Dark matter and LHC phenomenology in a left-right supersymmetric model (original) (raw)
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Physical Review D, 2010
We re-examine the prospects for the detection of Higgs mediated lepton flavor violation at LHC, at a photon collider and in τ decays such as τ → µη, τ → µγ. We allow for the presence of a large, model independent, source of lepton flavor violation in the slepton mass matrix in the τ − µ sector by the mass insertion approximation and constrain the parameter space using the τ LFV decays together with the B-mesons physics observables, the anomalous magnetic moment of the muon and the dark matter relic density. We further impose the exclusion limit on spin-independent neutralinonucleon scattering from CDMS and the CDF limits from direct search of the heavy neutral Higgs at the TEVATRON. We find rates probably too small to be observed at future experiments if models have to accommodate for the relic density measured by WMAP and explain the (g − 2)µ anomaly: better prospects are found if these two constraints are applied only as upper bounds. The spin-independent neutralino-nucleon cross section in the studied constrained parameter space is just below the present CDMS limit and the running XENON100 experiment will cover the region of the parameter space where the lightest neutralino has large gaugino-higgsino mixing.
Natural SUSY at LHC with right-sneutrino LSP
Journal of High Energy Physics
We study an extension of the minimal supersymmetric standard model (MSSM) with additional right-handed singlet neutrino superfields. While such an extension incorporates a mechanism for the neutrino mass, it also opens up the possibility of having the right-sneutrinos (ν) as the lightest supersymmetric particle (LSP). In this work, we focus on the viability of rather small (500 GeV) higgsino mass parameter (µ), an important ingredient for "naturalness", in the presence of such a LSP. For simplicity, we assume that the bino and wino mass parameters are much heavier; thus we only consider (almost) pure and compressed higgsino-like states, with small O(10 −2) gaugino admixture which nevertheless still affect the decay of the low-lying higgsino-like states, thus significantly affecting the proposed signatures at colliders. Considering only prompt decays of the higgino-like states, especially the lightest chargino, we discuss the importance of leptonic channels consisting of up to two leptons with large missing transverse energy to probe this scenario at the Large Hadron Collider (LHC). In addition we also comment on the dark matter predictions for the studied scenario.
A minimal supersymmetric left-right model, dark matter and signals at the LHC
European Physical Journal-special Topics, 2020
The left-right symmetric models extend the gauge group of the Standard Model enabling treatment of the left-and right-handed fermions in the same footing. The left-right symmetry requires the existence of right-handed neutrinos, leading naturally to non-zero masses for neutrinos. Here some aspects of a supersymmetric version of the leftright symmetric models are reviewed. Such models have many virtues, including possibility for dark matter without any new additional symmetry needed in order to have a stable lightest supersymmetric particle. In the model the lightest sneutrino or the lightest neutralino can form dark matter of the universe, at the same time fulfilling all the experimental constraints. The dark matter particle in the model can be very different from the dark matter typical in the minimal supersymmetric standard model. Specific signals for this kind of models at the LHC are also discussed.
LHC and lepton flavour violation phenomenology of a left-right extension of the MSSM
Journal of High Energy Physics, 2010
We review Lepton Flavour Violation (LFV) in the supersymmetric version of the seesaw mechanism (type I, II, III) and in Left-Right models. The LFV needed to explain neutrino masses and mixings is the only source of LFV and has experimental implications both in lowenergy experiments where we search for the radiative decays of leptons, and at the LHC where we look at its imprint on the LFV decays of the sparticles and on slepton mass splittings. We discuss how this confrontation between high-and low-energy LFV observables may provide information about the underlying mechanism of LFV.
