SUPERSYMMETRY @ LHC a Selection Why SUSY SUSY at the LHC Conclusions Ulrich Goerlach IPHC-IN2P3 CNRS ULP Strasbourg, France Why SUSY SUSY at the LHC (Some examples) Strategy for (early) discovery Mass reconstructruction (Model parameters) Conclusions Thanks to the many excellent talks at recent conferences ! Apologies to everybody, whose work is not mentioned!

Supersymmetry-Industry More than 7000 papers since 1990 "One day, all of these will be supersymmetric phenomenology papers."

Why SUperSYmmetry (I) Since over 35 years (theoretical) physicists love SUSY SUSY is naturally implemented in string theories SUSY is NOT a gauge symmetry, but the only and last extension of spacetime symmetry to be discovered partners for all SM fields: Q|Boson, spin J> = |Fermion, spin J + ½> Q|Fermion, spin J> = |Boson, spin J - ½>

Minimal Supersymmetric Standard Model SUSY Primer, S.P. Martin hep-ph/9709356

Why SUperSYmmetry (II) stabilises Higgs mass against loop corrections from new physics (gauge hierarchy, naturalness or fine-tuning problem) Leads to Higgs mass ≤ 135 GeV Planck scale 1028 eV, 10-35 m loop correction (all fermions up to cutoff scale L ) + free mass SUSY: ... + loop correction (scalars) Perfect cancellation: Soft breaking: Electroweak scale 1011 eV, 10-18 m

Top-Quark Mass at the Tevatron CDF & D0, hep-ex/0608032 Heinemeyer et al., hep-ph/0611373

Why SUperSYmmetry (II) SUSY modifies the running of the 3 coupling constants od the SM enough to assure unification of the four interactions at the GUT scale SUSY scale is  1 TeV SUSY is a broken Symmetry  many new heavy sparticles If R-Parity = (-1)3(B-L)+2S is conserved: sparticles are created in pairs The LSP is stable  Best dark matter candidate SUSY SM

SUperSYmmetry Breaking (SSB) Standard Model 19 free parameters SUSY breaking is completely unconstrained spontaneous SUSY breaking at high energy in hidden sector Symmetry breaking has to be mediated to lower energy  Effective Lagrangian (= ignorance w.r.t. SSB) at low energies, which is supersymmetric except for explicit soft SUSY-breaking terms M.S.S.M. unconstrained, many new parameters +105 (note: if RPV add + 48) Constrained models (cMSSM): Spontanous symmetry breaking is "mediated" to the EW scale mSUGRA (Supergravity, assuming universality at GUT scale) m0, m1/2, A0, tan β, sgn μ; +5 G.M.S.B. (Gauge(EW) Mediated) λ, Mmes, N5, tan β, sgn μ, Cgrav +6 A.M.S.B. (Anomaly mediated, SSB on different brane) m0, m3/2, tan β, sgn μ +4

SUSY Breaking II mSUGRA Supergravity (SUSY is local symmetry  Gravity Universal scalar and gaugino mass at GUT scale Gravity mediated from GUT- to EW-scale via RGE R-Parity conserved LSP is the neutralino, 10 Constrained MSSM (1245 paramètres) m0 : universal scalar mass m1/2 : universal gaugino mass A0 : tri-linear couplings tanb : VeV- ratio of the two higgs doublets sign(m) : sign of the Higgs mixing parameter Gives "pricise predictions" and can easily be connected to cosmological dark matter constraints

SUSY-breaking III Non constrained MSSM Generalised mSUGRA (give up universality of masses at GUT scale) GMSB Messengers (new chiral supermultiplets) EW gauge interactions  soft breaking terms in Lagrangian Gravitino is LSP : NLSP has finite lifetime ct  µm ..... km : Λ = universal soft SUSY breaking scale Mmes = messenger mass scale N5 = messenger index (number of multiplets) tan β, sgn μ, Cgrav Other SSB schemes R-Parity Violation (RPV)

0.094 < Wm h2 = nLSP  mLSP < 0.129 SUSY and dark Matter WMAP : 0.094 < Wm h2 = nLSP  mLSP < 0.129 rLSP =  LSP density LSP mass LSP density ~ 1/ s(  ) 10 lepton slepton (NLSP) s(  )  m2 / (m2  m2)2 ~ rLSP  (m2  m2)2 / m  m3 ~ Patrick Janot - GDR SUSY,8 avril 2005

