Unified TeV Scale Picture of Dark Matter and Baryogenesis

1. Unified TeV Scale Picture of Dark Matter and Baryogenesis R. N. Mohapatra University of Maryland Neutrino Telescope 2007, Venice (K. S. Babu, S. Nasri and R. N. M., hep-ph/0612357) Theme Group 2

2. Current Prevalent Thinking • Dark matter is either LSP of Supersymmetry or lightest Kaluza-Klein Mode in models with extra Dimensions with R~TeV^-1 or perhaps the axion. • Origin of Matter comes from different physics i.e. from Right handed neutrino decay in Seesaw models for neutrinos involving sphalerons. • Unrelated physics Theme Group 2

3. Dark Matter issues in MSSM • Getting the dark matter to fit into MSSM requires fine tuning: (i) Either Bino-Higgsino mixing must be fine tuned to get the right relic density Or (ii) Co-annihilation needed where stau and LSP nearly degenerate (within 20 GeV): requires adjustment of m^2_0. Theme Group 2

4. Co-annihilation-Details • LSP-Stau fine tuning: Theme Group 2

5. Dark Matter Constraints on MSSM Theme Group 2

6. Constraints at Higher tan beta Theme Group 2

7. Perhaps Gravitino Dark matter • Feng Takayama, Rajaraman;, • LSP Gravitino : Another alternative. Escapes direct detection. Similar constraints on MSSM parameter space  Ellis, Olive, Santoso, Spanos Theme Group 2

8. Yet SUSY has its own appeal • It stabilizes the weak scale against radiative corrections; • It leads to unification of gauge couplings. • So is there an extension of MSSM that preserves these good features, broadens the parameter space of MSSM and gives a unified picture of dark matter and origin of matter and neutrino masses? Theme Group 2

9. Neutrino mass extension of MSSM • Add three right handed neutrinos with heavy Majorana masses: • New superpotential: Leads to seesaw formula for neutrino masses: N-decay via leptogenesis leads to baryon asymmetry. Theme Group 2

10. Two points about this model: • Neutrino Observations do not require three RH neutrinos- two are enough.(the so-called 3X2 seesaw) • SUSY seesaw models for leptogenesis have some problems !! Theme Group 2

11. Issues with leptogenesis models • In typical scenarios, often the lightest RH neutrino masses are higher than the reheat temperature after inflation coming from gravitino abundance- posing a problem. (Davidson, Ibarra have a lower bound on MN of GeV ; also true in many interesting SO(10) models. The upper bound on T-reheat for generic TeV scale gravitinos is < GeV ; Kohri, Mori,Yotsuyanagi ) Theme Group 2

12. Upper bound on T-reheat (Kohri et al paper) Theme Group 2

13. New Model • Could it be that only two of the RH neutrinos are heavy and the third one is very light (i.e. TeV scale ) • We show that • (i) such a model can naturally arise from a simple symmetry; • (ii) In this case, one can have a unified TeV scale model for both baryogenesis, neutrino masses and dark matter. Theme Group 2

14. New proposal: XMSSM • 3x2 seesaw model with the third RH neutrino in the TeV scale and decoupled from the neutrino sector: • Plus a pair of color triplets: and with couplings: Impose R-parity symmetry as in MSSM. This simple extension provides a remarkably natural model for dark matter, neutrinos and baryogenesis andhas testable predictions !! Theme Group 2

15. Grand unification of this model • If and belong to full SU(5) multiplets 10 and 10-bar , Coupling unification is not affected. • Only the value of then final value of the GUT coupling changes. - Couplings motivated by SO(10) GUT: , part of 120 Higgs and 16 .16. 120 coupling leads to our interactions. - Discrete symmetry guarantees the third RH N decoupling naturally. (see later) Theme Group 2

16. Baryogenesis and Dark Matter • Mass ordering among particles: , MSUGRA boundary condition implies that Where are the real and imaginary parts of . is stable and is the dark matter candidate. N unstable and gives Theme Group 2

