We discuss 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 model offers the lightest right-handed sneutrino as a candidate for thermal dark matter. 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 discuss this scenario and identify favourable regions of the parameter space within mSUGRA.
The relic abundance of the lightest right-handed sneutrino dark matter in supersymmetric B-L extension of the standard model is revisited. We argue that it can form a bound state through the exchange of light B-L Higgs boson and a large non-perturbative Sommerfeld effect is obtained. We emphasized that with this effect the relic abundance of right-handed sneutrino will lie within the observational limits and the right-handed sneutrino will remain a viable dark matter candidate of mass order up to 1.5 TeV.
We consider an extension of nuMSSM with an extra U(1) that realizes D-term inflation driven by the right-handed sneutrino. Non-renormalizable terms in the Kahler potential and the superpotential are considered, the latter controlled by a suitable discrete R-symmetry. We find that, for subplanckian inflaton values, the predictions of inflationary parameters are compatible with observations, establishing the right-handed sneutrino driven inflation as a viable scenario.
We argue that the superpartner of the Dirac right-handed neutrino is a prime candidate for dark matter created from a 'mattergenesis' mechanism. We show that due to the smallness of the Yukawa couplings, a right-handed sneutrino density created in the early Universe would not be erased by annihilations, which remain out of thermal equilibrium. It would also not be drowned by a later, additional production of right-handed sneutrinos, as the relic density of the non-thermal right-handed sneutrinos is found to be generally negligible compared to the observed dark matter density. Mild constraints …
Right-handed neutrinos offer us the possibility of accommodating neutrino masses. In a supersymmetric model, this implies the existence of right-handed sneutrinos. Right-handed sneutrinos are expected to be as light as other supersymmetric particles if the neutrinos are Dirac fermions, or if the lepton-number breaking scale is at (or below) the supersymmetry (SUSY) breaking scale, assumed to be around the electroweak scale. Depending on the mechanism of SUSY breaking, the lightest right-handed sneutrino may be the lightest supersymmetric particle (LSP). We consider the unique hadron collider s…
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 microwav…
In this paper, we explore the parameter space for a Right-Handed (RH) sneutrino curvaton that can generate large non-Gaussianity without assuming any particular inflation sector. The mass of the RH sneutrino is suggested from a discussion on the initial condition of the curvaton field. It is shown that a small Yukawa coupling is generally required for a successful RH sneutrino curvaton. However, the Yukawa coupling can be larger if we consider the braneworld scenario. Some general discussion about the spectral index in curvaton scenario is also provided.
We consider a $U(1)'$ extended supersymmetric model with a right-handed neutrino superfield which can generate light neutrino mass by Type I seesaw mechanism. The lighter superpartner of the right-handed neutrino could be the scalar dark matter. These right-handed sneutrinos can come from the decay of $\tilde{Z'}$, superpartner of the extra gauge boson $Z'$. Left-right handed sneutrino mixings affect their decays further, giving rise to displaced "lepton flavour violating" signatures. A wino-like chargino NLSP (next to lightest supersymmetric particle) creates even more interesting decay topol…
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 t…
In this work we show that the supersymmetric economical SU(3)_C X SU(3)_L X U(1)_X (3-3-1) gauge model has a realistic candidate for self-interacting dark matter. In the model under consideration, the right-handed sneutrino is in bottom of the triplet, which is a singlet of the Standard Model SU(2)_L group. In addition, the right-handed sneutrino is the lightest slepton. By these properties, the right-handed sneutrino is weakly interacting with the Standard Model and stable without introduction of extra symmetry. From the Spergel-Steinhardt condition, the typical mass limit $\leq 10 $ MeV is d…
We explore right-handed sneutrino-antisneutrino mixing in a TeV scale B-L extension of the Minimal Supersymmetric Standard Model (MSSM), (B-L)SSM, where a type I seesaw mechanism of light neutrino mass generation is naturally implemented. The constraints imposed on the mass splitting between heavy right-handed sneutrino and the corresponding antisneutrino by the experimental limits set on the light neutrino masses are investigated. We also study direct pair production of such right-handed sneutrinos at the Large Hadron Collider (LHC) and its decay modes, emphasising that their decay into same-…
We consider supersymmetric model with right-handed (s)neutrinos where the neutrino masses are purely Dirac-type. We discuss cosmology based on such a scenario, paying particular attention to the case that the gravitino is the lightest superparticles (LSP) while the right-handed sneutrino is the next-LSP. It will be shown that the cosmological constraints on the gravitino-LSP scenario (in particular, those from the big-bang nucleosynthesis) are drastically relaxed in such a case. We will also consider the implication of such scenario to the structure formation.
