Gravitino Dark Matter in R-violating SUSY
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Transcript of Gravitino Dark Matter in R-violating SUSY
Gravitino Dark Matter Gravitino Dark Matter in R-violating SUSYin R-violating SUSY
M. Lola MEXT-CT-2004-014297
Work with N.E.Bomark, P.Osland and A.Raklev
ContentContent
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
In addition to couplings generating fermion masses,
also
- These violate lepton and baryon number
- If simultaneously present, unacceptable p decay
Motivation for R-violating supersymmetry
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
Ways out:
-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 DM in R-violating supersymmetry?Gravitino DM in R-violating supersymmetry?
3-body trilinear R-violating decays3-body trilinear R-violating decays
Chemtob, Moreau
Suppressed by:
- Gravitino vertex (~1/Mp)
-Phase space / fermion masses (for light gravitino and heavy fermions)
2-body bi-linear R-violating decays 2-body bi-linear R-violating decays
Takayama, YamaguchiBuchmuler et al.
Suppressed by:
- Gravitino vertex (~1/Mp)
-Neutralino-neutrino mixing (model dependent)
Radiative 2-body trilinear R-violating decaysRadiative 2-body trilinear R-violating decaysSL, P. Osland, A. Raklev
Suppressed by:
- Gravitino vertex (~1/Mp)
- Loop factors (~ fermion mass)
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)!
Radiative versus 3-body decaysRadiative versus 3-body decays
Couplings ~10^(-4) for consistency with the photon spectrum
NLSP decaysNLSP decays
- No source of suppression other than R-violating couplings
- Decay well before BBN compatible with gravitino DM
R-violating signals: couplings & LSP R-violating signals: couplings & LSP decaysdecays
Ordinary MSSM neutralino coupling
Neutr. Decays to 3 SM particles
R-parity violating coupling
(i.e. Why the top mass so much larger than all others?)
Invariance under symmetry determines mass hierarchies
Link to Flavour Effects Link to Flavour Effects in Fermion Masses 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
Flavour effects Flavour effects
If Z3 not flavour-blind, could chose even subsets within
- SM symmetries allow 45 R-violating operators
- Lepton & Baryon Parities forbid subsets of them
Baryon Parity: only
Lepton Parity: only
Bilinear R-violation allowed
-Bilinear R-violation forbidden-μ term i.e. by Giudice-Masiero mech.-or Hall, Lykken, Weinberg mech.
An example (King, Ross)
R-violating couplings of 3rd generation
(leading to large radiative decays) naturally higher
Neutrinos in R-violating SUSY
1-loop neutrino mass contributions:
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)
Different picture in SUSY!
For all processes at loop level:
For:
ConclusionsConclusions
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