Search

Among the most promising prospects for a theory of physics beyond the standard model is supersymmetry. In this talk, the latest results from the CMS experiment at the LHC on searches for supersymmetry produced through strong production and electroweak production channels are presented using 20/fb of data from the 8 TeV LHC run, with particular focus on gluino and stop searches. [ABSTRACT FROM AUTHOR]

A phenomenological model is presented which can be obtained as a local Swiss-Cheese Calabi-Yau string-theoretic compactification with a mobile D3- and fluxed stacks of wrapped D7-branes. It provides a natural realization of (reversed) μ-split-like supersymmetry wherein the squarks, sleptons, gauginos, higgsino and one of the Higgs doublets are very heavy while with some fine tuning, it is possible to obtain another light Higgs of mass 125 GeV. We discuss the role of the heavy quarks /sleptons and the light Higgs in (i) obtaining long-lived gluinos (a natural consequence of split SUSY), (ii) verifying that the NLSP decays to the gravitino LSP respects the BBN constraints with the lifetime of the LSP (gravitino) coming out to be of the order or larger than the age of the Universe, (iii) getting gravitino relic abundance of around 0.1 and (iv) obtaining electronic EDM close to the experimental upper bounds. [ABSTRACT FROM AUTHOR]

We compare and contrast three different sensitivity measures, $$\Delta _{\mathrm{EW}}^{-1}$$ , $$\Delta _{\mathrm{HS}}^{-1}$$ and $$\Delta _{\mathrm{BG}}^{-1}$$ that have been used in discussions of fine-tuning. We argue that though not a fine-tuning measure, $$\Delta _{\mathrm{EW}}$$ , which is essentially determined by the particle spectrum, is important because $$\Delta _{\mathrm{EW}}^{-1}$$ quantifies the minimum fine-tuning present in any theory with a specified spectrum. We emphasize the critical role of incorporating correlations between various model parameters in discussions of fine-tuning. We provide toy examples to show that if we can find high scale theories with specific correlations amongst parameters, the value of the traditional fine-tuning measure $$\Delta _{\mathrm{BG}}^{-1}$$ (which differs significantly from $$\Delta _{\mathrm{HS}}^{-1}$$ only when these correlations are important) would be close to $$\Delta _{\mathrm{EW}}^{-1}$$ . We then set up the radiatively driven natural supersymmetric framework that we advocate for phenomenological analyses of natural models of supersymmetry and review the implications of naturalness for LHC and ILC searches for SUSY as well as for searches for SUSY dark matter. [ABSTRACT FROM AUTHOR]

Results of searches for supersymmetry in events with significant missing transverse energy and two isolated leptons with the ATLAS experiment at the LHC are presented. Three analyses are presented here, the first two are analyses with leptons of opposite charge and same charge, respectively. The third one is an analysis that searches for an excess of same-flavour opposite-charge lepton pairs over those of different-flavour. Data corresponding to an integrated luminosity of 1 fb are analysed. [ABSTRACT FROM AUTHOR]

The LHC has delivered several fb of data in spring and summer 2011, opening new windows of opportunity for discovering phenomena beyond the Standard Model. A summary of the searches conducted by the ATLAS and CMS experiments based on about 1 fb of data is presented. [ABSTRACT FROM AUTHOR]

With data collected during the first half of the 2011 pp run of the Large Hadron Collider at $\sqrt{s} = 7$ TeV, a substantial data sample of high p triggers, corresponding to an integrated luminosity of 1.08 fb, has been collected by the ATLAS detector. Measurements of the production of top-quark pairs and single top quarks in different channels, the top-quark mass, the top-quark pair charge asymmetry and spin correlations, and the W helicity fractions in top-quark decays are presented, as well as two searches for new physics effects involving top-quark pairs. [ABSTRACT FROM AUTHOR]

Results are presented on a search for charged massive long-lived particles (CMLLPs), based on 5.2 fb of integrated luminosity collected with the D0 detector at the Fermilab Tevatron $p\!\bar{p}$ collider. This search selects events in which one or more particles are reconstructed as muons but their speed and ionization energy loss (d E/d x) are different from muons produced in beam-beam collisions. CMLLPs have been predicted by several theories of physics beyond the Standard Model. In this search we exclude pair-produced long-lived gaugino-like charginos with masses below 251 GeV and higgsino-like charginos with masses below 230 GeV at 95% CL, as well as long-lived stop quarks with masses below 265 GeV. We place cross-section limits on long-lived staus as 0.04 to 0.006 pb for stau masses in the range 100 to 300 GeV. [ABSTRACT FROM AUTHOR]

