SUSY LHC Darin Acosta University of Florida On behalf of the ATLAS and CMS Collaborations

HCP 2006, phys.ufl.edu2 Outline Concentrate on inclusive search strategies for SUSY New proto-analyses from CMS Physics TDR è Canonical SUSY searches : p Jets + Missing transverse energy p Lepton + jets + Missing transverse energy p Dileptons (OS, SS) + Jets + Missing transverse energy p Di-taus + jets + Missing transverse energy è Heavy Reconstructed Object based SUSY searches p Z0 + Missing transverse energy p top + Missing transverse energy è sParticle spectroscopy and spin analysis: MSSM Higgs covered in previous talk

HCP 2006, phys.ufl.edu3 Supersymmetry A symmetry between fermions and bosons è Avoids fine-tuning of SM, can lead to GUTs, prerequisite of String Theories, possible dark matter candidate (LSP) Generally assume LSP is stable (R p conservation) SUSY breaking mechanism is unknown  many params. mSUGRA: è Supergravity inspired model, 5 free parameters:  m 0, m 1/2, A 0, tan , Sign( µ)

HCP 2006, phys.ufl.edu4 Cross Sections and Signatures Complex decays chains è MET (LSP) è High P T jets ( q, g ) è Leptons ( , l, W, Z ) è Heavy flavor (high tan  ) A0=0, tan(β)=10, sign(µ)=+1 ~

HCP 2006, phys.ufl.edu5 The Large Hadron Collider Proton-proton collider,  s = 14 TeV Low luminosity phase: L = 2  cm -2 s -1 è 5 inelastic pile-up collisions High luminosity phase: L = cm -2 s -1 (100 fb -1 /yr) è 25 inelastic pile-up collisions Start-up slated for 2007, second half R = 4.5 km E = 7 TeV CERN CMS Atlas

HCP 2006, phys.ufl.edu6 The Compact Muon Solenoid (CMS) Expt. PbWO 4 Crystals:  / e detection Muon chambers Silicon Tracker: charged particle tracking and b/  id 4T magnet Hadronic calorimeter: Jets, missing E T ( ) One of two large general purpose experiments at the LHC

HCP 2006, phys.ufl.edu7 CMS at Surface Assembly Hall 2/06

HCP 2006, phys.ufl.edu8 A Toroidal LHC ApparatuS (ATLAS) Muon chambers Silicon and TRT Tracker 2T solenoid 0.6T Toroids Calorimeters (LAr):  / e, Jets, missing E T ( ) measurements Complementary detector technologies to CMS

HCP 2006, phys.ufl.edu9 ATLAS Underground 5/06

New Analysis Developments from CMS CERN/LHCC CERN/LHCC Published Coming June 2006

HCP 2006, phys.ufl.edu11 CMS Physics TDR CMS has recently published Volume 1 of its Physics Technical Design Report, with Volume 2 to come next month (but new results included here) è ATLAS Physics TDR: CERN/LHCC /15 Volume 1: è Compendium of detector performance, calibration & alignment strategies, and reconstruction algorithms for physics objects (e, , µ, , b, jet, MET) Volume 2: è Detailed study of several benchmark analyses, including SUSY, to demonstrate key performances of the detector and including all the methodology of a real data analysis p Background estimation, systematic uncertainties, etc. è Comprehensive collection of analyses that span most final state topologies to determine overall reach (e.g. mSUGRA) è Analyses based on GEANT4 detector simulations (or derived parameterizations) for backgrounds and signals and real reconstruction algorithms studied in Vol.1

Inclusive Search Strategies for Final States with MET

HCP 2006, phys.ufl.edu13 Strategy Use Missing Transverse Energy (MET) as the key signature for SUSY in analyses presented here è R p 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 è QCD multi-jets, W/Z+jets, t-tbar, diboson Optimize significance to determine cuts at a particular benchmark point(s) Determine 5  reach in mSUGRA space using fast simulation

HCP 2006, phys.ufl.edu14 MET Reconstruction Sum over calorimeter towers è Can correct for jets, muons MET Resolution è Measure from data è Use min-bias and prescaled jet triggers to measure resolution è CMS stochastic term ~0.6–0.7 Jet calibration crucial to improve resolution Variety of techniques possible è  -Jet balancing, di-jet balancing, è W mass constraint in hadronic W decays in top pair events p CMS: Achieve 3% JES uncertainty for E T >50 GeV with 1–10 fb -1 QCD Minbias

HCP 2006, phys.ufl.edu15 CMS Benchmark Test Points Basis of detailed studies è Low mass points for early LHC running but outside Tevatron reach è High mass points for ultimate LHC reach è Indirect constraints from WMAP for strict mSUGRA exclude most except LM1, 2, 6, 9

HCP 2006, phys.ufl.edu16 Inclusive MET + Jets Most sensitive signature For low mass Supersymmetry, no problem to have a large excess of events over the SM at the LHC Difficult part is to convince yourself that there is a real excess! è MET dataset cleanup p Use e.g. Tevatron-inspired event shape cuts for non-collision backgrounds (no LHC data yet!) Event EM fraction >0.1 Event charged fraction >0.175  1 vertex è Set up control regions that enhance background over signal to calibrate from data W/Z+jets, top pairs, QCD dijets è Understanding of systematic uncertainties p Sensitivity to Jet Energy Scale uncertainty and resolution D. Tsybychev, Fermilab-thesis EEMFECHGF