Lepton Flavour Violation and. Dark Matter Phenomenology
2013
GENERAL INTRODUCTION AND MOTIVATIONS One of the open questions in particle physics nowadays is the so-called flavour puzzle: why there is a hierarchical structure of fermion masses and mixings, and why there are two replicas of the lightest fermions? The leptonic sector presents even more challenging features than the quark sector, where the mixings between flavour eigenstates show an approximately perturbative texture. Indeed, in the neutrino sector the values of the mixing angles appear 'randomly' distributed, and one of the mixing angles is close to maximal. On the other hand, the masses of neutrinos are believed to be below ∼ 0.3 eV, i.e. six orders of magnitude smaller than the lightest charged fermion (the electron). This should be compared with the ∼ five orders of magnitude expanded by the masses of the nine charged fermions (from the electron to the top mass), more or less equally distributed in between. Certainly, the Standard Model (SM) can be trivially extended to accommodate neutrino masses. However, the previous huge gap between the neutrinos and the rest of SM particles has posed a strong motivation to develop theoretical models that could explain it. One of the most popular theoretical frameworks to accommodate such small neutrino masses is the socalled Seesaw mechanism. The idea is that right-handed (RH) neutrinos, which are singlets under the SM gauge group, can have large Majorana masses (as they are not controlled by the electroweak-breaking scale). Then the lightest (approximately pure left-handed) neutrinos get masses suppressed by the ratio of the Higgs VEV and the right-handed Majorana mass, thus becoming extremely light. The Seesaw scenario can be easily formulated within a supersymmetric framework. Indeed, this is highly motivated by the fact that the massive right-handed neutrinos introduce large (logarithmic) corrections to the Higgs mass, which worsens the notorious Hierarchy-Problem of the Standard Model. On the other hand, the neutrino Yukawa couplings must present an off-diagonal structure (to generate the neutrino mixings), which in turn induces off-diagonal entries in the slepton matrices. The latter may potentially trigger processes which violate Lepton flavour, for example µ → eγ.
Higgs sector of the MSSM: Lepton flavor violation at colliders and neutralino dark matter
2010
We examine the prospects for the detection of Higgs mediated lepton flavor violation at LHC and at a photon collider in the minimal supersymmetric standard model with large lepton flavor violating mass insertions in the µ − τ sector constraining the parameter space with several experimental bounds. We find rates probably too small to be observed at future experiments if models have to accommodate for a neutralino relic density as measured by WMAP and explain the (g − 2)µ anomaly: better prospects are found if these two constraints are applied only as upper bounds. The spin-independent neutralino-nucleon cross section in the studied constrained parameter space is just below the present CDMS limit while gamma rates from neutralino annihilation in the halo are strongly suppressed.
Neutrino mass, sneutrino dark matter and signals of lepton flavor violation in the MRSSM
Journal of High Energy Physics, 2010
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 Ω 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 2 nnññ for the right-handed sneutrinos, random matrices satisfying the Ω 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 2 nnññ terms radiatively generate appropriately small Majorana neutrino masses, with neutrino oscillation data favoring a mostly sterile lightest sneutrino with a dominantly µ/τ-flavored active component, and (iv) a sneutrino LSP with a significant µ component can lead to striking signals of e-µ flavor violation in dilepton invariant-mass distributions at the LHC.
Muong−2, Dark Matter, and Lepton Flavor Violation in SUSY-GUT’s
Letters in high energy physics, 2023
We perform an analysis of the predictions of several supersymmetric Grand Unified Theories (GUTs) for Dark Matter and the measurements of the muon anomalous magnetic moment (muon g − 2) consistent with possible Lepton Flavor Violating (LFV) signal in charged lepton decays. Each GUT predicts different Dark Matter (DM) scenarios, which can be used to classify SUSY models and contrast their predictions with experimental evidences. We find that models arising from SU(4) c × SU(2) L × SU(2) R can predict DM of cosmological interest while explaining the observed value of the muon g − 2. Furthermore, we show that when this framework is extended with a simple type 1 seesaw mechanism to explain neutrino masses, many models also predict charged LFV decays that can be observed in current experiments.
Invisible Higgs decay in a supersymmetric inverse seesaw model with light sneutrino dark matter
Journal of High Energy Physics, 2013
Within the framework of a constrained Minimal Supersymmetric Standard Model (cMSSM) augmented by an MSSM singlet-pair sector to account for the non-zero neutrino masses by inverse seesaw mechanism, the lightest supersymmetric particle (LSP) can be a mixed sneutrino with mass as small as 50 GeV, satisfying all existing constraints, thus qualifying as a light dark matter candidate. We study the possibility of the lightest neutral Higgs boson in this model decaying invisibly into a pair of sneutrino LSPs, thereby giving rise to novel missing energy signatures at the LHC. We perform a two-parameter global analysis of the LHC Higgs data available till date to determine the optimal invisible Higgs branching fraction in this scenario, and obtain a 2σ (1σ) upper limit of 0.25 (0.15). A detailed cut-based analysis is carried out thereafter, demonstrating the viability of our proposed signal vis-a-vis backgrounds at the LHC.