WIN 05, Delphi, Greece, June 2005Filip Moortgat, CERN WIN 05 Inclusive signatures: discovery, fast but not unambiguous Exclusive final states & long term measurements: towards understanding the underlying model Supersymmetry searches at the LHC Filip Moortgat, CERN

WIN 05, Delphi, Greece, June 2005Filip Moortgat, CERN Why SUSY is a good idea One of the most appealing extensions of the Standard Model: TeV-scale supersymmetry Solves several problems at once: dark matter candidate (e.g. lightest neutralino) opening towards a theory of gravity unification of gauge couplings hierarchy problem allows to explain why the Higgs mechanism works [= a symmetry between fermions and bosons, duplicates the SM particle spectrum, but not the couplings]

WIN 05, Delphi, Greece, June 2005Filip Moortgat, CERN SUSY models In general MSSM: many allowed soft SUSY breaking parameters (124) due to unknown nature of SUSY breaking mechanism = difficult to work with  use more constrained models Most popular: mSUGRA Also mGMSB, AMSB m 0, m 1/2, A 0, tan , sign( 

WIN 05, Delphi, Greece, June 2005Filip Moortgat, CERN The Large Hadron Collider (8 T !!) also AA and pA collisions; for PbPb : 5.5 TeV/nucleon and L = cm -2 s -1

WIN 05, Delphi, Greece, June 2005Filip Moortgat, CERN Generic SUSY signatures General characteristics of R-parity conserving SUSY: sparticles pair produced and LSP stable  large amount of missing transverse energy coloured sparticles are copiously produced and cascade down to the LSP with emission of many hard jets and often leptons Generic SUSY signatures are E T miss + multi-jets (and multi-leptons)

WIN 05, Delphi, Greece, June 2005Filip Moortgat, CERN Inclusive SUSY jets + E T miss 1,2,3 lepton + E T miss opposite sign (OS) or same sign (SS) di-leptons often several topologies simultaneously visible

WIN 05, Delphi, Greece, June 2005Filip Moortgat, CERN Jet + MET Signature: E T miss + jets  ~ 1 pb at 1 TeV → physics for startup significant reach after 1 yr with 300 fb-1, reach squarks and gluinos up to ~ 2.5 TeV (need good understanding of detector and backgrounds!)

WIN 05, Delphi, Greece, June 2005Filip Moortgat, CERN Variable that gives information on the “SUSY scale”: Et sum SM background SUSY (700 GeV) [Branson et al, ATLAS] Warning: model dependent plot!

WIN 05, Delphi, Greece, June 2005Filip Moortgat, CERN Same-sign dileptons Signal:Background: [Drozdetski et al, CMS]  ask for 2 SS leptons + hard jets + E T miss _

WIN 05, Delphi, Greece, June 2005Filip Moortgat, CERN Exclusive final states so far: inclusive measurements fast discovery, but does not unambiguously single out SUSY need to reconstruct sparticle decay chains and masses involved need to be prepared for all possible final states goal is to measure cross sections, BR’s (  couplings) and even spin of the sparticles LHC can not only discover SUSY, but also MEASURE its properties (if nature is kind)

WIN 05, Delphi, Greece, June 2005Filip Moortgat, CERN Coloured sparticle decays Region 1 Region 2, e.g. Region 3 [Pape, CMS]

WIN 05, Delphi, Greece, June 2005Filip Moortgat, CERN Neutralino2 decay signatures [Pape, CMS] Significant fraction of

WIN 05, Delphi, Greece, June 2005 Filip Moortgat, CERN Decay chain to dileptons 2 high p t isolated leptons 2 high p t jets missing E t Final state:

WIN 05, Delphi, Greece, June 2005Filip Moortgat, CERN Kinematic endpoints Kinematic endpoint technique: construct lepton/quark upper/lower endpoints and relate them to the masses in the decay chain E.g.: 4 unknown masses: 4 endpoints:  all masses can be determined Usually non-linear relations  all masses, not just differences Extra endpoints, or start from gluino  constraints