HCP 2006, phys.ufl.edu17 MET calibration using Z-candle Measure Z+jets with Z  µµ in data to normalize the Z  (invisible) contribution and calibrate MET spectrum With ~1fb -1 we will have enough Z+jets in the P T (Z)>200 region of interest to normalize within 5% the Z invisible process as well as W+jets through the W/Z ratio and lepton universality CMS

HCP 2006, phys.ufl.edu18 Inclusive MET + Jets Cuts è MET>200 + Clean-up è  3 jets: p E T > 180, 110, and 30 GeV p |  |< 1.7, 3, 3 è Cuts on  between jets and MET è H T =E T1 +E T2 +E T3 +MET >500 GeV è Indirect lepton veto Results è LM1 efficiency is 13% è S/B ~ 26 è Systematic uncertainty: ~6 pb -1 for 5  discovery Low jet multiplicity requirement reduces sensitivity to higher-order QCD corrections CMS

HCP 2006, phys.ufl.edu19 Add lepton, clean trigger Cuts ( LM1 ): è  1 isolated muon p p T > 30 GeV è MET > 130 GeV è  3 jets: p E T > 440, 440, and 50 GeV p |  |< 1.9, 1.5, and 3 è Cuts on  between jets and MET Background (10 fb -1 ) è 2.5 events, Systematic uncertainty 20% 30 fb -1 and 60 fb -1 : Re-optimised cuts for higher lumi Optimised cuts for 10 fb -1 luminosity 10 fb fb fb -1 A0=0, tan(β)=10, sign(µ)=+1 Inclusive MET+Jets+Muons m0m0 m 1/2

HCP 2006, phys.ufl.edu20 Same-Sign Muon Signature Signal: Background: Motivation and Strategy: è Clean objects for trigger and reconstruction (muons) p Reduced detector uncertainties vs pure Jets/MET è Low background (same-sign signature) è Isolate the SUSY diagrams with strong isolation and quality cuts on the reconstructed muons Theoretical studies include: è H. Baer et al. PR D41, #3 (1990); R. Barnett et al. PL B315 (1993), 349; K. Matchev and D. Pierce hep-ph/ (1999)

HCP 2006, phys.ufl.edu21 LEP Tevatron Same-Sign Muon: Reach Cuts ( LM1) : è 2 SS isolated muons p p T > 10 GeV è MET > 200 GeV è  3 jets: p E T 1 >175 GeV p E T 2 >130 GeV p E T 3 >55 GeV Background (10 fb -1 ) è 1.5 events è Systematic uncertainty 23% A0=0, tan(β)=10, sign(µ)=+1 Optimized cuts for 10 fb -1 luminosity CMS m0m0 m 1/2

HCP 2006, phys.ufl.edu22 MET + Opposite Sign Leptons Cuts ( LM1 ): è 2 OS SF isolated leptons p p T > 10 GeV è MET > 200 GeV è  2 jets: p E T 1 >100 GeV p E T 2 >60 GeV p |  | < 3 Background (1 fb -1 ) è 200 events, mostly t-tbar è Systematic uncertainty 20% LM1 Signal (1 fb -1 ) è 850 events CMS

HCP 2006, phys.ufl.edu23 Opposite Sign Leptons: Mass Edge Measure invariant mass distribution of same-flavor opposite-sign (SFOS) leptons as evidence for è or Striking signature: endpoint in mass spectrum exhibits sharp edge dependent on sparticle masses è è LM1 with 1 fb -1 : è with uncertainty on alignment and energy scale Subtract different favor leptons

HCP 2006, phys.ufl.edu24 Inclusive MET + Z 0 Catch è Mostly from q, g decays è Z 0 gives extra handle against non-resonant dilepton bkg Cuts ( LM4 ): è MET > 230 GeV è 2 OS SF leptons p p T (e) > 17 GeV, or  p T ( µ ) > 7 GeV è 81 < M ll < 96.5 GeV è  < 2.65 rad Background (10 fb -1 ) è SM: 200  40 (t-tbar + diboson) è Systematic uncertainty 20% LM4 Signal (10 fb -1 ) è 1550  30 e+e–e+e– ~ CMS

HCP 2006, phys.ufl.edu25 Inclusive MET + Top Catch stop decays to top Search ( LM1) : è MET>150 GeV è Hadronic top selection and 2C fit p 1 b-jet + 2 non-b jets p Use the W and top mass constraints to fit top and require good  2 è LM1: ~200 pb -1 for 5  observation!

sParticle Spectroscopy, circa “2010” End of decade: excess observed in a channel like one these shown! What are the masses? Is it SUSY? The fun begins…

HCP 2006, phys.ufl.edu27 MET + di-Tau Catch Measure di-tau endpoint and infer sparticle masses But no sharp reconstructed endpoint due to  è Fit to signal + background can be translated to endpoint measurement Measure a number of invariant mass distributions, e.g. è 2-tau, tau1+jet, tau2+jet, tau1+tau2+jet Extract the masses of the sparticles by solving for the kinematics of the decay chain; example measurement at 40 fb -1 at LM2: CMS

HCP 2006, phys.ufl.edu28 ATLAS sParticle

HCP 2006, phys.ufl.edu29 ATLAS Spin

HCP 2006, phys.ufl.edu30 Conclusions