[Show abstract][Hide abstract] ABSTRACT: The "$\mu$ from $\nu$" supersymmetric standard model ($\mu\nu$SSM) can
accommodate the newly discovered Higgs-like scalar boson with a mass around 125
GeV. This model provides a solution to the $\mu$-problem and simultaneously
reproduces correct neutrino physics by the simple use of right-handed neutrino
superfields. These new superfields together with the introduced $R$-parity
violation can produce novel and characteristic signatures of the $\mu\nu$SSM at
the LHC. We explore the signatures produced through two-body Higgs decays into
the new states, provided that these states lie below in the mass spectrum. For
example, a pair produced light neutralinos depending on the associated decay
length can give rise to displaced multi-leptons/taus/jets/photons with
small/moderate missing transverse energy. In the same spirit, a Higgs-like
scalar decaying to a pair of scalars/pseudoscalars can produce final states
with prompt multi-leptons/taus/jets/photons.
Journal of High Energy Physics 10/2014; 2014(11). DOI:10.1007/JHEP11(2014)102 · 6.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The extended field content of the "$\mu$ from $\nu$" supersymmetric standard
model ($\mu\nu$SSM) can accommodate very light scalars, pseudoscalars and
neutralinos in certain regions of the parameter space with leading right-handed
sneutrino and neutrino composition, respectively. Direct production of these
states at colliders is suppressed due to gauge singlet nature. Nevertheless,
production of these states is possible in the decay cascades of heavier ones.
In this letter we emphasis how these light states can lead to unusual signals
from $Z$ or $W^\pm$ boson decays at the LHC with prompt or displaced
multi-leptons/jets at the final states. These new modes would give distinct
evidence of new physics even when direct searches remain unsuccessful. We
address possibilities to probe these non-standard signatures with ongoing or
upcoming collider experiment.
[Show abstract][Hide abstract] ABSTRACT: Non-standard on-shell decays of $W^\pm$ and $Z$-bosons are possible within the framework of extended supersymmetric models. These possibilities are typically encountered in the regions of the parameter space with light singlet-like scalar(s), pseudoscalar(s) and neutralino(s). In this letter we emphasise how these states can lead to novel signals from $Z$ or $W^\pm$ boson decays at the LHC with prompt or displaced multi-leptons/jets/photons at the final states. These new modes would give distinct evidence of new physics even when direct searches remain unsuccessful. We address possibilities to probe these non-standard signatures with ongoing collider experiment or upcoming ones. We exemplify our observations with the "$\mu$ from $\nu$" supersymmetric standard model ($\mu\nu$SSM), where three generations of right-handed neutrino superfields are used to efface a number of shortcomings of the minimal version of supersymmetric models. We also extend our discussions for other variants of supersymmetric models which can accommodate similar signatures.
Physical Review D 02/2014; 91(3). DOI:10.1103/PhysRevD.91.035020 · 4.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The "$\mu$ from $\nu$" supersymmetric standard model ($\mu\nu$SSM) cures the
$\mu$-problem and concurrently reproduces measured neutrino data by using a set
of usual right-handed neutrino superfields. Recently, the LHC has revealed the
first scalar boson which naturally makes it tempting to test $\mu\nu$SSM in the
light of this new discovery. We show that this new scalar while decaying to a
pair of unstable long-lived neutralinos, can lead to a distinct signal with
non-prompt multileptons. With concomitant collider analysis we show that this
signal provides an unmistakable signature of the model, pronounced with light
neutralinos. Evidence of this signal is well envisaged with sophisticated
displaced vertex analysis, which deserves experimental attention.
[Show abstract][Hide abstract] ABSTRACT: The next-to-minimal supersymmetric standard model (NMSSM) is a R-parity
conserving model that solves the μ-problem of the minimal
supersymmetric standard model (MSSM) by adding a singlet superfield.
