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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). Current Prevalent Thinking.
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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
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
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
Co-annihilation-Details • LSP-Stau fine tuning: Theme Group 2
Dark Matter Constraints on MSSM Theme Group 2
Constraints at Higher tan beta Theme Group 2
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
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
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
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
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
Upper bound on T-reheat (Kohri et al paper) Theme Group 2
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
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
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
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
Scalar mass runnning to weak scale MSSM Assume scalar masses same at high scale. Theme Group 2
Decay mode of N-fermion • X-exchange gives a decay + anti-quark mode Theme Group 2
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
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
Estimate of Dominant contribution is from W-exchange and is: Gives: Right order. Theme Group 2
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
Releases the SUSY parameter space In NXMSSM Theme Group 2
Direct detection of dark matter Cross section about 10^(- 45) cm^2- In the observable range. Theme Group 2
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
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
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
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
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
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
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
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