17. Scalar mass runnning to weak scale MSSM Assume scalar masses same at high scale. Theme Group 2

18. Decay mode of N-fermion • X-exchange gives a decay + anti-quark mode Theme Group 2

19. Post Sphaleron Baryogenesis • Babu, R. N. M., Nasri, Phys Rev. Lett. 97, 131301 (2006) • Out of equilibrium condition (one of three Sakharov conditions) satisfied at: For , N goes out of equilibrium below its mass and is ready to generate baryons via its CP and baryon violating decay. Theme Group 2

20. Baryogenesis Diagrams • N decay to 3 quarks and anti-quarks are different due to CKM CP violation and interference between tree and one loop diagrams: (no sphalerons needed) + Theme Group 2

21. Estimate of Dominant contribution is from W-exchange and is: Gives: Right order. Theme Group 2

22. As Scalar dark matter Relic density: Annihilation channel Cross section: For reasonable choice of parameters, cross section is of order of a 0.1 pb and gives the right relic density. Theme Group 2

23. Releases the SUSY parameter space In NXMSSM Theme Group 2

24. Direct detection of dark matter Cross section about 10^(- 45) cm^2- In the observable range. Theme Group 2

25. A crucial experimental test • N-N-bar oscillation: Diagram involves Majorana N exchange • Effective strength: • Will lead to N-N-bar osc via the s-content in neutron. • Transition time expected to be around 10^8 sec. Theme Group 2

26. Present expt situation in N-N-bar Osc. Range accessible to current reactor fluxes: Present limit:ILL experiment: Baldoceolin et al. (1994) New proposal by Y. Kamyshkovet al for an expt at DUSEL GOAL: Figure of merit ~ Theme Group 2

27. Scheme of N-Nbar search experiment at DUSEL  Dedicated small-power TRIGA research reactor with cold neutron moderator  vn ~ 1000 m/s  Vertical shaft ~1000 m deep with diameter ~ 6 m at DUSEL  Large vacuum tube, focusing reflector, Earth magnetic field compensation system  Detector (similar to ILL N-Nbar detector) at the bottom of the shaft (no new technologies) Theme Group 2

28. Tests at LHC--New signatures (i) Monojet + missing energy signals from X-production in pp collision. (Missing energy is N) (ii) 4 jets + missing energy from: Theme Group 2

29. Symmetry giving this model Consider Seesaw model for neutrinos invariant under a that exchanges only RH neutrino field decouples from seesaw formula which now becomes a 3x2 seesaw involving and . Our singlet field then is N= ; N mass can be chosen in the 100 GeV range without affecting neutrino masses or other low energy observations !! Theme Group 2

30. Tests in neutrino mixings • 3X2 seesaw with 2 RH neutrinos: • For normal hierarchy, it necessarily predicts nonzero and of order ; hence testable. - Inverted hierarchy if is zero. Theme Group 2

31. Conclusion • A simple extension of MSSM that gives a unified TeV picture of dark matter and baryogenesis. Less fine tuned than MSSM. Embeddable into a seesaw model for neutrinos. • Opens up MSSM parameter space. • SUSY phenomenology (e.g. LHC signal) very different from MSSM. • Crucial test is Neutron-anti-neutron osc time in the observable range. Theme Group 2

32. Search for Baryon and Lepton Number Violations • International Workshop; • Sept. 20-22, 2007Lawrence Berkeley National Laboratory • U.S.A.Contact Information:Baryon-Lepton Workshop Mailstop 50R5008 Lawrence Berkeley National Laboratory One Cyclotron Road Berkeley, CA 94720-8158 U.S.A. Telephone: 1-510-486-4384 FAX: 1 –510-486-6738Email: CAThompson@lbl.gov • http://inpa.lbl.gov/BLNV/blnv.htm • Sponsored by: National Science Foundation, U.S. Department of Energy, Indiana University, Lawrence Berkeley National Laboratory, University of Maryland, North Carolina State University, University of Tennessee Theme Group 2