Richard Hollis University of Illinois at Chicago Heavy-Ions in CMS 24 th Winter Workshop on Nuclear Dynamics

CMS 2 5 th -12 th April 2008 Richard Hollis University of Illinois at Chicago 24 th Winter Workshop on Nuclear Dynamics Expected energy density at the LHC CMS Heavy-Ion program Study of QCD matter under extreme conditions √s NN =5.5 TeV Bulk observables (soft physics) Hard probes Ultra peripheral collisions √s=14 TeV First measurements of bulk observables Analysis exercise “…presents the capabilities of the CMS experiment to explore the rich heavy-ion physics programme offered by the CERN Large Hadron Collider (LHC).” dE T /d  → Bj J.D.Bjorken, Phys.Rev.D27(1983) 140 J. Phys. G: Nucl. Part. Phys. 34 (2007)

CMS 3 5 th -12 th April 2008 Richard Hollis University of Illinois at Chicago 24 th Winter Workshop on Nuclear Dynamics The CMS detector Under construction Data! Basic layout: Tracker E/M Cal. E/M Cal. Hadronic Cal. Hadronic Cal. Magnet Iron Return yoke Muon Chambers Transverse Slice Cosmic muon in CMS at full magnetic field

CMS 4 5 th -12 th April 2008 Richard Hollis University of Illinois at Chicago 24 th Winter Workshop on Nuclear Dynamics The CMS detector CMS  coverage Silicon tracker: |  |<2.5 Momentum resolution <2% for p T <100GeV and |  |<0.5. Calorimetry: ECal |  |<3, HB,HE,HF |  |<5, Castor 5 8 Wide energy-space range measure of jets Muon Chambers: |  |<2.5 Position/momentum along with a fast L1 response Castor Jet 0 22  22  Pixel+Strips Ecal Hcal Muons ZDC Calorimetry  Tracker 

Soft Physics in CMS centrality dN ch /d  identified low-p T spectra

CMS 6 5 th -12 th April 2008 Richard Hollis University of Illinois at Chicago 24 th Winter Workshop on Nuclear Dynamics Soft physics: Global Event Characterization Centrality: Forward E T measurements (CASTOR and Had. Cal.) Multiplicity: via single-pixel layers (PHOBOS-Style) Possible as the pixel layer occupancy is <2% for dN/d  ~3500 via integrated Spectra (next slides)

CMS 7 5 th -12 th April 2008 Richard Hollis University of Illinois at Chicago 24 th Winter Workshop on Nuclear Dynamics Soft physics: Global Event Characterization Good efficiency and resolution p T resolution ~1-2% (barrel)  K p Low-momentum tracking dE/dx measurement using the inner silicon layers PID for  ±, K ± (p<0.8 GeV/c) and protons (p<1.5 GeV/c) 14 TeV (Pythia)

CMS 8 5 th -12 th April 2008 Richard Hollis University of Illinois at Chicago 24 th Winter Workshop on Nuclear Dynamics Soft physics: Global Event Characterization Further PID: Neutral hadrons from decay topology ( , K 0, , , …) Comprehensive Low-p T physics program to study Freeze-out parameters: Chemical potential (  B ) and temperature Kinetic freeze-out temperature and radial flow Baryon transport and strangeness production

Hard Probes in CMS charged hadron spectra full jet reconstruction  -Jet

CMS 10 5 th -12 th April 2008 Richard Hollis University of Illinois at Chicago 24 th Winter Workshop on Nuclear Dynamics PbPb background [HYDJET 010 dN/d  ~2400] 190 GeV photon [PYTHIA] quenched jet [PYQUEN] Full CMS sim reco Large acceptance calorimetry (ECal+HCal) Fully reconstruct jets in heavy ion collisions Photon reconstruction in ECal 4T magnetic field Momentum resolution <2% Low fake rates High-Level Triggering Online inspection of all events extends p T reach to 250 GeV/c (1 year) minimum biasHLTriggered PbPb dNch/d  | y=0 =3500 Hard probes: CMS Capabilities

