Sneutrino Dark Matter Research Articles

Comparison of neutralino and sneutrino dark matter in a model with spontaneous CP violation

Supersymmetric extensions to the standard model provide viable dark matter candidates and can introduce additional charge-parity (CP) violation needed for obtaining the observed baryon asymmetry of the universe. We study the possibilities of scalar and neutralino dark matter with spontaneous CP violation in the next-to-minimal supersymmetric standard model with a right-handed neutrino. The observed relic density can be produced both by a neutralino or a right-handed sneutrino as the lightest supersymmetric particle but when CP is violated new annihilation channels become available and in general lower the relic density. We consider collider phenomenology for a number of benchmark points which all satisfy experimental constraints and have either the neutralino or the right-handed sneutrino contribute to the dark matter abundance.

Erratum: Dirac right-handed sneutrino dark matter and its signature in the gamma-ray lines [Phys. Rev. D86, 043515 (2012)

Erratum: Dirac right-handed sneutrino dark matter and its signature in the gamma-ray lines [Phys. Rev. D<b>86</b>, 043515 (2012)

Mixed sneutrino dark matter in light of the 2011 XENON and LHC results

In the context of supersymmetric models in which small Dirac neutrino masses are generated by supersymmetry breaking, a mainly right-handed (RH) mixed sneutrino can be an excellent cold dark matter (DM) candidate. We perform a global analysis of the Minimal Supersymmetric Standard Model (MSSM)+RH neutrino parameter space by means of Markov Chain Monte Carlo sampling. We include all relevant constraints from collider and dark matter searches, paying particular attention to nuclear and astrophysical uncertainties. Two distinct cases can satisfy all constraints: heavy sneutrino DM with mass of order 100 GeV, as well as light sneutrino DM with mass of about 3–6 GeV. We discuss the implications for direct and indirect dark matter searches, as well as for SUSY and Higgs searches at the LHC for both, the light and the heavy sneutrino dark matter case. The light sneutrino case is excluded by the 125–126 GeV Higgs signal.

Phenomenology of light sneutrino dark matter in cMSSM/mSUGRA with inverse seesaw

We study the possibility of a light Dark Matter (DM) within a constrained Minimal Supersymmetric Standard Model (cMSSM) framework augmented by a SM singlet-pair sector to account for the non-zero neutrino masses by inverse seesaw mechanism. Working within a 'hybrid' scenario with the MSSM sector fixed at high scale and the singlet neutrino sector at low scale, we find that, contrary to the case of the usual cMSSM where the neutralino DM cannot be very light, we can have a light sneutrino DM with mass below 100 GeV satisfying all the current experimental constraints from cosmology, collider as well as low-energy experiments. We also note that the supersymmetric inverse seesaw mechanism with sneutrino as the lightest supersymmetric partner can have enhanced same-sign dilepton final states with large missing transverse energy (mET) coming from the gluino- and squark-pair as well as the squark-gluino associated productions and their cascade decay through charginos. We present a collider study for the same-sign dilepton+jets+mET signal in this scenario and propose some distinctions with the usual cMSSM. We also comment on the implications of such a light DM scenario on the invisible decay width of an 125 GeV Higgs boson.

Dirac right-handed sneutrino dark matter and its signature in the gamma-ray lines

We show that a Dirac right-handed scalar neutrino can be weakly interacting massive particle in the neutrinophilic Higgs model. When the additional Higgs fields couple only to the leptonic sector through neutrino Yukawa couplings, the right number of relic density of dark matter can be obtained from thermal freeze-out of the dark matter annihilation into charged leptons and neutrinos. At present, this annihilation is suppressed by the velocity of dark matter. However one-loop annihilation cross section into $\gamma\gamma$ can be larger than that of the helicity suppressed annihilation into fermions, because relevant coupling constants are different. Hence, gamma-ray line signal which might have been observed in the Fermi-LAT is also able to be explained by its annihilation.

Astrophysical Constraints on the Scale of Left-Right Symmetry in Inverse Seesaw Models

We revisit the recently studied supersymmetric gauged inverse seesaw model [1] to incorporate astrophysical constraints on lightest supersymmetric particle (LSP) lifetime such that LSP constitutes the dark matter of the Universe. The authors in [1] considered light sneutrino LSP that can play the role of inelastic dark matter (iDM) such that desired iDM mass splitting and tiny Majorana masses of neutrinos can have a common origin. Here we consider a generalized version of this model without any additional discrete symmetry. We point out that due to spontaneous R-parity(Rp=(-1)3(B-L)+2s) breaking in such generic supersymmetric gauged inverse seesaw models, LSP can not be perfectly stable but decays to standard model particles after non-renormalizable operators allowed by the gauge symmetry are introduced. We show that strong astrophysical constraints on LSP lifetime makes sneutrino dark matter more natural than standard neutralino dark matter. We also show that long-livedness of sneutrino dark matter constrains the left right symmetry breaking scale MR＜104 GeV.

