Heavy Quark Jet Quenching with Collisional plus Radiative Energy Loss and Path Length Fluctuations

Wicks, Simon; Horowitz, W. A.; Djordjevic, Magdalena; Gyulassy, Miklós

doi:10.1016/j.nuclphysa.2006.11.102

Cited by 84 publications

(95 citation statements)

References 8 publications

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“…This energy loss is expected to occur via medium-induced gluon radiation [21,22] and elastic collisional energy loss processes [23][24][25] and it depends on the QCD Casimir coupling factor of the parton (larger for gluons than for quarks) and on the parton mass [26][27][28][29]. Other mechanisms, such as in-medium hadron formation and dissociation, can be envisaged as particularly relevant for heavy-flavour hadrons due to their small formation times [30][31][32].…”

Section: Jhep07(2015)051mentioning

confidence: 99%

Inclusive, prompt and non-prompt J/ψ production at mid-rapidity in Pb-Pb collisions at s N N = 2.76 $$ \sqrt{s_{\mathrm{NN}}}=2.76 $$ TeV

Adam

Adamová

Aggarwal

et al. 2015

J. High Energ. Phys.

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Abstract:The transverse momentum (p T ) dependence of the nuclear modification factor R AA and the centrality dependence of the average transverse momentum p T for inclusive J/ψ have been measured with ALICE for Pb-Pb collisions at √ s NN = 2.76 TeV in the e + e − decay channel at mid-rapidity (|y| < 0.8). The p T is significantly smaller than the one observed for pp collisions at the same centre-of-mass energy. Consistently, an increase of R AA is observed towards low p T . These observations might be indicative of a sizable contribution of charm quark coalescence to the J/ψ production. Additionally, the fraction of non-prompt J/ψ from beauty hadron decays, f B , has been determined in the region 1.5 < p T < 10 GeV/c in three centrality intervals. No significant centrality dependence of f B is observed. Finally, the R AA of non-prompt J/ψ is discussed and compared with model predictions. The nuclear modification in the region 4.5 < p T < 10 GeV/c is found to be stronger than predicted by most models. The ALICE collaboration 26 IntroductionHeavy-ion collisions at high energies allow the study of strongly interacting matter under extreme conditions. Calculations based on Quantum-Chromo-Dynamics (QCD) on the lattice indicate that the hot and dense medium created in these collisions behaves like a strongly coupled Quark-Gluon Plasma (QGP) [1][2][3][4]. Heavy quarks are an important probe for the properties of this state of matter, since they are produced via hard partonic collisions at a very early stage and thus experience the complete evolution of the system. Quarkonium states, i.e. bound states of a heavy quark and anti-quark such as the J/ψ meson (cc state) are of particular interest. It was predicted that the J/ψ formation is suppressed in a QGP due to the screening of the cc potential in the presence of free colour charges [5]. Experimentally, a suppression of the inclusive J/ψ yield in heavy-ion collisions relative to the corresponding yield in pp, scaled by the number of binary nucleon-nucleon collisions, has been observed at the Super Proton Synchrotron (SPS) [6][7][8] and the Relativistic Heavy Ion Collider (RHIC) [9,10]. The level of suppression was found to be similar at SPS and RHIC, despite the significantly different collision energy. More recently, the nuclear modification of J/ψ was also measured for Pb-Pb collisions at the LHC [11][12][13]. While at high transverse momentum (p T > 4 GeV/c) the suppression factor is at the same level as the one observed at RHIC in the low p T region, a significant reduction of the suppression is measured towards lower p T . This has been interpreted as the effect of an additional contribution to J/ψ production at low p T , due to the combination of correlated or uncorrelated c and c quarks [14,15]. This contribution becomes sizable at LHC energies, since the number of cc pairs is much higher than at lower energies. Assuming that a deconfined phase is produced and that all the J/ψ are dissociated, this process happens at the chemical freezeout stage of the fireball ...