We propose a scenario for realizing inflation in the framework of supersymmetric B-L extension of the Standard Model. We find that one of the associated right-handed sneutrinos (the superpartner of the Standard Model singlet fermion) can provide a new non-trivial inflationary trajectory at tree level (therefore breaking B-L during inflation). As soon as the inflation ends, the right-handed sneutrino falls into the supersymmetric vacuum, with a vanishing vacuum expectation value, so that B-L symmetry is restored. In this class of models, the B-L gauge symmetry will be radiatively broken at a Te…
We consider cosmological implications of supersymmetric models with right-handed (s)neutrinos where the neutrino masses are purely Dirac-type. We pay particular attention to the case where gravitino is the lightest superparticle while one of the right-handed sneutrinos is next-to-the-lightest superparticle. We study constraints from big-bang nuleosynthesis and show that the constraints could be relaxed compared to the case without right-handed sneutrinos. As a result, the gravitino-dark-matter scenario becomes viable with relatively large value of the gravitino mass. We also discuss constraint…
We show that mostly right-handed Dirac sneutrino is a viable supersymmetric light dark matter candidate. While the Dirac sneutrino scattering with nuclei is dominantly through the $Z$ boson exchange and is stringently constrained by the invisible decay width of $Z$ boson, it is possible to realize a large enough cross section with nucleon to account for possible signals observed at direct dark matter searches such as CDMS II-Si or CoGeNT. Even if the XENON100 limit is taken into account, a small part of signal region for CDMS II-Si events remains outside the excluded region by XENON100.
The recent intriguing measurements of $R_{K}$ and $R_{K^*}$ are important hints of new physics that violates lepton universality. We analyze the semileptonic decays $b \to s \ell^+ \ell^-$ in the framework of the $B-L$ extension of Minimal Supersymmetric Standard Model (MSSM) with Inverse Seesaw (BLSSMIS). A salient feature of this model is that one of the right-handed sneutrino can be light and the neutrino Yukawa couplings are of order one. We show that the box diagram mediated by right-handed sneutrino, higgsino-like chargino, and light stop can account simultaneously for both $R_{K}$ and $…
We propose an alternative mechanism for leptogenesis at the electroweak scale, through the decays of a left-handed sneutrino. This scenario may be realized in supersymmetric models with non-zero Majorana masses for the neutrino superfield that lead to mixing and mass splitting between the left-handed sneutrino and the corresponding antisneutrino. Soft supersymmetry breaking provides new sources of CP violation in sneutrino-antisneutrino mixing that can generate a lepton asymmetry in decays of the left-handed sneutrino. We show how the three Sakharov conditions for generating the observed baryo…
Supersymmetry relates neutrinos with their superpartners, sneutrinos. Unlike neutrinos, sneutrinos may decay visibly in colliders. We discuss how we could get information from neutrino Yukawa couplings in the NMSSM extended with right-handed neutrinos, if the right-handed sneutrinos are within the reach of the colliders.