Identifying sneutrino dark matter: Interplay between the LHC and direct search

Under $R$ parity, the lightest supersymmetric particle (LSP) is stable and may serve as a good dark matter candidate. The $R$ parity can be naturally introduced with a gauge origin at the TeV scale. We go over why a TeV scale $B\ensuremath{-}L$ gauge extension of the minimal supersymmetric standard model is one of the most natural, if not demanded, low energy supersymmetric models. In the presence of a TeV scale Abelian gauge symmetry, the (predominantly) right-handed sneutrino LSP can be a good dark matter candidate. Its identification at the LHC is challenging because it does not carry any standard model charge. We show how we can use the correlation between the LHC experiments (dilepton resonance signals) and the direct dark matter search experiments (such as CDMS and XENON) to identify the right-handed sneutrino LSP dark matter in the $B\ensuremath{-}L$ extended minimal supersymmetric standard model.

Light sneutrino dark matter at the LHC

In supersymmetric (SUSY) models with Dirac neutrino masses, a weak-scale trilinear $ {A_{\tilde{\nu }}} $ term that is not proportional to the small neutrino Yukawa couplings can induce a sizable mixing between left and right-handed sneutrinos. The lighters neutrino mass eigenstate can hence become the lightest SUSY particle (LSP) and a viable dark matter candidate. In particular, it can be an excellent candidate for light dark matter with mass below ∼ 10 GeV. Such a light mixed sneutrino LSP has a dramatic effect on SUSY signatures at the LHC, as charginos decay dominantly into the light sneutrino, $ {\tilde{\nu }_1} $ , plus a charged lepton, and neutralinos decay invisibly into $ {\tilde{\nu }_1}\nu $ . We perform a detailed study of the LHC potential to resolve the light sneutrino dark matter scenario by means of three representative benchmark points with different gluino and squark mass hierarchies. We study in particular the determination of the $ {\tilde{\nu }_1} $ mass from cascade decays involving charginos, using the m T2 variable. Moreover, we address measurements of additional invisible sparticles, in our case $ {\tilde{Z}_{1,2}} $ , and the question of discrimination against the MSSM.

Right-handed sneutrino dark matter in U(1)′ seesaw models and its signatures at the LHC

We suggest a real right-handed sneutrino, $\tilde N_1$, as a good dark matter candidate in a supersymmetric $Z'$ model realizing the seesaw mechanism. When the extra gaugino, $\tilde Z'$, is lighter than $Z'$, the thermal freeze-out of the dark matter annihilation to right-handed neutrinos, $ \tilde{N}_1 \tilde{N}_1 \to NN$, through the $t$-channel $\tilde Z'$ exchange is shown to produce the right dark matter density. It is essential to include the decay and inverse decay of $N$ in this process, otherwise $N$ decouples too early and thus dark matter is overproduced. At the LHC, the search for the seesaw mechanism can be made by observing the signatures of $pp \to \tilde Z' \tilde Z' \to NN + \ptmiss$ as $\tilde Z'$ can be copiously produced from the cascade decays of gluinos/squarks, which is complementary to the search of $pp\to Z' \to NN$. This may also open up a promising new channel of finding the Higgs boson from the displaced $N$ decay.

Neutrino mass, sneutrino dark matter and signals of lepton flavor violation in the MRSSM

We study the phenomenology of mixed-sneutrino dark matter in the Minimal R-Symmetric Supersymmetric Standard Model (MRSSM). Mixed sneutrinos fit naturally within the MRSSM, as the smallness (or absence) of neutrino Yukawa couplings singles out sneutrino A-terms as the only ones not automatically forbidden by R-symmetry. We perform a study of randomly generated sneutrino mass matrices and find that (i) the measured value of $\Omega_{DM}$ is well within the range of typical values obtained for the relic abundance of the lightest sneutrino, (ii) with small lepton-number-violating mass terms $m_{nn}^{2} {\tilde n} {\tilde n}$ for the right-handed sneutrinos, random matrices satisfying the $\Omega_{DM}$ constraint have a decent probability of satisfying direct detection constraints, and much of the remaining parameter space will be probed by upcoming experiments, (iii) the $m_{nn}^{2} {\tilde n} {\tilde n}$ terms radiatively generate appropriately small Majorana neutrino masses, with neutrino oscillation data favoring a mostly sterile lightest sneutrino with a dominantly mu/tau-flavored active component, and (iv) a sneutrino LSP with a significant mu component can lead to striking signals of e-mu flavor violation in dilepton invariant-mass distributions at the LHC.

