Detection of SUSY Signals in Stau-Neutralino

Transcription

1 Detection of SUSY Signals in Stau-Neutralino Coannhilation at the LHC - Finger Print of CDM - R. Arnowitt, 1) A. Aurisano, 1)* B. Dutta, 1) T. Kamon, 1) V. Khotilovich, 1)* N. Kolev, ) P. Simeon, 1)** D. Toback, 1) P. Wagner 1)* 1) Department of Physics, Texas A&M University ) Department of Physics, Regina University, Canada * Graduate Student ** Undergraduate Student The 14th International Conference on Supersymmetry and the Unification of Fundamental Interactions Irvine, California, USA June 1-17, 006 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 1

2 Cosmology, SUSY, WIMP Stau neutralino coannihilation in minimal supergravity (msugra) model Prospects of detection of SUSY in coannihilation region at the LHC Conclusion and Future Tasks 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders

3 THINKING ABOUT THE UNIVERSE Early Universe Cosmological Connection? 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 3

4 Cosmology, SUSY, and WIMP Astrophysics χ ~ 1 CDM = Neutralino ( ) 0 Ω χ ~ 0 h ~ σ annv = pb x f 0 πα 8m 1 σ ann v dx SUSY SUSY is an interesting class of models to provide a massive neutral particle (m ~ 100 GeV) and weakly interacting (WIMP). 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 4

5 CDM = Neutralino ; NLSP = stau ( ) Ω CDM χ ~ 1 τ ~ 1 M / e 0 M msugra naturally provides a lighter stau. M ~ M ~ τ 1 χ 0 1 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 5

6 Minimal Supergravity (msugra) 4 parameters + 1 sign m 1/ 1/ m 00 Common gaugino mass at at M G Common scalar mass at at M G A at 00 Trilinear couping at M G tanβ <H d at u >/<H d > at the electroweak scale sign(µ) Sign of of Higgs mixing parameter (W (W = µ H u H d d )) Experimental Constraints i. M Higgs > 114 GeV M chargino > 104 GeV ii..x10 4 < Br (b s γ)< 4.5x10 4 iii Ω ~ 0h < < χ 1 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 6

7 Cosmologically Allowed Region tanβ = 40, µ > 0, A 0 = 0 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 7

8 Feature of Coannihilaion Region M M ~ τ M ~ 0 = 5 ~ 1 χ 1 15 Small M GeV ~ τ τ ~ χ Can we measure M at colliders? 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 8

9 Cosmology, SUSY, WIMP Stau neutralino coannihilation in minimal supergravity (msugra) model Prospects of detection of SUSY in coannihilation region at the LHC [1] LHC τ analysis: R. Arnowitt, B. Dutta, T. Kamon, N. Kolev, D. Toback, hep-ph/060318, to appear in PLB. [] LHC 3τ analysis: R. Arnowitt, A. Aurisano, B. Dutta, T. Kamon, N. Kolev, P. Simeon, D. Toback, P. Wagner, in preparation. Conclusion and Future Tasks 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 9

10 SUSY Signature at the LHC Squark-Gluino Production high energy low energy ~ τ ~ + + τ 1 τ + τ χ 1 χ ~ Triggering the jets and missing E T E T miss + jets + τ s 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 10

11 THINKING ABOUT TAU TO FIND THE TAU S Assumption: ε τ = 50% fake (f j τ ) = 1%. τ Pencil-like jet jet with 1 or or 3 tracks 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 8 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 9 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 11

12 E miss T + j + τ Analysis (I) [1] ISAJET + ATLFAST sample of E T miss, jets, and at least taus with p T vis > 40, 0 GeV and ε τ = 50%, fake (f j τ ) = 1%. Optimized cuts : E T jet1 > 100 GeV; E T jet > 100 GeV; E T miss > 180 GeV; E T jet1 + E T jet + E T miss > 600 GeV [] Number of SUSY and SM events (10 fb 1 ): Top : 115 events W+jets : 44 events SUSY : 590 events top SUSY M gluino = 830 GeV ( M = 10.6 GeV) 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 1

