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SUSY at LHC

SUSY at LHC. Bhaskar Dutta Texas A&M University. Discovery Time…. We are about to enter into an era of major discovery. Dark Matter: we need new particles to explain the content of the universe. Standard Model: we need new physics. Supersymmetry solves both problems!.

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SUSY at LHC

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  1. SUSY at LHC Bhaskar Dutta Texas A&M University SUSY Theory at the LHC

  2. Discovery Time… We are about to enter into an era of major discovery Dark Matter: we need new particles to explain the content of the universe Standard Model: we need new physics Supersymmetry solves both problems! The super-particles are distributed around the weak scale Our best chance to observe SUSY is at the LHC LHC: The only experiment which directly probes TeV scale Future results from Planck, direct and indirect detection in tandem with LHC will confirm a model Model SUSY Theory at the LHC

  3. Collision of 2 Galaxy Clusters 1 2 3 4 splitting normal matter and dark matter apart – Another Clear Evidence of Dark Matter – (8/21/06) Ordinary Matter (NASA’s Chandra X Observatory) time Approximately the same size as the Milky Way Dark Matter (Gravitational Lensing) SUSY Theory at the LHC 3

  4. SUSY at the LHC High PT jet [mass difference is large] DM The pT of jets and leptons depend on the sparticle masses which are given by models Colored particles get produced and decay into weakly interacting stable particles R-parity conserving DM (or l+l-, t+t-) High PT jet The signal : jets + leptons + missing ET SUSY Theory at the LHC

  5. Example Analysis Kinematical Cuts, Event Selection - 4 jets +ETmiss • PTj1>100 GeV, PTj2,3,4> 50 GeV • Meff > 400 GeV (Meff  PTj1+PTj2+PTj3+PTj4+ ETmiss) • ETmiss > Max [100, 0.2 Meff] Paige, Hinchliffe et al. , Phys. Rev. D 55 (1997) 5520 SUSY Theory at the LHC

  6. Background Typical SUSY events are 105 events for 10 fb-1, while BG rate is 109-8 for W, Z, t tbar production. The cuts need to be optimized Large amount of missing energy, high pT jets, large numbers of jets and leptons are good handles on signal SUSY Theory at the LHC

  7. SUSY Models MSSM has more than 100 parameters The number of parameters can be reduced in different models Minimal Model: minimal supergravity (mSUGRA)/CMSSM Nonuniversal SUGRA model, Anomaly mediated, NMSSM, Compressed- SUSY Mixed Moduli, Gauge Mediated, non-critical string model, Split SUSY, Long lived NLSP models, GUT less models, Planck scale SU(5), SO(10) models etc.. Once SUSY is discovered, models will be searched based on typical signals These models also will be simultaneously tested at the underground , satellite experiments from their characteristic features. SUSY Theory at the LHC Let LHC Decide

  8. MHiggs > 114 GeV Mchargino > 104 GeV 2.2x10-4 < Br (b s g)< 4.5x10-4 (g-2)m Minimal Supergravity (mSUGRA) Let us use the simplest model to describe the reach of LHC 4 parameters + 1 sign m1/2 Common gaugino mass at MG m0 Common scalar mass at MG A0 Trilinear couping at MG tanb<Hu>/<Hd> at the electroweak scale sign(m) Sign of Higgs mixing parameter (W(2) = m HuHd) Experimental Constraints SUSY Theory at the LHC

  9. Reach at the LHC Use Jets + leptons + ETmiss discovery channel. 5s 5s ATLAS ATLAS Sensitivity only weakly dependent on A0, tan(b) and sign(m). Tovey’02 M. Tytgat (SUSY’07) SUSY Theory at the LHC

  10. Measurement of Masses +… We need to measure the masses of the particles. Model parameters need to be determined to check the cosmological status. [Allanach, Belanger, Boudjema and Pukhov’04] If we observe missing energy, then we have a possible dark matter candidate . [ LHC experiments sensitive only to LSP lifetimes <1 ms (≪ tU ~ 13.7 Gyr) ] Using the model parameters we need to calculate relic density SUSY Theory at the LHC

