Publications (22)82.73 Total impact
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ABSTRACT: The "$\mu$ from $\nu$" supersymmetric standard model ($\mu\nu$SSM) can accommodate the newly discovered Higgslike 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 righthanded 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 twobody 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 multileptons/taus/jets/photons with small/moderate missing transverse energy. In the same spirit, a Higgslike scalar decaying to a pair of scalars/pseudoscalars can produce final states with prompt multileptons/taus/jets/photons.  [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 righthanded 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 multileptons/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 nonstandard signatures with ongoing or upcoming collider experiment.  [Show abstract] [Hide abstract]
ABSTRACT: Nonstandard onshell 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 singletlike 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 multileptons/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 nonstandard 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 righthanded 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.  [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 righthanded 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 longlived neutralinos, can lead to a distinct signal with nonprompt 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 nexttominimal supersymmetric standard model (NMSSM) is a Rparity conserving model that solves the μproblem 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 nexttominimal 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.  [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 righthanded neutrino superfields. Since this mechanism breaks Rparity, a peculiar structure for the mass matrices is generated. The neutral Higgses are mixed with the right and lefthanded 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 MSSMlike Higgs into two lightest neutralinos, with the latter decaying inside the detector leading to displaced vertices, and producing final states with 4 and 8 bjets plus missing energy. Final states with leptons and missing energy are also found.  [Show abstract] [Hide abstract]
ABSTRACT: Motivated by the recent reconfirmation by CoGENT of the lowenergy excess of events observed last year, and the recent improved limits from the XENON100 experiment that are in contention with the CoGENT data, we reexamine the low mass neutralino region of the Minimal Supersymmetric Standard Model and of the NexttoMinimal 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 reinvoke 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 spinindependent 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 idealHiggslike 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, $(g2)_\mu$ 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 singletlike Higgs with a mostly singlinolike 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 spinindependent direct detection cross section acts as a key discriminator between ideal Higgs points and the hard to detect singlinolike points.  [Show abstract] [Hide abstract]
ABSTRACT: 35 pages, 14 figures and 8 tables  [Show abstract] [Hide abstract]
ABSTRACT: The $\mu \nu$SSM proposes to use righthanded 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 neutralinoneutrino mass matrix of the $\mu \nu$SSM, the effective neutrino mass matrix. In particular we discuss certain limits of this matrix that clarify the neutrinosector 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 righthanded 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: Rparity 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, 1519 Nov. 2009.  [Show abstract] [Hide abstract]
ABSTRACT: The munuSSM provides a solution to the muproblem of the MSSM and explains the origin of neutrino masses by simply using righthanded neutrino superfields. Given that Rparity 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 0.120 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.  [Show abstract] [Hide abstract]
ABSTRACT: We perform a first global exploration of the constrained nexttominimal 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 righthanded 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.  [Show abstract] [Hide abstract]
ABSTRACT: We perform a first global exploration of the Constrained NexttoMinimal 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 Rparity breaking couplings between the righthanded 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 lefthanded 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.  [Show abstract] [Hide abstract]
ABSTRACT: The mu nu SSM is a supersymmetric standard model that solves the mu problem of the MSSM using the Rparity breaking couplings between the righthanded neutrino superfields and the Higgses in the superpotential, lambda(i)(nu) over cap (c)(i)(H) over cap (d)(H) over cap (u). The mu term is generated spontaneously through sneutrino vacuum expectation values, mu = lambda(i) <(nu) over tilde (c)(i)>, once the electroweak symmetry is broken. In addition, the couplings. kappa(ijk)(nu) over cap (c)(i)(nu) over cap (c)(j)(nu) over cap (c)(k) 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 mu nu SSM. 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 lefthanded 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. 
Article: Neutralino dark matter in the NMSSM
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ABSTRACT: We analyze the direct detection of neutralino dark matter in the framework of the NexttoMinimal 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 neutralinonucleon 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 singletlike Higgs can escape accelerator constraints allowing for scenarios with large cross sections, and a very interesting phenomenology.  [Show abstract] [Hide abstract]
ABSTRACT: The viability of the lightest neutralino as a dark matter candidate in the nexttominimal 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 lowenergy 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 singletlike Higgses and when the neutralino is either light enough so that some annihilation channels are kinematically forbidden, or has a large singlino component. 
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ABSTRACT: The fact that neutrinos are massive suggests that the minimal supersymmetric standard model (MSSM) might be extended in order to include three gaugesinglet 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 nexttoMSSM (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.
Publication Stats
452  Citations  
82.73  Total Impact Points  
Top Journals
Institutions

20122014

University of Buenos Aires
 Department of Physics (FI)
Buenos Aires, Buenos Aires F.D., Argentina


20112012

Université ParisSud 11
Orsay, ÎledeFrance, France


20082011

The University of Sheffield
 Department of Physics and Astronomy
Sheffield, England, United Kingdom


20042007

Universidad Autónoma de Madrid
 Departamento de Física Teórica
Madrid, Madrid, Spain
