370 research outputs found

    U(1)B3L2U(1)_{B_3-L_2} Explanation of the Neutral Current BB-Anomalies

    Get PDF
    We investigate a speculative short-distance force, proposed to explain discrepancies observed between measurements of certain neutral current decays of BB hadrons and their Standard Model predictions. The force derives from a spontaneously broken, gauged U(1)B3L2U(1)_{B_3-L_2} extension to the Standard Model, where the extra quantum numbers of Standard Model fields are given by third family baryon number minus second family lepton number. The only fields beyond those of the Standard Model are three right-handed neutrinos, a gauge field associated with U(1)B3L2U(1)_{B_3-L_2} and a Standard Model singlet complex scalar which breaks U(1)B3L2U(1)_{B_3-L_2}, a `flavon'. This simple model, via interactions involving a TeV scale force-carrying ZZ^\prime vector boson, can successfully explain the neutral current BB-anomalies whilst accommodating other empirical constraints. In an ansatz for fermion mixing, a combination of up-to-date BB-anomaly fits, LHC direct ZZ^\prime search limits and other bounds rule out the domain 0.15 TeV<MZ<< M_{Z^\prime} < 1.9 TeV at the 95%\% confidence level. For more massive ZZ^\primes, the model possesses a {\em flavonstrahlung}\ signal, where pppp collisions produce a ZZ^\prime and a flavon, which subsequently decays into two Higgs bosons

    The impact of the ATLAS zero-lepton, jets and missing momentum search on a CMSSM fit

    Full text link
    Recent ATLAS data significantly extend the exclusion limits for supersymmetric particles. We examine the impact of such data on global fits of the constrained minimal supersymmetric standard model (CMSSM) to indirect and cosmological data. We calculate the likelihood map of the ATLAS search, taking into account systematic errors on the signal and on the background. We validate our calculation against the ATLAS determinaton of 95% confidence level exclusion contours. A previous CMSSM global fit is then re-weighted by the likelihood map, which takes a bite at the high probability density region of the global fit, pushing scalar and gaugino masses up.Comment: 16 pages, 7 figures. v2 has bigger figures and fixed typos. v3 has clarified explanation of our handling of signal systematic

    Uncertainties in the lightest CP even Higgs boson mass prediction in the minimal supersymmetric standard model: fixed order versus effective field theory prediction

    Get PDF
    We quantify and examine the uncertainties in predictions of the lightest CPCP even Higgs boson pole mass MhM_h in the Minimal Supersymmetric Standard Model (MSSM), utilising current spectrum generators and including some three-loop corrections. There are two broadly different approximations being used: effective field theory (EFT) where an effective Standard Model (SM) is used below a supersymmetric mass scale, and a fixed order calculation, where the MSSM is matched to QCD×\timesQED at the electroweak scale. The uncertainties on the MhM_h prediction in each approach are broken down into logarithmic and finite pieces. The inferred values of the stop mass parameters are sensitively dependent upon the precision of the prediction for MhM_h. The fixed order calculation appears to be more accurate below a supersymmetry (SUSY) mass scale of MS1.2M_S \approx 1.2 TeV, whereas above this scale, the EFT calculation is more accurate. We also revisit the range of the lightest stop mass across fine-tuned parameter space that has an appropriate stable vacuum and is compatible with the lightest CPCP even Higgs boson hh being identified with the one discovered at the ATLAS and CMS experiments in 2012; we achieve a maximum value of 1011\sim 10^{11} GeV

    The calculation of sparticle and Higgs decays in the minimal and next-to-minimal supersymmetric standard models: SOFTSUSY4.0

    Get PDF
    We describe a major extension of the SOFTSUSY spectrum calculator to include the calculation of the decays, branching ratios and lifetimes of sparticles into lighter sparticles, covering the next-to-minimal supersymmetric standard model (NMSSM) as well as the minimal supersymmetric standard model (MSSM). This document acts as a manual for the new version of SOFTSUSY, which includes the calculation of sparticle decays. We present a comprehensive collection of explicit expressions used by the program for the various partial widths of the different decay modes in the appendix

    ATLAS diboson excess could be an R -parity violating dismuon excess

    Get PDF
    We propose a new possible explanation of the ATLAS di-boson excess: that it is due to heavy resonant slepton production, followed by decay into di-smuons. The smuon has a mass not too far from the W and Z masses, and so it is easily confused with W or Z bosons after its subsequent decay into di-jets, through a supersymmetry violating and R-parity violating interaction. Such a scenario is not currently excluded by other constraints and remains to be definitively tested in Run II of the LHC. Such light smuons can easily simultaneously explain the discrepancy between the measurement of the anomalous magnetic moment of the muon and the Standard Model prediction.This work of B.C.A. has been partially supported by STFC grant ST/L000385/1. The work of P.S.B.D. is supported in part by a TUM University Foundation Fellowship and the DFG cluster of excellence “Origin and Structure of the Universe”.This is the author accepted manuscript. The final version is available from the American Physical Society via http://dx.doi.org/10.1103/PhysRevD.93.03501

    The dark side of mSUGRA

    Get PDF
    We study the mu<0 branch of the minimal supergravity ansatz of the minimal supersymmetric standard model. The extent to which mu<0 is disfavoured compared to mu>0 in global fits is calculated with Markov Chain Monte Carlo methods and bridge sampling. The fits include state-of-the-art two-loop MSSM contributions to the electroweak observables M_W and sin^2 theta_w^l, as well as the anomalous magnetic moment of the muon (g-2)_mu, the relic density of dark matter and other relevant indirect observables. mu<0 is only marginally disfavoured in global fits and should be considered in mSUGRA analyses. We estimate that the ratio of probabilities is P(mu0)=0.07-0.16