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Implications of DM at the LHC

Implications of DM at the LHC. “Get Ready for Physics at the LHC” RECAPP HRI, Allahabad 16-20 th February, 2009. M.Guchait TIFR,Mumbai. Outline. Dark Matter candidate and Model. Constrained parameter space. SUSY and LHC.

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Implications of DM at the LHC

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  1. Implications of DM at the LHC “Get Ready for Physics at the LHC” RECAPP HRI, Allahabad 16-20th February, 2009 M.Guchait TIFR,Mumbai

  2. Outline Dark Matter candidate and Model Constrained parameter space SUSY and LHC Co-annihilation region and probing at LHC

  3. Dark matter Candidates WMAP Supersymmetry offers: Neutralino Gravitino Axino sneutrino Talk by P. Osland The heavy photon BH in the Little Higgs model The KK photon in UED model ……………………

  4. DM at LHC? During last ~30 years a lot of progress in HEP • renormalizabiity of SU(2) X U(1) with Higgs mechanism • asymptotic freedom, QCD as a gauge theory of strong interaction.. …….. Experimental discovery • Fermions(USA), Bosons( Higgs yet to find)(Europe) Technical theoretical progress, confirmed by experiment • Higher order calculations, Lattice QCD… • EW corrections, running of αS , CKM parameters …. DM?

  5. Anything New ?

  6. Cosmology and Particle Physics Can we verify if the DM particles expected to be produced at LHC? Can we look for a signal at the LHC that is a reasonable direct consequences of the assumption that the neutralino is the DM particle?

  7. Tasks at LHC Reconstruct entire parameter space of the model Calculate relic density and compare it with the WMAP measurements Also the inputs from direct detection experiment are need to be matched.

  8. Model: mSUGRA Parameters: AT EW scale, spectrum calculator: ISASUGRA SuSpect SoftSUSY Relic density calculations: microOMEGA DarkSUSY

  9. Constrained Parameter space The “Funnel region”, m0 ~ m1/2, where rapidly annihilate via Direct s-channel pseudoscalar Higgs poles, which opens up for large tanβ region The “Focus region”, where m0 is too large,LSP is higgsino like X .Tata et. al ‘06 S.P.Das, A.Datta, M.Maity, MG, ‘07 “Co-annihiliation” region m1/2 >> m0, sfermion-LSP Co-annihilating particles are almost degenerate,LSP Bino like

  10. mSUGRA constrained after WMAP Very much parameter Space dependent See talk by A. Datta

  11. Stau – coannihilation regionat LHC

  12. Sparticle Production at LHC LHC is a gluon factory: Interactions are mediated by QCD, mainly depends on masses

  13. Generic Signal SUSY events are High ET events Cross sections are low PP → QCD(jets) → top pair → W/Z +jets Leptons (≥ 2) jets (≥ 3-4) MET( ≥ 100 GeV) Talk by A. Datta

  14. Signal and Background PP → QCD(jets) → top pair → W/Z +jets Signal to be suppressed by order of ~ 105 Experimental issues Machine backgrounds Hot and dead channels Cosmic muons Beam halo Understanding MET is very important

  15. Stau-coannihilation WMAP data favours ΔM = 5-15 GeV Need large value of

  16. Co-annihilation region and LHC tau lepton is too soft, some help may come from boosted Stau1. Same advantages are there because of presence of harder accompanied visible products. Arnowitt et. al 2007 R.M.Godbole, MG, D.P.Roy 2008

  17. Work done by Arnowitt et. al Final states depend on all mSUGRA parameters Tt, W/Z+jets, QCD SM Backgrounds: OS – LS combination help to reduce the SM and SUSY backgrounds

  18. Contd… Reconstructed the decay chain using the kinematic variables Measured these variables, then invert it Masses

  19. Contd.. From the measurements of masses, possible to Reconstruct mSUGRA parameters Calculate relic density. Uncertaintity: 11(6.2)% for L =10(30)/fb

  20. Our work Polarized Gauge+Higgs couplings Gauge part Higgs Part

  21. Polarization in mSUGRA is calculated for a entire region of mSUGRA parameter space µ > 0 is mostly positive and >0.9 µ < 0

  22. Tau decay and polarization CM angular distributions

  23. Energy distributions

  24. Energy Sharing among decay products

  25. Variable for experimentalobservation Tracker measurement Construct Calorimeter measurement Some uncertainty may come from Calorimeters But PFA give better measurements,less error

  26. Signal and Backgrounds LO 0.46 2.4 1.3 ~ 500 pb Backgrounds: Top production, with t → bW ~ 1000 pb W+jets QCD SUSY

  27. Tools Event Generation PYTHIA Only tau TAUOLA is modified to simulate tau decays from SUSY cascade decays. TAUOLA CMSJET For jet reconstruction and missing energy Calculations from Calorimeters, CMSJET Analysis

  28. Benchmark Point and Masses

  29. Tau jet tau jets are constructed using generator level Informations with a leading track momentum > 6 GeV. Tracker isolation(narrow jet): Only one (leading) charged track inside the signal cone ΔR=0.1 There is no other charged track in a surrounding isolation cone of size, ΔR=0.3 with charged track pT >3(1) GeV.

  30. Cuts Softest taujet Bg rejection cuts

  31. Effects of tracker isolation 3 GeV II. III. 1 GeV

  32. QCD jet faking as tau jets QCD: pt=15-40 GeV

  33. SM background estimation

  34. Softest tau jet: Signal and Bg Signal No R cut Total Bg Pt of softest tau jet Fake Bg

  35. Softest tau jet: Signal and Bg With R cut Signal Total Bg

  36. Signal and backgrounds Total signal:731(414) SUSY bg : 814(249) SM bg : 427(110)

  37. Signal and Background events = 467/306 = 1.52 ±0.16 178/180 = 0.98±0.14 A ~3σ effect is expected at 10/fb luminosity This will go up ~10σ for luminosity 100/fb

  38. Softest tau jet: Signal and Bg ΔM sensitivity With R cut ΔM=15 GeV = 1.34±0.10 ΔM=10 GeV Estimation of ΔM with Accuracy 50% at 1.5σ for 10/fb, For 100/fb the significance level at 5σ

  39. Summary Stau – coannihilation region can be probed with mass Reconstructions as well. Use tau polarization is of tremendous useful;particulalry to suppres The Background; unlike the other analysis where BG is reduced by OS-LS, present case has the benefit of utlizing a much larger fraction of the SUSY events. Excess events of backgrounds can be observed with a reasonable statistics ΔM can be measured with a 50% accuracy for 10/fb Di-tau analysis will also give some benefits, under preparation

  40. Back Up

  41. WIMP model They are stable,neutral,weakly interacting particles with Interaction cross sections large enough that they were in thermal equilibrium for some periods of time in the early universe. The cross section results from an interaction mediated by a particle whose mass is of the order of ~ 100 GeV. Masses are very close to the mass scale to EW symmetry breaking Hints of New Physics ?

  42. Neutralino Annihilation A,B = q qbar, l lbar A,B = WW,ZZ A,B=WH,ZH

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