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 investigate the prospects for the discovery of a neutral Higgs boson produced with one bottom quark followed by Higgs decay into a pair of bottom quarks at the CERN Large Hadron Collider (LHC) and the Fermilab Tevatron Collider. We work within the framework of the minimal supersymmetric standard model. The dominant physics background is calculated with realistic acceptance cuts and efficiencies including the production of , , (; ), , and . Promising results are found for the CP-odd pseudoscalar () and the heavier CP-even scalar () Higgs bosons with masses up to 800 GeV for the LHC with an integrated luminosity (L) of and up to 1 TeV for . [Copyright &y& Elsevier]

Abstract: We report the results of a search for associated production of charginos and neutralinos using a data set corresponding to an integrated luminosity of 2.3 fb−1 collected with the DØ experiment during Run II of the Tevatron proton–antiproton collider. Final states containing three charged leptons and missing transverse energy are probed for a signal from supersymmetry with four dedicated trilepton event selections. No evidence for a signal is observed, and we set limits on the product of production cross section and leptonic branching fraction. Within minimal supergravity, these limits translate into bounds on and that are well beyond existing limits. [Copyright &y& Elsevier]

Abstract: A search for supersymmetric partners of quarks is performed in the topology of multijet events accompanied by at least one tau lepton decaying hadronically and large missing transverse energy. Approximately 1 fb−1 of collision data from the Fermilab Tevatron Collider at a center of mass energy of 1.96 TeV recorded by the DØ detector is analyzed. Results are combined with the previously published DØ inclusive search for squarks and gluinos. No evidence of physics beyond the Standard Model is found and lower limits on the squark mass up to 410 GeV are derived in the framework of minimal supergravity with , and , in the region where decays to tau leptons dominate. Gaugino masses are excluded up to 172 GeV. [Copyright &y& Elsevier]

Abstract: We investigate, which lightest supersymmetric particles can be obtained via a non-vanishing lepton- or baryon-number violating operator at the grand unification scale within the R-parity violating minimal supergravity model. We employ the full one-loop renormalization group equations. We take into account restrictions from the anomalous magnetic moment of the muon and , as well as collider constraints from LEP and the Tevatron. We also consider simple deformations of minimal supergravity models. [Copyright &y& Elsevier]

Abstract: The modest addition of the dimension-5 term to the superpotential of the minimal supersymmetric standard model (MSSM) originated from physics beyond the MSSM (BMSSM) has a significant impact on the scenario of the Higgsino-dominated neutralino state being the lightest supersymmetric particle (LSP). It increases the mass difference between the LSP and the lighter chargino as well as that between the LSP and the second-lightest neutralino. This enhances the LHC discovery potential of the chargino and neutralino decays, producing more energetic charged leptons or pions than the decays without the BMSSM corrections. Furthermore, the coannihilation between the lighter chargino or second-lightest neutralino and the LSP is reduced substantially such that the LSP mass does not have to be very heavy. Consequently, an almost pure Higgsino LSP with its mass in the BMSSM can account for all the relic density of cold dark matter in the Universe unless is too large. [Copyright &y& Elsevier]

Abstract: We report results of a search for the pair production of the lightest supersymmetric partner of the top quark, , using a data set corresponding to an integrated luminosity of 1 fb−1 collected by the DØ detector at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron collider. Both scalar top quarks are assumed to decay into a b quark, a charged lepton and a scalar neutrino. The search is performed in the electron plus muon and dielectron final states. The signal topology consists of two isolated leptons, missing transverse energy, and jets. We find no evidence for this process and exclude regions of parameter space in the framework of the minimal supersymmetric standard model. [Copyright &y& Elsevier]

Abstract: A search for pair production of the lightest supersymmetric partner of the top quark, , is performed in the lepton+jets channel using 0.9 fb−1 of data collected by the DØ experiment. Kinematic differences between and the dominant top quark pair production background are used to separate the two processes. First limits from Run II of the Fermilab Tevatron Collider for the scalar top quark decaying to a chargino and a b quark () are obtained for scalar top quark masses of 130–190 GeV and chargino masses of 90–150 GeV. [Copyright &y& Elsevier]

