Inclusive SUSY Searches at CMS with Emphasis on Detector Systematics R. Cavanaugh (on behalf of CMS) University of Florida SUSY06 CMS Detector Background Calibrations Inclusive Search Strategies Detector Systematics Results

14 June, 2006R. Cavanaugh, Florida, SUSY062 CMS Detector MUON BARREL Drift Tube Chambers ( DT ) Resistive Plate Chambers ( RPC ) SUPERCONDUCTING COIL IRON YOKE Silicon Microstrips Pixels TRACKER Cathode Strip Chambers (CSC ) Resistive Plate Chambers (RPC) MUON ENDCAPS Total weight : 12,500 t Overall diameter : 15 m Overall length : 21.6 m Magnetic field : 4 Tesla CALORIMETERS ECAL Scintillating PbWO4 crystals HCAL Plastic scintillator/brass sandwich

14 June, 2006R. Cavanaugh, Florida, SUSY063 SUSY Signature: MET + Jets + … Squark gluino production Full Geant4 Detector Simulation 6 hard jets leptons 2 LSPs + 4 ’s

14 June, 2006R. Cavanaugh, Florida, SUSY064 Jet/MET Reconstruction Performance Jets Low luminosity Pileup included E T Resolution Stochastic term  125% / √E T Constant term  3% Angular Resolution High E T Jets: better than calo cell size (  x  = x 0.087) Missing Transverse Energy Low luminosity Pileup included from QCD Stochastic term  123% / √  E T  1700 GeV  E T   700 GeV P T dijets   50 GeV observed MET MET  Resolution Low MET : approaches Jet size High MET : approaches calo cell size QCD MET Jets CMS

14 June, 2006R. Cavanaugh, Florida, SUSY065 MET Cleaning from Tevatron MET is very powerful SUSY discriminator Difficult part is to convince yourself that there is a real excess! Tevatron teaches us MET is not easily understood! Non-collisional backgrounds Beam halo Cosmic muons Detector Effects Instrumental Noise Hot/dead channels (DQM) D. Tsybychev, Fermilab-thesis Run II V. Shary CALOR04 Run II junk jets e/ 

14 June, 2006R. Cavanaugh, Florida, SUSY066 Early Study of MET Cleaning in CMS (of course, Real Data will be different!) Apply clean up cuts to remove fake high MET events (inspired by CDF & D0)  1 central jet (|  |<1.7) with  4 tracks  1 vertex F em > 0.1 (Event Electromagnetic Frac.) F ch > (Event Charged Fraction) Affect on SUSY Signal CMS Response to Beam Halo Simulation of LHC Point 5 tt full sim. Pileup not included Pileup included CMS

14 June, 2006R. Cavanaugh, Florida, SUSY067 QCD Multijet Background Dijets typically back to back MET from jet E mismeasurement Suppress by requiring Well separated Jet & MET objects Typically  3 jets Cut on H T (~ 2 p Hat T ) Muon triggers (include isol.) helps…a lot!  Prescaled jet triggers extract the low E T shape and normalisation directly from data No cuts “  Trigger” “  Trigger” + E T Jet1 >900 GeV “  Trigger”+ E T Jet1 >900 + MET>200 GeV Level 1 CMS

14 June, 2006R. Cavanaugh, Florida, SUSY068 Electroweak Multijet Backgrounds: Z  Standard Candle Large MET and  3 Jets expected from Z(  ) +  3 jets W(  (e) ) +  3 jets W(  ) +  2 jets Z + n-Jets x-sect   s N Measure from  2 Jets Data Z(  ) +  2 jets Z(  ee) +  2 jets Normalise MC to Data for  3 Jets Assume lepton universality For W + n-jets, use Reduces / Avoids Systematics due to QCD Scale, PDFs (possibly), ISR/FSR, Jet Energy Scale, etc Major Syst. Become Luminosity, Measurement of R, Uncertainty on  (N jet ) Still requires tuning MC to Data for kinematic dists. 5% precision (~lumi) expected to be achieved with 1.5 fb-1 CMS Z(  ) +  2 jets Z(  ) +  2 jets (Z peak normalised) Z(  ) +  2 jets (Z peak) CMS See Marc Buehler’s talk from D0, yesterday