The invisible signals of right-handed sneutrino decays originating from a Z' are analysed at the Large Hadron Collider. The possibility of accessing these events helps disentangling the B-L extension of Minimal Supersymmetric Standard Model from more popular scenarios of Supersymmetry. We assess the scope of the CERN machine in establishing the aforementioned signatures when accompanied by mono-jet, single-photon or Z-radiation probes through sophisticated signal-to-background simulations carried out in presence of parton shower, hadronisation as well as detector effects. We find substantial s…
This work deals with right handed sneutrino as thermal cold dark matter candidate. This scalar emerges in a supersymmetric version of $SU(3)_c \otimes SU(3)_L \otimes U(1)_X$ gauge model where right handed neutrinos are a natural component of leptonic chiral scalar supermultiplets. We first consider the issue of a $125$~GeV Higgs boson mass in this model, showing that constraints on stop mass and trilinear soft coupling are considerably alleviated compared to MSSM. Then we investigate the region of parameter space that is consistent with right handed sneutrino as thermal cold dark matter, unde…
We investigate the parameter space of a supersymmetric model with an extended U(1) gauge symmetry in which the RH sneutrino is a thermal dark matter candidate. In this scenario, annihilation of RH sneutrinos proceeds mainly through Higgs or Z' exchange. We find that sneutrinos in the mass range from 50GeV to more than 1 TeV can be consistent with both the WMAP limit and the direct detection upper limits. Powerful constraints from new gauge boson searches at the LHC as well as from $ΔM_s$ are incorporated. Depending on the choice of the U(1) charge, these scenarios will be further probe by dire…
Right-handed sneutrinos are natural components of left-right symmetric supersymmetric models where the gauge sector is extended to include right-handed weak interactions. Unlike in other models where right-handed sneutrinos are gauge singlets, here the right sneutrino is part of a doublet and could be a dark matter candidate whose annihilation proceeds via gauge interactions. We investigate this possibility, and find that relic density, low-energy observable and direct supersymmetry search constraints can be satisfied when the lightest supersymmetric particle is a right-handed sneutrino. We in…
We consider supersymmetric models with right-handed neutrinos where neutrino masses are purely Dirac-type. In this model, right-handed sneutrino can be the lightest supersymmetric particle and can be a viable candidate of cold dark matter of the universe. Right-handed sneutrinos are never thermalized in the early universe because of weakness of Yukawa interaction, but are effectively produced by decays of various superparticles. We show that the present mass density of right-handed sneutrino can be consistent with the observed dark matter density.
We extend the constrained minimal supersymmetric model (CMSSM) by adding a right-handed neutrino superfield ($ν$CMSSM) which decouples close to the GUT scale. We study the effects of a right-handed neutrino on the low energy spectrum and focus on the predictions for dark matter properties. We pay particular attention to the realization of the light (left-handed) sneutrino which can be the next-to-lightest supersymmetric particle (NLSP) with either the neutralino or gravitino as the lightest supersymmetric particle (LSP). Notably, for the case of a neutralino LSP with a sneutrino NLSP, there ar…
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 Supersymmetric partner (a right-handed sneutrino) is the Dark Matter (DM) candidate, by exploiting a `dijet + dilepton + Missing Transverse Energy' (MET) signature. We show that, unlike the miminal realisation of Supersymmetry (SUSY), i.e., the MSSM, for which the DM candidate is a much heavier (fermionic) state (a neutralino), this non-minimal SUSY model offers one with a much lighter (bosonic) state (a sneutrino) as DM, wh…
In this paper we investigate the $(g-2)_μ$ discrepancy in the context of the R-parity conserving next-to-minimal supersymmetric Standard Model plus right-handed neutrinos superfields. The model has the ability to reproduce neutrino physics data and includes the interesting possibility to have the right-handed sneutrino as the lightest supersymmetric particle and a viable dark matter candidate. Since right-handed sneutrinos are singlets, no new contributions for $δa_μ$ with respect to the MSSM and NMSSM are present. However, the possibility to have the right-handed sneutrino as the lightest sup…
In order to have massive neutrinos, the right-handed neutrino/sneutrino superfield ($N$) need to be introduced in supersymmetry. In the framework of NMSSM (the MSSM with a singlet $S$) such an extension will dynamically lead to a TeV-scale Majorana mass for the right-handed neutrino through the $SNN$ coupling when $S$ develops a vev (the free Majorana mass term is forbidden by the assumed $Z_3$ symmetry). Also, through the couplings $SNN$ and $SH_uH_d$, the SM-like Higgs boson (a mixture of $H_u$, $H_d$ and $S$) can naturally couple with the right-handed neutrino/sneutrino. As a result, the Te…