Abstract: We present an extensive analysis of gauge-mediated supersymmetry breaking models with minimal and non-minimal flavour violation. We first demonstrate that low-energy, precision electroweak, and cosmological constraints exclude large “collider-friendly” regions of the minimal parameter space. We then discuss various possibilities how flavour violation, although naturally suppressed, may still occur in gauge-mediation models. The introduction of non-minimal flavour violation at the electroweak scale is shown to relax the stringent experimental constraints, so that benchmark points, that are also cosmologically viable, can be defined and their phenomenology, i.e. squark and gaugino production cross sections with flavour violation, at the LHC can be studied. [Copyright &y& Elsevier]

Abstract: We suggest an NMSSM scenario, motivated by dark matter constraints, that may disguise itself as a much simpler mSUGRA scenario at the LHC. We show how its non-minimal nature can be revealed, and the bino–singlino mass difference measured, by looking for soft leptons. [Copyright &y& Elsevier]

Abstract: Determining the spin of new particles is critical in identifying the true theory among various extensions of the Standard Model at the next generation of colliders. Quantum interference between different helicity amplitudes was shown to be effective when the final state is fully reconstructible. However, many interesting new physics processes allow only for partial reconstruction. In this Letter, we show how the interference effect can be unambiguously extracted even in processes that have two-fold ambiguity, by considering the correlation between two decay planes in collisions. [Copyright &y& Elsevier]

The energy frontier is currently at the Fermilab Tevatron accelerator, which collides protons and antiprotons at a center-of-mass energy of 1.96 TeV. The luminosity delivered to the CDF and DØ experiments has now surpassed the 4 fb−1. This paper reviews the most recent direct searches for Higgs bosons and beyond-the-standard-model ( BSM) physics at the Tevatron. The results reported correspond to an integrated luminosity of up to 2.5 fb−1 of Run II data collected by the two Collaborations. Searches covered include the standard model ( SM) Higgs boson (including sensitivity projections), the neutral Higgs bosons in the minimal supersymmetric extension of the standard model ( MSSM), charged Higgs bosons and extended Higgs models, supersymmetric decays that conserve or violate R-parity, gauge-mediated supersymmetric breaking models, long-lived particles, leptoquarks, compositeness, extra gauge bosons, extra dimensions, and finally signature-based searches. Given the excellent performance of the collider and the continued productivity of the experiments, the Tevatron physics potential looks promising for discovery with the coming larger data sets. In particular, evidence for the SM Higgs boson could be obtained if its mass is light or near 160 GeV. The observed (expected) upper limits are currently a factor of 3.7 (3.3) higher than the expected SM Higgs boson cross section at m H=115 GeV and 1.1 (1.6) at m H=160 GeV at 95% C.L. [ABSTRACT FROM AUTHOR]

Supersymmetry is one of the best-motivated candidates for physics beyond the standard model that might be discovered at the LHC. There are many reasons to expect that it may appear at the TeV scale, in particular because it provides a natural cold dark-matter candidate. The apparent discrepancy between the experimental measurement of g μ−2 and the standard-model value calculated using low-energy e+ e− data favours relatively light sparticles, accessible to the LHC. A global likelihood analysis including this, other electroweak precision observables and B decay observables suggests that the LHC might be able to discover supersymmetry with 1/fb or less of integrated luminosity. The LHC should be able to discover supersymmetry via the classic missing-energy signature, or in alternative phenomenological scenarios. The prospects for discovering supersymmetry at the LHC look very good. [ABSTRACT FROM AUTHOR]

I discuss part of the program of work towards discoveries at the LHC with seeds for orientation and navigation in the parameter space given an anticipated multitude of excesses at start-up. [ABSTRACT FROM AUTHOR]

The existence of dark matter provides strong evidence for physics beyond the standard model. Extending the standard model with the Peccei–Quinn symmetry and/or supersymmetry, compelling dark-matter candidates appear. For the axion, the neutralino, the gravitino, and the axino, I review primordial production mechanisms, cosmological and astrophysical constraints, experimental searches, and prospects for experimental identification. [ABSTRACT FROM AUTHOR]

