J. F. Owens

Publications (5)7.37 Total impact

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  Available from: Xin-Nian Wang

  Article: Gamma-Jet Tomography of Quark-Gluon Plasma in High-Energy Nuclear Collisions

  Hanzhong Zhang, J. F. Owens, Enke Wang, Xin-Nian Wang
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  ABSTRACT: Within the next-to-leading order (NLO) perturbative QCD (pQCD) parton model, suppression of away-side hadron spectra associated with a high $p_{T}$ photon due to parton energy loss is shown to provide a complete tomographic picture of the dense matter formed in high-energy heavy-ion collisions at RHIC. Dictated by the shape of the $\gamma$-triggered jet spectrum in NLO pQCD, hadron spectra at large $z_T=p_T^{h}/p_T^{\gamma} \stackrel{>}{\sim} 1$ are more susceptible to parton energy loss and therefore are dominated by surface emission of $\gamma$-triggered jets, whereas small $z_{T}$ hadrons mainly come from fragmentation of jets with reduced energy from volume emission. These lead to different centrality dependence of the hadron suppression in different regions of $z_{T}$. Comment: 4 pages, 3 figures, proceedings for QM 2009 conference
  07/2009;
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  Available from: Xin-Nian Wang

  Article: Tomography of high-energy nuclear collisions with photon-hadron correlations.

  Hanzhong Zhang, J F Owens, Enke Wang, Xin-Nian Wang
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  ABSTRACT: 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. Because of the sharp falloff of the gamma-jet spectrum in momentum imbalance pTjet-pTgamma>0 in NLO PQCD, hadron spectra at large zT=pTh/pTgamma greater than approximately 1 are more susceptible to parton energy loss and therefore are dominated by surface emission of gamma-associated jets with almost no energy loss, whereas small zT hadrons mainly come from the volume emission of jets with reduced energy. These lead to different centrality dependence of the gamma-hadron suppression for different values of zT. Therefore, a complete measurement of the suppression of gamma-triggered hadron spectra allows a true tomographic study of the quark-gluon plasma in high-energy heavy-ion collisions.
  Physical Review Letters 07/2009; 103(3):032302. · 7.37 Impact Factor
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  Article: A NLO analysis on fragility of dihadron tomography in high energy $AA$ collisions

  Hanzhong Zhang, J. F. Owens, Enke Wang, X. -N. Wang
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  ABSTRACT: The dihadron spectra in high energy $AA$ collisions are studied within the NLO pQCD parton model with jet quenching taken into account. The high $p_T$ dihadron spectra are found to be contributed not only by jet pairs close and tangential to the surface of the dense matter but also by punching-through jets survived at the center while the single hadron high $p_T$ spectra are only dominated by surface emission. Consequently, the suppression factor of such high-$p_T$ hadron pairs is found to be more sensitive to the initial gluon density than the single hadron suppression factor.
  05/2008;
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  Available from: Xin-Nian Wang

  Article: Punch-through jets in $A+A$ collisions at RHIC/LHC

  Hanzhong Zhang, J. F. Owens, Enke Wang, X. -N. Wang
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  ABSTRACT: High $p_T$ single and dihadron production is studied within a NLO pQCD parton model with jet quenching in high energy $A+A$ collisions at the RHIC/LHC energy. A simultaneous $\chi^2$-fit to both single and dihadron spectra can be achieved within a narrow range of energy loss parameter. Punch-through jets are found to result in the dihadron suppression factor slightly more sensitive to medium than the single hadron suppression factor at RHIC. Such jets at LHC are found to dominate high $p_T$ dihadron production and the resulting dihadron spectra are more sensitive to the initial parton distribution functions than the single hadron spectra.
  05/2008;
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  Available from: Xin-Nian Wang

  Article: Dihadron Tomography of High-Energy Nuclear Collisions in NLO pQCD

  Hanzhong Zhang, J. F. Owens, Enke Wang, Xin-Nian Wang
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  ABSTRACT: Back-to-back dihadron spectra in high-energy heavy-ion collisions are studied within the next-to-leading order (NLO) perturbative QCD parton model with jet quenching incorporated via modified jet fragmentation functions due to radiative parton energy loss in dense medium. The experimentally observed appearance of back-to-back dihadrons at high $p_T$ is found to originate mainly from jet pairs produced close and tangential to the surface of the dense matter. However, a substantial fraction of observed high $p_T$ dihadrons also comes from jets produced at the center of the medium after losing finite amount of energy. Consequently, the suppression factor of such high-$p_T$ hadron pairs is found to be more sensitive to the initial gluon density than the single hadron spectra that are dominated by surface emission. A simultaneous $\chi^2$-fit to both the single and dihadron spectra can be achieved within a narrow range of the energy loss parameters $\epsilon_0=1.6-2.1$ GeV/fm. Because of the flattening of the initial jet production spectra, high $p_T$ dihadrons at the LHC energy are found to be more robust as probes of the dense medium.
  02/2007;