We consider an extension of the Next-to-Minimal Supersymmetric Standard Model by three right-handed neutrinos and a pair of neutrinophilic Higgs superfields. The small neutrino masses arise naturally from a small vacuum expectation value of the additional Higgs fields (hence without lepton number violation), while the lightest right-handed sneutrinos can constitute asymmetric Dark Matter. The right-handed sneutrino and baryon asymmetries are connected through equilibrium processes in the early universe, explaining the coincidence of the DM and baryon abundances. We show that particle physics a…
We reconsidered leptogenesis scenario from right-handed (s)neutrino produced by the decay of inflaton. Besides the well-investigated case that the neutrino decays instantaneously after the production, leptogenesis is possible if neutrino decays after it dominates the universe. In the latter case, right-handed (s)neutrino can decay either while it is relativistic or after it becomes non-relativistic. Especially, the first case has not been discussed seriously in literatures. Resultant lepton asymmetry and constraints from the gravitino problem are studied in broad parameter region, including al…
We show that the lightest right-handed sneutrino in TeV scale supersymmetric B-L model with inverse seesaw mechanism is a viable candidate for cold dark matter. We find that it accounts for the observed dark matter relic abundance in a wide range of parameter space. The spin-independent cross section of B-L right-handed sneutrino is consistent with the recent results CDMS II and XENON experiments and it is detectable in future direct detection experiments. Although the B-L right-handed sneutrinos annihilate into leptons, the PAMELA results can not be explained in this model unless a huge boost…
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 generatio…
We consider the conditions which must be satisfied for a Majorana RH sneutrino, a massive right-handed (RH) sneutrino associated with the see-saw mechanism of Majorana neutrino masses, to play the role of the curvaton. Planck-scale suppressed non-renormalizable terms in the RH neutrino superpotential must be eliminated to a high order if the RH sneutrino curvaton is to dominate the energy density before it decays, which can be achieved via an R-symmetry which is broken to R-parity by the Giudice-Maseiro mechanism. In order to satisfy the thermalization constraint, one RH neutrino mass eigensta…
We study an extension of the MSSM with a singlet S with coupling SH1H2 in order to solve the mu problem as in the NMSSM, and right-handed neutrinos 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 can not only be thermal relic dark matter but also have a large enough scattering cross section with nuclei to detect it directly in near future, in contrast with most of other right-…
We study the light-element abundances in supersymmetric model where the right-handed sneutrino is the lightest superparticle (LSP), assuming that the neutrino masses are purely Dirac-type. In such a scenario, the lightest superparticle in the minimal supersymmetric standard model sector (which we call MSSM-LSP) becomes long-lived, and thermal relic MSSM-LSP may decay after the big-bang nucleosynthesis starts. We calculate the light-element abundances including non-standard nuclear reactions induced by the MSSM-LSP decay, and derive constraints on the scenario of right-handed sneutrino LSP.
We consider the possibility that a right-handed sneutrino can serve as the source of energy density perturbations leading to structure formation in cosmology. The cosmological evolution of a coherently oscillating condensate of right-handed sneutrinos is studied for the case where reheating after inflation is due to perturbative inflaton decays. For the case of Dirac neutrinos, it is shown that some suppression of Planck scale-suppressed corrections to the right-handed neutrino superpotential is necessary. cH^2 corrections to the sneutrino mass squared term must also be suppressed during infla…
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 neutralino and right handed sneutrino as the lightest supersymmetric particle, but when CP is violated, the new annihilation channels lower the achieved relic…
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 p…
We discuss a D-term inflation scenario where a right-handed sneutrino can be an inflaton field leading to a viable inflation and leptogenesis, with a minimal form of Kähler potential. The decay of an inflaton sneutrino can non-thermally create large enough lepton asymmetry. Its entropy production is also big enough to ameliorate the gravitino problem caused by too high a reheating temperature from the decay of a symmetry breaking field.
