Observables in heavy-ion collisions at CMS Haidong Liu

outline The CMS detector Review of the ‘golden’ observables Other interesting observables for me LHC schedule (latest version)

CMS detectors –Silicon pixel detector –Silicon microstrip tracker –Electromagnetic Calorimeter –Hadronic Calorimeter –Superconducting Solenoid –Muon detectors Drift Tubes (barrel) Cathode Strip Chambers (endcaps) Resistive Plate Chambers (barrel+endcaps) –CASTOR Calorimeter (forward) –Zero Degree Calorimeter (forward) (Jet with cone size R=0.5)

Low p T PID spectra for 5.5 TeV

Event plane resolution b=9fm of Pb+Pb collisions -- the expected resolution is 0.37 rad with ECAL NA49 Phys. Rev. C PHOBOS nucl-ex/ PHOBOS Nucl. Phys. A –26 STAR AIP Conf. Proc –4 Voloshin S A and Poskanzer A M Phys. Lett. B –32 Kolb P F, Sollfrank J and Heinz U W,Phys. Rev. C Teaney D, Lauret J and Shuryak E V nucl-th/ Φ simu -Φ reco J. Phys. G: Nucl. Part. Phys. 34 (2007)

high p T charged particle spectra Expected reach (0.5 nb -1 ): p T ~ 300 GeV/c (inclusive hadrons)

Jet Jet E T reco resolution Jet E T distributions for 1 month data

Expected quarkonia signals in one month data (di-muon) Assuming no quarkonia suppression Solid line: Both μ |η|<2.4 dashed line: Both μ |η|<0.8 Acceptance J. Phys. G: Nucl. Part. Phys. 34 (2007)

Stat. errors of Y’/Y ratios (arbitrary) Curves are calculations for different initial conditions and different assumption of T diss

Z 0  μμ signal 1 month data: ~11000 (Z  μμ) J. Phys. G: Nucl. Part. Phys. 34 (2007)

Tagged Jet An ideal way to measure parton energy loss in the medium

Other interesting observables Open charm & bottom –D  K+π –D  K+μ+ν μ (K μ correlations) –B +  J/psi K + (BR~0.001) –B 0  J/psi K 0 (BR~0.001) –X-section and flow are both very interesting Z boson reconstruction –Z  e+e- (BR 3.4%) –Z  Jets

For B and D reconstruction pion efficiencies in pp and PbPb collisions Ks in pp Pixel+tracker 1.Low pt track efficiency is not bad 2.Ks can be reconstructed nicely 3.dEdx can help on PID

D  K+e+ν e (K e correlations at STAR) 3<p T (e)<6 GeV/c  Φ<36 degree PYthia simulation at 200 GeV

D  K+e+ν e (K e correlations at STAR) Run5 & Run6 pp data

Z boson reconstruction Z  e+e- (BR 3.4%) –Large energy electrons (>50 GeV) identification should be easy Z  Jets –Huge background –Depends on the study of the jet reco algorithm

LHC schedule Preparing for mid-November start of beam operations –A few weeks for first collisions from then –First 7 TeV collisions in week before Christmas break Initial operations at 7 TeV ( ) –“Energy scan” (0.9, 7, 8-10TeV) Pb+Pb run still scheduled at the end of p+p run –Now foreseen to start Nov

Thank you

CMS detectors –Silicon pixel detector –Silicon microstrip tracker –Electromagnetic Calorimeter –Hadronic Calorimeter –Superconducting Solenoid –Muon detectors Drift Tubes (barrel) Cathode Strip Chambers (endcaps) Resistive Plate Chambers (barrel+endcaps) –CASTOR Calorimeter –Zero Degree Calorimeter L~10 34 cm -2 s -1 L~10 27 cm -2 s -1 (Jet with cone R=0.5)

Photon tagged jets Isolated photon + away side jet CMS NOTE HIN Unquenched FF Quenched FF models used in this analysis PYQUEN: selected QCD channels w/ jet quenching PYTHIA: selected QCD channels w/o jet quenching HYDJET: underlying corresponding Pb+Pb events Ratio of quenched and unquenched FF Detailed quantitative studies of medium- induced parton energy- loss possible.