Observation and studies of jet quenching in PbPb collisions at {radical}(s{sub NN})=2.76 TeV

Jet production in PbPb collisions at a nucleon-nucleon center-of-mass energy of 2.76 TeV was studied with the Compact Muon Solenoid (CMS) detector at the LHC, using a data sample corresponding to an integrated luminosity of 6.7 {mu}b{sup -1}. Jets are reconstructed using the energy deposited in the CMS calorimeters and studied as a function of collision centrality. With increasing collision centrality, a striking imbalance in dijet transverse momentum is observed, consistent with jet quenching. The observed effect extends from the lower cutoff used in this study (jet p{sub T}=120 GeV/c) up to the statistical limit of the available data sample (jet p{sub T}{approx_equal}210 GeV/c). Correlations of charged particle tracks with jets indicate that the momentum imbalance is accompanied by a softening of the fragmentation pattern of the second most energetic, away-side jet. The dijet momentum balance is recovered when integrating low transverse momentum particles distributed over a wide angular range relative to the direction of the away-side jet.

[1]  M. Cacciari,et al.  The anti-$k_t$ jet clustering algorithm , 2008, 0802.1189.

[2]  J. Putschke.  First fragmentation function measurements from full jet reconstruction in heavy-ion collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV by STAR , 2008, 0809.1419.

[3]  Ina Ruck,et al.  USA , 1969, The Lancet.

[4]  Andrea Benaglia,et al.  Transverse-Momentum and Pseudorapidity Distributions of Charged Hadrons in pp Collisions at root s=7 TeV , 2010 .

[5]  Marcelino B. Santos,et al.  CMS Physics : Technical Design Report Volume 1: Detector Performance and Software , 2006 .

[6]  Appel.  Jets as a probe of quark-gluon plasmas. , 1986, Physical review. D, Particles and fields.

[7]  João Paulo Teixeira,et al.  The CMS experiment at the CERN LHC , 2008 .

[8]  M. Cacciari,et al.  The Catchment Area of Jets , 2008, 0802.1188.

[9]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[10]  S. Salur.  First direct measurement of jets in $\sqrt{s_{\mathit {NN}}}=200~\mbox{GeV}$ heavy ion collisions by STAR , 2008, 0809.1609.

[11]  E. al.,et al.  Formation of dense partonic matter in relativistic nucleus–nucleus collisions at RHIC: Experimental evaluation by the PHENIX Collaboration , 2004, nucl-ex/0410003.

[12]  C. Vries,et al.  Nuclear charge and magnetization density distribution parameters from elastic electron scattering , 1974 .

[13]  R. Hwa,et al.  Quark-Gluon Plasma 3 , 2004 .

[14]  Matteo Cacciari,et al.  Fluctuations and asymmetric jet events in PbPb collisions at the LHC , 2011, 1101.2878.

[15]  G. S. Averichev,et al.  Strangeness production in STAR , 2008, 0809.0823.

[16]  S. Mrenna,et al.  Pythia 6.3 physics and manual , 2003, hep-ph/0308153.

[17]  A. A. Ocampo Rios,et al.  Dijet azimuthal decorrelations in pp collisions at √s=7 TeV. , 2011, Physical review letters.

[18]  C. Henderson,et al.  The PHOBOS Perspective on Discoveries at RHIC , 2005 .

[19]  J. Yarba,et al.  Identification and Filtering of Uncharacteristic Noise in the CMS Hadron Calorimeter , 2010 .

[20]  C. Salgado,et al.  Jet quenching , 2005 .

[21]  S. Salur.  First direct measurement of jets in √ sNN = 200 GeV heavy ion collisions by STAR , 2009 .

[22]  McLerran,et al.  Jets in expanding quark-gluon plasmas. , 1986, Physical review. D, Particles and fields.

[23]  Giorgio Parisi,et al.  Exponential Hadronic Spectrum and Quark Liberation , 1975 .

[24]  Hayes,et al.  Review of Particle Physics. , 1996, Physical review. D, Particles and fields.

[25]  E. al.,et al.  Experimental and theoretical challenges in the search for the quark-gluon plasma: The STAR Collaboration's critical assessment of the evidence from RHIC collisions , 2005, nucl-ex/0501009.

[26]  J. Collins,et al.  Superdense Matter: Neutrons Or Asymptotically Free Quarks? , 1975 .

[27]  I. P. Lokhtin,et al.  A model of jet quenching in ultrarelativistic heavy ion collisionsand high- pT hadron spectra at RHIC , 2006 .

[28]  M. Cacciari,et al.  Pileup subtraction using jet areas , 2007, 0707.1378.

[29]  E. Shuryak.  Theory of Hadronic Plasma , 1977 .

[30]  Bin Zhang,et al.  Multiphase transport model for relativistic heavy ion collisions , 2005 .

[31]  R M Buckingham,et al.  Observation of a centrality-dependent dijet asymmetry in lead-lead collisions at sqrt[S(NN)] =2.76 TeV with the ATLAS detector at the LHC. , 2010, Physical review letters.

[32]  F. T. Collaboration,et al.  Inclusive cross section and correlations of fully reconstructed jets in sNN=200GeV Au + Au and p+p collisions , 2009, 0908.1799.

[33]  Marcelino B. Santos,et al.  CMS Physics Technical Design Report, Volume II: Physics Performance , 2007 .

[34]  C. Salgado,et al.  Introductory lectures on jet quenching in heavy ion collisions , 2007, 0712.3443.

[35]  J. Nystrand,et al.  Single and Double Photonuclear Excitations in Pb+Pb Collisions at the LHC , 2010 .

[36]  Peter Steinberg,et al.  Glauber Modeling in High Energy Nuclear Collisions , 2007, nucl-ex/0701025.

[37]  M. Cacciari,et al.  Jet reconstruction in heavy ion collisions , 2010, 1010.1759.

[38]  J. Nystrand,et al.  Single and double photonuclear excitations in Pb+Pb collisions at {radical}(s{sub NN})=2.76 TeV at the CERN Large Hadron Collider , 2010, 1011.4908.

[39]  Quark gluon plasma and color glass condensate at RHIC? The Perspective from the BRAHMS experiment , 2005 .

[40]  D. d’Enterria.  Selective Tracer Signals of the QCD Plasma State , 2010 .

[41]  O. Kodolova,et al.  The performance of the jet identification and reconstruction in heavy ions collisions with CMS detector , 2007 .

[42]  M. K. Lee,et al.  Results from PHENIX on Deuteron and Anti-Deuteron Production in Au+Au Collisions at RHIC , 2004, nucl-ex/0409006.

[43]  E. Bruna.  Measurements of jet structure and fragmentation from full jet reconstruction in heavy ion collisions at RHIC , 2009, 0907.4788.

[44]  F. Karsch,et al.  Thermodynamics and In-Medium Hadron Properties from Lattice QCD , 2003, hep-lat/0305025.