Abstract: We apply a rigorous statistical analysis to the Constrained MSSM to derive the most probable ranges of the diffuse gamma radiation flux from the direction of the Galactic center and of the positron flux from the Galactic halo due to neutralino dark matter annihilation, for several different choices of the halo model and propagation model parameters. We find that, for a specified halo profile, and assuming flat priors, the 68% probability range of the integrated γ-ray flux spans about one order of magnitude, while the 95% probability range can be much larger and extend over four orders of magnitude (even exceeding five for a tiny region at small neutralino mass). The detectability of the signal by GLAST depending primarily on the cuspiness of the halo profile. The positron flux, on the other hand, appears to be too small to be detectable by PAMELA, unless the boost factor is at least of order ten and/or the halo profile is extremely cuspy. We also briefly discuss the sensitivity of our results to the choice of priors. [Copyright &y& Elsevier]

In grand-unified theories (GUT), non-universal boundary conditions for the gaugino masses may arise at the unification scale and may affect the observability of the neutral MSSM Higgs bosons ( h/ H/ A) at the LHC. The implications of such non-universal gaugino masses are investigated for Higgs boson production in the SUSY cascade decay chain $\tilde{g}\rightarrow \tilde{q}q$ , $\tilde{q}\rightarrow \tilde{\chi_{2}}q$ , $\tilde{\chi_{2}}\rightarrow \tilde{\chi_{1}}h/H/A$ , $h/H/A\rightarrow b\bar{b}$ produced in pp interactions. In the singlet representation with universal gaugino masses only the light Higgs boson can be produced in this cascade with the parameter region of interest for us, while with non-universal gaugino masses heavy neutral MSSM Higgs boson production may dominate. The allowed parameter space in the light of the WMAP constraints on the cold dark-matter relic density is investigated in the above scenarios for gaugino mass parameters. We also demonstrate that combination of representations can give the required amount of dark matter in any point of the parameter space. In the non-universal case we show that heavy Higgs bosons can be detected in the cascade studied in parameter regions with the WMAP preferred neutralino relic density. [ABSTRACT FROM AUTHOR]

Abstract: The search for the top squark () within the kinematic reach of Tevatron Run II is of great contemporary interest. Such a can explain the baryon asymmetry of the universe provided . Moreover if is small, where is the lightest supersymmetric particle (LSP), the dark matter relic density as obtained from the WMAP data may be explained via -LSP coannihilation. In this scenario the decay is likely to occur with 100% branching ratio but for small Δm the conventional signal becomes unobservable. We propose a new search strategy based on the signature accompanied by an isolated cluster of energy which arises from a decaying heavy particle with characteristic decay length. Our preliminary simulations with Pythia indicate that for this signal may be observable while somewhat lager may still provide hints of new physics. [Copyright &y& Elsevier]

Abstract: The sensitivity of the lightest supersymmetric particle relic density calculation to the variation of the cosmological expansion rate before nucleosynthesis is discussed. Such a modification of the expansion rate, even extremely modest and with no consequence on the cosmological observations, can greatly enhance the calculated relic density, and therefore change the constraints on the SUSY parameter space drastically. We illustrate this variation in two examples of SUSY models, and show that it is unsafe to use the lower bound of the WMAP limits in order to constrain supersymmetry. We therefore suggest to use only the upper value . [Copyright &y& Elsevier]

Abstract: We study the CP-violating terms of the spin–spin correlations in chargino production , and their subsequent two-body decays into sneutrinos plus leptons. We propose novel CP-sensitive observables with the help of T-odd products of the spin–spin terms. These terms depend on the polarizations of both charginos, with one polarization perpendicular to the production plane. We identify two classes of CP-sensitive observables; one requires the reconstruction of the production plane, the other not. Our framework is the Minimal Supersymmetric Standard Model with complex parameters. [Copyright &y& Elsevier]

