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Register a new userVery light right-handed sneutrino dark matter in the NMSSM
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Very light right-handed (RH) sneutrinos in the Next-to-Minimal Supersymmetric Standard Model can be viable candidates for cold dark matter. We investigate the prospects for their direct detection, addressing their compatibility with the recent signal observed by the CoGeNT detector, and study the implications for Higgs phenomenology. We find that in order to reproduce the correct relic abundance very light RH sneutrinos can annihilate into either a fermion-antifermion pair, very light pseudoscalar Higgses or RH neutrinos. If the main annihilation channel is into fermions, we point out that RH sneutrinos could naturally account for the CoGeNT signal. Furthermore, the lightest Higgs has a very large invisible decay width, and in some cases the second-lightest Higgs too. On the other hand, if the RH sneutrino annihilates mostly into pseudoscalars or RH neutrinos the predictions for direct detection are below the current experimental sensitivities and satisfy the constraints set by CDMS and XENON. We also calculate the gamma ray flux from RH sneutrino annihilation in the Galactic centre, including as an interesting new possibility RH neutrinos in the final state. These are produced through a resonance with the Higgs and the resulting flux can exhibit a significant Breit-Wigner enhancement.
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We consider the production of right-handed (RH) sneutrino dark matter in a model of Dirac neutrino where neutrino Yukawa coupling constants are very small. Dark matter RH sneutrinos are produced by scatterings and decays of thermal particles in the early Universe without reaching thermal equilibrium due to the small Yukawa couplings. We show that not only decays of thermal particles but also the thermal scatterings can be a dominant source as well as non-thermal production in a scenario with light sneutrinos and charged sleptons while other supersymmetric particles are heavy. We also discuss the cosmological implications of this scenario.
In this paper we offer an explanation of the $(g-2)_mu$ discrepancy in a R-parity conserving supersymmetric model with right-handed neutrinos in which the right-handed sneutrino is a viable dark matter candidate. We find that our scenario satisfies all up to date constraints including the latest results on $(g-2)_{mu}$. Since right-handed sneutrinos are singlets, no new contributions for $delta a_{mu}$ with respect to the next to minimal supersymmetric Standard Model are present. However, the possibility to have the right-handed sneutrino as the lightest supersymmetric particle opens new ways to escape Large Hadron Collider and dark matter constraints. We find that dark matter masses within $10 lesssim m_{tilde{ u}_{R}} lesssim 600$ GeV are fully compatible with current experimental constraints. In addition, future dark matter direct detection experiments will be able to explore a sizable portion of the allowed parameter space with $m_{tilde{ u}_{R}} lesssim 300$ GeV, while indirect detection experiments will be able to probe a much smaller fraction within $200 lesssim m_{tilde{ u}_{R}} lesssim 350$ GeV.
We study the possibility of measuring neutrino Yukawa couplings in the Next-to-Minimal Supersymmetric Standard Model with right-handed neutrinos (NMSSMr) when the lightest right-handed sneutrino is the Dark Matter (DM) candidate, by exploiting a `dijet + dilepton + Missing Transverse Energy signature. We show that, contrary to the miminal realisation of Supersymmetry (SUSY), the MSSM, wherein the DM candidate is typically a much heavier (fermionic) neutralino state, this extended model of SUSY offers one with a much lighter (bosonic) state as DM that can then be produced at the next generation of $e^+e^-$ colliders with energies up to 500 GeV or so. The ensuing signal, energing from chargino pair production and subsequent decay, is extremely pure so it also affords one with the possibility of extracting the Yukawa parameters of the (s)neutrino sector. Altogether, our results serve the purpose of motivating searches for light DM signals at such machines, where the DM candidate can have a mass around the electroweak scale.
Very light dark matter is usually taken to consist of uncharged bosons such as axion-like particles or dark photons. Here, we consider the prospect of very light, possibly even sub-eV dark matter carrying a net charge that is (approximately) conserved. By making use of the Affleck-Dine mechanism for its production, we show that a sizable fraction of the energy density can be stored in the asymmetric component. We furthermore argue that there exist regions of parameter space where the energy density contained in symmetric particle-antiparticle pairs without net charge can to some degree be depleted by considering couplings to additional fields. Finally, we make an initial foray into the phenomenology of this scenario by considering the possibility that dark matter is coupled to the visible sector via the Higgs portal.
We consider the possibility of having a MeV right-handed neutrino as a dark matter constituent. The initial reason for this study was the 511 keV spectral line observed by the satellite experiment INTEGRAL: could it be due to an interaction between dark matter and baryons? Independently of this, we find a number of constraints on the assumed right-handed interactions. They arise in particular from the measurements by solar neutrino experiments. We come to the conclusion that such particles interactions are possible, and could reproduce the peculiar angular distribution, but not the rate of the INTEGRAL signal. However, we stress that solar neutrino experiments are susceptible to provide further constraints in the future.
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