Search

In minimal supergravity (mSUGRA) or CMSSM, one of the main co-annihilating partners of the neutralino is the lightest stau, $\tilde{\tau}_1$. In the presence of flavour violation in the right-handed sector, the co-annihilating partner would be a flavour mixed state. The flavour effect is two-fold: (a) It changes the mass of $\tilde{\tau}_{1}$, thus modifying the parameter space of the co-annihilation and (b) flavour violating scatterings could now contribute to the cross-sections in the early Universe. In fact, it is shown that for large enough δ~0.2, these processes would constitute the dominant channels in co-annihilation regions. The amount of flavour mixing permissible is constrained by flavour violating τ→ μ or τ→ e processes. For Δ mass insertions, the constraints from flavour violation are not strong enough in some regions of the parameter space due to partial cancellations in the amplitudes. In mSUGRA, the regions with cancelations within LFV amplitudes do not overlap with the regions of co-annihilations. In non-universal Higgs model (NUHM), however, these regions do overlap leading to significant flavoured co-annihilations. At the LHC and other colliders, these regions can constitute for interesting signals. [ABSTRACT FROM AUTHOR]

Abstract: We consider a recently proposed supersymmetric radiative seesaw model which is coupled with the minimal supergravity. The conventional R parity and invariance are imposed, which ensures the existence of a multi-component dark matter system. We assume that the pair of the lightest neutralino and the fermionic component of the inert Higgs supermultiplet is dark matter. If is lighter than , and the lightest neutral inert Higgs boson is kinematically forbidden to decay (third dark matter), the allowed region in the plane increases considerably, where and are the universal soft-supersymmetry-breaking scalar and gaugino mass, respectively, although the dominant component of the multi-component dark matter system is . There is a wide allowed region above the recent LHC limit. [Copyright &y& Elsevier]

Abstract: We investigate the recent CDF measurement of the which shows excess over the Standard Model. We consider minimal supergravity motivated models (mSUGRA)/CMSSM and grand unified models, SU(5) and SO(10). In the grand unified models, the neutrino mixings provide an additional source of squark flavor violation through the quark–lepton unification. In the context of minimal SU(5) model, we find that the new CDF measurement has imposed a lower bound on the branching ratio of for a large CP phase in the mixing. Recall that there have been indication for a large CP phase in mixing from (Tevatron and LHCb) and dimuon asymmetry (D0). We also predict for the possible range of values of . [Copyright &y& Elsevier]

Constraints on dark matter from the first CMS and ATLAS SUSY searches are investigated. It is shown that within the minimal supergravity model, the early search for supersymmetry at the LHC has depleted a large portion of the signature space in dark matter direct detection experiments. In particular, the prospects for detecting signals of dark matter in the XENON and CDMS experiments are significantly affected in the low neutralino mass region. Here the relic density of dark matter typically arises from slepton coannihilations in the early universe. In contrast, it is found that the CMS and ATLAS analyses leave untouched the Higgs pole and the Hyperbolic Branch/Focus Point regions, which are now being probed by the most recent XENON results. Analysis is also done for supergravity models with non-universal soft breaking where one finds that a part of the dark matter signature space depleted by the CMS and ATLAS cuts in the minimal SUGRA case is repopulated. Thus, observation of dark matter in the LHC depleted region of minimal supergravity may indicate non-universalities in soft breaking. [ABSTRACT FROM AUTHOR]

Abstract: The CMS and the ATLAS Collaborations have recently reported on the search for supersymmetry with 35 pb−1 of data and have put independent limits on the parameter space of the supergravity unified model with universal boundary conditions at the GUT scale for soft breaking, i.e., the mSUGRA model. We extend this study by examining other regions of the mSUGRA parameter space in and . Further, we contrast the reach of CMS and ATLAS with 35 pb−1 of data with the indirect constraints, i.e., the constraints from the Higgs boson mass limits, from flavor physics and from the dark matter limits from WMAP. Specifically it is found that a significant part of the parameter space excluded by CMS and ATLAS is essentially already excluded by the indirect constraints and the fertile region of parameter space has yet to be explored. We also emphasize that gluino masses as low as 400 GeV but for squark masses much larger than the gluino mass remain unconstrained and further that much of the hyperbolic branch of radiative electroweak symmetry breaking, with low values of the Higgs mixing parameter μ, is essentially untouched by the recent LHC analysis. [Copyright &y& Elsevier]