We study the possibility of observing lepton number violation in the right-handed sneutrino sector of the Next-to-Minimal Supersymmetric Standard Model extended with right-handed neutrinos. The scalar potential introduces a lepton number violating mass term for the right-handed sneutrinos, which generates a phase difference that results in oscillations between the sneutrino and antisneutrino. If we have light higgsinos and right-handed sneutrinos, the sneutrino decay width is determined by the tiny Yukawa couplings, which allows the phase difference to accumulate before the sneutrino decays. W…
In this paper, we consider large non-Gaussianity generated after D-term inflation in the case that the adiabatic curvature perturbation produced is dominated by a right-handed (RH) sneutrino curvaton. The cosmic string problem can also be evaded with around 10% contribution to the CMB power spectrum and the spectral index $n_s \simeq 1$. The non-Gaussianity produced can be as large as $10<f_{NL}<100$ for the right-handed sneutrino mass being around $m_Φ=10 {GeV}$ with the Yukawa coupling $λ_ν\sim 10^{-10}$. In this case, the lightest neutrino mass is $10^{-10}{eV}$ which favors RH sneutrino le…
The left-handed sneutrino in the Minimal Supersymmetric Standard Model (MSSM) has been ruled out as a viable thermal dark matter candidate, due to conflicting constraints from direct detection experiments and from the measurement of the dark matter relic density. The intrinsic fine-tuning problem of the MSSM, however, motivates an extension with a new U(1)' gauge symmetry. We show that in the U(1)'-extended MSSM the right-handed sneutrino becomes a good thermal dark matter candidate. We identify two generic parameter space regions where the combined constraints from relic density determination…
In this paper, we consider the effect of two right-handed sneutrino curvaton decays and investigate the parameter space. We compare the difference of the result between single- and two-curvaton cases. We find one Yukawa coupling of the right-handed snetrinos can be as large as $λ\sim 0.1$ while the other one is much smaller which is consistent with the idea that only one generation of the neutrino mass may be much smaller than others. When the curvatons decay, we assume both of them subdominate the energy density of the universe. We find that, unlike a single curvaton case, here a small or neg…
We consider supersymmetric models in which the right-handed sneutrino is a viable WIMP dark matter candidate. These are either simple extensions of the Minimal Supersymmetric Standard Model or models with the addition of an extra U(1) group. All of them can explain small neutrino masses, through either the Inverse or the Linear Seesaw mechanism. We investigate the properties of the dark matter candidate naturally arising in these scenarios. We check for phenomenological bounds, such as correct relic abundance, consistency with direct detection cross section limits and laboratory constraints. E…
When the minimal supersymmetric standard model is augmented by three right-handed neutrino superfields, one generically predicts that the neutrinos acquire Majorana masses. We postulate that all supersymmetry (SUSY) breaking masses as well as the Majorana masses of the right-handed neutrinos are around the electroweak scale and, motivated by the smallness of neutrino masses, assume that the lightest supersymmetric particle (LSP) is an almost-pure right-handed sneutrino. We discuss the conditions under which this LSP is a successful dark matter candidate. In general, such an LSP has to be nonth…
We propose a chaotic inflation model in which the lightest right-handed sneutrino serves as the inflaton and the predicted values of the spectral index and tensor-to-scalar ratio are consistent with the Planck data. Interestingly, the observed magnitude of primordial density perturbations is naturally explained by the inflaton mass of order $10^{13}$GeV, which is close to the right-handed neutrino mass scale suggested by the seesaw mechanism and the neutrino oscillation experiments. We find that the agreement of the two scales becomes even better in the neutrino mass anarchy. We show that the …
We investigate the collider signatures of neutral and charged Long-Lived Particles (LLPs), predicted by the Supersymmetric $B-L$ extension of the Standard Model (BLSSM), at the Large Hadron Collider (LHC). The BLSSM is a natural extension of the Minimal Supersymmetric Standard Model (MSSM) that can account for non-vanishing neutrino masses. We show that the lightest right-handed sneutrino can be the Lightest Supersymmetric Particle (LSP), while the Next-to-the LSP (NLSP) is either the lightest left-handed sneutrino or the left-handed stau, which are natural candidates for the LLPs. We analyze …
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 TeV scale. We go over why a TeV scale B-L gauge extension of the minimal supersymmetric standard model (MSSM) 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 ch…
In the minimal supersymmetric standard model (MSSM) the lightest superpartner of the left-handed neutrinos is ruled out of being a candidate of dark matter because of its large elastic cross-section with the nucleus mediated via Z-boson. We resurrect it by extending the MSSM with two triplets with opposite hypercharge. The addition of the triplets not only play a role in generating small Majorana masses for the left-handed active neutrinos but also make the lightest sneutrino a viable candidate for dark matter. We then discuss the relevant parameter space in details which can give rise to the …
Recently a model of chaotic inflation was proposed, where the right handed sneutrinos drive the baryogenesis. We study some of the details of the model, particularly the aspect of CP violation, and determine the number of right handed sneutrinos required for the viability of such models.
