A new mechanism for large boost factor from DM conversions

1. A new mechanism for large boost factor from DM conversions Yu-Feng Zhou collaborators: Ze-Peng Liu, Yue-Liang Wu Institute of theoretical physics (ITP), Chinese Academy of Sciences (CAS). work in progress

2. Outline • Introduction • The recent DM search results and implications • The stability of DM and the CP symmetry • The boost factor problem • A new source of boost factor from late time DM conversions • Numerical results and simple models • Summary

3. Evidences of DM from gravitational effects Gravitational curves Large scale structure Bullet cluster Strong lensing CMB Weak lensing

4. Searching for non-gravitational effects balloon Cherenkov telescope Satellite underground collider

5. Hint of DM ? Positron fraction Nature 458, 607 (2009) PAMELA if interpreted as DM signal • Large annihilation cross section now, boost factor problem. • Sommerfeld enhancement ? • Resonance enhancement ? • Non-thermal DM ? • DM may slightly decay ? • Mainly annihilation/decay into leptons, not quarks • Light final states <1GeV ? • Leptophilic interaction ? background

6. Hint of DM? electrons plus positrons ATIC/PPB-BETS • Excess in the total flux • peak at ~600 GeV • rapid drop below 800GeV Fermi LAT • Spectrum harder than expected background with power index around ~3. Large boost factor still needed Nature, 456, 2008,362-365 Phys.Rev.Lett.102:181101,2009

7. Under ground experiments Hint on light DM ? DAMA CoGent CDMS-II J. Li’s Talk CDMS-II, arXiv:0912.3592 CoGeNT, arXiv:1002.4703, Xenon100, arXiv:1005.0380

8. Symmetries for DM stability • Symmetries important for keeping particle stable electron:U(1) em. symmetry, lightest charged particle proton: U(1) B-L symmetry, lightest baryon • DM are often protected by symmetries Well known examples SUSY: R-parity, UED: KK-parity, Little Higgs: T-parity

9. DM in minimal extensions of the SM Simplest extension to SM: scalar DM P and CP broken SM Scalar DM Silveira, Zee, 1985 McDondald, 1994, Burgess, Pospelov & Veldhuis, 2001 Barger,Langacker, KcCaskey, 2007 Shafi, Okada, 2009 He,Li, Tsai, 2007,2009 Extension to LRM with scalar DM auto stable ! P and CP symmetry Left-Right Model Scalar DM Guo, Wang, Wu, YFZ, Zhuang,PRD79,055015(2009);

10. A LR model with spontaneous P and CP violation • Gauge interaction: Flavor contents • Two bi-doublet required for spontaneous CP violation. • Only one bi-doublet cannot give the correct CP phase P- and CP-transformations

11. If P and CP are only broken spontaneously After EWSB • S_D does not participate gauge Interactions, as it is gauge singlet • Require that S_D does not develop a nonzero VEV  S_D a DM particle

12. Relic density and direct detection • Parameter space from relic density • Prediction for direct detection rate one bi-doublet case two bi-doublet case Guo, Wang, Wu, YFZ, Zhuang,PRD79,055015(2009);

13. A special case: large Yukawa couplings to light quarks • Relic density is dominated by heavy quark, not light ones • DM-nucleus scattering is sensitive to light quark Yukawa couplings

14. DM decay through soft C-breaking terms • Including soft C-breaking term Guo, Wu, YFZ, PRD81,075014 (2010) dominant part: C- and P-even tiny part: C-odd

15. Guo, Wu, YFZ, PRD81,075014 (2010) mass parameters Consider 3 cases with final states dominated by different lepton flavor PAMELA • Explain PAMELA data well. for all type of lepton final states. • mu/tau final states favored by Fermi • tau-lepton final states predict High neutrino-induced muon flux. Fermi

16. Predictions for up-going muon flux Triplets couple to neutrinos and charged-leptons with the same strength Guo, Wu, YFZ, PRD81,075014 (2010) up-going muon flux can reach the current SK bound

17. Diffuse gamma-rays LH-III case SH-III case Inverse Compton scattering (ICS) ICS ICS FSI FSI VIB VIB Final state radiation (FSI) Virtual internal bremsstrahlung (VIB) ICS ICS FSI FSI VIB VIB Guo, Wu, YFZ, PRD81,075014 (2010)

18. The std. WIMP annihilation cross section is too small to account for the PAMELA/Fermi data Positron flux Boost factor The boost factor problem Bergstrom, Edsjo, Zaharijas, PRL103,031103,09’

19. Possible origins of boost factor Boot factor for DM annihilation • Local clumps Via Lactea II: in subhalo? B~ 4-15, • Temperature-dependent ann. cross section • Sommerfeld enhancement • Resonance enhancement Diemand, et al, 0805.1244, Nature Sommerfeld, Ann. Phy 403, 257 (1931). J. Hisano, S. Matsumoto and M. M. Nojiri, Phys. Rev. D 67 (2003) Phys. Rev. Lett. 92, 031303 (2004) Feldman, Liu, Nath, 09 Ibe, Murayama, Yanagida, 09 Guo, Wu, 09 Other mechanism: DM decay, non-thermal DM ….