SUSY Dark Matter 0.094 < rLSP < 0.129 SUSY (e.g. mSUGRA) parameter space strongly constrained by cosmology (e.g. WMAP satellite) data. mSUGRA A0=0, tan(b) = 10, m>0 Ellis et al. hep-ph/0303043 'Focus point' region: significant h component to LSP enhances annihilation to gauge bosons ~ Slepton Co-annihilation region: LSP ~ pure Bino. Small slepton-LSP mass difference makes measurements difficult. Disfavoured by BR (b  s) = (3.2  0.5)  10-4 (CLEO, BELLE) c01 t1 t g/Z/h ~ c01 l lR ~ Also 'rapid annihilation funnel' at Higgs pole at high tan(b), stop co-annihilation region at large A0 'Bulk' region: t-channel slepton exchange - LSP mostly Bino. 'Bread and Butter' region for LHC Expts. 0.094    h2  0.129 (WMAP) 0.094 < rLSP < 0.129

Some SUSY Phenomenology 1 fb squarks gluinos Production cross sections: squarks gluinos Decay modes depend on mass spectrum

Benchmark points CMS 21h 21Z Low mass points for early LHC running but above Tevatron reach High-mass points for ultimate LHC reach Indirect WMAP constraints except LM1, 2, 6, 9 (in favor of signatures) LM1 10 LM5 LM9 LM2 35 SPS1a tanb=10 (ATLAS) 21h 21Z

SPS1a point This point has been extensively studied by Atlas (fast simulation), favourable at LHC m0= 100 GeV, m1/2= 250 GeV, A0= -100 GeV, tan(β)=10 , μ>0 light sleptons Higgs at the limit of LEP reach Moderately heavy gluinos and squarks Heavy and light gauginos

Best strategy for mSUGRA is : ETmiss + jets + n-leptons SUSY Signatures Q: What do we expect SUSY events @ LHC to look like? A: Look at typical decay chain: proton Strongly interacting sparticles (squarks, gluinos) dominate production. Gauginos and quarks g cascade decays to LSP. Event topology: High pT jets (from squark/gluino decay) Large ETmiss signature (from LSP) High pT leptons, b-jets, t-jets (depending on model parameters) Closest equivalent SM signature (Background) is tgWb. Best strategy for mSUGRA is : ETmiss + jets + n-leptons

Selection of SUSY topics at LHC Global selection of SUSY events Inclusive analyses, discovery reach MET and jets Adding leptons Single muons same-sign dimuon opposite-sign same flavor dielectron and dimuon opposite-sign same flavor hadronic ditau trileptons at high m0 Z0 and Higgses Top stop Reconstruction of sparticle masses Di-Leptons ee mm taus Adding jets (Spin determination) (Model parameters)

ETmiss + jets candidate event display ETmiss =360 GeV, ET (1)=330 GeV, ET (2)=140 GeV, ET (3)=60 GeV

Analysis Results(LM1) Selected SUSY and Standard Model background events for 1 fb-1. * (S) is ~13% with S/B ratio ~26. The 5 discovery can be reached by using ~6 pb-1 data collection (w/ sys+stat uncertainties in the significance estimation) CMS CMS Meff ETmiss *Due to limited Monte Carlo event generation the analysis path on QCD data is carried out without topological cuts and ILV. The estimate is conservative and based on the parameterization of the efficiency for cleanup and ILV requirements for ETmiss > 700 GeV

But: Missing Transverse Energy Clean up cuts needed: cosmics, beam halo, dead channels, QCD

Effect of QCD Topological Reqs. (Acceptance Efficiency) QCD Data and Cleanup QCD jet production cross-section is very large at LHC. (j(2), (ETmiss)) > 20 deg QCD jets  2 + ETmiss > 93 GeV Missing transverse energy in QCD jet production mostly due to jet mis-measurements and detector resolution. CMS CMS CMS 3) SUSY LM1 QCD Effect of QCD Topological Reqs. (Acceptance Efficiency) min(j, (ETmiss)) > 0.3 rad Multi jets and large missing transverse energy data sample is dominated by QCD! SUSY LM1 ~90% QCD ~15%

MET Calibration Using Z-Candle Measure Z+jets with Z mm in data to normalize Z nn (invisible) contribution and calibrate MET spectrum With ~1fb-1 we will have enough Z+jets in the PT(Z)>200 GeV region of interest to normalize within 5% the invisible Z process as well as W+jets through the W/Z ratio and lepton universality dN/dPTmiss