CMS 11 5 th -12 th April 2008 Richard Hollis University of Illinois at Chicago 24 th Winter Workshop on Nuclear Dynamics Jet reconstruction utilizes Hcal and Ecal Iterative cone (R=0.5) + Background subtraction High efficiency and purity for E T >50 GeV jets Good energy resolution for E T >100 GeV Jets reconstructed up to E T ~ 0.5 TeV Estimated for one “year” of running PbPb 0.5 nb -1 (or 3.9x10 9 events,10 6 sec) Hard probes: Reconstructing Jets

CMS 12 5 th -12 th April 2008 Richard Hollis University of Illinois at Chicago 24 th Winter Workshop on Nuclear Dynamics Hard probes:  -Jet Direct probe for in-medium energy loss Reconstruction Photon ID: combine Ecal/Hcal/tracker to form  isolation cuts

CMS 13 5 th -12 th April 2008 Richard Hollis University of Illinois at Chicago 24 th Winter Workshop on Nuclear Dynamics Hard probes:  -Jet Direct probe for in-medium energy loss Reconstruction Photon ID: combine Ecal/Hcal/tracker to form  isolation cuts Use of Multivariate analysis For  = 60%, fake  = 3.5% selected working point

CMS 14 5 th -12 th April 2008 Richard Hollis University of Illinois at Chicago 24 th Winter Workshop on Nuclear Dynamics Hard probes:  -Jet Direct probe for in-medium energy loss Reconstruction Photon ID: combine Ecal/Hcal/tracker to form  isolation cuts Use of Multivariate analysis For  = 60%, fake  = 3.5%, S/B=4.5

CMS 15 5 th -12 th April 2008 Richard Hollis University of Illinois at Chicago 24 th Winter Workshop on Nuclear Dynamics Hard probes:  -Jet Direct probe for in-medium energy loss Reconstruction Photon ID: combine Ecal/Hcal/tracker to form  isolation cuts Use of Multivariate analysis For  = 60%, fake  = 3.5%, S/B=4.5 Away-side jet selection E T > 30 GeV, |  |< 2, ,jet  > Calculate dN/dξ Charged tracks in R=0.5 cone around jet axis PbPb background [HYDJET 010 dN/d  ~2400] 190 GeV photon [PYTHIA] quenched jet [PYQUEN] Full CMS sim reco Defining Fragmentation Functions: ξ = log(E T /p T ) E T usually defined from parton E T of the jet. Here, the  E T is used as we are trying to quantify partonic jet quenching.

CMS 16 5 th -12 th April 2008 Richard Hollis University of Illinois at Chicago 24 th Winter Workshop on Nuclear Dynamics Hard probes:  -Jet Direct probe for in-medium energy loss Final Measurement Reconstruction using non- quenched and quenched MC Fragmentation functions differ Medium modification of fragmentation functions can be discriminated with high significance Significant difference between Non-quenched and Quenched Analysis method has discriminatory power Low-p T High-p T suppressed

Heavy Flavor in CMS J/  and  ’  family

CMS 18 5 th -12 th April 2008 Richard Hollis University of Illinois at Chicago 24 th Winter Workshop on Nuclear Dynamics Heavy Flavor:  family Reconstructed      - in CMS PbPb underlying event: dN/dy ~3500 CMS: precise measurements of muons: tracker +  chambers

CMS 19 5 th -12 th April 2008 Richard Hollis University of Illinois at Chicago 24 th Winter Workshop on Nuclear Dynamics Heavy Flavor:  family PbPb=2500 Signal/Background~1 Clear separation of states Direct probe of QGP formation “Step suppression” of charmonium/bottomonium resonances Sensitive to QGP temperature Reconstruction performance Excellent dimuon mass resolution ~1% of the quarkonium mass for full  Best Signal/Background at LHC Clean separation of the states

