A systematic study of direct photon production in heavy ion collisions

Vitev, Ivan; Zhang, Ben-Wei

doi:10.1016/j.physletb.2008.10.019

Cited by 60 publications

(82 citation statements)

References 31 publications

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“…The CNM [18] effects we consider include nuclear shadowing (here implemented as coherent power corrections) and initial state energy loss. These are calculated in the same framework as previously used for light hadrons [19][20][21][22][23][24][25][26] and open heavy flavor [27][28][29]. We also consider transverse momentum broadening [19,[28][29][30] (as a model for the Cronin effect).…”

Section: Introductionmentioning

confidence: 99%

High transverse momentum quarkonium production and dissociation in heavy ion collisions

2013

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We calculate the yields of quarkonia in heavy ion collisions at RHIC and the LHC as a function of their transverse momentum. Based upon non-relativistic quantum chromodynamics, our results include both color-singlet and color-octet contributions and feed-down effects from excited states. In reactions with ultra-relativistic nuclei, we focus on the consistent implementation of dynamically calculated nuclear matter effects, such as coherent power corrections, cold nuclear matter energy loss, and the Cronin effect in the initial state. In the final state, we consider radiative energy loss for the color-octet state and collisional dissociation of quarkonia as they traverse through the QGP. Theoretical results are presented for J/ψ and Υ and compared to experimental data where applicable. At RHIC, a good description of the high-pT J/ψ modification observed in central Cu+Cu and Au+Au collisions can be achieved within the model uncertainties. We find that measurements of J/ψ yields in proton-nucleus reactions are needed to constrain the magnitude of cold nuclear matter effects. At the LHC, a good description of the experimental data can be achieved only in mid-central and peripheral Pb+Pb collisions. The large five-fold suppression of prompt J/ψ in the most central nuclear reactions may indicate for the first time possible thermal effects at the level of the quarkonium wavefunction at large transverse momenta.

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Section: Introductionmentioning

confidence: 99%

High transverse momentum quarkonium production and dissociation in heavy ion collisions

2013

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“…For the study of γ-hadron correlation in this paper, we will focus mainly on photons with isolation cuts. Therefore, we can neglect those photons that are produced via induced bremsstrahlung [12], jet-photon conversion [13] and thermal production [14,15] in high-energy heavy-ion collisions.To take into account parton energy loss in γ-hadron correlation in high-energy heavy-ion collisions, we will use an effective form of medium modified FF's as in previous studies [6,16] with an average energy loss,for a quark (gluon energy loss is 9/4 of a quark) produced arXiv:0902.4000v1 [nucl-th] …”

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confidence: 99%

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confidence: 99%

Tomography of High-Energy Nuclear Collisions with Photon-Hadron Correlations

et al. 2009

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Within the next-to-leading order (NLO) perturbative QCD (pQCD) parton model, suppression of away-side hadron spectra associated with a high pT photon due to parton energy loss is studied in high-energy heavy-ion collisions. Dictated by the shape of the γ-associated jet spectrum in NLO pQCD, hadron spectra at large zT = p h T /p γ T > ∼ 1 are more sensitive to parton energy loss and therefore are dominated by surface emission of γ-associated jets, whereas small zT hadrons mainly come from fragmentation of jets with reduced energy which is controlled by the volume emission. These lead to different centrality dependence of the γ-hadron suppression for different values of zT . Therefore, a complete measurement of the suppression of γ-triggered hadron spectra, including its dependence on the orientation of the γ-hadron pair with respect to the reaction plane, allows the extraction of the spatial distribution of jet quenching parameters, achieving a true tomographic study of the quark-gluon plasma in high-energy heavy-ion collisions.PACS numbers: 12.38. Mh, 24.85.+p; Jet quenching [1] or suppression of large p T hadrons, caused by parton energy loss due to strong interaction between jets and the dense medium, has become a powerful tool for the study of properties of the quark-gluon plasma [2] in high-energy heavy-ion collisions. Experimental studies of jet quenching include suppression of single [3,4], dihadron (back-to-back) [5] and γ-hadron spectra. The strong suppression of large p T single hadron spectra and its centrality dependence at the Relativistic Heavy-ion Collider (RHIC) [3,5], indicate a picture of surface emission of jets. Most of jets, initially produced at the center of collisions, undergo large amount of energy loss and do not contribute to the final observed large p T hadron spectra. High p T dihadrons, on the other hand, come not only from jet pairs close and tangential to the surface of the dense medium but also from punch-through jets originating from the center of the system [6], leading to their increased sensitivity to the initial gluon density as compared to single hadrons.We will focus in this paper on the study of γ-triggered away-side hadron spectra in heavy-ion collisions within the next-to-leading order (NLO) perturbative QCD (pQCD) parton model. Since a photon does not interact in QCD with the dense medium, its energy approximately reflects that of the initial jet in γ-jet events prior to jet propagation through the medium. One can therefore study the medium modification of the full jet fragmentation function (FF) [7,8]. By selecting γ-hadron pairs with different values of z T = p h T /p γ T , which could be larger than 1 due to radiative correction in NLO pQCD, one can effectively control hadron emission from different regions of the dense medium and therefore extract the corresponding jet quenching parameters.Within pQCD parton model, the NLO corrections (α e α 2 s ) to photon and photon-hadron production cross sections include 1-loop corrections to 2 → 2 tree level processes and 2 → 3...

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“…Integrating out the jet and including the relevant tree level processes we evaluate the inclusive Z 0 production cross section. We find that cold nuclear matter effects [10,11] …”

Section: Z 0 -Tagged Jetsmentioning

confidence: 76%

“…Theoretical predictions for the attenuation of inclusive jets are shown in the left panel of Figure 1 for two radii R = 0.2, 0.6. Our results include final-state QGP-induced radiative energy loss effects [9] and initial-state cold nuclear matter effects [10,11]. Preliminary ATLAS results [3] are also shown for comparison.…”

Section: Quenching Of Inclusive Jetsmentioning

confidence: 99%

NLO analysis of inclusive jet, tagged jet and di-jet production in Pb+Pb collisions at the LHC

Vitev¹

2011

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

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Abstract. We present results and predictions at next-to-leading order for the recent LHC lead-lead run at a center-of-mass energy of 2.76 TeV per nucleonnucleon pair. Specifically, we focus on the suppression the single and double inclusive jet cross sections and demonstrate how the di-jet asymmetry, recently measured by ATLAS and CMS, can be extracted from this general result. The case of jets tagged by an electroweak boson is exemplified by the Z 0 +jet channel. We predict a signature transition from enhancement to suppression of the tagged jet related to the medium-induced modification of the parton shower. Finally, we clarify the relation between the suppression of inclusive jets, tagged jets and dijets and the quenching of inclusive particles on the example of the recent ALICE charged hadron attenuation data.

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A systematic study of direct photon production in heavy ion collisions

Cited by 60 publications

References 31 publications

High transverse momentum quarkonium production and dissociation in heavy ion collisions

High transverse momentum quarkonium production and dissociation in heavy ion collisions

Tomography of High-Energy Nuclear Collisions with Photon-Hadron Correlations

NLO analysis of inclusive jet, tagged jet and di-jet production in Pb+Pb collisions at the LHC

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