14 June, 2006R. Cavanaugh, Florida, SUSY069 Benchmark Test Points Basis of detailed studies in soon to be released CMS Physics TDR Vol. 2 Low mass points for early LHC running but outside Tevatron reach High mass points for ultimate LHC reach Indirect constraints from WMAP for strict mSUGRA exclude most except LM1, 2, 6, 9 Benchmark Optimisation Point

14 June, 2006R. Cavanaugh, Florida, SUSY0610 Inclusive Jet + MET Search Selection Criteria MET>200 GeV + Clean-up  3 jets: E T > 180, 110, 30 GeV Indirect lepton veto Cuts on  between jets and MET H T /M eff =E T1 +E T2 +E T3 +MET>500 GeV Results: LM1 efficiency is 13%, S/B ~ 26 : Number of events (below) for 1 fb -1 ~6 pb -1 for 5  discovery Lower jet multiplicity requirement reduces sensitivity to higher-order QCD corrections CMS

14 June, 2006R. Cavanaugh, Florida, SUSY0611 Inclusive Muon + Jet + MET Search Add muon  clean trigger Cuts ( LM1 )  1 isolated muon p T > 30 GeV MET > 130 GeV  3 jets: E T > 440, 440, and 50 GeV |  |< 1.9, 1.5, and 3 Cuts on  between jets and MET Backgrounds (10 fb -1 ) LM1 Signal (10 fb -1 ) 311 events Single-  “OR” Di-  p T of leading muon (GeV) Trigger Efficiency mSUGRA LM-1 No Cuts HLT + Pre-selection SUSY LM1 SM Backgrounds CMS

14 June, 2006R. Cavanaugh, Florida, SUSY0612 Inclusive SS Dimuon + Jet + MET Even cleaner signature Low background due to same sign requirement Concentrate here on Identifying the SUSY diagrams giving prompt muons Strong muon isolation & tight quality cuts Selection Critera Muon trigger Muon isolation Muon track parameters High PT jets Large Missing Transverse Energy Background (10 fb-1) 1.5 (ttbar) events LM1 Signal (10 fb-1) 341 events 65% efficient at identifying SUSY diagrams, 90% pure

14 June, 2006R. Cavanaugh, Florida, SUSY0613 Jet Energy Calibration/Systematics Direct photon production: qg → q  (90%) qqbar → g  (10%) p T (Jet) = p T (  ) use peak position to eliminate effect of tail from ISR Estimated Jet Energy Scale Uncertainty: Between 3% and 10% for P T  [20, 50] GeV ttbar  WWbb  jjl bb Rescale jet with relative energy shift  C Fit resulting W mass spectrum & constrain to world avg. m W (  C|data) = M W PDG Compare with Monte Carlo For ~6 fb-1:  C meas = ± 0.26 % (  C true = %) Requires well understood b-tag (tracker) Limited by pileup syst. uncertainty: 3% measured shift  C meas  C(%) t JES Systematic Uncertainty for P T > 50 GeV  jet CMS

14 June, 2006R. Cavanaugh, Florida, SUSY0614 MET Shape Systematics CMS Study effect of non-Gaussian tails in jet E T resolution contributing to fake MET Approx. 15% of all jets are mismeasured Exaggerate non-Gaussian Tails Weight each jet (up to 3) in event Jet in Non-Gaussian tail: 1.15 Jet in Gaussian peak : 1.00 Combine into one event weight Three different scenarios 3 jets under measured 2 jets under measured 1 jet under measured Overall Systematic Effect :  7% t