Abstract: Simple SUSY GUT models based on the gauge group require Yukawa coupling unification, in addition to gauge coupling and matter unification. The Yukawa coupling unification places strong constraints on the expected superparticle mass spectrum, with scalar masses while gaugino masses are quite light. A problem generic to all supergravity models comes from overproduction of gravitinos in the early universe: if gravitinos are unstable, then their late decays may destroy the predictions of Big Bang nucleosynthesis. We present a Yukawa-unified SUSY GUT scenario which avoids the gravitino problem, gives rise to the correct matter–antimatter asymmetry via non-thermal leptogenesis, and is consistent with the WMAP-measured abundance of cold dark matter due to the presence of an axino LSP. To maintain a consistent cosmology for Yukawa-unified SUSY models, we require a re-heat temperature , an axino mass around , and a PQ breaking scale . [Copyright &y& Elsevier]

Abstract: We present a search for the pair production of scalar top quarks, , using 995 pb−1 of data collected in collisions with the DØ detector at the Fermilab Tevatron Collider at . Both scalar top quarks are assumed to decay into a charm quark and a neutralino (), where is the lightest supersymmetric particle. This leads to a final state with two acoplanar charm jets and missing transverse energy. We find the yield of such events to be consistent with the standard model expectation, and exclude sets of and masses at the 95% C.L. that substantially extend the domain excluded by previous searches. [Copyright &y& Elsevier]

Abstract: We explore the Higgs sector in the supersymmetric economical 3–3–1 model and find new features in this sector. The charged Higgs sector is revised, i.e., in difference of the previous work, the exact eigenvalues and states are obtained without any approximation. In this model, there are three Higgs bosons having masses equal to that of the gauge bosons—the W and extra X and Y. There is one scalar boson with mass of 91.4 GeV, which is closed to the Z boson mass and in good agreement with present limit: 89.8 GeV at 95% CL. The condition of eliminating for charged scalar tachyon leads to splitting of VEV at the first symmetry breaking, namely, . The interactions among the Standard Model gauge bosons and scalar fields in the framework of the supersymmetric economical 3–3–1 model are presented. From these couplings, at some limit, almost scalar Higgs fields can be recognized in accordance with the Standard Model. The hadronic cross section for production of the bilepton charged Higgs boson at the CERN LHC in the effective vector boson approximation is calculated. Numerical evaluation shows that the cross section can exceed 35.8 fb. [Copyright &y& Elsevier]

Abstract: We present a precision calculation of the transverse-momentum and invariant-mass distributions for supersymmetric particle pair production at hadron colliders, focusing on Drell–Yan like slepton pair and slepton–sneutrino associated production at the CERN Large Hadron Collider. We implement the joint resummation formalism at the next-to-leading logarithmic accuracy with a process-independent Sudakov form factor, thus ensuring a universal description of soft-gluon emission, and consistently match the obtained result with the pure perturbative result at the first order in the strong coupling constant, i.e. at . We also implement three different recent parameterizations of non-perturbative effects. Numerically, we give predictions for production and compare the resummed cross section with the perturbative result. The dependence on unphysical scales is found to be reduced, and non-perturbative contributions remain small. [Copyright &y& Elsevier]

Abstract: A data sample corresponding to an integrated luminosity of 2.1 fb−1 collected by the DØ detector at the Fermilab Tevatron Collider was analyzed to search for squarks and gluinos produced in collisions at a center-of-mass energy of 1.96 TeV. No evidence for the production of such particles was observed in topologies involving jets and missing transverse energy, and 95% C.L. lower limits of 379 GeV and 308 GeV were set on the squark and gluino masses, respectively, within the framework of minimal supergravity with , , and . The corresponding previous limits are improved by 54 GeV and 67 GeV. [Copyright &y& Elsevier]

Abstract: We report results of a search for supersymmetry (SUSY) with gauge-mediated symmetry breaking in di-photon events collected by the D0 experiment at the Fermilab Tevatron Collider in 2002–2006. In 1.1 fb−1 of data, we find no significant excess beyond the background expected from the standard model and set the most stringent lower limits to date for a standard benchmark model on the lightest neutralino and chargino masses of 125 GeV and 229 GeV, respectively, at 95% confidence. [Copyright &y& Elsevier]

Abstract: Data collected by the D0 detector at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron Collider have been used to search for pair production of the lightest supersymmetric partner of the top quark decaying into . The search is performed in the and μμ final states. No evidence for this process has been found in data samples of approximately 400 pb−1. The domain in the [] plane excluded at the 95% C.L. is substantially extended by this search. [Copyright &y& Elsevier]

