The angular structure of jet quenching within a hybrid strong/weak coupling model

Casalderrey-Solana, Jorge; Gulhan, D.; Milhano, José Guilherme; Pablos, Daniel; Rajagopal, Krishna

doi:10.1016/j.nuclphysbps.2017.05.083

Cited by 3 publications

(37 citation statements)

References 253 publications

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“…This picture was further corroborated within a diagrammatic calculation of the two-gluon emission spectrum in the limit of strong ordering of their respective emission times [22]. Recently, both Monte-Carlo studies [23,24] and analytical calculations [25,26], have highlighted the role of jet fluctuations that arise from in-medium splittings on observables that are sensitive to energy loss in heavy-ion collisions.…”

Section: Introductionmentioning

confidence: 64%

“…At large formation times, t f L, we can neglect the factors in the integrands of Eqs. (24) and (25), to find that…”

Section: Qualitative Discussion Of Scalesmentioning

confidence: 99%

“…The quadrupole Q(τ L , τ ) plays only a role for the "in-in" term, see Eq. (24). Looking in detail, the first term in (29) describes the survival probability of a (real) dipole with fixed transverse size b ⊥ ∼ θτ at the moment of formation, propagating the remaining distance to the end of the medium.…”

Section: Derivation Of the Spectrummentioning

confidence: 99%

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Mapping collinear in-medium parton splittings

et al. 2020

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We map the spectrum of 1 → 2 parton splittings inside a medium characterized by a transport coefficientq onto the kinematical Lund plane, taking into account the finite formation time of the process. We discuss the distinct regimes arising in this map for in-medium splittings, pointing out the close correspondence to a semi-classical description in the limit of hard, collinear radiation with short formation times. Although we disregard any modifications of the original parton kinematics in course of the propagation through the medium, subtle modifications to the radiation pattern compared to the vacuum baseline can be traced back to the physics of color decoherence and accumulated interactions in the medium. We provide theoretical support to vacuum-like emissions inside the medium by delimiting the regions of phase space where it is dominant, identifying also the relevant time-scales involved. The observed modifications are shown to be quite general for any dipole created in the medium.

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Section: Introductionmentioning

confidence: 64%

“…At large formation times, t f L, we can neglect the factors in the integrands of Eqs. (24) and (25), to find that…”

Section: Qualitative Discussion Of Scalesmentioning

confidence: 99%

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Mapping collinear in-medium parton splittings

et al. 2020

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“…To address the multi-scale dynamics of QCD jets in strongly coupled plasma more fully, in Refs. [111][112][113] two of us together with coauthors have introduced and developed a phenomenological hybrid strong/weak coupling approach to analyzing jet quenching. In this approach, different physical processes of relevance for the interaction of developing jet showers with the quark gluon plasma are treated differently: the production and evolution of the jet shower is treated perturbatively, because the physics governing these processes is expected to be weakly coupled, while the interaction between each of the partons formed in the shower with the medium is assumed to follow the rate of energy loss of an energetic quark in strongly coupled plasma obtained via holographic calculations in Refs.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper we remedy a lacuna in the hybrid model of Refs. [111][112][113]. In the model as developed to now, when a parton in the jet shower splits, the two resulting offspring partons are treated as if they separately and independently lose energy to the plasma from the moment of the splitting.…”

Section: Introductionmentioning

confidence: 99%

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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Charged-particle nuclear modification factors in PbPb and pPb collisions at s N N = 5.02 $$ \sqrt{s_{\mathrm{N}\;\mathrm{N}}}=5.02 $$ TeV

Khachatryan

Sirunyan

Tumasyan

et al. 2017

J. High Energ. Phys.

164

123

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The spectra of charged particles produced within the pseudorapidity window |η| < 1 at √ s NN = 5.02 TeV are measured using 404 µb −1 of PbPb and 27.4 pb −1 of pp data collected by the CMS detector at the LHC in 2015. The spectra are presented over the transverse momentum ranges spanning 0.5 < p T < 400 GeV in pp and 0.7 < p T < 400 GeV in PbPb collisions. The corresponding nuclear modification factor, R AA , is measured in bins of collision centrality. The R AA in the 5% most central collisions shows a maximal suppression by a factor of 7-8 in the p T region of 6-9 GeV. This dip is followed by an increase, which continues up to the highest p T measured, and approaches unity in the vicinity of p T = 200 GeV. The R AA is compared to theoretical predictions and earlier experimental results at lower collision energies. The newly measured pp spectrum is combined with the pPb spectrum previously published by the CMS collaboration to construct the pPb nuclear modification factor, R pA , up to 120 GeV. For p T > 20 GeV, R pA exhibits weak momentum dependence and shows a moderate enhancement above unity. The CMS collaboration 241 IntroductionThe charged-particle transverse momentum (p T ) spectrum is an important tool for studying parton energy loss in the dense QCD medium, known as the quark gluon plasma (QGP), that is produced in high energy nucleus-nucleus (AA) collisions [1,2]. In such collisions, high-p T particles, which originate from parton fragmentation, are sensitive to the amount of energy loss that the partons experience traversing the medium. By comparing highp T particle yields in AA collisions to predictions of theoretical models, insight into the fundamental properties of the QGP can be gained. Over the years, a number of results have been made available by experiments at SPS [3,4], at RHIC [5][6][7][8], and at the CERN LHC [9][10][11]. The modification of high-p T particle production is typically quantified using the ratio of the charged-particle p T spectrum in AA collisions to that of pp collisions, scaled by the average number of binary nucleon-nucleon collisions, N coll . This quantity is known as the nuclear modification factor, R AA , and can also be formulated as function of p T as R AA (p T ) = dN AA /dp T N coll dN pp /dp T = dN AA /dp T T AA dσ pp /dp T , ( 1) where N AA and N pp are the charged-particle yields in AA collisions and pp collisions, and σ pp is the charged-particle cross section in pp collisions. The ratio of N coll with the total inelastic pp cross section, defined as T AA = N coll /σ pp inel , is known as the nuclear overlap function and can be calculated from a Glauber model of the nuclear collision geometry [12]. In this work we adopt natural units, such that c = 1.-1 - JHEP04(2017)039The factor of 5 suppression observed in the R AA of charged hadrons and neutral pions at RHIC [5][6][7][8] was an indication of strong medium effects on particle production in the final state. However, the RHIC measurements were limited to a p T range below 25 GeV and a collision energy...

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The angular structure of jet quenching within a hybrid strong/weak coupling model

Cited by 3 publications

References 253 publications

Mapping collinear in-medium parton splittings

Mapping collinear in-medium parton splittings

Resolution effects in the hybrid strong/weak coupling model

Charged-particle nuclear modification factors in PbPb and pPb collisions at s N N = 5.02 $$ \sqrt{s_{\mathrm{N}\;\mathrm{N}}}=5.02 $$ TeV

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