13 E miss T + j + τ Analysis (II) p T vis > 40, 0 GeV M peak M max = 78.7 GeV p T vis > 40, 40 GeV 10 fb 1 OS LS OS LS [3] OS di-tau mass histogram, subtract off LS mass histogram. OS LS counts (10 fb 1 ) for M ττ < 100 GeV: Top : 6 counts W+jets : 1 count SUSY : 15 counts How to Establish the Discovery [1] N OS LS (Number of OS LS counts) [] Clear peak (M peak ) and end-point (M max ) in di-tau mass distribution for OS LS pairs [3] M peak is used to determine M p Tτ > 0 GeV is essential! 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 13

14 τ Analysis : Discovery Luminosity 10-0 fb fb 1 Negligible f j τ dependence +5% [Assumption] The gluino mass is measured with δm/m gluino = ±5% in a separate analysis. 5% A small M can be detected in first few years of LHC. 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 14

15 τ Analysis : Accuracy in M Negligible f j τ dependence We extract M from M peak. I. δm peak = r.m.s(m peak ) / N OS LS II. δm/m gluino = ±5% M = 10 ± GeV (10 fb -1 ) 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 15

16 Reach in m 1/? tanβ = 40, 40, µ > 0 A =0 0 0 =0 Sliding cut on E T jet1 + E T jet + E T miss m 1/ 1/ = 360 GeV With 100 fb 1, the LHC could probe m 1/ up to ~700 GeV 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 16

17 E miss T + 1j + 3 3τ Analysis Much smaller SM background, but a lower acceptance [1] ISAJET + PGS (*) sample of E T miss, 1 jet and at least 3 taus with p T vis > 40, 40, 0 GeV and ε τ = 50%, fake (f j τ ) = 1%. Final cuts : E T jet1 > 100 GeV, E T miss > 100 GeV, E T jet1 + E T miss > 400 GeV (*) [] Select OS low di-tau mass pairs, subtract off LS pairs Small dependence on the uncertainty of f j τ Note: f j τ = 0% 1.6 counts/fb 1 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 17

18 Remark: 3 3τ events with Jet τ Fakes What is accepted by OS LS? Analysis τ 3τ Process ττ τj τττ ττj ~ 0 0 χ ~ χ yes no yes yes ~ 0 χ ~ ± χ 1 yes no yes yes ~ 0 0 χ ~ χ yes no yes 1 Can produce ττ and τj pairs τj pairs will be cancelled in OS LS, but ττ pairs from χ 0 contribute in the ττj case to the N OS LS counting. Doesn t affect M measurement! The uncertainty on the jet τ fake rate is required to be known, but M measurement is not significantly effected even if the fake rate has a 0% systematic uncertainty. 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 18

19 3τ Analysis: Combined Results Use N OS LS and M ττ to independently measure M Both produce high quality measurements As in the τ analysis, we assume a gluino mass Dominant uncertainty 5% uncertainty on M gluino 1 Combined results: M = 10 ± 1. 3 GeV (30 fb ) 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 19

20 3τ Analysis: Measure M and M gluino Next: combine N OS LS and M ττ values to measure M and M gluino simultaneously Counts drop with M gluino Mass rises with M gluino M gluino (GeV) M gluino (GeV) 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 0

21 3τ Analysis: : Accuracy in M M & Mgluino % - 15% (10-30 fb 9% - 6% (10-30 fb -1-1 ) ) 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 1

22 Cosmology, SUSY, WIMP Stau neutralino coannihilation in minimal supergravity (msugra) model Prospects of detection of SUSY in coannihilation region at the LHC Conclusion and Future Tasks 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders

23 Conclusion Signals in the stau-neutralino coannihilation region are studied using msugra model as a bench mark scenario ( M ~ 10 GeV) LHC: Two analyses with visible p Tτ > 0 GeV: τ analysis: Discovery with 10 fb 1 δ M / M ~ 18% using M peak with 5% gluino mass error 3τ analysis: Combine N OS-LS and M peak measurements δ M / M ~13% with 30 fb 1 and 5% gluino mass error δ M/ M ~15% and δm gluino /M gluino ~6% with no gluino mass assumption The analyses can be done for the other models that don t suppress χ 0 production. As a comparison, δ M/ M ~ 10% (500 fb 1 ) at the ILC if we implement a very forward calorimeter to reduce two-photon background. V. Khotilovich, R. Arnowitt, B.Dutta, T. Kamon, Phys. Lett. B618, 18 (005) 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 3

24 Appendix 1: Reference Points m 1/ 1/ = GeV GeV M gluino = 830 GeV 6/15/06 Detection of SUSY Signals in Stau Neutralino Coannihilation at Colliders 4