Presentation on theme: "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,"— Presentation transcript:
Gravitino Dark Matter & R-Parity Violation M. Lola MEXT-CT (work with P. Osland and A. Raklev) Prospects for the detection of Dark Matter Spain, September 2007 (ENTAPP)
Neutralinos Gravitinos Sneutrinos Axinos Severe constraints to allowed parameter space by combined studies of BBN and NLSP decays LEP data Direct Searches SUSY (MSSM) Dark Matter Candidates
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 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 Gravitino LSP in R-violating supersymmetry?
3-body trilinear R-violating decays Chemtob, Moreau Suppressed by: - Gravitino vertex (~1/Mp) -Phase space / fermion masses (for light gravitino and heavy fermions)
Radiative decays dominate for: Smaller gravitino masses R and L violation via operators of the 3 rd 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)!
Radiative versus 3-body decays
Lifetime versus SUSY masses
Max allowed couplings (photon spectra & DM considerations)
Photon Spectra (bilinear R-violation) - Non-shaded area compatible with photon spectra - Possible solution to EGRET data for gravitinos ≥ 5 GeV (Takayama, Yamaguchi)
NLSP decays - No source of suppression other than R-violating couplings - Decay well before BBN compatible with gravitino DM
-SM symmetries allow 45 R-violating operators - Lepton & Baryon Parities forbid subsets of them Lepton Parity: only Baryon Parity: only Flavour effects If Z3 not flavour-blind, could chose even subsets within
(i.e. Why the top mass so much larger than all others?) Invariance under symmetry determines mass hierarchies Link to Flavour Effects in Fermion Masses Charges such that only Top-coupling 0 flavour charge X All others forbidden, only appear in higher orders Higher charge (lower generation) implies larger suppression
An example (King, Ross) R-violating couplings of 3 rd generation (leading to large radiative decays) naturally higher Mixing effects important & can affect decays
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