Abstract: Supersymmetry (SUSY) remains one of the leading candidates for physics beyond the Standard Model, and the search for SUSY will be a central focus of future collider experiments. Complementary information on the viability and character of SUSY can be obtained via the analysis of precision electroweak measurements. In this review, we discuss the prospective implications for SUSY of present and future low energy precision studies. [Copyright &y& Elsevier]

Abstract: Results are presented from the first underground data run of ZEPLIN-II, a 31kg two-phase xenon detector developed to observe nuclear recoils from hypothetical weakly interacting massive dark matter particles. Discrimination between nuclear recoils and background electron recoils is afforded by recording both the scintillation and ionisation signals generated within the liquid xenon, with the ratio of these signals being different for the two classes of event. This ratio is calibrated for different incident species using an AmBe neutron source and 60Co γ-ray sources. From our first 31 live days of running ZEPLIN-II, the total exposure following the application of fiducial and stability cuts was 225kg×days. A background population of radon progeny events was observed in this run, arising from radon emission in the gas purification getters, due to radon daughter ion decays on the surfaces of the walls of the chamber. An acceptance window, defined by the neutron calibration data, of 50% nuclear recoil acceptance between 5keVee and 20keVee, had an observed count of 29 events, with a summed expectation of 28.6±4.3 γ-ray and radon progeny induced background events. These figures provide a 90% c.l. upper limit to the number of nuclear recoils of 10.4 events in this acceptance window, which converts to a WIMP–nucleon spin-independent cross-section with a minimum of 6.6×10−7 pb following the inclusion of an energy-dependent, calibrated, efficiency. A second run is currently underway in which the radon progeny will be eliminated, thereby removing the background population, with a projected sensitivity of 2×10−7 pb for similar exposures as the first run. [Copyright &y& Elsevier]

Abstract: We developed a three-dimensional gaseous tracking device and performed a direction-sensitive dark matter search in a surface laboratory. By using 150 Torr carbon-tetrafluoride (CF4) gas, we obtained a sky map drawn with the recoil directions of the carbon and fluorine nuclei, and set the first limit on the spin-dependent WIMP (Weakly Interacting Massive Particles)-proton cross section by a direction-sensitive method. Thus, we showed that a WIMP-search experiment with a gaseous tracking device can actually set limits. Furthermore, we demonstrated that this method will potentially play a certain role in revealing the nature of dark matter when a low-background large-volume detector is developed. [Copyright &y& Elsevier]

The LHC (CMS) discovery potential in the search for supersymmetry and lepton-flavor violation in neutralino decays using the e ± µ∓ + E signature is studied. A detailed study is done for the CMS test points LM1-LM9. It is shown that, for the point LM1, it is possible to detect lepton-flavor violation in neutralino decays with lepton-flavor-violating branching Br( $$\tilde \chi _2^0 $$ → µ± e ∓ $$\tilde \chi _1^0 $$ ) ≥ 0.04 Br( $$\tilde \chi _2^0 $$ → e + e − $$\tilde \chi _1^0 $$ , µ+ µ− $$\tilde \chi _1^0 $$ ) for an integral luminosity of 10 fb−1. The discovery potential in the mSUGRA-SUSY scenario with tan β = 10, sgn(µ) = + in the ( m 0, m 1/2) plane using the e ± µ∓ + E signature is determined. [ABSTRACT FROM AUTHOR]

Abstract: The first underground data run of the ZEPLIN-II experiment has set a limit on the nuclear recoil rate in the two-phase xenon detector for direct dark matter searches. In this Letter the results from this run are converted into the limits on spin-dependent WIMP-proton and WIMP-neutron cross-sections. The minimum of the curve for WIMP-neutron cross-section corresponds to at a WIMP mass of around 65 GeV. [Copyright &y& Elsevier]

Abstract: This paper presents our interpretation and understanding of the different backgrounds in the EDELWEISS-I data sets. We analyze in detail the several populations observed, which include gammas, alphas, neutrons, thermal sensor events and surface events, and try to combine all data sets to provide a coherent picture of the nature and localization of the background sources. In light of this interpretation, we draw conclusions regarding the background suppression scheme for the EDELWEISS-II phase. [Copyright &y& Elsevier]