  11. Dilepton Edge Measurement • Deacy of results into dilepton invariant mass edge sensitive to combination of masses ofsparticles. • Can perform SM & SUSY background subtraction using distribution • e+e- + m+m- - e+m- - m+e- • Position of edge measured with precision ~ 0.5% (30 fb-1). • m0 = 100 GeV • m1/2 = 300 GeV • A0 = -300 GeV • tan(b) = 6 • sgn(m) = +1 e+e- + m+m- Point 5 ATLAS 30 fb-1 atlfast Physics TDR SUSY Theory at the LHC

  12. Measurements with Squarks ~ qL ~ ~ c02 ~ c01 q l l l ~ qL ~ ~ c02 c01 q h lq edge llq edge b b 1% error (100 fb-1) 1% error (100 fb-1) Point m0 m1/2 A0 tan(b) sign(m) LHC Point 5 100 300 300 2 +1 • Use Dilepton edge for reconstruction of decay chain. • Make invariant mass combinations of leptons and jets. • multiple constraints on combinations of four masses. • Measurement of individual sparticle masses. bbq edge llq threshold 1% error (100 fb-1) 2% error (100 fb-1) TDR, Point 5 TDR, Point 5 TDR, Point 5 TDR, Point 5 ATLAS ATLAS ATLAS ATLAS SUSY Theory at the LHC

  13. Model Independent Masses Sparticle Expected precision (100 fb-1) qL 3% 02 6% lR 9% 01 12% ~ ~ ~ ~ • Measurements from edges from different jet/lepton combinations to obtain ‘model-independent’ mass measurements. ~ ~ c01 lR ATLAS ATLAS Mass (GeV) Mass (GeV) ~ ~ c02 qL ATLAS ATLAS LHC Point 5 Mass (GeV) Mass (GeV) Accuracies using many of such observables: 2% (m0), 0.6% (m1/2), 9% (tanb), 16% (A0) Similar analysis, P. Beatle (SUSY 07); M. Rauch (SUSY 07) SUSY Theory at the LHC

  14. Higgsino vs Gaugino … ~ ~ 01 01  ~ ~ ~ ~ ~ ~ 02 02 01 02 01 02 and : Higgsinos, three gaugino masses are very close Kitano, Nomura’06 l+l- With M( )-M( ) <MZ Mslepton > Mz Gaugino Like and The spectrum terminates at m(l+l-)max Using other observables like Mllq Mlq, MT, it is Possible to measure squark and the neutralino mass with An accuracy of 2% and 10% Higgsino Shapes looks different, 2 scenarios can be distinguished SUSY Theory at the LHC

  15. Dark Matter Allowed Regions We choose mSUGRA model. However, the results can be generalized. [Focus point region] the lightest neutralino has a larger higgsino component [A-annihilation funnel region] This appears for large values of m1/2 [Neutralino-stau coannihilation region] Bulk region-almost ruled out SUSY Theory at the LHC

  16. Focus Point : Jets+leptons Typical mSUGRA point:m0=2910; A0=0; m1/2=350; m>0; tanb=30; Large sfermion mass, smaller gaugino masses comparatively LHC events characterized by high jet, b-jet, isol. lepton multiplicity Baer, Barger, Shaughnessy, Summy, Wang ‘07 _ _ Gluino decays into t t c0, t b c+- (mostly)] Higher jet, b-jet, lepton multiplicity requirement increase the signal over background rate SUSY Theory at the LHC

  17. Focus Point : Jets+leptons… Require cuts: n(j) ≥ 7, n(b) ≥ 2, AT≥ 1400 GeV ETmiss+SETjet+SETlepton Gluino mass can be measured with an accuracy 8% Baer, Barger, Shaughnessy, Summy, Wang ‘07 SUSY Theory at the LHC

  18. Focus Point: Leptons ~ ~ ~ ~ c03 → c01 ll c02 → c01 ll Z0→ ll ATLAS 300 fb-1 Preliminary • Large m0 sfermions are heavy • m0=3550 GeV; m1/2=300 GeV; A0=0; tanß=10 ; μ>0 • Direct three-body decays c0n → c01 +2 leptons • Edges give m(c0n)-m(c01) ~ ~ ~ ~ Tovey, PPC’07 Similar analysis: Error (M2-M1)~ 0.5 GeV G. Moortgat-Pick (SUSY 07) SUSY Theory at the LHC