We study LHC signatures of displaced vertices and long-lived charged particles within the context of the Next-to-Minimal Supersymmetric Standard Model with right-handed (RH) sneutrinos. In this construction the RH neutrino can be produced directly from Higgs decays or in association with a RH sneutrino when the latter is the lightest supersymmetric particle. The RH neutrino is generally long-lived, since its decay width is proportional to the neutrino Yukawa, a parameter which is predicted to be small. The RH neutrino late decay can therefore give rise to displaced vertices at the LHC, which c…
The prevalent Dark Matter (DM) candidate of the (B-L) Supersymmetric Standard Model (BLSSM) is the Right Handed (RH) sneutrino. In this work we assess the ability of ground and space based experiments to establish the nature of this particle, through indirect and collider detection.
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 …
We show that the $B-L$ Supersymmetric Standard Model with Inverse Seesaw (BLSSMIS) provides new Dark Matter (DM) candidates (lightest right-handed sneutrino and lightest $B-L$ neutralino) with mass of order few hundreds GeV, while most of other SUSY spectrum can be quite heavy, consistently with the current Large Hadron Collider (LHC) constraints. We emphasize that the thermal relic abundance and direct detection experiments via relic neutralino scattering with nuclei impose stringent constraints on the $B-L$ neutralinos. These constraints can be satisfied by few points in the parameter space …
The $(B-L)$ Supersymmetric Standard Model (BLSSM) motivates several Dark Matter (DM) candidates beyond the Minimally Supersymmetric Standard Model (MSSM). We assess the comparative naturalness of the two models and discuss the potential detection properties of a particular candidate, the Right-Handed (RH) sneutrino.
It is shown that "right" sneutrino can be the lightest supersymmetric particle. Clearly, this possibility will drastically change decay chains of SUSY particles. The sneutrino production at next linear colliders has been analyzed in this scenario.
The inclusion of right-chiral sneutrino superfields is a rather straightforward addition to a supersymmetric scenario. A neutral scalar with a substantial right sneutrino component is often a favoured dark matter candidate in such cases. In this context, we focus on the tentative signal in the form of a monochromatic photon, which may arise from dark matter annihilation and has drawn some attention in recent times. We study the prospect of such a right sneutrino dark matter candidate in the contexts of both MSSM and NMSSM extended with right sneutrino superfields, with special reference to the…
An alternative to the conventional see-saw mechanism is proposed to explain the origin of small neutrino masses in supersymmetric theories. The masses and couplings of the right-handed neutrino field are suppressed by supersymmetry breaking, in a way similar to the suppression of the Higgs doublet mass, $μ$. New mechanisms for light Majorana, Dirac and sterile neutrinos arise, depending on the degree of suppression. Superpartner phenomenology is greatly altered by the presence of weak scale right-handed sneutrinos, which may have a coupling to a Higgs boson and a left-handed sneutrino. The sne…
Supergravity corrections due to the energy density of a right-handed sneutrino can generate a negative mass squared for the inflaton, flattening the inflaton potential and reducing the spectral index and inflaton energy density. For the case of D-term hybrid inflation, we show that the spectral index can be lowered from the conventional value n = 0.98 to a value within the range allowed by the latest WMAP analysis, n = 0.951^{+0.015}_{-0.019}. The modified energy density is consistent with non-observation of cosmic strings in the CMB if n < 0.946. The WMAP lower bound on the spectral index imp…
The similarity of the observed densities of baryons and cold dark matter suggests that they have a common or related origin. This can be understood in the context of the MSSM with right-handed (RH) sneutrinos if cold dark matter is due to a d = 4 flat direction condensate of very weakly coupled RH sneutrino LSPs and the baryon asymmetry is generated by Affleck-Dine leptogenesis along the d = 4 (H_{u}L)^{2} flat direction. The correct density of RH sneutrino dark matter is obtained if the reheating temperature is in the range 10^{6}-10^{8} GeV. A cold dark matter isocurvature perturbation close…
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 $γγ$ can be larger than that of the helicity suppressed annihilation into fermions, bec…
