The µνSSM solves the µ problem of supersymmetric models and reproduces neutrino data, simply using couplings with right-handed neutrinos ν's. Given that these couplings break explicitly R parity, the gravitino is a natural candidate for decaying dark matter in the µνSSM. In this work we carry out a complete analysis of the detection of µνSSM gravitino dark matter through γ-ray observations. In addition to the two-body decay producing a sharp line, we include in the analysis the three-body decays producing a smooth spectral signature. We perform first a deep exploration of the low-energy parameter space of the µνSSM taking into account that neutrino data must be reproduced. Then, we compare the γ-ray fluxes predicted by the model with Fermi-LAT observations. In particular, with the 95% CL upper limits on the total diffuse extragalactic γ-ray background using 50 months of data, together with the upper limits on line emission from an updated analysis using 69.9 months of data. For standard values of bino and wino masses, gravitinos with masses larger than about 4 GeV, or lifetimes smaller than about 10 28 s, produce too large fluxes and are excluded as dark matter candidates. However, when limiting scenarios with large and close values of the gaugino masses are considered, the constraints turn out to be less stringent, excluding masses larger than 17 GeV and lifetimes smaller than 4 × 10 25 s. c iν c jν c k .(2.1)If the γν channel is not always the dominant gravitino decay channel, the lifetime (3.3) gets

In R-parity violating supersymmetry, the gravitino as the lightest supersymmetric particle (LSP) is a good candidate for dark matter, with the interesting characteristic to be detectable through γ-ray telescopes. We extend this analysis considering an axino next-to-LSP (NLSP) as a coexisting dark matter particle contributing with a detectable signal in the γ-ray spectrum. The analysis is carried out in the framework of the µνSSM, which solves the µ problem reproducing simultaneously neutrino data only with the addition of right-handed neutrinos. We find that important regions of the parameter space can be tested by future MeV-GeV γ-ray telescopes through the line signal coming from the decay of the axino NLSP into photon-neutrino. In a special region, a double-line signal from axino NLSP and gravitino LSP is possible with both contributions detectable. IntroductionGravitino (ψ 3/2 ) LSP or axino (ã) LSP are interesting candidates for dark matter (DM) in the framework of supersymmetry (SUSY). In addition, in SUSY models where there is Rparity violation (RPV) these particles decay with a lifetime longer than the age of the Universe, producing a line signal potentially detectable in γ-ray telescopes. This was analyzed for the gravitino LSP in Refs. [1][2][3][4][5][6][7][8][9][10][11] in the context of bilinear/trilinear RPV models [12], and in Refs. [13][14][15][16] in the 'µ from ν' supersymmetric standard model (µνSSM) [17]. Similar analyses for axino LSP in bilinear/trilinear RPV models were carried out in Refs. [18][19][20][21][22][23][24][25][26][27].In a recent work [28], we analyzed a multicomponent DM scenario with axino LSP and gravitino NLSP. This is a decaying dark matter (DDM) scenario, where the gravitino in addition to the RPV decay channel into photon-neutrino, also undergoes an R-parity conserving (RPC) decay into axion-axino. The analysis was carried out in the framework of the µνSSM, where couplings involving right-handed neutrinos are introduced solving the µ-problem and reproducing simultaneously the neutrino data [17,[29][30][31][32]. A brief discussion and bibliography about the interesting phenomenology associated to the µνSSM, can be found in Ref. [28], where it was shown that significant regions of the parameter space of the model can be probed through a line signal coming from the axino decay. A doubleline signal as smoking gun through the further contribution of the gravitino decay is also possible in a subset of those regions.Here we want to extend our previous work, analyzing the opposite DDM scenario where the gravitino is the LSP and the axino the NLSP. Their masses, although model dependent can be of the same order in several realistic scenarios [33][34][35][36][37] such as in supergravity, and therefore if the axino (gravitino) is the LSP the gravitino (axino) becomes naturally the NLSP. As a consequence, the NLSP decays into the LSP plus an axion. In this not yet explored RPV scenario with gravitino LSP and axino NLSP, we will study its cosmological properties as well as the associa...

R-parity conserving supersymmetric models with right-handed (RH) neutrinos are very appealing since they could naturally explain neutrino physics and also provide a good dark matter (DM) candidate such as the lightest supersymmetric particle (LSP). In this work we consider the next-to-minimal supersymmetric standard model (NMSSM) plus RH neutrino superfields, with effective Majorana masses dynamically generated at the electroweak scale (EW). We perform a scan of the relevant parameter space and study both possible DM candidates: RH sneutrino and neutralino. Especially for the case of RH sneutrino DM we analyse the intimate relation between both candidates to obtain the correct amount of relic density. Besides the well-known resonances, annihilations through scalar quartic couplings and coannihilation mechanisms with all kind of neutralinos, are crucial. Finally, we present the impact of current and future direct and indirect detection experiments on both DM candidates.