Dark matter and neutrino masses in the R-parity violating NMSSM

C-C Jean-Louis (1) , G Moreau (1)

1 UP11 - Université Paris-Sud - Paris 11

The R-Parity symmetry Violating (RPV) version of the Next-to-Minimal Supersymmetric Standard Model (NMSSM) is attractive simultaneously with regard to the so-called µ-problem and the accommodation of three-flavor neutrino data at tree level. In this context, we show here that if the Lightest Supersymmetric Particle (LSP) is the gravitino, it possesses a lifetime larger than the age of the universe since its RPV induced decay channels are suppressed by the weak gravitational strength. This conclusion holds if one considers gravitino masses ∼ 10 2 GeV like in supergravity scenarios, and is robust if the lightest pseudoscalar Higgs field is as light as ∼ 10 GeV [ as may occur in the NMSSM ]. For these models predicting in particular an RPV neutrino-photino mixing, the gravitino lifetime exceeds the age of the universe by two orders of magnitude. However, we find that the gravitino cannot constitute a viable dark matter candidate since its too large RPV decay widths would then conflict with the flux data of last indirect detection experiments. The cases of a sneutrino LSP or a neutralino LSP as well as the more promising gauge-mediated supersymmetry breaking scenario are also discussed. Both the one-flavor simplification hypothesis and the realistic scenario of three neutrino flavors are analyzed. We have modified the NMHDECAY program to extend the neutralino mass matrix to the present framework. 1 I Introduction In supersymmetry, the superpartner of the graviton, namely the so-called gravitino, plays a central theoretical role as it constitutes the gauge fermion of supergravity theories [ 1, 2 ]. From the cosmological point of view, the gravitino may be the Lightest Supersymmetric Particle (LSP), depending on the way supersymmetry is broken, and hence constitute a stable dark matter candidate [ 3 ]. Interestingly, one could even assume supersymmetric models where the R-parity symmetry [ 4 ] is violated. Then the gravitino becomes unstable due to new decay channels into Standard Model (SM) particles induced by the R-Parity Violating (RPV) interactions. However, because of the small gravitational interaction and possibly weak RPV couplings, the gravitino lifetime can still exceed the age of the universe (by several orders of magnitude) in the particular case of RPV bilinear terms [ 5 ] remaining thus a realistic dark matter candidate. This scenario can yield a complete cosmological framework also incorporating leptogenesis and nucleosynthesis, as recently shown in Ref. [ 6 ]. In such a scenario, the gravitino decays into SM particles lead to specific signatures in high-energy cosmic rays ; the produced flux of gamma rays and positrons can even account [ 7 ] respectively for the extragalactic component of the excess in the HEAT [ 8 ] data. The decaying gravitinos could also constitute an interpretation (see below) of the exotic positron source recently discovered by the PAMELA Collaboration [ 9 ].

Mots clés: Physical Sciences

C-C Jean-Louis, G Moreau. Dark matter and neutrino masses in the R-parity violating NMSSM. Journal of Physics G: Nuclear and Particle Physics, 2010, 37 (10), pp.105015. ⟨10.1088/0954-3899/37/10/105015⟩. ⟨hal-00600767⟩