1. Little Higgs Model Dark Matter and Its Implications at the LHC Chuan-Ren Chen (NTNU) KIAS-NCTS Joint Workshop 2014 @ High-1 2/9 – 2/15 In collaboration with H-C Tsai, M-C Lee

2. Outline CRC (NTNU) 2 LHT BSM EXP, OBS predictions explanations constraints evidences

3. Higgs boson CRC (NTNU) 3 July 4 2012 @ CERN Higgs boson is discovered, a significant step for understanding of EWSB!

4. Naturalness “Problem” CRC (NTNU) 4

5. 5 “Solution”

6. Little Higgs Model CRC (NTNU) 6

7. Cancellation CRC (NTNU) 7

8. Little Higgs Model CRC (NTNU) 8

9. Little Higgs Model w/ T-parity CRC (NTNU) 9

10. New Particles CRC (NTNU) 10 + SM particles T-parity Even T-parity Odd * parameters: f, k q, k l, λ 1, m h * The lightest T-odd particle is stable dark matter candidate

11. Higgs Pheno. CRC (NTNU) 11 m h (GeV) gg -> h production is always suppressed CRC, Tobe, Yuan, hep-ph/0602211 t, T +, q -

12. Higgs Pheno. CRC (NTNU) 12 gg -> h -> γ γ is suppressed CRC, Tobe, Yuan, hep-ph/0602211 Han, Wang, Yang, Zhu, 1301.0090

13. Dark Matter CRC (NTNU) 13 Some evidences A nonbaryonic, “dark”, charge-neutral object which interacts weakly with normal matters

14. Dark Matter at LHT CRC (NTNU) 14 two possible candidates: heavy photon, T-odd neutrinos dark matter: T-odd partner of photon T-odd partner of neutrino

15. Dark Matter & LHT CRC (NTNU) 15 Ωh2Ωh2 can fit relic density data well. XENON100 HOWEVER Direct search of DM excludes >> Planck+WMAP

16. CRC (NTNU) 16 “heavy neutrino” can NOT be a dark matter KK neutrino in UED model relic density elastic scattering w/ nuclei ~ 2x10-3 pb >> 10-9 pb (current limit) same as SM coupling Servant, Tait, hep-ph/0206071 Servant, Tait, hep-ph/0209262

17. Dark Matter & LHT CRC (NTNU) 17 two possible candidates: heavy photon, T-odd neutrinos dark matter: T-odd partner of photon T-odd partner of neutrino dark matter:

18. Dark Matter & LHT CRC (NTNU) 18 M h = 125 GeV solution? Yes, M AH ≳ M h /2 For heavier A H, co-annihilation is needed!

19. w/ light T-odd leptons CRC (NTNU) 19 M h = 125 GeV are so light! LHC should be able to produce lots of them.

20. light T-odd leptons at LHC 8 TeV CRC (NTNU) 20 f (GeV) dilepton + met lepton + met large production cross section 1 ~ 10 pb met only 100%

21. arbitrary P t (e) (GeV) CRC (NTNU) 21 dilepton + met dilepton + MET search at LHC: slepton pair or chargino pair in SUSY NO Constraint

22. MT2 (GeV) arbitrary CRC (NTNU) 22 dilepton + met dilepton + MET search at LHC: NO Constraint slepton pair or chargino pair in SUSY kill all signals

23. CRC (NTNU) 23 one lepton + MET search at LHC: f (GeV) lepton + met search for W’ one high pt lepton + large MT M T (GeV) M T > 1 TeV kill signal NO constraint from current data

24. light T-odd leptons at LHC 8 TeV CRC (NTNU) 24 arbitrary P t (e) (GeV) f (GeV) dilepton + met lepton + met met only charged lepton is soft! can contribute mono-jet + met signal at LHC soft direct search is very challenging!

25. mono-jet +MET at LHC CRC (NTNU) 25 95% C.L. exclusion 2.8 pb 0.16 pb 0.05 pb 0.02 pb SR3: jet P t > 350 GeV NO constraint from current data

26. CRC (NTNU) 26 w/ light T-odd quarks d, u: 3 down-, 3 up-type todd quarks degenerate case inconsistent with stable heavy quark search at colliders However, ∵ ( M t_ - M AH ) < M W < M top top partner ONLY has 4-body decay channel, decay life time is too long!

27. CRC (NTNU) 27 w/ non-degenerate T-odd quarks projective LUX 2014 can explore M AH up to ~190 GeV, future expts can explore whole parameter space.

28. CRC (NTNU) 28 arbitrary P t (j) (GeV) HUGE production cross section, jet pt is very soft! light T-odd quarks at the LHC contributes to mono-jet BSM search at LHC. dijet + MET search is very challenging!

29. CRC (NTNU) 29 95% C.L. exclusion 2.8 pb 0.16 pb 0.05 pb 0.02 pb f < ~1.4 TeV (M AH < ~ 220 GeV) is DISFAVORED. light T-odd quarks at the LHC

30. CRC (NTNU) 30 Summary  With M h = 125 GeV, co-annihilation is needed for heavier (not ~ M h /2) dark matter in LHT model to explain current universe.  In co-annihilation region, T-odd new heavy fermions should be very light, large production cross section at the LHC.  The small mass difference between dark matter and T-odd leptons makes collider search very difficult.  light T-odd top quark partner decays “too late” -> not allowed by collider searches.  mono-jet + MET from light T-odd quarks + 1jet production at the LHC exceed current limit if M AH < 220 GeV.  Future DM direct search exps can explore whole parameter space.

31. CRC (NTNU) 31 Back UP

32. w/ light T-odd leptons CRC (NTNU) 32 M h = 125 GeV are so light! LHC should be able to produce lots of them. Planck2013 + WMAP-9yrs

33. CRC (NTNU) 33

34. CRC (NTNU) 34

35. EW constraints CRC (NTNU) 35