentioning

confidence: 99%

Section: Jhep02(2014)068mentioning

confidence: 99%

Effects of fluid velocity gradients on heavy quark energy loss

Lekaveckas

Rajagopal

2014

“…At zeroth order, namely ideal fluid, there is only one coefficient function which has to be specified. In N = 4 SYM field theory, this coefficient has been already found [10] 3 . Rigorously speaking, covariant drag force to this order may be given by:…”

mentioning

confidence: 70%

“…the quarks constrained to move in the zero rapidity plane. More importantly, it should be noted that our method in [10] was not able to give the drag force exerted on a quark with non-vanishing initial rapidity. In this paper however, we give a solution for the "covariant drag force" in a general fluid dynamical flow, completely answering the questions remained unresolved about a general quark moving through The Bjorken flow.…”

mentioning

confidence: 93%

“…Fluid/Gravity duality is able to perturbatively constructs the asymptotically AdS5 background dual to every boundary fluid dynamical flow, order by order, in a boundary derivative expansion. In [10] we explained "how" to use this duality and to compute the drag force in a general flow perturbatively . Then as an example we computed the first order corrected drag force exerted on specific quarks in Bjorken flow, i.e.…”

mentioning

confidence: 99%

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Moving quark in a general fluid dynamical flow

Abbasi

Davody

2013

Self Cite

We determine the most general form of the covariant drag force exerted on a quark moving through a fluid dynamical flow. Up to first order in derivative expansion, our general formula requires the specification of seven coefficient functions. We use the perturbative method introduced in arXiv:1202.2737 and find all these coefficients in the hydrodynamic regime of a N = 4 SYM plasma. Having this general formula, we can obtain the rate of the energy and momentum loss of a quark, namely the drag force, in a general flow. This result makes it possible to perturbatively study the motion of heavy quarks moving through the Bjorken flow up to first order in derivative expansion.

Hydrodynamic excitations from chiral kinetic theory and the hydrodynamic frames

Abbasi

Taghinavaz

Naderi

2018

Self Cite

In the framework of chiral kinetic theory (CKT), we consider a system of right-and left-handed Weyl fermions out of thermal equilibrium in a homogeneous weak magnetic field. We show that the Lorentz invariance implies a modification in the definition of the momentum current in the phase space, compared to the case in which the system is in global equilibrium. Using this modified momentum current, we derive the linearized conservation equations from the kinetic equation up to second order in the derivative expansion. It turns out that the eigenmodes of these equations, namely the hydrodynamic modes, differ from those obtained from the hydrodynamic in the Landau-Lifshitz (LL) frame at the same order. We show that the modes of the former case may be transformed to the corresponding modes in the latter case by a global boost. The velocity of the boost is proportional to the magnetic field as well as the difference between the right-and left-handed charges susceptibility.We then compute the chiral transport coefficients in a system of non-Abelian chiral fermions in the no-drag frame and by making the above boost, obtain the well-known transport coeffiecients of the system in the LL frame. Finally by using the idea of boost, we reproduce the AdS/CFT result for the chiral drag force exerted on a quark at rest in the rest frame of the fluid, without performing any holographic computations.