WIN 05, Delphi, Greece, June 2005 Filip Moortgat, CERN Final states with dileptons (1) M(ll): very sharp end point, triangular shape (due to spinless slepton)  [Biglietti et al, ATLAS][Chiorboli et al, CMS]

WIN 05, Delphi, Greece, June 2005 Filip Moortgat, CERN Final states with dileptons (2) M(l1q): M(l2q):  Can distinguish M(l1q) max from M(l2q) max M(llq): M(llq) [ATLAS]

WIN 05, Delphi, Greece, June 2005 Filip Moortgat, CERN Gluino reconstruction Choose dilepton pairs close to the edge; then  can reconstruct and [Chiorboli et al, CMS] assuming can be at rest in the frame of

WIN 05, Delphi, Greece, June 2005 Filip Moortgat, CERN Final state with taus often decays to taus instead of electrons/muons can we use hadronic tau final states? [Biglietti et al, ATLAS] endpoint smeared out

WIN 05, Delphi, Greece, June 2005 Filip Moortgat, CERN Decay chain to h 0 or Z 0

WIN 05, Delphi, Greece, June 2005 Filip Moortgat, CERN Final states with h 0 or Z 0 Higgs peak can be reconstructed from 2 b-jets  could be a h 0 discovery channel ! (even for light H 0 and A 0 ) Z 0 reconstructed from di-lepton decay Decay chain is shorter than for di- leptons  e.g. start from gluino M(q 1 h 0 ),M(q 2 h 0 ),M(qq),M(qqh 0 ) to determine 4 masses M(bb) [Paige, ATLAS] [Moortgat, CMS] h0h0 A 0,H 0

WIN 05, Delphi, Greece, June 2005 Filip Moortgat, CERN GMSB signatures In GMSB, the light gravitino is the LSP  Who is NLSP? Neutralino is NLSP Stau is NLSP  E T miss + ,  or long- lived particles  dE/dx and TOF TOF measurement in the CMS muon DT’s [Wrochna, CMS]

WIN 05, Delphi, Greece, June 2005 Filip Moortgat, CERN SUSY spin measurement [Barr, ATLAS] Make use of spin correlations in decay of squark: no spin correlations

WIN 05, Delphi, Greece, June 2005 Filip Moortgat, CERN SUSY spin measurements (2) washes out for antisquarks, but in pp colliders  more squarks produced than antisquarks  Visible asymmetry: (500 fb -1 ) [Barr, ATLAS] no spin correlations

WIN 05, Delphi, Greece, June 2005Filip Moortgat, CERN Conclusions If TeV-scale SUSY exists, its discovery at the LHC should be (relatively) fast, using inclusive signatures The LHC can measure sparticle properties: reconstruction of masses in sparticle decay chains, mainly using kinematic endpoints Ultimately would like to measure spins and couplings (WIN 05  WINO 5?) only 750 days to startup … so focusing on being ready for first day physics now!

WIN 05, Delphi, Greece, June 2005Filip Moortgat, CERN Backup

WIN 05, Delphi, Greece, June 2005Filip Moortgat, CERN Cross the LHC “Well known”processes, don’t need to keep all of them … New Physics!! This we want to keep!!

WIN 05, Delphi, Greece, June 2005Filip Moortgat, CERN CMS

WIN 05, Delphi, Greece, June 2005Filip Moortgat, CERN ATLAS

WIN 05, Delphi, Greece, June 2005Filip Moortgat, CERN Civil Engineering UXC 55 USC 55

WIN 05, Delphi, Greece, June 2005 Filip Moortgat, CERN End points and configurations

WIN 05, Delphi, Greece, June 2005Filip Moortgat, CERN Higgs to sparticles If accessible, we may exploit the sparticle decay modes: A, H   2 0  2 0  4l + E T miss