14 June, 2006R. Cavanaugh, Florida, SUSY0615 Expected CMS Reach for 1 fb -1

14 June, 2006R. Cavanaugh, Florida, SUSY0616 Expected CMS Reach for 10 fb -1

14 June, 2006R. Cavanaugh, Florida, SUSY0617 Conclusion CMS has recently completed several inclusive SUSY analyses for potential discovery Full detector simulation, reconstruction All backgrounds included Estimate low P T QCD from pre-scaled jet triggers Estimate EW from Z  Standard Candle Systematic uncertainties Jet Energy Scale, MET Shape, Misalignment, etc Results to be published in CMS Physics Technical Design Report Vol. 2 With 1fb -1, CMS can discover (or exclude) all of the low mass benchmark points Including expected systematic effects Low mass SUSY visible almost immediately Provided systematic effects are under control Current CMS focus is now on commissioning and startup scenarios

Backup Slides

14 June, 2006R. Cavanaugh, Florida, SUSY0619

14 June, 2006R. Cavanaugh, Florida, SUSY0620 The CMS Calorimeters EM calorimeter |  | < 3 : PbW0 4 crystals 1 longitudinal section/preshower 1.1  =  Central Hadronic |  | < 1.7 : Brass/scintillator Hadronic Outer – long. sections (|  | =0)  =  Forward calorimeter 2.9 <  < 5: Fe/quartz fibers  = ~0.175  0.17 Hcal barrel and EndCap EM barrel and EndCap Very Forward Calorimeter Endcap Hadronic 1.3< |  | < 3 : Brass/scintillator +WLS 2/3 longitudinal sections 10  = ~0.15  0.17 Hadronic Outer

14 June, 2006R. Cavanaugh, Florida, SUSY0621 Muon System 1.6 ME4/1 restored MB1 MB2 MB3 MB4 ME1 ME2 ME3

14 June, 2006R. Cavanaugh, Florida, SUSY0622 Early Jet Energy Calibration Require at least one of the two leading jets to have |  |<1. Call it the “barrel jet”, the other jet is called the “probe jet”. If both jets have |  |<1 then they are both barrel and probe jets. Require “Barrel Jet” P T = “Probe” Jet P T Can be used at Startup! “Data” shown here could be taken in 1 low lumi running Single day’s data taking could calibrate CMS with decent precision. A statistical error of better than 0.5% for every 0.1 unit of eta in the Barrel. A statistical error of better than 2% for every 0.1 units of eta in the Endcap and HF dijet CMS

14 June, 2006R. Cavanaugh, Florida, SUSY0623 Use Track and Muon System ( Z  ) to Calibrate Calorimeter (MET) Variation on a Z  Candle theme Derive MET corrections from Z  Sample Apply to SUSY Sample (to test) Some fine tuning required But basically works CMS SUSY LM1

14 June, 2006R. Cavanaugh, Florida, SUSY0624 Inclusive Search Strategies Use Missing Transverse Energy (MET) as the key signature for SUSY in analyses presented here R-parity conservation, neutral LSP SUSY benchmark points studied in detail using GEANT-based detector simulation and full reconstruction algorithms Consider all backgrounds as well as lepton fakes QCD multi-jets, W/Z+jets, t-tbar, diboson Optimize significance to determine cuts at a particular benchmark point(s) Anticipate systematic effects and estimate uncertainties Determine 5  reach in mSUGRA space using fast simulation

14 June, 2006R. Cavanaugh, Florida, SUSY0625 Inclusive OS Dilepton + Jet + MET Cuts ( LM1 ): 2 OS SF isolated leptons (e,µ) p T > 10 GeV MET > 200 GeV  2 jets: E T 1 >100 GeV E T 2 >60 GeV |  | < 3 Background (1 fb -1 ) 200 events, mostly t-tbar Systematic uncertainty 20% LM1 Signal (1 fb -1 ) 850 events Subtract different favor leptons m ll max = 80.4  0.5 (stat)  1.0 (misalign) GeV

14 June, 2006R. Cavanaugh, Florida, SUSY0626 Effects of Misalignment Misalign Tracker and Muon System separately Evaluate the impact on the dilepton end point Two scenarios: First Data, 6 months, 100 pb -1 to 1 fb -1 di-muon efficiency decreased by ~30% di-electron efficiency decreased by ~10% Long Term, >6 months, >1fb -1 di-muon efficiency decreased by ~13% di-electron efficiency decreased by ~2% CMS