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Section: Jhep07(2015)051mentioning

confidence: 99%

Inclusive, prompt and non-prompt J/ψ production at mid-rapidity in Pb-Pb collisions at s N N = 2.76 $$ \sqrt{s_{\mathrm{NN}}}=2.76 $$ TeV

Adam

Adamová

Aggarwal

et al. 2015

J. High Energ. Phys.

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“…Consequently, they probe the medium properties while they propagate through it [10][11][12][13]. In particular, the color charge and mass dependence of the partonic energy loss can be studied by comparing the suppression of heavy-flavor hadrons and hadrons carrying light quarks only [14,15].…”

Section: Introductionmentioning

confidence: 99%

Measurement of electrons from semileptonic heavy-flavor hadron decays inppcollisions ats=2.76 TeV

Abelev¹,

Adam²,

Adamová³

et al. 2015

Phys. Rev. D

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The p T -differential production cross section of electrons from semileptonic decays of heavy-flavor hadrons has been measured at midrapidity in proton-proton collisions at ffiffi ffi s p ¼ 2.76 TeV in the transverse momentum range 0.5 < p T < 12 GeV=c with the ALICE detector at the LHC. The analysis was performed using minimum bias events and events triggered by the electromagnetic calorimeter. Predictions from perturbative QCD calculations agree with the data within the theoretical and experimental uncertainties.

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“…As shown in WHDG and elsewhere [7], the computationally expensive integrations over the geometry of the QGP cannot be reduced to a simple 'average length' prescription. Indeed, this computation time is essential to produce radiative + collisional energy loss calculations consistent with the pion data.There are large theoretical uncertainties in the WHDG results [8]. Very significant to the electron prediction is the uncertainty in the charm and bottom cross-sections.…”

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confidence: 99%

Improving a radiative plus collisional energy loss model for application to RHIC and LHC

Wicks

Gyulassy²

2007

J. Phys. G: Nucl. Part. Phys.

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Abstract. With the QGP opacity computed perturbatively and with the global entropy constraints imposed by the observed dN ch /dy ≈ 1000, radiative energy loss alone cannot account for the observed suppression of single non-photonic electrons. Collisional energy loss is comparable in magnitude to radiative loss for both light and heavy jets. Two aspects that significantly affect the collisional energy loss are examined: the role of fluctuations, and the effect of introducing a running QCD coupling as opposed to the fixed α s = 0.3 used previously. IntroductionNon-photonic single electron data [1,2], which present an indirect probe of heavy quark energy loss, have significantly challenged the underlying assumptions of jet tomography theory. A much larger suppression of electrons than predicted [3] was observed in the p T ∼ 4 − 8 GeV region. "These data falsify the assumption that heavy quark quenching is dominated by [pQCD based] radiative energy loss when the bulk [weakly coupled] QCD matter parton density is constrained by the observed dN/dy ≈ 1000 rapidity density of produced hadrons." [4] WHDG [4] revisited the assumption that pQCD collisional energy loss is negligible compared to radiative energy loss [5,6]. As argued there, and references therein, "the elastic component of the energy loss cannot be neglected when considering pQCD jet quenching." As shown in WHDG and elsewhere [7], the computationally expensive integrations over the geometry of the QGP cannot be reduced to a simple 'average length' prescription. Indeed, this computation time is essential to produce radiative + collisional energy loss calculations consistent with the pion data.There are large theoretical uncertainties in the WHDG results [8]. Very significant to the electron prediction is the uncertainty in the charm and bottom cross-sections. There are also theoretical uncertainties in the energy loss mechanisms. Here, two aspects of the collisional energy loss will be examined with the aim of improving the energy loss model. Collisional energy loss fluctuationsSimilar to radiative energy loss, the fluctuations of collisional energy loss around the mean affect the quenching of the quark spectra. Collisional fluctuations are often modelled in a Fokker-Planck formalism, characterized by two numbers or functions: drag and diffusion. WHDG implemented an approximation to this scheme applicable for small energy loss by giving the collisional loss a gaussian width around the mean, with σ 2 = 2T ǫ , where ǫ is the mean energy loss given by a leading log calculation.

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Heavy Quark Jet Quenching with Collisional plus Radiative Energy Loss and Path Length Fluctuations

Cited by 84 publications

References 8 publications

Inclusive, prompt and non-prompt J/ψ production at mid-rapidity in Pb-Pb collisions at s N N = 2.76 $$ \sqrt{s_{\mathrm{NN}}}=2.76 $$ TeV

Inclusive, prompt and non-prompt J/ψ production at mid-rapidity in Pb-Pb collisions at s N N = 2.76 $$ \sqrt{s_{\mathrm{NN}}}=2.76 $$ TeV

Measurement of electrons from semileptonic heavy-flavor hadron decays inppcollisions ats=2.76 TeV

Improving a radiative plus collisional energy loss model for application to RHIC and LHC

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