Status of CMS and the road to first physics results Jordan Nash For the CMS Collaboration – ICFA Seminar – SLAC October 2008

Outline  CMS Status  Commissioning so far  Commissioning plans with first data  Physics Topics for the first fb -1  QCD/JETS  Electroweak  New Physics

The CMS Detector

Minus end just before closure

CMS Closed for September 10 th

Last detector to Install  When the detector was closed for the September beam running, all elements of CMS were installed except for the pre- Shower detector in front of the Crystal endcaps  The Preshower detector will soon be completed, and installed during the winter shutdown  “D’s” undergoing final assembly cold testing now

Commissioning with Cosmics z (at surface) [cm] x (at surface) [cm] Tracker ECAL HCAL Muon System 3 T Sept 10 0 T Position of track extrapolated to surface. Clearly see shaft Position of track extrapolated to surface. Clearly see shaft More than 300M events recorded during summer

Tracks passing through the ECAL  Cosmic running used to test  triggers,  operation of all detectors  Example: Trigger using Drift Tubes  Validate Calorimeter e-gamma Trigger  Verify pre-calibration of ECAL  in detector units  in detector units Reconstructed clusters matching muon tracks (DT triggered events) Energy deposited in 3x3 ECAL cluster matched to a muon track

Muon reconstruction at 3T Reconstructed Muon Momentum using Drift Tubes Magnet closed for the first time underground late in the summer Before the Sept 10 Running field raised to 3 T Magnet closed for the first time underground late in the summer Before the Sept 10 Running field raised to 3 T

Tracker operation and alignment  Cosmics used to align tracking detectors  Significant improvement from construction parameters possible already  Multiple algorithms for alignment validated  Look at performance using “split” muons CRUZET4 before alignment after alignment

First view of LHC Beam HCAL ECAL LHC Tunnel profile visible Muon DT

Calorimetric response  Splash on collimators  2 X 10 9 p hitting the collimator  150 m upstream from the detector  Tremendous amount of energy deposited in the detector  DAQ able to cope with enormous events Ecal Endcap Ecal Barrel Correlation between total energy in ECAL and HCAL

Conditions with beam captured HCAL Endcap Endcap Muon Trigger Rate for circulation and then capture of beam

Beam Halo Events ME+1ME+2ME+3ME+4 Occupancy in Endcap Muon System Discs

Next Steps 300M events at 3.8 T (CRAFT)  Goals  Improved alignment of tracking detectors  Want sufficient events passing through pixel detector  Experience of continuous operation of complete detector at full field  Will then open CMS to install the preshower detector 75 M events in first few days

What do we expect to do with first collisions ?  Plan over the last year has been to study what to extract from the first few pb -1  Re-discover the SM  Event rates for SM processes are large  Rate W ~ 10 8 /fb -1  Rate Z ~ 10 7 /fb -1  Rate tt ~ 10 6 /fb -1  Understand detectors  e.g. W/Z used for precision calibrations  Understand backgrounds in searches for new physics, and precision measurements  Concentrate on data driven methods for determining backgrounds

Early studies of event properties  Enormous QCD Cross section  New territory in terms of Jet E T  Underlying event measured with very first data  Understand environment at 14 TeV  Tune MC models  Observables N ch, P T Sum Tevatron LHC Different Tunes/Models

Jets/QCD  Potential for discovery of Contact interactions in Dijets,  4 TeV for 10 pb -1  7 TeV for 100 pb -1  10 TeV for 1 fb -1  Measurement of Inclusive Jet Cross Section  Understanding of Jet Energy scales, resolutions  PDF Uncertainties Energy Scale Uncertainty 100 pb -1

Calibrating Jets/Missing E T  Missing ET  Vital for many physics channels  calibration is difficult  Sensitive to Hot/Dead Channels  Instrumental effects can create large fake signals  Need Real data  Need to correct for  Jet Energy  , e  Data Driven methods for Jet Energy Scale Corrections  e.g. DiJet Balance –relative  Z+Jets - absolute

Early Z Measurement 10 pb -1 ~4.6K e + e - pairs in the 70<M e,e <110 mass region ~5.5K μ + μ - pairs in the 70<M μ, μ <140 mass region. The Z produces a very clean signal. Use Tag and Probe to calculate efficiencies from Data 2 Isolated High P T (20 GeV) tracks (muons) 2 Isolated High E T (20 GeV) electrons, loose electron ID 2 Isolated High P T (20 GeV) tracks (muons) 2 Isolated High E T (20 GeV) electrons, loose electron ID