Here we study different aspects of this model. Firstly, using Bayesian
statistics, we discuss the constrained next-to-minimal supersymmetric
standard model (CNMSSM) scenario. We place special emphasis on analysing
the neutralino as a dark matter candidate. Additionally, using the
nested sampling (NS) algorithm, we focus our analysis on a particular
region of the parameter space. Results obtained scanning the low energy
parameter space of the NMSSM, searching for low mass neutralinos, are
discussed.
Journal of Physics Conference Series 09/2012; 384(1):2014-. DOI:10.1088/1742-6596/384/1/012014
[Show abstract][Hide abstract] ABSTRACT: The μνSSM is a supersymmetric standard model that accounts for light neutrino masses and solves the μ problem of the MSSM by simply using right-handed neutrino superfields. Since this mechanism breaks R-parity, a peculiar structure for the mass matrices is generated. The neutral Higgses are mixed with the right- and left-handed sneutrinos producing 8 × 8 neutral scalar mass matrices. We analyse the Higgs sector of the μνSSM in detail, with special emphasis in possible signals at colliders. After studying in general the decays of the Higges, we focus on those processes that are genuine of the μνSSM, and could serve to distinguish it form other supersymmetric models. In particular, we present viable benchmark points for LHC searches. For example, we find decays of a MSSM-like Higgs into two lightest neutralinos, with the latter decaying inside the detector leading to displaced vertices, and producing final states with 4 and 8 b-jets plus missing energy. Final states with leptons and missing energy are also found.
Journal of High Energy Physics 10/2011; 2011(10). DOI:10.1007/JHEP10(2011)020 · 6.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Motivated by the recent re-confirmation by CoGENT of the low-energy excess of
events observed last year, and the recent improved limits from the XENON-100
experiment that are in contention with the CoGENT data, we re-examine the low
mass neutralino region of the Minimal Supersymmetric Standard Model and of the
Next-to-Minimal Supersymmetric Standard Model, both without assuming gaugino
mass unification. We make several focused scans for each model, determining
conservative constraints on input parameters. We then determine how these
constraints are made increasingly stringent as we re-invoke our experimental
constraints involving the dark matter relic abundance, collider constraints
from LEP and the Tevatron, and then from flavour physics, as a series of
successive 2 sigma hard cuts. We find that for both models, when all relevant
constraints are applied in this fashion, we do not generate neutralino LSPs
that possess a spin-independent scattering cross section in excess of 10^-5 pb
and a mass ~7 GeV < m_chi < ~9 GeV that is necessary in order to explain the
CoGENT observations.
[Show abstract][Hide abstract] ABSTRACT: We examine the extent to which it is possible to realize the NMSSM "ideal
Higgs" models espoused in several papers by Gunion et al in the context of
partially universal GUT scale boundary conditions. To this end we use the
powerful methodology of nested sampling. We pay particular attention to whether
ideal-Higgs-like points not only pass LEP constraints but are also acceptable
in terms of the numerous constraints now available, including those from the
Tevatron and $B$-factory data, $(g-2)_\mu$ and the relic density $\Omega h^2$.
In general for this particular methodology and range of parameters chosen, very
few points corresponding to said previous studies were found, and those that
were found were at best $2\sigma$ away from the preferred relic density value.
Instead, there exist a class of points, which combine a mostly singlet-like
Higgs with a mostly singlino-like neutralino coannihilating with the lightest
stau, that are able to effectively pass all implemented constraints in the
region $80<m_h<100$. It seems that the spin-independent direct detection cross
section acts as a key discriminator between ideal Higgs points and the hard to
detect singlino-like points.
