908 research outputs found

    Impact of CMS Multi-jets and Missing Energy Search on CMSSM Fits

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    Recent CMS data significantly extend the direct search exclusion for supersymmetry. We examine the impact of such data on global fits of the constrained minimal supersymmetric standard model (CMSSM) to indirect and cosmological data. By simulating supersymmetric signal events at the LHC, we construct a likelihood map for the recent CMS data, validating it against the exclusion region calculated by the experiment itself. A previous CMSSM global fit is then re-weighted by our likelihood map. The CMS results nibble away at the high fit probability density region, transforming probability distributions for the scalar and gluino masses. The CMS search has a non-trivial effect on tan beta due to correlations between the parameters implied by the fits to indirect data.Comment: 15 pages, 8 figures. v2 has an appendix added with further checks of A0-tan beta independence, expected sensitivity curves added to Fig 2a and typos fixed. v3 has extended discussion of re-weighting procedure and egregious points in the appendix. v4 minor changes due to very strict (but good) refere

    Theoretical Uncertainties in Sparticle Mass Predictions

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    We contrast the sparticle spectra obtained from three modern publicly available codes along model lines in minimal supersymmetric standard model (MSSM) parameter space. From this we gain an idea of the uncertainties involved with sparticle spectra calculations. The differences in predicted sparticle masses are typically at the several percent-level. In the focus-point scenario, there are differences of 30% in the weak gaugino masses. These uncertainties need to be reduced in order to obtain accurate information about fundamental models of supersymmetry breaking.Comment: revTex4 style. Softsusy homepage is at http://allanach.home.cern.ch/allanach/softsusy.html Written for Snowmass 2001. Replaced version has updated reference. 3 pages, 3 figure

    Large Hadron Collider constraints on a light baryon number violating sbottom coupling to a top and a light quark

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    We investigate a model of R-parity violating (RPV) supersymmetry in which the right-handed sbottom is the lightest supersymmetric particle, and a baryon number violating coupling involving a top is the only non-negligible RPV coupling. This model evades proton decay and flavour constraints. We consider in turn each of the couplings lambda"_{313} and lambda"_{323} as the only non-negligible RPV coupling, and we recast two recent Large Hadron Collider (LHC) measurements and searches (CMS top transverse momentum p_T(t) spectrum and ATLAS multiple jet resonance search) in the form of constraints on the mass-coupling parameter planes. We delineate a large region in the parameter space of the mass of the sbottom (m_{b_R}) and the lambda"_{313} coupling that is ruled out by the measurements, as well as a smaller region in the parameter space of m_{b_R} and lambda"_{323}. A certain region of the m_{b_R}-lambda"_{313} parameter space was previously found to successfully explain the anomalously large ttbar forward backward asymmetry measured by Tevatron experiments. The entire region is excluded at the 95% CL by CMS measurements of the top p_T spectrum. We also present p_T(ttbar) distributions of the forward-backward asymmetry for this model.Comment: 9 pages, 9 figures. v2 has minor corrections, in part due to extra diagrams at order alpha_s^2 lamba''^

    Comparison of SUSY mass spectrum calculations

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    We provide a comparison of the results of four SUSY mass spectrum calculations in mSUGRA: Isajet, SuSpect, SoftSusy, and SPheno. In particular, we focus on the high tan(beta) and focus point regions, where the differences in the results are known to be large.Comment: Contribution to SUSY02, 17-23 Jun 2002, DESY Hamburg, 7 page

    Quasi-Fixed Points and Charge and Colour Breaking in Low Scale Models

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    We show that the current LEP2 lower bound upon the minimal supersymmetric standard model (MSSM) lightest Higgs mass rules out quasi-fixed scenarios for string scales between 10^6 and 10^{11} GeV unless the heaviest stop mass is more than 2 TeV. We consider the implications of the low string scale for charge and colour breaking (CCB) bounds in the MSSM, and demonstrate that CCB bounds from F and D-flat directions are significantly weakened. For scales less than 10^{10} GeV these bounds become merely that degenerate scalar mass squared values are positive at the string scale.Comment: 17 pages, 4 figures. Replacement has added discussion on errors due to alpha_s(MZ) errors, as well as deviations from the quasi-fixed point. Text has been clarifie

    The Case for Future Hadron Colliders From BK()μ+μB \to K^{(*)} \mu^+ \mu^- Decays

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    Recent measurements in BK()μ+μB \to K^{(*)} \mu^+ \mu^- decays are somewhat discrepant with Standard Model predictions. They may be harbingers of new physics at an energy scale potentially accessible to direct discovery. We estimate the sensitivity of future hadron colliders to the possible new particles that may be responsible for the anomalies: leptoquarks or ZZ^\primes. We consider luminosity upgrades for a 14 TeV LHC, a 33 TeV LHC, and a 100 TeV pppp collider such as the FCC-hh. Coverage of ZZ^\prime models is excellent: for narrow particles, with perturbative couplings that may explain the bb-decay results for ZZ^\prime masses up to 20 TeV, a 33 TeV 1 ab1^{-1} LHC is expected to cover most of the parameter space up to 8 TeV in mass, whereas the 100 TeV FCC-hh with 10 ab1^{-1} will cover all of it. A smaller portion of the leptoquark parameter space is covered by future colliders: for example, in a μ+μjj\mu^+\mu^-jj di-leptoquark search, a 100 TeV 10 ab1^{-1} collider has a projected sensitivity up to leptoquark masses of 12 TeV (extendable to 21 TeV with a strong coupling for single leptoquark production), whereas leptoquark masses up to 41 TeV may in principle explain the anomalies.Comment: 24 pages, 10 figures. v2: Improved discussion and references added, version submitted to JHE