Discovering SUSY and Evaluating MSUSY RPC models signature: MET + several high-pT jets  Build discriminating variable Meff: where Coannihilation point Full sim 20.6fb−1 SUSY signal SM Bkg (Herwig)

SUSY inclusive search Effective mass Effective mass (after bkg. subtraction) ATLAS Preliminary ATLAS Preliminary 0-lepton mode, L=1fb-1 0-lepton mode, L=1fb-1 Correct 30% over-estimate 30% under-estimate signal MSUSY~1TeV ATLAS Preliminary background Result with fast simulation. only scale is changed (slope is same). Important to understand background scale and slope.

Inclusive MET + Jets + Muons Add lepton  clean trigger A0 = 0, tan(b) = 10, sign(m) = +1 Cuts optimized @LM1 1 isolated muon pT > 30 GeV MET > 130 GeV 3 jets: ET> 440, 440, and 50 GeV ||< 1.9, 1.5, and 3 Cuts on  between jets and MET 30 fb-1 and 60 fb-1 : Re-optimised cuts for higher lumi m1/2 Optimised cuts for 10 fb-1 luminosity Background (10 fb-1) m0 2.5 ev, systematic uncertainty ~20%

Same-Sign Muon Reach Even cleaner signature with low background A0 = 0, tan(b) = 10, sign(m) = +1 Even cleaner signature with low background due to same-sign requirement LEP Tevatron 100 fb-1 Optimized cuts for 10 fb-1 luminosity m1/2 Cuts optimized @LM1 2 SS isolated muons pT > 10 GeV MET > 200 GeV 3 jets: ET1>175 GeV ET2>130 GeV ET3>55 GeV 1 fb-1 m0 Background (10 fb-1) 1.5 ev, systematic uncertainty ~23%

Top is SM physics, SUSY -background and -signal Inclusive MET + Top Catch stop decays to top Top is SM physics, SUSY -background and -signal Strong top analysis group (ex-D0) in Strasbourg (IPHC) Cuts optimized @LM1 MET>150 GeV Hadronic top selection and 2C fit 1 b-jet + 2 non-b jets Use the W and top mass constraints to fit top and require good 2 LM1 signal LM1 ~200 pb-1 for 5 observation sys. uncertainty ~12%

Inclusive Higgs Search in SUSY events proton proton Inclusive Higgs Search in SUSY events

Inclusive Higgs Search LM5 1 fb-1 Consider Dominant squark decay chain in a significant domain of mSUGRA parameter space m(h)=116 GeV LM5 full simulation selection MET > 200 GeV ET (jet 1,2,3,4) > 200,150,50,30 GeV 2 tagged hi-quality b-jets in the same hemisphere closest in h-f-space Signal efficiency ~ 8%, main bkgd. – ttbar 5 s excess with 1.5 fb-1 m(h) = 112.9  6.6(stat.)  7.5(syst.) GeV

Inclusive SUSY searches Search strategy based on different signatures Low mass SUSY(mgluino~500 GeV) shows excess in many channels for O(100) pb-1 Time for discovery determined by:  Time to understand the detector performance, Etmiss tails, jet scale,lepton id  Time collect SM control samples such as W+jets, Z+jets, top..

Two leptons in a cascade LM2 tanb=35 proton proton Two leptons in a cascade LM2 tanb=35

Di-Lepton Mass Edge Measure invariant mass distribution of same-flavor opposite-sign (SFOS) leptons as evidence for Endpoint in mass spectrum exhibits sharp edge dependent on sparticle masses Subtract different flavour leptons LM with 1 fb-1, fit result (expected 81 GeV):

LM2 compatible with WMAP result Probing this sector of SUSY essential Dominique J. Mangeol Cascade decays at LM2 LM2 Point m0 = 185 GeV m1/2 = 350 GeV tan β = 35 A0 = 0; μ > 0 Cascade decays At large tanb, suppressed ___ tanb=10 ___ tanb=35 At lower tanb One could measure tanb by the branching ratio !? UG SUSY is one of the main physics topics of the CMS group in Strasbourg (IPHC) hep-ph/0306219 BF for :96% LM2 compatible with WMAP result Probing this sector of SUSY essential BUT…

Experimentally difficult !!!! Dominique J. Mangeol Always one very soft tau per event To reconstruct a full cascade we need to tag both tau's produced by neutralino2 and stau Experimentally difficult !!!!