Models of supersymmetric dark matter and their predictions in light of CDMS

We consider the prospects of supersymmetric dark matter in light of the recent results announced by the CDMS experiment. In this Letter, we investigate the status of: (i) neutralino dark matter in models of minimal supergravity, (ii) neutralino dark matter in models with nonuniversal Higgs masses, and (iii) sneutrino dark matter in the U(1)B−L extension of the minimal supersymmetric standard model; and discuss the predictions of these models for the LHC, Tevatron, IceCube and PAMELA.

Neutrino-flavoured sneutrino dark matter

A simple theory of supersymmetric dark matter (DM) naturally linked to neutrino flavour physics is studied. The DM sector comprises a spectrum of mixed lhd-rhd sneutrino states where both the sneutrino flavour structure and mass splittings are determined by the associated neutrino masses and mixings. Prospects for indirect detection from solar capture are good due to a large sneutrino-nucleon cross-section afforded by the inelastic splitting (solar capture limits exclude an explanation of DAMA/LIBRA). We find parameter regions where all heavier states will have decayed, leaving only one flavour mixture of sneutrino as the candidate DM. Such regions have a unique `smoking gun' signature--sneutrino annihilation in the Sun produces a pair of neutrino mass eigenstates free from vacuum oscillations, with the potential for detection at neutrino telescopes through the observation of a hard spectrum of nu_mu and nu_tau (for a normal neutrino hierarchy). Next generation direct detection experiments can explore much of the parameter space through both elastic and inelastic scattering. We show in detail that the observed neutrino masses and mixings can arise as a consequence of supersymmetry breaking effects in the sneutrino DM sector, consistent with all experimental constraints.

Sneutrino dark matter: Symmetry protection and cosmic ray anomalies

We present an $R$-parity conserving model of sneutrino dark matter within a Higgsphilic $U(1{)}^{\ensuremath{'}}$ extension of the minimal supersymmetric standard model. In this theory, the $\ensuremath{\mu}$ parameter and light Dirac neutrino masses are generated naturally upon the breaking of the $U(1{)}^{\ensuremath{'}}$ gauge symmetry. One of the right-handed sneutrinos is the lightest supersymmetric particle. The leptonic and hadronic decays of another sneutrino, taken to be the next-to-lightest superpartner, allow for a natural fit to the recent results reported by the PAMELA experiment. We perform a detailed calculation of the dark matter relic density in this scenario, and show that the model is consistent with the ATIC and Fermi LAT experiments.

Prospects for indirect detection of sneutrino dark matter with IceCube

We investigate the prospects for indirect detection of right-handed sneutrino dark matter at the IceCube neutrino telescope in a $U(1{)}_{B\ensuremath{-}L}$ extension of the minimal supersymmetric standard model. The capture and annihilation of sneutrinos inside the Sun reach equilibrium, and the flux of produced neutrinos is governed by the sneutrino-proton elastic scattering cross section, which has an upper bound of $8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}\text{ }\text{ }\mathrm{pb}$ from the ${Z}^{\ensuremath{'}}$ mass limits in the $B\ensuremath{-}L$ model. Despite the absence of any spin-dependent contribution, the muon event rates predicted by this model can be detected at IceCube since sneutrinos mainly annihilate into leptonic final states by virtue of the fermion $B\ensuremath{-}L$ charges. These subsequently decay to neutrinos with 100% efficiency. The Earth muon event rates are too small to be detected for the standard halo model irrespective of an enhanced sneutrino annihilation cross section that can explain the recent PAMELA data. For modified velocity distributions, the Earth muon events increase substantially and can be greater than the IceCube detection threshold of 12 events ${\mathrm{km}}^{\ensuremath{-}2}\text{ }{\mathrm{yr}}^{\ensuremath{-}1}$. However, this only leads to a mild increase of about 30% for the Sun muon events. The number of muon events from the Sun can be as large as roughly 100 events ${\mathrm{km}}^{\ensuremath{-}2}\text{ }{\mathrm{yr}}^{\ensuremath{-}1}$ for this model.

