Dihadron Tomography of HighEnergy Nuclear Collisions inNexttoLeading Order Perturbative QCD
Abstract
Backtoback dihadron spectra in highenergy heavyioncollisions are studied within the nexttoleading order (NLO)perturbative QCD parton model with jet quenching incorporated viamodified jet fragmentation functions due to radiative parton energy lossin dense medium. The experimentally observed appearance of backtobackdihadron sat high p_T is found to originate mainly from jet pairsproduced close and tangential to the surface of the dense matter.However, a substantial fraction of observed high p_T dihadrons also comesfrom jets produced at the center of the medium after losing finite amountof energy. Consequently, the suppression factor of such highp_T hadronpairs is foundto be more sensitive to the initial gluon density than thesingle hadron spectra that are dominated by surface emission. Asimultaneous chi2fit to both the single and dihadron spectra can beachieved within an arrow range of the energy loss parametersepsilon_0=1.62.1 GeV/fm. Because of the flattening of the initial jetproduction spectra, high p_T dihadrons at the LHC energy are found to bemore robust as probes of the dense medium.
 Authors:
 Publication Date:
 Research Org.:
 COLLABORATION  Huazhong NormalU./China
 OSTI Identifier:
 923204
 Report Number(s):
 LBNL62151
Journal ID: ISSN 00319007; PRLTAO; R&D Project: NTCOST; BnR: KB0301020; TRN: US0801791
 DOE Contract Number:
 DEAC0205CH11231
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Physical Review Letters; Journal Volume: 98; Related Information: Journal Publication Date: 25 May 2007
 Country of Publication:
 United States
 Language:
 English
 Subject:
 72; FRAGMENTATION; GLUONS; HADRONS; PROBES; PRODUCTION; QUANTUM CHROMODYNAMICS; QUENCHING; SPECTRA; TOMOGRAPHY; Dihadron Dijet Jet quenching QGP
Citation Formats
Zhang, Hanzhong, Owens, Joseph F., Wang, Enke, and Wang, XinNian. Dihadron Tomography of HighEnergy Nuclear Collisions inNexttoLeading Order Perturbative QCD. United States: N. p., 2007.
Web. doi:10.1103/PhysRevLett.98.212301.
Zhang, Hanzhong, Owens, Joseph F., Wang, Enke, & Wang, XinNian. Dihadron Tomography of HighEnergy Nuclear Collisions inNexttoLeading Order Perturbative QCD. United States. doi:10.1103/PhysRevLett.98.212301.
Zhang, Hanzhong, Owens, Joseph F., Wang, Enke, and Wang, XinNian. Wed .
"Dihadron Tomography of HighEnergy Nuclear Collisions inNexttoLeading Order Perturbative QCD". United States.
doi:10.1103/PhysRevLett.98.212301. https://www.osti.gov/servlets/purl/923204.
@article{osti_923204,
title = {Dihadron Tomography of HighEnergy Nuclear Collisions inNexttoLeading Order Perturbative QCD},
author = {Zhang, Hanzhong and Owens, Joseph F. and Wang, Enke and Wang, XinNian},
abstractNote = {Backtoback dihadron spectra in highenergy heavyioncollisions are studied within the nexttoleading order (NLO)perturbative QCD parton model with jet quenching incorporated viamodified jet fragmentation functions due to radiative parton energy lossin dense medium. The experimentally observed appearance of backtobackdihadron sat high p_T is found to originate mainly from jet pairsproduced close and tangential to the surface of the dense matter.However, a substantial fraction of observed high p_T dihadrons also comesfrom jets produced at the center of the medium after losing finite amountof energy. Consequently, the suppression factor of such highp_T hadronpairs is foundto be more sensitive to the initial gluon density than thesingle hadron spectra that are dominated by surface emission. Asimultaneous chi2fit to both the single and dihadron spectra can beachieved within an arrow range of the energy loss parametersepsilon_0=1.62.1 GeV/fm. Because of the flattening of the initial jetproduction spectra, high p_T dihadrons at the LHC energy are found to bemore robust as probes of the dense medium.},
doi = {10.1103/PhysRevLett.98.212301},
journal = {Physical Review Letters},
number = ,
volume = 98,
place = {United States},
year = {Wed Jan 17 00:00:00 EST 2007},
month = {Wed Jan 17 00:00:00 EST 2007}
}

Dihadron spectra in highenergy heavyion collisions are studied within the nexttoleading order perturbative QCD parton model with modified jet fragmentation functions due to jet quenching. Highp{sub T} backtoback dihadrons are found to originate mainly from jet pairs produced close and tangential to the surface of the dense matter. However, a substantial fraction also comes from jets produced at the center with finite energy loss. Consequently, highp{sub T} dihadron spectra are found to be more sensitive to the initial gluon density than the single hadron spectra that are more dominated by surface emission. A simultaneous {chi}{sup 2} fit to both themore »

SingleInclusive Jet Production In ElectronNucleon Collisions Through NextToNextToLeading Order In Perturbative QCD
We compute the Oσ ^{2}σ ^{2} _{s} perturbative corrections to inclusive jet production in electronnucleon collisions. This process is of particular interest to the physics program of a future Electron Ion Collider (EIC). We include all relevant partonic processes, including deepinelastic scattering contributions, photoninitiated corrections, and partonparton scattering terms that first appear at this order. Upon integration over the finalstate hadronic phase space we validate our results for the deepinelastic corrections against the known nexttonexttoleading order (NNLO) structure functions. Our calculation uses the Njettiness subtraction scheme for performing higherorder computations, and allows for a completely differential description of the deepinelasticmore » 
Comment on “Singleinclusive jet production in electron–nucleon collisions through nexttonexttoleading order in perturbative QCD” [Phys. Lett. B 763 (2016) 52–59]
In the cross section for singleinclusive jet production in electron nucleon collisions, the distribution of a quark in an electron appears at nexttonexttoleading order. The numerical calculations in Ref. [1] were carried out using a perturbative approximation for the distribution of a quark in an electron. We point out that that distribution receives nonperturbative QCD contributions that invalidate the perturbative approximation. Here, those nonperturbative effects enter into cross sections for hardscattering processes through resolvedelectron contributions and can be taken into account by determining the distribution of a quark in an electron phenomenologically. 
Comment on “Singleinclusive jet production in electron–nucleon collisions through nexttonexttoleading order in perturbative QCD” [Phys. Lett. B 763 (2016) 52–59]
In the cross section for singleinclusive jet production in electron nucleon collisions, the distribution of a quark in an electron appears at nexttonexttoleading order. The numerical calculations in Ref. [1] were carried out using a perturbative approximation for the distribution of a quark in an electron. We point out that that distribution receives nonperturbative QCD contributions that invalidate the perturbative approximation. Here, those nonperturbative effects enter into cross sections for hardscattering processes through resolvedelectron contributions and can be taken into account by determining the distribution of a quark in an electron phenomenologically.