Early W Measurement  Single Isolated High P T Lepton  Muon (>25 GeV), Electron (>30 GeV)  QCD Background estimation from Data  Invert Isolation Cuts  Missing E T Shape from Data  Use γ */ Ζ  ll events  Measure missing E T excluding the 2 nd lepton  Event rates (at 10 TeV are about 70% the rate at 14 Tev) 28K W  e ν events and ~ 6K QCD events 64K W  μν events and ~16K QCD events

W Mass –precision measurements  1 fb -1 gives M W to about 40 MeV/c 2  Limit energy linearity(e), MET scale(  )  10 fb -1 measure M W to about 20 MeV/c 2  (statistical uncertainty 15 Mev/c 2 )  Ultimate precision about 15 MeV/c 2  Limited by MET Scale, resolution  Theoretical uncertainties PDFs, P T (W)

WZ/ZZ  Understanding vital for searches  These are major irreducible backgrounds for searches  Ultimately measure TGCs 300 pb -1 Events per fb -1 Find Same Flavour Opposite Sign leptons for Z candidate P T Leptons > 15 GeV Add 3 rd lepton with P T > 20 GeV Form M T with Missing E T -Require M T > 50 GeV Find Same Flavour Opposite Sign leptons for Z candidate P T Leptons > 15 GeV Add 3 rd lepton with P T > 20 GeV Form M T with Missing E T -Require M T > 50 GeV

Looking for Supersymmetry  Signatures  Leptons  Jets  Missing Energy  Requires excellent understanding of the detector  Builds on our measurements of SM processes

SUSY parameter space  Where to look?  Detailed studies at a set of potential SUSY mass scenarios  Full MC analysis  Understand analysis strategies, systematic uncertainties  Extrapolate to cover the full plane using Fast simulation  Low Mass points for early discovery potential  High Mass points for looking near potential limits

Early SUSY searches  Jets + Missing E T signature  >= 3 Jets (180, 110, 30 GeV),  H T > 500 GeV, Missing E T > 200 GeV  Must control backgrounds, and understand missing transverse energy –  QCD events with mis-measurements have very different topologies  Irreducible background from Z to neutrino decays  Use Z + Jets (Z to leptons) to estimate bkgd  Also Use  + jets  Remove photon LM1 1 fb -1

HM Points/DiJets  Jets+Missing E T at HM points  H T > 1500 GeV,  Missing E T > 600 GeV  Also looking at new variables  Look at Dijet events using discriminator suggested by Randall/Tucker-Smith  Two High P T Jets (HT > 500 GeV)   > 0.55  Sensitive to squark pair production HM1 1 fb -1

Missing E T + Jets + leptons  Two Same Sign Muons  P T > 10 GeV  >= 3 Jets (175/130/55) GeV  Missing E T > 200 GeV  Backgrounds in these channels are very low  SM Backgrounds produce opposite sign leptons  At least 1 isolated Muon  P T > 30 GeV  >= 3 Jets  (440/440/50) GeV  Missing E T > 120 GeV  Signal/Background High

SUSY Searches Summary 10 fb -1

Discovering SUSY parameters  No Mass peak, but kinematic edges possible to observe  Same Flavour Opposite Sign leptons  P T > 10 GeV  >= 3 Jets (120/80/30) GeV  Missing E T > 200 GeV  Estimate backgrounds from Opposite flavour events  Fit for endpoint  Sensitivity (statistical)  ~1 GeV/c 2 for 1 fb -1 Signal Bkgd

Cascade Higgs Decays  Other Possible BSM extensions have similar signatures (i.e. leptons, jets, large missing E T, )  Technicolor  ED  Little Higgs  May be possible to see Hadronic h decays with large missing E T signatures

Heavy Stable Charged Particles 32  Models with Charged Stable Particles  GMSB - staus  Kaluza-Klein taus  Long lived stop  ct  of order meters  Measure Time of Flight in the Muon DT system  Measure DE/Dx in the Tracker  Momentum from Tracking

Conclusions  CMS Detector will be complete and commissioned at the start of next year’s run  Substantial data collected at full field with all detectors  Experience of 24/7 operation  Rapid understanding of first data will be vital to be ready for early discoveries  Physics preparation concentrating on preparing data-driven analysis to:  Recover SM  Understand detector performance  Look for evidence of new physics  Many new physics signals detectable with a few fb -1

Expecte d Day 0 Ultimat e goals ECAL uniformity ~4%< 1% Lepton energy0.5-2%0.1% HCAL uniformity 2-3%< 1% Jet energy<10%1% Expected Day 0 Goals for Physics Tracker alignment  m in R  O (10  m)