Right-handed sneutrino dark matter in the NMSSM

We study the properties of the right-handed sneutrino and its viability as a WIMP dark matter candidate in an extended version of the NMSSM in which a right-handed neutrino superfield is included with a coupling to the singlet Higgs in order to provide non-vanishing Majorana neutrino masses. We perform a systematic study of the parameter space, including LEP constraints and experimental bounds on low-energy observables. We investigate the conditions under which the right-handed sneutrino has the correct relic abundance and the dominant annihilation channels. Next we calculate the theoretical predictions for the sneutrino-proton elastic scattering cross section and compare it with present and future experimental sensitivities. We find that sneutrinos with a mass in the range of 5-200 GeV can reproduce the observed dark matter relic density without being excluded by direct dark matter searches and for natural values of the input parameters. Interestingly, the predicted scattering cross section is generally within the reach of future experiments. Finally, we comment on the possible implications for collider physics.

Sneutrino dark matter and the observed anomalies in cosmic rays

We revisit sneutrino dark matter in light of the recent results from the PAMELA and ATIC experiments. In the U(1)B−L extension of the minimal supersymmetric standard model the right-handed sneutrino is a natural candidate for thermal dark matter. Sneutrino annihilation at the present time can be considerably enhanced due to the exchange of the lightest field in the Higgs sector that breaks U(1)B−L. The annihilation mainly produces taus (or muons) by the virtue of B−L charges. A sneutrino mass in the 1–2 TeV range provides a good fit to the PAMELA data and a reasonable fit to the ATIC data. Within this mass range the sneutrino–nucleon elastic scattering cross section is 10−11–10−9 pb, which might be probed by upcoming and future direct detection experiments. In addition, if (at least) one of the neutrinos is dominantly a Dirac fermion, the sneutrino can provide a unified picture of dark matter and inflation.

Cosmic rays from leptonic dark matter

If dark matter possesses a lepton number, it is natural to expect the dark-matter annihilation and/or decay mainly produces the standard model leptons, while negligible amount of the antiproton is produced. To illustrate such a simple idea, we consider a scenario that a right-handed sneutrino dark matter decays into the standard model particles through tiny R-parity violating interactions. Interestingly enough, charged leptons as well as neutrinos are directly produced, and they can lead to a sharp peak in the predicted positron fraction. Moreover, the decay of the right-handed sneutrino also generates diffuse continuum gamma rays which may account for the excess observed by EGRET, while the primary antiproton flux can be suppressed. Those predictions on the cosmic-ray fluxes of the positrons, gamma rays and antiprotons will be tested by the PAMELA and FGST observatories.

Right-handed sneutrino as thermal dark matter

We study an extension of the minimal supersymmetric standard model with a singlet supermultiplet $S$ with coupling $S{H}_{1}{H}_{2}$ in order to solve the $\ensuremath{\mu}$ problem as in the next-to-minimal supersymmetric standard model, and right-handed neutrino supermultiplets $N$ with couplings $SNN$ in order to generate dynamically electroweak-scale Majorana masses. We show how in this model a purely right-handed sneutrino can be a viable candidate for cold dark matter in the Universe. Through the direct coupling to the singlet, the sneutrino cannot only be thermal relic dark matter but also have a large enough scattering cross section with nuclei to detect it directly in the near future, in contrast with most other right-handed sneutrino dark matter models.

Thermal right-handed sneutrino dark matter in theFD-term model of hybrid inflation

We compute the relic abundance of the right-handed sneutrinos in the supersymmetric F-D-term model of hybrid inflation. As well as providing a natural solution to the mu- and gravitino overabundance problems, the F-D-term model offers a new viable candidate to account for the cold dark matter in the Universe: the lightest right-handed sneutrino. In particular, the F-D-term model predicts a new quartic coupling of purely right-handed sneutrinos to the Higgs doublets that thermalizes the sneutrinos and makes them annihilate sufficiently fast to a level compatible with the current cosmic microwave background data. We analyze this scenario in detail and identify favourable regions of the parameter space within the framework of minimal supergravity, for which the lightest right-handed sneutrino becomes the thermal dark matter, in agreement with WMAP observations of cosmological inflation. Constraints derived from direct dark matter searches experiments are presented.

Right-handed sneutrino condensate cold dark matter and the baryon-to-dark matterratio

The similarity of the observed densities of baryons and cold dark matter suggests thatthey have a common or related origin. This can be understood in the context ofthe MSSM with right-handed (RH) sneutrinos if cold dark matter is due to ad = 4 flat direction condensate of very weakly coupled RH sneutrino LSPs andthe baryon asymmetry is generated by Affleck–Dine leptogenesis along thed = 4 (HuL)2 flatdirection. The correct density of RH sneutrino dark matter is obtained if the reheating temperature is in therange 106–108 GeV. A cold dark matter isocurvature perturbation close to presentobservational bounds is likely in the case of inflation driven by aD-term orby an F-term with suppressed Hubble corrections to theA-terms. An observable baryon isocurvature perturbation is also possible in the case ofD-term inflation models.