Event-by-event fluctuations in the medium-induced jet evolution

Escobedo, Miguel Ángel; Iancu, Edmond

doi:10.1007/jhep05(2016)008

Cited by 19 publications

(40 citation statements)

References 59 publications

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“…This means that both the average and the typical deviation are of the same order of magnitude and that both are of the size of ω br . Details on the derivation of these results are given in [1].…”

Section: The 2-point Function and The Fluctuations Of The Energy Lossmentioning

confidence: 99%

“…We show that under suitable approximations, the jet evolution is a Markovian stochastic process, which is exactly solvable. For this process, we construct exact analytic solutions for all the n-point correlation functions describing the gluon distribution in the space of energy [1,2]. Using these results, we study the event-by-event distribution of the energy lost by the jet at large angles and of the multiplicities of the soft particles which carry this energy.…”

Section: Introductionmentioning

confidence: 99%

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Jet evolution in a dense medium: event-by-event fluctuations and multi-particle correlations

Espinosa¹,

Iancu²

2017

Proceedings of the European Physical Society Conference on High Energy Physics — PoS(EPS-HEP2017)

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We study the gluon distribution produced via successive medium-induced branchings by an energetic jet propagating through a weakly-coupled quark-gluon plasma. We show that under suitable approximations, the jet evolution is a Markovian stochastic process, which is exactly solvable. For this process, we construct exact analytic solutions for all the n-point correlation functions describing the gluon distribution in the space of energy [1,2]. Using these results, we study the event-by-event distribution of the energy lost by the jet at large angles and of the multiplicities of the soft particles which carry this energy. We find that the event-by-event fluctuations are huge: the standard deviation in the energy loss is parametrically as large as its mean value [1]. This has important consequences for the phenomenology of di-jet asymmetry in Pb+Pb collisions at the LHC: it implies that the fluctuations in the branching process can contribute to the measured asymmetry on an equal footing with the geometry of the di-jet event (i.e. as the difference between the in-medium path lengths of the two jets). We compute the higher moments of the multiplicity distribution and identify a remarkable regularity known as Koba-Nielsen-Olesen (KNO) scaling [2]. These predictions could be tested via eventby-event measurements of the di-jet asymmetry.

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Section: The 2-point Function and The Fluctuations Of The Energy Lossmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Jet evolution in a dense medium: event-by-event fluctuations and multi-particle correlations

Espinosa¹,

Iancu²

2017

Proceedings of the European Physical Society Conference on High Energy Physics — PoS(EPS-HEP2017)

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“…In order to quantify the importance of the energy loss we will compute its variance (more details on the computation are given in [1])…”

Section: The 2-point Function and The Fluctuations Of The Energy Lossmentioning

confidence: 99%

“…With this we have the contribution to D (2) from all the branchings that happen at time τ , to get the full result we just need to integrate for all τ . Similarly to what happens with D, it is possible to solve this evolution analytically making the approximation K → K 0…”

Section: The 2-point Function and The Fluctuations Of The Energy Lossmentioning

confidence: 99%

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Event-by-event picture for the medium-induced jet evolution

Escobedo

Iancu

2017

Nuclear and Particle Physics Proceedings

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Abstract. We discuss the evolution of an energetic jet which propagates through a dense quark-gluon plasma and radiates gluons due to its interactions with the medium. Within perturbative QCD, this evolution can be described as a stochastic branching process, that we have managed to solve exactly. We present exact, analytic, results for the gluon spectrum (the average gluon distribution) and for the higher n-point functions, which describe correlations and fluctuations. Using these results, we construct the event-byevent picture of the gluon distribution produced via medium-induced gluon branching.In contrast to what happens in a usual QCD cascade in vacuum, the medium-induced branchings are quasi-democratic, with offspring gluons carrying sizable fractions of the energy of their parent parton. We find large fluctuations in the energy loss and in the multiplicity of soft gluons. The multiplicity distribution is predicted to exhibit KNO (Koba-Nielsen-Olesen) scaling. These predictions can be tested in Pb+Pb collisions at the LHC, via event-by-event measurements of the di-jet asymmetry. Based on [1,2].

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Resolution effects in the hybrid strong/weak coupling model

Hulcher

Pablos

Rajagopal

2018

J. High Energ. Phys.

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Within the context of a hybrid strong/weak coupling model of jet quenching, we study the consequences of the fact that the plasma produced in a heavy ion collision cannot resolve the substructure of a collimated parton shower propagating through it with arbitrarily fine spatial resolution. We introduce a screening length parameter, L res , proportional to the inverse of the local temperature in the plasma, estimating a range for the value of the proportionality constant via comparing weakly coupled QCD calculations and holographic calculations appropriate in strongly coupled plasma. We then modify the hybrid model so that when a parton in a jet shower splits, its two offspring are initially treated as unresolved, and are only treated as two separate partons losing energy independently after they are separated by a distance L res . This modification delays the quenching of partons with intermediate energy, resulting in the survival of more hadrons in the final state with p T in the several GeV range. We analyze the consequences of different choices for the value of the resolution length, L res , and demonstrate that introducing a nonzero L res results in modifications to the jet shapes and jet fragmentations functions, as it makes it more probable for particles carrying a small fraction of the jet energy at larger angles from the jet axis to survive their passage through the quark-gluon plasma. These effects are, however, small in magnitude, something that we confirm via checking for effects on missing-p T observables. arXiv:1707.05245v1 [hep-ph]

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Event-by-event fluctuations in the medium-induced jet evolution

Cited by 19 publications

References 59 publications

Jet evolution in a dense medium: event-by-event fluctuations and multi-particle correlations

Jet evolution in a dense medium: event-by-event fluctuations and multi-particle correlations

Event-by-event picture for the medium-induced jet evolution

Resolution effects in the hybrid strong/weak coupling model

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