  19. Bulk Region ~ ~ ~ 01 g uL ~ ~ l 02 The most part of this region in mSUGRA is experimentally (Higgs mass limit, bs g) ruled out Relic density is satisfied by t channel selectron, stau and sneutrino exchange Perform the end point analysis to determine the masses mSUGRA point: m0=70; A0=-300 m1/2=250; m>0; tanb=10; Nojiri, Polsello, Tovey’05 The error of relic density: 0.108 ± 0.01(stat + sys) ~ Includes: (+0.00,−0.002 )M(A); (+0.001, −0.011) tan β; (+0.002,−0.005) m(t2) [With a luminosity 300 fb-1, tt edge controlled to 1 GeV] SUSY Theory at the LHC

  20. Coannihilation Signatures Griest, Seckel ’91 Mass of another sparticle comes close to the neutralino: both of them are thermally available. This region appears for small m0 and m1/2 values and therefore will be accessible within a short time For smal tanb this region has e,m,t in the signals For large tanb this region has t in the signals SUSY Theory at the LHC

  21. Coann. Signatures (tanb=10) • Small slepton-neutralino mass difference gives soft leptons • Low electron/muon/tau energy thresholds crucial. • Study point chosen within region: • m0=70 GeV; m1/2=350 GeV; A0=0; tanß=10 ; μ>0; • Decays of c02 to both lL and lR kinematically allowed. • Double dilepton invariant mass edge structure; • Edges expected at 57 / 101 GeV Preliminary ATLAS 100 fb-1 • ETmiss>300 GeV • 2 OSSF leptons PT>10 GeV • >1 jet with PT>150 GeV • OSSF-OSOF subtraction applied Tovey, PPC’07 SUSY Theory at the LHC

  22. Coannihilation Region (tanb=40) tanb = 40, m > 0, A0 = 0 Can we measure DM at colliders? SUSY Theory at the LHC

  23. Coann. Signatures (tanb=40) Hard t p p p p Soft t Soft t Hard t Hard t In Coannihilation Region of SUSY Parameter Space: Soft t Soft t Final state: 3/4 ts+jets +missing energy Use hadronically decayingt SUSY Theory at the LHC

  24. Four Observables • Sort τ’s by ET (ET1 > ET2 > …) and use OS-LS method to extract t pairs from the decays • NOS-LS • ditau invariant mass (Mtt) • PT of the low energy t to estimate the mass difference DM • jet-t-t invariant mass: Mjtt D. Toback’s talk, parallel session Arnowitt, B.D., Kamon, Toback, Kolev,’06; Arnowitt, Arusano,B.D., Kamon, Toback,Simeon,’06; Arnowitt,B.D., Gurrola, Kamon, Krislock, Toback, to appear; D. Toback, talk [this conf] SUSY Theory at the LHC

  25. SUSY Parameters Since we are using 4 variables, we can measure DM, Mgluino and the universality relation of the gaugino masses i.e. Mgluino measured from the Meff method may not be accurate for this parameter space since the tau jets may pass as jets in the Meff observable. The accuracy of measuring these parameters are important for calculating relic density. EVENTS WITH CORRECT FINAL STATE : 2t + 2j + ETmiss APPLY CUTS TO REDUCE SM BACKGROUND (W+jets, t-tbar,…) ETmiss > 180 GeV, ETj1 > 100 GeV, ETj2 > 100 GeV, ETmiss + ETj1 + ETj2 > 600 GeV ORDER TAUS BY PT & APPLY CUTS ON TAUS: WE EXPECT A SOFT t AND A HARD t PTall > 20 GeV, PTt1 > 40 GeV SUSY Theory at the LHC

  26. Mttvisin ISAJET ETvis(true) > 20, 20 GeV ETvis(true) > 40, 20 GeV Number of Counts / 1 GeV ETvis(true) > 40, 40 GeV ETt > 20 GeV is essential! Version 7.69 (m1/2 = 347.88, m0 = 201.1)  Mgluino = 831 • Chose di-t pairs from neutralino decays with • (a) |h| < 2.5 • (b) t = hadronically-decaying tau SUSY Theory at the LHC

  27. Determination of m0 , m1/2 DM and Mgluinom0 , m1/2, (for fixed A0 and tanb) We determine dm0/m0 ~ 1.2% and dm1/2/m1/2 ~2 % dWh2/Wh2 ~ 7% (10 fb-1) (for A0=0, tanb=40) SUSY Theory at the LHC