[Show abstract][Hide abstract] ABSTRACT: The $\mu \nu$SSM proposes to use right-handed neutrino supermultiplets in order to generate the $\mu$ term and neutrino masses simultaneously. We discuss neutrino physics and the associated electroweak seesaw mechanism in this model. We show how to obtain, from the neutralino-neutrino mass matrix of the $\mu \nu$SSM, the effective neutrino mass matrix. In particular we discuss certain limits of this matrix that clarify the neutrino-sector behavior of the model. We also show that current data on neutrino masses and mixing angles can easily be reproduced. These constraints can be fulfilled even with a diagonal neutrino Yukawa matrix, since this seesaw does not involve only the right-handed neutrinos but also the MSSM neutralinos. To obtain the correct neutrino angles turns out to be easy due to the following characteristics of this seesaw: R-parity is broken and the relevant scale is the electroweak one. Comment: 7 pages, 1 figure. Talk given at "BUE, CTP International Conference on Neutrino Physics in the LHC Era", Luxor, Egypt, 15-19 Nov. 2009.
[Show abstract][Hide abstract] ABSTRACT: The munuSSM provides a solution to the mu-problem of the MSSM and explains the origin of neutrino masses by simply using right-handed neutrino superfields. Given that R-parity is broken in this model, the gravitino is a natural candidate for dark matter since its lifetime becomes much longer than the age of the Universe. We consider the implications of gravitino dark matter in the munuSSM, analyzing in particular the prospects for detecting gamma rays from decaying gravitinos. If the gravitino explains the whole dark matter component, a gravitino mass larger than 20GeV is disfavored by the isotropic diffuse photon background measurements. On the other hand, a gravitino with a mass range between 0.1-20 GeV gives rise to a signal that might be observed by the FERMI satellite. In this way important regions of the parameter space of the munuSSM can be checked.
Journal of Cosmology and Astroparticle Physics 03/2010; 3(03):028-028. DOI:10.1088/1475-7516/2010/03/028 · 5.81 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We perform a first global exploration of the constrained next-to-minimal supersymmetric standard model using Bayesian statistics. We derive several global features of the model and find that, in some contrast to initial expectations, they closely resemble those of the constrained minimal supersymmetric standard model. This remains true even away from the decoupling limit which is nevertheless strongly preferred. We present ensuing implications for several key observables, including collider signatures and predictions for direct detection of dark matter.
[Show abstract][Hide abstract] ABSTRACT: The μνSSM provides a solution to the μ problem of the MSSM and explains the origin of neutrino masses by simply using right-handed neutrino superfields. We have completed the analysis of the vacua in this model, studying the possibility of spontaneous CP violation through complex Higgs and sneutrino vacuum expectation values. As a consequence of this process, a complex MNS matrix can be present. Besides, we have discussed the neutrino physics and the associated electroweak seesaw mechanism in the μνSSM, including also phases. Current data on neutrino masses and mixing angles can easily be reproduced.
Journal of High Energy Physics 08/2009; 2009(08):105. DOI:10.1088/1126-6708/2009/08/105 · 6.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We perform a first global exploration of the Constrained Next-to-Minimal Supersymmetric Standard Model using Bayesian statistics. We derive several global features of the model and find that, in some contrast to initial expectations, they closely resemble the Constrained MSSM. This remains true even away from the decoupling limit which is nevertheless strongly preferred. We present ensuing implications for several key observables, including collider signatures and predictions for direct detection of dark matter.
[Show abstract][Hide abstract] ABSTRACT: The μνSSM is a supersymmetric standard model that solves the μ problem of the MSSM using the R-parity breaking couplings between the right-handed neutrino superfields and the Higgses in the superpotential, λi cidu. The μ term is generated spontaneously through sneutrino vacuum expectation values, μ = λici, once the electroweak symmetry is broken. In addition, the couplings κijkcicjck forbid a global U(1) symmetry avoiding the existence of a Goldstone boson, and also contribute to spontaneously generate Majorana masses for neutrinos at the electroweak scale. Following this proposal, we have analysed in detail the parameter space of the μνSSM. In particular, we have studied viable regions avoiding false minima and tachyons, as well as fulfilling the Landau pole constraint. We have also computed the associated spectrum, paying special attention to the mass of the lightest Higgs. The presence of right and left-handed sneutrino vacuum expectation values leads to a peculiar structure for the mass matrices. The most important consequence is that neutralinos are mixed with neutrinos, and neutral Higgses with sneutrinos.
