Collider Constraints On Low Mass WIMP

1. Collider Constraints On Low Mass WIMP Haipeng An, University of Maryland Shanghai Jiao Tong University In collaboration with Xiangdong Ji, Lian-Tao Wang 中国科学院理论物理研究所冬季研讨会 -- 暗物质与重子物质起源2010.12.13-15

2. Outlines • Experiments; • Possible Interactions Between WIMP and SM particles; • Tevatron Constraints on the parameter space; • Tevatron Constraints on direct detection cross section; • Relic abundance; • Flavor changing neutral currents.

3. Direct Detection Experiments • CoGeNT Observed excess could be explained by WIMP signal with mass in the range of 6~11 GeV. Cross section 10-41~10-40 cm2. • CRESST-II CaWO4 32 events cannot be explained by known background. Can be explained by WIMP with mass around smaller than 15 GeV. And the cross section is about a few times 10-41 cm2 . • XENON100 Poisson smearing, null-result. New XENON100 result with a detecting power ten times larger will be published soon.

4. 15 GeV 5 GeV Direct Detection Experiments

5. Relic abundance • Thermal freezing-out • Thermal freezing-in (Multi-components) • SuperWIMP • Asymmetric dark matter • ... ... • Using relic abundance as a lower bound

6. Study the properties of large extra dimension models Tevatron Constraints • Leading jet ET > 80 GeV; • pT of second jet < 30 GeV; • Vetoing any third jet with ET > 20 GeV; • Missing ET > 80 GeV. • 1 fb-1 of data from Tevatron, 8449 events observed. • SM background 8663±332; • Hard process is good enough. Goodman, Ibe, Rajaraman, Shepherd, Tait, Yu (1005.1286, 1008.1783); Bai, Fox, Harnik (1005.3797). Aaltonen et al. [CDF Collaboration], PRL 101, 181602, 2008.

7. Contact Operator • In the work by Irvine group, effective four particle interaction is used to study the Tevatron constraint and LHC prediction. • However, in Tevatron the center-of-mass energy of the proton-anti-proton pair is 1.96 TeV, therefore if the mass of the intermediate particle is around a few hundred GeV, the interaction cannot be considered as a contact interaction. • Furthermore, if the result of CoGeNT is induced by elastic SI, MI collision between dark matter and nuclei, the effective coupling can be written as

8. Z-boson mediator • MDM << MZ. • Coupling between MZ and DM should be smaller than 0.02. • Relic abundance is too large.

9. Standard Model Higgs • If dark matter is a fermion, since the Yukawa couplings to light quarks are small. The relic abundance is too large. • However, if dark matter is a scalar, the relic abundance constraint can be avoided. (Xiao-gang’s talk)

10. Possible Interactions • SM Higgs + Scalar dark matter is still possible. • Dark matter: Complex Scalar (Φ), Dirac Fermion (χ). • Mediator: Scalar (H’), Vector (Z’). • T-channel annihilation, colored particle. (Will be study elsewhere). • More complicated cases …

11. gD=0.5, 1, 2, 3, 5 MZ’ = 5 GeV M* Vector Mediator with Fermion WIMP

12. gD=0.5, 1, 2, 3, 5 430 GeV 450 GeV 480 GeV 500 GeV Tevatron constraint Cannot saturate Tevatron bound in perturbative region Contact operator case Vector Mediator with Fermion WIMP

13. 15 GeV 5 GeV Vector mediator Scalar dark matter Scalar mediator fermion dark matter Vector mediator fermion dark matter Vector Mediator with Fermion WIMP

14. Dipole Interaction • Perturbatively • Non-perturbatively

15. Dipole Interaction

16. Quark EDM (QCD sum rules) Pospelov, Ritz PRD 63, 073015 Direct detection cross section • Hadronic matrix elements • Electric Dipole coupling Belanger, Boudjema, Pukhov, Semenov “MicrOMEGAs2.2” (0803.2360). Fan, Reece, Wang (1008.1591).

17. Direct detection cross section • Power counting SI: Spin-independent ~ O(1) SD: Spin-dependent ~ O(10-3~10-4) MI: Momentum-indenpent ~ O(1) MD: Momentum-dependent ~ O(10-6)

18. Magnetic Interaction

19. Tevatron Constraints on Direct Detection Cross Section MZ’ < M* constraint on gZ’ does not depend on gD. σ ∝ gD- 2 gD=1 gD=0.5

20. Tevatron Constraints on Direct Detection Cross Section MDM=5 GeV MDM=15 GeV

21. Relic Abundance • Ωh2 ≈ 0.1pb / σ. • We choose gD=1 as a benchmark scenario to study the relic abundance. • During the thermal annihilation MDM/T ≈ 20, during this era, dark matter particles are non-relativistic. • For some operators the annihilation cross section are suppressed by v2. JPC Group state of spin-1/2 fermion anti-fermion pair can only be 0-+ and 1--

22. 5 GeV, 7 GeV, 10 GeV, 12 GeV, 15 GeV Tevatron Constraints on Relic Abundance (MZ’>80 GeV)

23. Factor of 10 Tevatron Constraints on Relic Abundance (MZ’>80 GeV) σ ∝ MDM2 NR suppression

24. Factor of 102 Dipole coupling (MZ’>80 GeV) σ ∝ MDM4

25. Scalar Mediator with Fermion DM

26. Vector Mediator and Scalar DM

27. Scalar Mediator with Scalar Dark Matter (MZ’>80 GeV)

28. Different Energy Scales • Collider: In the case of Mmediator < M*, the mediator is produced on-shell and then decay to DM-anti-DM pair, the energy flowing into the DM anti-DM pair is just Mmediator. • Thermal annihilation: The energy flowing into Z’ is 2MDM. Therefore, if the coupling is dimensional -1, like the dipole interaction case, the collider constraint on the thermal annihilation cross section is enhanced by a factor of (MDM/MZ’)2. Whereas, if the coupling is dimension 1, like the scalar mediator with scalar dark matter case, the constraint on thermal annihilation cross section is weakened by a factor of (MDM/MH’)2.

29. LEP II constraints on Z’ coupling to leptons • If the MZ’ > 209 GeV, in the case of B-xL model, the constraint on x is that MZ’/gZ’ > 6.2x TeV. • If MZ’ < 209 GeV, the coupling between Z’ and leptons should be smaller than 10-2. • In the case of gD=1, MZ’=80 GeV, MD=15 GeV, ge=gmu=gtau=0.01, the relic abundance is Ωh2 = 0.58, which is about 5 times larger than the observed one. Since Ωh2 ~ 0.1pb / σ, the contribution of the annihilation cross section from hadronic sector needs to be at least 5 time larger than from the lepton sector. • If gD gets larger, the constraint from thermal relic abundance is weakened.

30. Possible Interactions at gD=1, Mmediator>80 GeV • Other interactions are either suppressed by velocity or suppressed by MD / MZ’. • Except for the case of scalar mediator and scalar DM, the allowed cases are also stringently constrained.

31. Flavor Changing Neutral Current • Quark rotation matrices can induce tree-level FCNC. In the case of new scalar mediator. • If the vector mediator is non-universally coupled to quarks, it also suffers from tree-level FCNC constraints.

32. Summary • We consider elastic, single component, dark matter, specifically, complex scalar and Dirac fermion. The mediator we can considered are vector and real scalar. • In our study, the interaction is conducting by a propagating particle instead of a contact operator. • Collider constraints on the direct detection and relic abundance is studied especially for heavy mediator cases (M>80 GeV, gD=1).