Stopping distance for high energy jets in weakly coupled quark-gluon plasmas

Arnold, Peter; Cantrell, Sean A.; Xiao, Wei

doi:10.1103/physrevd.81.045017

Cited by 26 publications

(42 citation statements)

References 20 publications

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“…whereᾱ ≡ α s N c /π, with N c the number of colors, will be referred to as the stopping time [20]. It is the time at which most of the energy of the incoming parton has been radiated into soft gluons (with typically x 0.1).…”

Section: The Ideal In-medium Qcd Cascadementioning

confidence: 99%

“…The factor √ x may then be combined with t * in order to define an effective time scale for the branching of a gluon carrying the fraction x of the initial energy, t * (x) = t * √ x. This time scale decreases as x decreases, meaning that the rate of emission of soft gluons is higher the softer the gluon: it follows that gluon splittings occur faster and faster as one moves down the cascade, and, as a result, it takes a finite time (of order t * ) to transport a finite amount of energy form x = 1 down to x = 0 [20]. It is actually convenient to make this x-dependent time scale more evident, and write Eq.…”

Section: The Ideal In-medium Qcd Cascadementioning

confidence: 99%

“…In other words, the branchings accelerate, and as a result it takes a finite time to transport a finite amount of energy from the leading particle to gluons carrying vanishingly small amounts of energy. This time, which we shall refer to as the stopping time [20], is infinite for the DGLAP cascade in which t * (ω) is independent of ω.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Energy flow along the medium-induced parton cascade

Blaizot

Mehtar-Tani

2016

Annals of Physics

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We discuss the dynamics of parton cascades that develop in dense QCD matter, and contrast their properties with those of similar cascades of gluon radiation in vacuum. We argue that such cascades belong to two distinct classes that are characterized respectively by an increasing or a constant (or decreasing) branching rate along the cascade. In the former class, of which the BDMPS, medium-induced, cascade constitutes a typical example, it takes a finite time to transport a finite amount of energy to very soft quanta, while this time is essentially infinite in the latter case, to which the DGLAP cascade belongs. The medium induced cascade is accompanied by a constant flow of energy towards arbitrary soft modes, leading eventually to the accumulation of the initial energy of the leading particle at zero energy. It also exhibits scaling properties akin to wave turbulence. These properties do not show up in the cascade that develops in vacuum. There, the energy accumulates in the spectrum at smaller and smaller energy as the cascade develops, but the energy never flows all the way down to zero energy. Our analysis suggests that the way the energy is shared among the offsprings of a splitting gluon has little impact on the qualitative properties of the cascades, provided the kernel that governs the splittings is not too singular.

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Section: The Ideal In-medium Qcd Cascadementioning

confidence: 99%

Section: The Ideal In-medium Qcd Cascadementioning

confidence: 99%

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Energy flow along the medium-induced parton cascade

Blaizot

Mehtar-Tani

2016

Annals of Physics

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“…2 TðQ=TÞ 1=2 [16,17]. The dominant interaction is between the hard particles and the thermal bath, not among the hard particles themselves [5,13], and therefore the equilibration depends only on averaged features of the initial condition.…”

mentioning

confidence: 99%

Approach to Equilibrium in Weakly Coupled Non-Abelian Plasmas

2014

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We follow the time evolution of non-Abelian gauge bosons from far-from-equilibrium initial conditions to thermal equilibrium by numerically solving an effective kinetic equation that becomes accurate in the weak coupling limit. We consider isotropic initial conditions that are either highly overoccupied or underoccupied. We find that overoccupied systems thermalize through a self-similar cascade reaching equilibrium in multiples of a thermalization time t eq ≈ 72:=ð1 þ 0.12 log λ −1 Þ × 1=λ 2 T, whereas underoccupied systems undergo a "bottom-up" thermalization in a time t eq ≈ ½34: þ 21: logðQ=TÞ= ð1 þ 0.037 log λ −1 Þ × ðQ=TÞ 1=2 =λ 2 T, where Q is the characteristic momentum scale of the initial condition. We apply this result to model initial stages of heavy-ion collisions and find rapid thermalization roughly in a time Qt eq ≲ 10 or t eq ≲ 1 fm=c. Non-Abelian far-from-equilibrium plasmas occur in many cosmological pre-or reheating scenarios [1] or due to possible cosmological phase transitions [2], as well as in the early stages of heavy-ion collisions. These far-from-equilibrium systems may be overoccupied, such that the energy is spread out in longer wavelength modes than in thermal equilibrium but with stronger fields. This is the case, e.g., for fields generated through parametric resonance, and in heavy-ion collisions, at least in the limit of asymptotically large center of mass energies, where the initial condition may be described by using the colorglass-condensate framework [3]. Alternately, far-fromequilibrium systems may be underoccupied, such that the system consists of fewer, but more energetic, quasiparticles than the corresponding thermal system. This is the case in, e.g., Planck-suppressed decay of inflatons [4]. Also, even though the initial condition of heavy-ion collisions is overoccupied, it has been demonstrated by Baier, Mueller, Schiff, and Son [5] (see also [6]) that the longitudinal expansion renders the prethermal fireball underoccupied before it reaches local thermal equilibrium.This has motivated several numerical [7][8][9][10][11][12] and analytical [13,14] works to study simple far-from-equilibrium model systems, in particular, that of a single species of gauge bosons in a (nonexpanding) flat space-time with statistically isotropic initial conditions at weak coupling, which we investigate in this Letter with both over-and underoccupied initial conditions. In both cases, we follow the time evolution of the system from the initial far-fromequilibrium state to thermal equilibrium and extract the thermalization time, which we define as the exponent governing relaxation of the deviation of the first moment of the distribution function, hjpji ¼ R p jpjfðpÞ= R p fðpÞ, from its equilibrium value hjpji T at late times:In the overoccupied case, early dynamics fall onto a nonthermal attractor solution: if the initial momentum scale characterized by Q 2 ≡ hp 2 ðt ¼ 0Þi is much smaller than the momentum scale of the target thermal system, then the scattering time of the initial system τ ini...

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“…For a review, see, for example, [27], or the list of reviews cited in the introduction of [28]. For explicit results for stopping distance, see [26]. 3 Technical note: at weak coupling, the relevant scale is really the inverse Debye screening length ∼ gT , and so the relevant coupling is α s (gT ).…”

Section: Pos(confinement X)030mentioning

confidence: 99%

Round Table on Quark-gluon plasma: What is it and how do we find out?

Foka¹,

Arnold²,

Florkowski³

et al. 2013

Proceedings of XTH Quark Confinement and the Hadron Spectrum — PoS(Confinement X)

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We present a panel discussion about our current state of knowledge about the Quark-Gluon Plasma. The nine panelists were asked to address the question: What do we want to know about the quark-gluon plasma, and how can we find the answers? The contributions illuminate our present understanding and highlight various aspects of the ongoing debate about the future directions of relativistic heavy-ion collision research.Xth Quark Confinement and the Hadron Spectrum,

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Stopping distance for high energy jets in weakly coupled quark-gluon plasmas

Cited by 26 publications

References 20 publications

Energy flow along the medium-induced parton cascade

Energy flow along the medium-induced parton cascade

Approach to Equilibrium in Weakly Coupled Non-Abelian Plasmas

Round Table on Quark-gluon plasma: What is it and how do we find out?

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