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