CMS 20 5 th -12 th April 2008 Richard Hollis University of Illinois at Chicago 24 th Winter Workshop on Nuclear Dynamics Heavy Flavor:  family N  ~ year statistical reach Broad  coverage p T (GeV/c)  Direct probe of QGP formation “Step suppression” of charmonium/bottomonium resonances Sensitive to QGP temperature Reconstruction performance Excellent dimuon mass resolution ~1% of the quarkonium mass for full  Best Signal/Background at LHC Clean separation of the states Broad  -coverage and high-p T reach Using HLT selection

CMS 21 5 th -12 th April 2008 Richard Hollis University of Illinois at Chicago 24 th Winter Workshop on Nuclear Dynamics Heavy Flavor: J/  and  ’ Direct probe of QGP formation “Step suppression” of charmonium/bottomonium resonances Sensitive to QGP temperature Reconstruction performance Excellent dimuon mass resolution ~1% of the quarkonium mass for full  Best Signal/Background at LHC Clean separation of the states Broad  -coverage and high-p T reach Using HLT selection N J/  ~1.8×10 5 Di-muon mass reconstruction 1-year statistical reach Broad  coverage PbPb=2500  J/y =35MeV/c 2 |  |<2.4 S/B~1.2 J/  acceptance p T (GeV/c) 

Ultra Peripheral in CMS

CMS 23 5 th -12 th April 2008 Richard Hollis University of Illinois at Chicago 24 th Winter Workshop on Nuclear Dynamics Ultra peripheral collisions:  photo-production At LHC the accelerated Pb nucleus can produce strong electromagnetic field due to the coherent action of the Z = 82 proton charges Equivalent photon flux E  max ~ 80 GeV  Pb: cm E max ≈ 1. TeV/n (~3×e+p HERA)  : cm E max ≈ 160 GeV (~LEP) Measure the gluon distribution function in the nucleus (  Pb) low background simpler initial state  Pb→  photo-production in CMS Unexplored (x,Q 2 ) regime: Pin down amount of low-x suppression in the Pb nuclear PDF (compared to the proton PDF) dAueA

CMS 24 5 th -12 th April 2008 Richard Hollis University of Illinois at Chicago 24 th Winter Workshop on Nuclear Dynamics Summary CMS has a broad and exciting heavy ion program, including: Bulk observables (soft physics)

CMS 25 5 th -12 th April 2008 Richard Hollis University of Illinois at Chicago 24 th Winter Workshop on Nuclear Dynamics Summary CMS has a broad and exciting heavy ion program, including: Jet physics Quarkonia and heavy-quarks Ultra peripheral collisions

CMS 26 5 th -12 th April 2008 Richard Hollis University of Illinois at Chicago 24 th Winter Workshop on Nuclear Dynamics Vintage Years Ahead CMS DATA 2008 GENEVE, SWITZERLAND 2000 PHYSICISTS, (INCL) 50 HEAVY-IONS Produced by CERN, distributed via your local T1 center. GOVERNMENT WARNING: (1) ACCORDING TO THE SURGEON GENERAL, ANALYZING CMS DATA MAY CAUSE SEVERE EUPHORIA. (2) ANALYZING CMS DATA MAY IMPAIR YOUR ABILITY TO DRIVE, PLEASE DON’T ANALYZE DATA WHILST YOU DRIVE $12 CHF 452m (1995 budget) “Physics World” 1 st May 2000

CMS 27 5 th -12 th April 2008 Richard Hollis University of Illinois at Chicago 24 th Winter Workshop on Nuclear Dynamics The CMS detector central detectors transverse slice Global Event Characterization: Silicon tracker: (  ±, K ±, p), , K 0 (via displaced vertices) Infer energy density, freeze-out temperatures and chemical potential... Specific Probes: Calorimetry: e ±,  and hadronic jets probe of early times and jet-medium interactions, energy loss… Muon Chambers: μ ± (from J/ψ,  ) (heavy) quark energy loss and sensitivity to QGP temperature…