Motivations for introducing supersymmetry in high-energy physics are discussed along with the possibility of discovering supersymmetry at the Large Hadron Collider (LHC). Various regions of the space of parameters of the minimal supersymmetric standard model are analyzed, and phenomenological manifestations of supersymmetry inherent in these regions are discussed. The discovery potential of LHC at the planned luminosity is indicated for various channels. [ABSTRACT FROM AUTHOR]

Abstract: We present a first and extensive study of threshold resummation effects for supersymmetric (SUSY) particle production at hadron colliders, focusing on Drell–Yan like slepton-pair and slepton–sneutrino associated production. After confirming the known next-to-leading order (NLO) QCD corrections and generalizing the NLO SUSY-QCD corrections to the case of mixing squarks in the virtual loop contributions, we employ the usual Mellin N-space resummation formalism with the minimal prescription for the inverse Mellin-transform and improve it by resumming -suppressed and a class of N-independent universal contributions. Numerically, our results increase the theoretical cross sections by 5 to 15% with respect to the NLO predictions and stabilize them by reducing the scale dependence from up to 20% at NLO to less than 10% with threshold resummation. [Copyright &y& Elsevier]

Abstract: The supersymmetric extension of the economical 3–3–1 model is presented. The constraint equations and the gauge boson identification establish a relation between the vacuum expectation values (VEVs) at the top and bottom elements of the Higgs triplet χ and its supersymmetric counterpart . Because of this relation, the exact diagonalization of neutral gauge boson sector has been performed. The gauge bosons and their associated Goldstone ones mix in the same way as in non-supersymmetric version. This is also correct in the case of gauginos. The eigenvalues and eigenstates in the Higgs sector are derived. The model contains a heavy neutral Higgs boson with mass equal to those of the neutral non-Hermitian gauge boson and a charged scalar with mass equal to those of the W boson in the Standard Model, i.e., . This result is in good agreement with the present estimation: , . We also show that the boson sector and the fermion sector gain masses in the same way as in the non-supersymmetric case. [Copyright &y& Elsevier]

Abstract: Slepton pairs can be produced in vector–boson fusion processes at hadron colliders. The next-to-leading order QCD corrections to the electroweak production cross section for jets at order have been calculated and implemented in an NLO parton-level Monte Carlo program. Numerical results are presented for the CERN large hadron collider. [Copyright &y& Elsevier]

Abstract: We investigate the fermionic decays of top squarks and bottom squarks in the Minimal Supersymmetric Standard Model with complex parameters , μ, and . In the analysis we particularly take into account the cosmological bounds imposed by WMAP data. We plot the CP phase dependences of stop and sbottom decay widths. [Copyright &y& Elsevier]

Abstract: A search for the pair production of scalar top quarks, , has been performed in 360 pb−1 of data from collisions at a center-of-mass energy of 1.96 TeV, collected by the DØ detector at the Fermilab Tevatron collider. The decay mode considered is , where is the lightest supersymmetric particle. The topology analyzed therefore consists of a pair of acoplanar heavy-flavor jets with missing transverse energy. The data and standard model expectation are in agreement, and a 95% C.L. exclusion domain in the () plane has been determined, extending the domain excluded by previous experiments. [Copyright &y& Elsevier]

Abstract: We review the theoretical motivations and experimental status of searches for stable massive particles (SMPs) which could be sufficiently long-lived as to be directly detected at collider experiments. The discovery of such particles would address a number of important questions in modern physics including the origin and composition of dark matter in the universe and the unification of the fundamental forces. This review describes the techniques used in SMP-searches at collider experiments and the limits so far obtained on the production of SMPs which possess various colour, electric and magnetic charge quantum numbers. We also describe theoretical scenarios which predict SMPs along with the phenomenology needed to model their production at colliders and interactions with matter. In addition, the interplay between collider searches and open questions in cosmology such as dark matter composition is addressed. [Copyright &y& Elsevier]

Abstract: If the energy density of the Universe before nucleosynthesis is dominated by a scalar field ϕ that decays and reheats the plasma to a low reheating temperature , neutralinos may be warm dark matter particles. We study this possibility and derive the conditions on the production mechanism and on the supersymmetric spectrum for which it is viable. Large values of the μ parameter and of the slepton masses are characteristic features of these models. We compute the expected direct detection cross sections and point out that split-SUSY provides a natural framework for neutralino warm dark matter. [Copyright &y& Elsevier]