20. Constraints from relic density J. L. Feng, M. Kaplinghat and H. B. Yu, Phys. Rev. Lett. 104, 151301 (2010) arXiv:1005.4678 • Refined analysis at freeze-out • Cut-off of resonance, recoupling • Force-carrier production & • decay rates • Kinetic decoupling • Self-interaction efficiency, • non-thermality • Other constraints • Halo shape • CMB, protohalo J. Zavala, M. Vogelsberger and S. D. M. White, Phys. Rev. D 81, 083502 (2010) M. Kamionkowski and S. Profumo, Phys. Rev. Lett. 101,261301 (2008)

21. Large boost requires Large annihilation cross section Still the correct relic density Impossible for one-component thermal DM? Multi-component DM Models with hidden sectors naturally have multi-DM DM may have SUSY partners Neutrinos are already (tiny) part of DM boost from simply mixed thermal multi-DM ? (No) Boost factor from interacting multi-DM ?(Possible) Boost factor in multi-component DM models(with temperature independent ann. cross sections) For thermal relic large cross section Always reduces signal

22. Thermal evolution of interacting multi-DM The components can be converted • Thermal evolution for interacting DM • Use common variable

23. Nature of the DM conversion • The role of large • Keep the components in chemical equilibrium for a long time • Convert the heavy DM into the light

24. The total density • The total density at equilibrium • The total density evolves like an ordinary WIMP at early time Nontrivial z-dependence in effective cross section

25. Two component case • The effective cross section • A interesting limit • Approximate form

26. Thermal evolution for two-component DM • Thermal equilibrium • Departure from thermal equilibrium but still in chemical Equilibrium • Late time DM conversion at large z • Slow conversion characterized by r(z) • Crossing point • Freeze-out after Freeze-out condition Y1(z) increased eventually

27. The condition for a large boost factor • Large internal degree of freedom of Y2: • Small mass difference: • Cross sections satisfy: • Approximate expression for the boost factor

28. Numerical results • Equilibrium • Equilibrium density Y2

29. Numerical results • Equilibrium • Equilibrium density Y2 • Equilibrium density Y1

30. Numerical results • Equilibrium • Equilibrium density Y2 • Equilibrium density Y1 • If no conversion • Decoupling of Y2

31. Numerical results • Equilibrium • Equilibrium density Y2 • Equilibrium density Y1 • If no conversion • Decoupling of Y2 • Decoupling of Y1

32. Numerical results • Equilibrium • Equilibrium density Y2 • Equilibrium density Y1 • If no conversion • Decoupling of Y2 • Decoupling of Y1 • With conversion • Evolution of Y2

33. Numerical results • Equilibrium • Equilibrium density Y2 • Equilibrium density Y1 • If no conversion • Decoupling of Y2 • Decoupling of Y1 • With conversion • Evolution of Y2 • Evolution of Y1

34. Numerical results • Equilibrium • Equilibrium density Y2 • Equilibrium density Y1 • If no conversion • Decoupling of Y2 • Decoupling of Y1 • With conversion • Evolution of Y2 • Evolution of Y1 • Evolution of Y1+Y2

35. Numerical results B vs mass difference B vs relative cross sections

36. A generic model Add to the SM

37. Cross sections

38. Parameter set (off resonance) Cross sections Boost factors Parameters and boost factor • Parameter set (near resonance)

39. Summary • In multi-DM models, DM conversion can significantly modify the thermal evolution of each DM component. • The relic density of the DM component may not always inversely proportional to it’s annihilation cross section. Through conversions from heavier DM components, the relic density of light DM can be enhanced, leading to large boost factors. • The boost is mostly temperature independent. For generic models with large conversion rate the boost fact can reach ~100-1000. Thank You !

40. backups

41. Diffusion eq. Positron signals Sources from DM decay Background

42. The Sommerfeld enhancement N. Arkani-Hamed, et al, Phys. Rev. D 79, 015014(2009) Sommerfeld enhancement factor S:

43. International Coordinators: Shafi, Qaisar (Delaware), Aprile, Elena (Columbia U.) Wang, Tsz-king Henry(IOP,) Wefel, John (Louisiana State U.) Matsumoto, Shigeki (IPMU), Su, Shu-Fang (Arizona U.) Geng, Chao-Qiang ( NCTS ), Local Coordinators: Bi, Xiao-Jun (IHEP) Ni,Kai-Xuan (SJTU) Yang, Chang-Geng (IHEP) Yue, Qian (Tsinghua U.) Zhou, Yu-Feng (ITP ) KITPC 2011 programDark matter and new physics Sept. 21-Nov. 06, 2011 (7-week)

44. Numerical results Large boost factor if mass diff. is small With conversion no conversion B~1000 B~150

45. The Sommerfeld effect A. Sommerfeld, Annalen der Physik 403, 257 (1931). J. Hisano, S. Matsumoto and M. M. Nojiri, Phys. Rev. D 67 (2003) Phys. Rev. Lett. 92, 031303 (2004)

46. Constraints from relic density J. L. Feng, M. Kaplinghat and H. B. Yu, Phys. Rev. Lett. 104, 151301 (2010) Irreducible process

47. Ackerman,buckley,Carroll, Kamonkowski 08’ Feng, Tu, Yu 08’, Feng, Kaplinghat, Tu, Yu 09’ Foot etal. 10’ Pospelov, Ritz, voloshin 07’ Gpoalakrishnal,Jung,Wells 08’ Gpoalakrishnal,Lee,Wells 08’ Mambrini 10’ Symmetries for hidden sector DM • Hidden sector U(1) symmetry exact U(1) Broken U(1): a massive Z’, a scalar • Hidden custodial symmetry vector DM Custodial symmetry SU(2)_C keep vector bosons stable SM Hidden sector DM Symmetry not shared wiht SM sector Higgs portal kinetic mixing Hambye 08’