  28. Higgs non-universality The most common extension of mSUGRA Case 2. Case 1. Drees’00; Baer Belyaev, Mustafayev, Profumo, Tata’05 Ellis, Olive, Santoso’03 LHC signal: A, H and H+- will be relatively light, and more accessible to direct LHC searches ~ There can be light uR, cR squarks, small m: leads to light and oi +i SUSY Theory at the LHC

  29. Moduli-Mediation KKLT model: type IIB string compactification with fluxes MSSM soft terms have been calculated, Choi, Falkowski, Nilles, Olechowski, Pokorski Ratio of the modular mediated and anomaly mediated is given by a phenomenological parameter a Choi, Jeong, Okumura, Falkowski, Lebedev, Mambrini,Kitano, Nomura Baer, Park, Tata, Wang’06,07 SUSY Theory at the LHC

  30. GUT-less and Moduli Mediation Ellis, Olive, Sandick’07 m is smaller in the GUT - less case for this Example. MM-AMSB GUT-less SUSY Theory at the LHC

  31. Other Examples… ~ ~ ~ 01 01 02 g  Stop NLSP: stop charm+ Bino-wino Coannihilation, Mixed Wino coannihilation In these cases, the lightest chargino and the second lightest neutralino are very close to the lightest neutralino : decay opens up along with other three body decay modes Baer et. al.’05 Gravitino LSP (mass around 100 GeV…) and sleptons NLSP Long-lived charged particles: One can find that the sleptons to decay after a long time Feng, Su, Takayama, ’04 Gladyshev, Kazakov, Paucar’05’07 NMSSM: This model can have extra Z’, sneutrino as dark matter candidate, In the context of of intersecting Brane Models [ Kumar, Wells’ 06] Higgs signal at the LHC Dermisek, Gunion’05 Moretti et al ‘06 SUSY Theory at the LHC

  32. Other Examples… Martin,’07; Baer et al,’07 “Compressed” MSSM: − m2Hu = 1.92 M 23 + 0.16 M2 M3 − 0.21 M 22 − 0.33 M3 At − 0.074 M2 At +… Naturalness argument : M3 is small, use M3<(M2,M1) at the GUT scale Relic density is satisfied by neutralino annihilation via t –t bar production, stop coannihilation etc. The GUT scale parameters are M1,2,3= 500, 750, 250, A0 = -500, m0 = 342GeV A typical sample of ``compressed" mass spectrum with W h2 = 0.11 Reduction of leptons in the signal. Inflation and MSSM :Flat directions LLE, UDD etc. Smaller sparticle masses are needed once the constraints from ns, dH are included Allahverdi, Dutta, Mazumdar,07 Little Hierarchy :Smaller stop mass is needed Ratazzi et al’06, Dutta, Mimura’07 SUSY Theory at the LHC

  33. EGRET-SUSY EGRET excess of diffuse galactic gamma rays is explained as a signal of supersymmetric dark matter annihilation Fitted SUSY parameters m0=1400 GeV tanβ=50 m1/2=180 GeV A0=0.5m0 De Boer, Sander, ZhukovGladyshev, Kazakov’05,’06 ATLAS Gluino decays have a clear signature (4μ + 4jets + PT + up to 4 secondary vertices). Expected # of events for ATLAS after 1year of running with LHC luminosity 1034 cm-2s-1is around 150 CMS tri-lepton discovery potential of this region DeBoer, Zhukov, Nigel ,Sander,’06, ‘07 Bednyakov, Budagov, Gladyshev, Kazakov, Khoriauli, Khramov, Khubua’06’07 SUSY Theory at the LHC

  34. Conclusion LHC is a great machine to discover supersymmetry which would solve problems in particle physics and cosmology Signature contains missing energy (R parity conserving) many jets and leptons : Discovering SUSY should not be a problem! Once SUSY is discovered, attempts will be made to connect particle physics to cosmology The masses and parameters will be measured, models will be investigated Four different cosmological motivated regions of the minimal SUGRA model have distinct signatures Based on these measurement, the dark matter content of the universe will be calculated to compare with WMAP/PLANCK data. SUSY Theory at the LHC

  35. Conclusion… I hope not… The search for Weapons of Mass Destruction SUSY Theory at the LHC

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