Heavy Ion Collision Measurements at the LHC Using the CMS Detector David Krofcheck on behalf of the CMS Collaboration IAS-CERN Workshop, Singapore, March 26 th So, what happens at the LHC besides Higgs hunting?
p, K, p, n, f, L, D, X, W, d D. Krofcheck IAS-CERN Workshop, Singapore 2
The CMS Detector - Overall picture Muon Detectors < 2.5 Beam Scintillators (NZ) Pixel and Silicon-Strip Tracker Excellent momentum resolution Large acceptance < 2.5 3.8 T Solenoid Hermetic calorimeter coverage ECAL + HCAL < 3.0 Forward HCAL 3.0 < 5.0 DAQ+Trigger: Dedicated triggers for Jets, Photons, Muon, high p T charged particles, etc. D. Krofcheck IAS-CERN Workshop, Singapore 3
Basic nuclear physics jargon as needed Probing the sqgp with the CMS highlights, too much to discuss! Dijets energy balance γ jet energy loss Electroweak probes (Z 0,W ± ), Quarkonia suppression Nuclear Modification Factors (R AA ) Particle correlations flow, dihadrons Basic Summary D. Krofcheck IAS-CERN Workshop, Singapore 4
The CMS Detector - single particle detection 4T D. Krofcheck IAS-CERN Workshop, Singapore 5
The CMS Detector - better than a cartoon
Measure the overlap of two ions or number of participating or colliding nucleons by measuring energy in forward calorimeters Energy in calorimeters is ~ to the number of participating nucleons in the overlap region (Glauber Model) Rate of high p T processes is ~ to the number of colliding pairs of quarks and gluons D. Krofcheck IAS-CERN Workshop, Singapore 7
What Pixel detectors and Forward calorimeters see peripheral central peripheral central D. Krofcheck IAS-CERN Workshop, Singapore 8
Jet production in pp collisions jet-jet correlation in QCD vacuum D. Krofcheck IAS-CERN Workshop, Singapore 9
Jet production in PbPb collisions jet-jet correlation in QCD medium γ jet correlation to probe the medium? D. Krofcheck IAS-CERN Workshop, Singapore 10
E-ΔΕ 1 Δφ Dijet imbalance in PbPb collisions E-ΔΕ 2 Phys. Rev. C 84, 024906 (2011) D. Krofcheck IAS-CERN Workshop, Singapore 11
Selecting jets in PbPb collisions Phys. Rev. C 84, 024906 (2011) peripheral central D. Krofcheck IAS-CERN Workshop, Singapore 12
Dijets in PbPb - asymmetry in central collisions PLB 712 (2012) 176 D. Krofcheck IAS-CERN Workshop, Singapore 13
Observed momentum imbalance in γ jet correlation Linar Boltzman Transport PLB 718 (2013) 773 elastic parton scattering induced gluon emission Wang&Zhu arxiv:1302.5874
Observed deviation between γ jet from PbPb collisions Mean x J CMS Significant deviation of x J in PbPb compared to PYTHIA + HYDJET PLB 718 (2013) 773 Wang & Zhu arxiv:1302.5874 D. Krofcheck IAS-CERN Workshop, Singapore 15
Observed deviation between γ jet from PbPb collisions PLB 718 (2013) 773 Wang & Zhu arxiv:1302.5874 D. Krofcheck IAS-CERN Workshop, Singapore 16
Electroweak bosons passing through sqgp D. Krofcheck IAS-CERN Workshop, Singapore 17 PRL 106 (2011) 212301 PLB 715 (2012) 66
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PLB 710 (2012) 256 D. Krofcheck IAS-CERN Workshop, Singapore 19
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EPJC 72 (2012)1945 D. Krofcheck IAS-CERN Workshop, Singapore 23
Heavy Mesons as sqgp Thermometers D. Krofcheck IAS-CERN Workshop, Singapore 24
Upsilon ( ϒ ) excited state sequential melting D. Krofcheck IAS-CERN Workshop, Singapore 25
Dimuons detected in PbPb collisions with the CMS D. Krofcheck IAS-CERN Workshop, Singapore 26
PRL 109 (2012) 222301 D. Krofcheck IAS-CERN Workshop, Singapore 27
PRL 109 (2012) 222301 D. Krofcheck IAS-CERN Workshop, Singapore 28
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PRL 109 (2012) 222301 D. Krofcheck IAS-CERN Workshop, Singapore 30
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Azimuthal Anisotropy of particle emission D. Krofcheck IAS-CERN Workshop, Singapore 32
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Azimuthal Anisotropy of particle emission PRC 87 (2013) 042301 Good agreement with ALICE, except in most peripheral events D. Krofcheck IAS-CERN Workshop, Singapore 35
Azimuthal Anisotropy of particle emission Path length dependent Energy loss at high P T PRC 87 (2013) 042301 D. Krofcheck IAS-CERN Workshop, Singapore 36
Di-hadron correlations: mountains, ridges, valleys Hooker Valley, Mt Cook National Park, New Zealand D. Krofcheck IAS-CERN Workshop, Singapore 37
p+p p+pb Pb+Pb JHEP (2011) 076 JHEP (2009) 091 PLB (2013) 795 D. Krofcheck IAS-CERN Workshop, Singapore 38
Summary In relativistic nucleus-nucleus collisions at the RHIC and the LHC sqgp Medium affects dijets and jets correlated with gamma/z 0 (gamma, Z and W particles appear to be unscathed) sqgp Medium suppresses particle cross sections (seen in R AA ) sqgp Medium melts early time probes (upsilon and J/psi) sqgp affects particle correlations ( ridges seen in pp, ppb and PbPb?) Need reference pp data for meaningful PbPb comparisons CMS HI group looking at many observables to describe sqgp D. Krofcheck IAS-CERN Workshop, Singapore 39
Backup slides
Summary We used dijets to compare PbPb collisions to pp at different impact parameters and transverse momenta Dijets can be strongly imbalanced in momentum as a result of passing through the QCD medium We observe γ jet correlations Measuring the γ and jet energies may tell us about the energy loss mechanism of in-medium partons. D. Krofcheck ICHEP, Melbourne Dijet Imbalance in 2.76 TeV PbPb Collisions 41
PLB 710 (2012) 256
CMS preliminary D. Krofcheck IAS-CERN Workshop, Singapore 45
Azimuthal Anisotropy of particle emission PRC 87 (2013) 042301 D. Krofcheck IAS-CERN Workshop, Singapore 46
Observed angular correlation between γ jet in PbPb collisions PLB 718 (2013) 773 No significant angular decorrelation is observed for -jet pairs γ jet Correlation across PbPb overlap D. Krofcheck IAS-CERN Workshop, Singapore 47
Observed angular correlation between the PbPb dijets D. Krofcheck IAS-CERN Workshop, Singapore 48
Dijets in PbPb are more imbalanced than PYTHIA+HYDJET Unbalanced Balanced D. Krofcheck IAS-CERN Workshop, Singapore 49
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