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Gravitino Dark Matter & R-Parity Violation

Gravitino Dark Matter & R-Parity Violation. M. Lola MEXT-CT-2004-014297 (work with P. Osland and A. Raklev). Prospects for the detection of Dark Matter Spain, September 2007 (ENTAPP). SUSY (MSSM) Dark Matter Candidates. Neutralinos Gravitinos Sneutrinos Axinos

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Gravitino Dark Matter & R-Parity Violation

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  1. Gravitino Dark Matter & R-Parity Violation M. Lola MEXT-CT-2004-014297 (work with P. Osland and A. Raklev) Prospects for the detection of Dark Matter Spain, September 2007 (ENTAPP)

  2. SUSY (MSSM) Dark Matter Candidates • Neutralinos • Gravitinos • Sneutrinos • Axinos • Severe constraints to • allowed parameter space • by combined studies of • BBN and NLSP decays • LEP data • Direct Searches

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

  4. R-violating couplings & LSP decays

  5. Gravitino LSP 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 • 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

  11. Lifetime versus SUSY masses

  12. Max allowed couplings (photon spectra & DM considerations)

  13. Photon Spectra (bilinear R-violation) (Takayama, Yamaguchi) - Non-shaded area compatible with photon spectra - Possible solution to EGRET data for gravitinos ≥ 5 GeV

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

  15. Flavour effects • SM symmetries allow 45 R-violating operators • Lepton & Baryon Parities forbid subsets of them • Lepton Parity:only • Baryon Parity:only If Z3 not flavour-blind, could chose even subsets within

  16. 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

  17. An example (King, Ross) • R-violating couplings of 3rd generation (leading to large radiative decays) naturally higher • Mixing effects important & can affect decays

  18. Conclusions • Significant parameter space where radiative decays dominate over tree-body ones • Lifetime long enough for gravitino DM AND observable R-violation in colliders • NLSP decays easily compatible with BBN • Photon spectrum consistent with measurements • Results sensitive to flavour effects • Probe Flavour Structure of Fundamental Theory

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