Abstract: We systematically establish the hyper-surface within the , top quark mass , universal gaugino mass , and vector-like mass parameter volume which is compatible with the application of the no-scale supergravity boundary conditions, particularly the vanishing of the Higgs bilinear soft term , near to the Planck mass at the point of ultimate -lipped unification. is elevated from the penultimate partial unification near the traditional GUT scale at a mass by the inclusion of extra -theory derived heavy vector-like multiplets. We demonstrate that simultaneous adherence to all current experimental constraints, most importantly contributions to the muon anomalous magnetic moment , the branching ratio limit on , and the 7-year WMAP relic density measurement, dramatically reduces the allowed solutions to a highly non-trivial “golden strip” with , , , and , effectively eliminating all extraneously tunable model parameters. We emphasize that the consonance of the theoretically viable range with the experimentally established value is an independently correlated “postdiction”. The predicted range of is testable at the Large Hadron Collider (LHC). The partial lifetime for proton decay in the leading channels falls around , testable at the future DUSEL and Hyper-Kamiokande facilities. [Copyright &y& Elsevier]

The CMS and ATLAS Collaborations have recently published the results of initial direct LHC searches for supersymmetry analyzing ∼35/pb of data taken at 7 TeV in the centre of mass. We incorporate these results into a frequentist analysis of the probable ranges of parameters of simple versions of the minimal supersymmetric extension of the Standard Model (MSSM), namely the constrained MSSM (CMSSM), a model with common non-universal Higgs masses (NUHM1), the very constrained MSSM (VCMSSM) and minimal supergravity (mSUGRA). We present updated predictions for the gluino mass, $m_{\tilde{g}}$, the light-Higgs boson mass, M, BR( B→ μ μ) and the spin-independent dark matter scattering cross section, $\sigma^{\mathrm{SI}}_{p}$. The CMS and ATLAS data make inroads into the CMSSM, NUHM1 and VCMSSM (but not mSUGRA) parameter spaces, thereby strengthening previous lower limits on sparticle masses and upper limits on $\sigma^{\mathrm{SI}}_{p}$ in the CMSSM and VCMSSM. The favoured ranges of BR( B→ μ μ) in the CMSSM, VCMSSM and mSUGRA are close to the Standard Model, but considerably larger values of BR( B→ μ μ) are possible in the NUHM1. Applying the CMS and ATLAS constraints improves the consistency of the model predictions for M with the LEP exclusion limits. [ABSTRACT FROM AUTHOR]

No-scale supergravity is a framework where it is possible to naturally explain radiative electroweak symmetry breaking and correlate it with the effective SUSY breaking scale. Many string compactifications have a classical no-scale structure, resulting in a one-parameter model (OPM) for the supersymmetry breaking soft terms, which results in a highly constrained subset of mSUGRA. We investigate the allowed supersymmetry parameter space for a generic one-parameter model taking into account the most recent experimental constraints. We also survey the possible signatures which may be observable at the Large Hadron Collider (LHC). Finally, we compare collider signatures of OPM to those from a model with non-universal soft terms, in particular those of an intersecting D6-brane model. [ABSTRACT FROM AUTHOR]

Abstract: In Grand Unified Theories (GUTs), the Standard Model (SM) gauge couplings need not be unified at the GUT scale due to the high-dimensional operators. Considering gravity mediated supersymmetry breaking, we study for the first time the generic gauge coupling relations at the GUT scale, and the general gaugino mass relations which are valid from the GUT scale to the electroweak scale at one loop. We define the index k for these relations, which can be calculated in GUTs and can be determined at the Large Hadron Collider and the future International Linear Collider. Thus, we give a concrete definition of the GUT scale in these theories, and suggest a new way to test general GUTs at future experiments. We also discuss five special scenarios with interesting possibilities. With our generic formulae, we present all the GUT-scale gauge coupling relations and all the gaugino mass relations in the and models, and calculate the corresponding indices k. Especially, the index k is 5/3 in the traditional and models that have been studied extensively so far. Furthermore, we discuss the field theory realization of the flux effects on the SM gauge kinetic functions in F-theory GUTs, and calculate their indices k as well. [ABSTRACT FROM AUTHOR]

Supersymmetry and extra dimensions are the two most promising candidates for new physics at the TeV scale. Supersymmetric particles or extra-dimensional effects could soon be observed at the Large Hadron Collider. We propose a simple but effective method to discriminate the two models: the analysis of isolated leptons with high transverse momentum. Black hole events are simulated with the CATFISH black hole generator. Supersymmetry simulations use a combination of PYTHIA and ISAJET, the latter providing the mass spectrum. Our results show that the measure of the dilepton invariant mass provides a promising signature to differentiate supersymmetry and black hole events at the Large Hadron Collider. Analysis of event-shape variables and multilepton events complement and strengthen this conclusion. [ABSTRACT FROM AUTHOR]