Event selection Dominique J. Mangeol 2 t, DR(t,t)<2 Large Etmiss ( 2 LSP's) 2 energetic jets (one for each cascade) at least two hadronic tau's with DR(t,t)<2 2 t, DR(t,t)<2 Cut Etmiss>150GeV Main backgrounds: QCD multi-jet events (50%) ttbar (39%) W+jets (11%) Cut 2 jets avec Et>150GeV

Discovery potential of SUSY in di-tau final states Dominique J. Mangeol Discovery potential of SUSY in di-tau final states Generalizing LM2 results to any m0,m1/2 values and for tanb=10 and 35 5s discovery contours systematics on background accounted for SUSY with di-tau final states could be discovered very early in LHC running

SUSY Mass Spectrum Measurement Dominique J. Mangeol SUSY Mass Spectrum Measurement End-Point technique: With this cascade: 3 observables Hence: Fully resolved system of equations Position of end-point not changed by loss of neutrinos, but much more difficult to extract !!!

End-Point extraction (di-tau's) Dominique J. Mangeol End-Point extraction (di-tau's) Large Combinatorial background due to multiple candidates Need to understand this background to extract end-points: Fit the background distribution Fit the distribution sum signal+background For di-tau invariant mass: Di-tau from have always opposite charge Di-tau from combinatorics estimated with same charge di-tau Measure invariant masses Extract end-points from the fits at 40fb-1 95±5 GeV

Invariant mass distribution with tau's and jets extraction of end-points Dominique J. Mangeol 298±7 GeV 559±11 GeV 596±12 GeV 780±20 GeV

From end-points to masses Dominique J. Mangeol From end-points to masses aFor one set of end-points several mass combinations are possible depending on sparticle mass hierarchy hypothesis In this analysis, 2 hypotheses returns a physical solution: Used for mass calculation

From End-point to masses Dominique J. Mangeol From End-point to masses E5 end-point is used to choose between the 2 solutions: E5 calculated using the 2 mass solution gives 765GeV in case (1) and 815 GeV in case (2) E5 extracted from the mass invariant gives 780±20GeV aIn better agreement with case 1 (LM2) CMS Note 2006/096

Di-lepton Endpoint in Various mSUGRA Scenarii Depending on point: different shape, number of edges, 2-body vs 3-body decay, … Coannihilation Focus Point ATLAS MC truth lL MC truth lR Full sim 6.9fb−1 signal Full Sim 20.6fb−1 2 edges for left and right slepton m0 large, heavy scalars  no sleptons in  decays direct 3-body decay: small BR at least 1 lepton with small pT S. Laplace, "Mass Reconstruction Methods"

Sbottom and Gluino Masses: Near The l+l- Endpoint Near l+l- endpoint: LSP and l+l- are at rest in frame, thus can evaluate momentum (approximation): where and are known from endpoints b b Add 1 or 2 b-jet to get sbottom and gluino masses: and Correlation between and SPS1a Fast sim 300 fb-1 =2.2 GeV Wrong associated b-jet SUSY bkg Spread from p(2)approximation is common to both masses Gluino mass Gluino – sbottom masses B.K. Gjelsten et al, ATL-PHYS-2004-007 S. Laplace, "Mass Reconstruction Methods"

Obtaining the Fundamental Model Parameters LHC Measurements SUSY Model Ex: mSUGRA m0, m1/2, A0, tan, sgn() Spectrum Generator (Ex: SUSPECT, SoftSUSY, …) Ex: endpoints Fit: 2 Mes. Note: better to exploit edges than masses (correlations) S. Laplace, "Mass Reconstruction Methods" R. Lafaye, T. Plehn, D. Zerwas, hep-ph/0512028

An Example List of measurements (300 fb-1) SFITTER program: mSUGRA Parameter determination R. Lafaye, T. Plehn, D. Zerwas, hep-ph/0512028 Note: m(ll) most powerful input (m0 driven by 1st and 2nd generation slepton sector) Sign(μ) fixed

Conclusions SUSY is the most likely extension of the Standard Model proton Conclusions Let's get one !!! SUSY is the most likely extension of the Standard Model SUSY can be discovered within the first (two?) years of data taking If(!) we understand our detectors (ETmiss, Ejets) well Complicated and long decay chains can be reconstructed With 300 fb-1 a large fraction of the SUSY spectrum will be reconstructed at LHC ( and ILC) Thank you!!