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Bhaskar Dutta Texas A&M University

Measurement of Relic Density at the LHC. Arxiv: Phys. Lett.B: 649:73, 2007; 639:46, 2006. Bhaskar Dutta Texas A&M University. Collaborators: R. Arnowitt, A. Gurrola, T. Kamon, A. Krislock, D. Toback. SUSY in Early Stage at the LHC. (or l + l - , t+t- ).

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Bhaskar Dutta Texas A&M University

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  1. Measurement of Relic Density at the LHC Arxiv: Phys. Lett.B: 649:73, 2007; 639:46, 2006 Bhaskar Dutta Texas A&M University Collaborators: R. Arnowitt, A. Gurrola, T. Kamon, A. Krislock,D. Toback Measurement of Relic Density at the LHC

  2. SUSY in Early Stage at the LHC (or l+l-, t+t-) The signal to look for: 4 jet + missing ET Measurement of Relic Density at the LHC

  3. Example Analysis Kinematical Cuts and Event Selection • ETj1>100 GeV, ETj2,3,4> 50 GeV • Meff > 400 GeV (Meff  ETj1+ETj2+ETj3+ETj4+ ETmiss) • ETmiss > Max [100, 0.2 Meff] Hinchliffe et al. Phys. Rev. D 55 (1997) 5520 Measurement of Relic Density at the LHC

  4. Relic Density and Meff SUSY scale is measured with an accuracy of 10-20% • This measurement does not tell us whether the model can generate the right amount of dark matter • The dark matter content is measured with an accuracy of around 6% at WMAP • Question: To what accuracy can we calculate the relic density based on the measurements at the LHC? Measurement of Relic Density at the LHC

  5. Analysis Strategy • We establish dark matter allowed regions from the detailed features of the signals. • We accurately measure the masses and model parameters (all four mSUGRA parameters). • We calculate the relic density and compare that with WMAP observation. Measurement of Relic Density at the LHC

  6. Minimal Supergravity (mSUGRA) MHiggs > 114 GeV Mchargino > 104 GeV 2.2x10-4 < Br (b s g)< 4.5x10-4 iv. (g-2)m 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 : 3 s descripency Measurement of Relic Density at the LHC

  7. 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 [In this talk] Measurement of Relic Density at the LHC

  8. Relic Density Calculation +… In the stau-neutralino coannihilation region Griest, Seckel ’91 Measurement of Relic Density at the LHC

  9. Our Reference Point m1/2 = 351, m0 = 210, tanb = 40, m >0, A0 = 0 [ISAJET version 7.69] Measurement of Relic Density at the LHC

  10. SUSY Anatomy SUSY Masses 97% 100% (CDM) Meff (4 jets + ETmiss) M(jtt) M(tt) pT(t) ETmiss+ jets + >2t Measurement of Relic Density at the LHC

  11. pTsoft Slope and Mtt pT and Mtt distributions in true di-t pairs from neutralino decay with |h|< 2.5 Number of Counts / 2 GeV Slope of pT distribution of “soft t” contains ΔM information Low energy t’s are an enormous challenge for the detectors ETvis(true) > 20, 20 GeV Number of Counts / 1 GeV ETvis(true) > 40, 20 GeV ETvis(true) > 40, 40 GeV Measurement of Relic Density at the LHC

  12. 180 Measurement of Relic Density at the LHC Measurement of Relic Density at the LHC 12

  13. Mtt Distribution Clean peak even for low DM We choose the peak position as an observable. Measurement of Relic Density at the LHC

  14. Mtt Distribution Mpeaktt depends on m0, m1/2, A0 and tanb Measurement of Relic Density at the LHC

  15. Mjtt Distribution Mtt < Mttendpoint Jets with ET > 100 GeV Jtt masses for each jet Choose the 2nd large value Squark Mass = 660 GeV Squark Mass = 840 GeV Peak value depends on squark mass We choose the peak position as an observable. Measurement of Relic Density at the LHC

  16. Mjtt Distribution Mpeak depends on m0, m1/2 jtt Measurement of Relic Density at the LHC

  17. Meff Distribution • ETj1>100 GeV, ETj2,3,4> 50 GeV [No e’s, m’s with pT > 20 GeV] • Meff > 400 GeV (Meff ETj1+ETj2+ETj3+ETj4+ ETmiss[No b jets; eb ~ 50%]) • ETmiss > max [100, 0.2 Meff] At Reference Point Meffpeak = 1220 GeV (m1/2 = 335 GeV) Meffpeak = 1331 GeV (m1/2 = 365 GeV) Meffpeak = 1274 GeV Measurement of Relic Density at the LHC

  18. Meffpeak vs. m0, m1/2 m1/2 (GeV) m0 (GeV) Meffpeak …. insensitive to A0 and tanb. Measurement of Relic Density at the LHC

  19. Meff(b) Distribution • ETj1>100 GeV, ETj2,3,4> 50 GeV [No e’s, m’s with pT > 20 GeV] • Meff(b)> 400 GeV (Meff(b)ETj1=b+ETj2+ETj3+ETj4+ ETmiss[j1 = b jet]) • ETmiss > max [100, 0.2 Meff] At Reference Point Meff(b)peak = 933 GeV (m1/2 = 335 GeV) Meff(b)peak = 1122 GeV (m1/2 = 365 GeV) Meff(b)peak = 1026 GeV Meff(b) can be used to determine A0 and tanb even without measuring stop and sbottom masses Measurement of Relic Density at the LHC

  20. Meff(b)peak vs. X m1/2 m0 tanb A0 Meff(b)peak …. sensitive to A0 and tanb. Measurement of Relic Density at the LHC

  21. Determining Model Parameters m0=205 4; m1/2=350 4.2; A0=0 16; tanb= 40 0.8 =748 25; =831 21; =10.6 2; =141 19; = 260 15; The Model parameters are solved by inverting the following functions: (10 fb-1) We can also determine the sparticle masses using these observables and a few additional ones, e.g., M(peak)jt, etc Gaugino Universality can be checked (at 15% level)! Measurement of Relic Density at the LHC

  22. Relic Density and Luminosity • How does the uncertainty in the Dark Matter relic density change with Luminosity? L= 50 fb-1 L= 10 fb-1 dWh2/Wh2 ~ 6% (30 fb-1) Measurement of Relic Density at the LHC

  23. Conclusion m0=205 4; m1/2=350 4.2; A0=0 16; tanb= 40 0.8 Meff will establish the existence of SUSY Different observables are needed to establish the dark matter allowed regions in a SUSY model at the LHC • Analysis with visible ETt > 20 GeV establishes stau-neutralino coannihilation region The mSUGRA parameters are determined using : 1) Meffpeak 2)Mjttpeak 3)Mttpeak 4) Meffpeak(b) (10 fb-1) dWh2/Wh2 ~ 6% (30 fb-1) Squark, Gluino, stau, neutralino(1,2) can be determined without using mSUGRA assumptions Gaugino universality can be checked at 15% level Measurement of Relic Density at the LHC

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