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Gravitino Dark Matter in R-violating SUSY: Compatibility with Observable R-Violation & Collider Signals

Explore the possibility of gravitino as dark matter despite broken R-parity in R-violating SUSY models. Investigate decays of gravitino under R-violation along with collider outcomes. Understand the implications of different decay modes including 3-body trilinear, 2-body bi-linear, and radiative decays. Consider the stability, loop factors, and mixing effects affecting the decay processes. Examine the connections to flavor effects in fermion masses and neutrino contributions. Evaluate the prospects for both dark matter presence and detectable R-violation at colliders based on the gravitino decay scenarios.

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Gravitino Dark Matter in R-violating SUSY: Compatibility with Observable R-Violation & Collider Signals

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  1. Gravitino Dark Matter in R-violating SUSY M. Lola MEXT-CT-2004-014297 Work with N.E.Bomark, P.Osland and A.Raklev

  2. Content Dark Matter: Is observable R-violation compatible with SUSY DM? Gravitino decays in R-violating SUSY Couplings & Flavour Effects Link to Lepton flavour violation: R-violation versus MSSM Conclusions

  3. Motivation for R-violating supersymmetry In addition to couplings generating fermion masses, also - These violate lepton and baryon number - If simultaneously present, unacceptable p decay

  4. Ways out: X Either kill all couplings via R-parity (SM: +1 , SUSY: -1) LSP: stable, dark matter candidate Colliders: Missing energy • Or allow subsets by baryon / lepton parities LSP: unstable – lose (?) a dark matter candidate Colliders: Multi-lepton/jet events

  5. Gravitino DM in R-violating supersymmetry? • If LSP a gravitino, its decays very suppressed by Mp • The lighter the gravitino, the longer the lifetime Questions:can gravitinos be DM even with broken R-parity? Can we hope for BOTH DM AND R-violation in colliders? Answer:depends on how gravitinos decay under R-violation

  6. 3-body trilinear R-violating decays Chemtob, Moreau Suppressed by: • Gravitino vertex (~1/Mp) • Phase space / fermion masses (for light gravitino and heavy fermions)

  7. 2-body bi-linear R-violating decays Takayama, Yamaguchi Buchmuler et al. Suppressed by: • Gravitino vertex (~1/Mp) • Neutralino-neutrino mixing (model dependent)

  8. Radiative 2-body trilinear R-violating decays SL, P. Osland, A. Raklev Suppressed by: • Gravitino vertex (~1/Mp) • Loop factors (~ fermion mass)

  9. Radiative decays dominate for: Smaller gravitino masses R and L violation via operators of the 3rd generation Small neutrino-neutralino mixing Large gravitino lifetime (can be DM), due to: Gravitational suppression of its couplings Smallness of R-violating vertices Loop, phase space, or mixing effects Maximum stability (neither radiative nor tree-level decays)!

  10. Radiative versus 3-body decays Couplings ~10^(-4) for consistency with the photon spectrum

  11. NLSP decays - No source of suppression other than R-violating couplings - Decay well before BBN compatible with gravitino DM

  12. R-violating signals: couplings & LSP decays R-parity violating coupling Ordinary MSSM neutralino coupling Neutr. Decays to 3 SM particles

  13. Link to Flavour Effects in Fermion Masses (i.e. Why the top mass so much larger than all others?) Invariance under symmetry determines mass hierarchies • Charges such that only Top-coupling 0 flavour charge XAll others forbidden, only appear in higher orders Higher charge(lower generation) implies larger suppression

  14. Flavour effects • SM symmetries allow 45 R-violating operators • Lepton & Baryon Parities forbid subsets of them Baryon Parity:only Bilinear R-violation allowed • Bilinear R-violation forbidden • μ term i.e. by Giudice-Masiero mech. • or Hall, Lykken, Weinberg mech. Lepton Parity:only If Z3not flavour-blind, could chose even subsets within

  15. An example (King, Ross) R-violating couplings of 3rd generation (leading to large radiative decays) naturally higher

  16. Neutrinos in R-violating SUSY 1-loop neutrino mass contributions:

  17. R-violation: Correlated Rates depending on coupling combinations (A. de Gouvea, S.L, K. Tobe) To be compared with 160 and 0.92 in MSSM (where on shell photon penguin dominates)

  18. Different picture in SUSY!

  19. For all processes at loop level:

  20. For:

  21. Conclusions • R-violating SUSY equally motivated with MSSM • Interesting signals but also strong bounds • Possible to have both gravitino DM AND observable R-violation in colliders • Results sensitive to flavour effects Probe Flavour Structure of Fundamental Theory

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