Journal of High Energy Physics 12/2008; 2008(12):099. DOI:10.1088/1126-6708/2008/12/099 · 6.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We analyze the direct detection of neutralino dark matter in the framework of the Next-to-Minimal Supersymmetric Standard Model. Taking into account all the available constraints from LEPII and Tevatron, including bounds from the muon anomalous magnetic moment and flavor constraint as $b \to s \gamma $, we compute the neutralino-nucleon cross section and compare the results with the sensitivity of dark matter detectors. We also study the relic abundance of neutralinos, comparing it with WMAP observations. We show that a light singlet-like Higgs can escape accelerator constraints allowing for scenarios with large cross sections, and a very interesting phenomenology.
Journal of Physics A Mathematical and Theoretical 04/2007; DOI:10.1088/1751-8113/40/25/S35 · 1.58 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The viability of the lightest neutralino as a dark matter candidate in the next-to-minimal supersymmetric standard model is analysed. We carry out a thorough analysis of the parameter space, taking into account accelerator constraints as well as bounds on low-energy observables, such as the muon anomalous magnetic moment and rare K and B meson decays. The neutralino relic density is also evaluated and consistency with present bounds imposed. Finally, the neutralino direct detection cross section is calculated in the allowed regions of the parameter space and compared to the sensitivities of present and projected dark matter experiments. Regions of the parameter space are found where experimental constraints are fulfilled, the lightest neutralino has the correct relic abundance and its detection cross section is within the reach of dark matter detectors. This is possible in the presence of very light singlet-like Higgses and when the neutralino is either light enough so that some annihilation channels are kinematically forbidden, or has a large singlino component.
Journal of Cosmology and Astroparticle Physics 03/2007; 2007(06). DOI:10.1088/1475-7516/2007/06/008 · 5.81 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The fact that neutrinos are massive suggests that the minimal supersymmetric standard model (MSSM) might be extended in order to include three gauge-singlet neutrino superfields with Yukawa couplings of the type H2Lnuc. We propose to use these superfields to solve the mu problem of the MSSM without having to introduce an extra singlet superfield as in the case of the next-to-MSSM (NMSSM). In particular, terms of the type nuc H1H2 in the superpotential may carry out this task spontaneously through neutrino vacuum expectation values. In addition, terms of the type (nuc)3 avoid the presence of axions and generate effective Majorana masses for neutrinos at the electroweak scale. On the other hand, these terms break lepton number and R parity explicitly. For Dirac masses of the neutrinos of order 10(-4) GeV, eigenvalues reproducing the correct scale of neutrino masses are obtained.
[Show abstract][Hide abstract] ABSTRACT: We analyse the direct detection of neutralino dark matter in the framework of the Next-to-Minimal Supersymmetric Standard Model. After performing a detailed analysis of the parameter space, taking into account all the available constraints from LEPII, we compute the neutralino-nucleon cross section, and compare the results with the sensitivity of detectors. We find that sizable values for the detection cross section, within the reach of dark matter detectors, are attainable in this framework. For example, neutralino-proton cross sections compatible with the sensitivity of present experiments can be obtained due to the exchange of very light Higgses with $m_{h_1^0}\lsim 70$ GeV. Such Higgses have a significant singlet composition, thus escaping detection and being in agreement with accelerator data. The lightest neutralino in these cases exhibits a large singlino-Higgsino composition, and a mass in the range $50\lsim m_{\tilde\chi_1^0}\lsim 100$ GeV.
Journal of High Energy Physics 09/2004; 2004(12). DOI:10.1088/1126-6708/2004/12/048 · 6.11 Impact Factor