367 research outputs found

    A hybrid method for determining particle masses at the Large Hadron Collider with fully identified cascade decays

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    A new technique for improving the precision of measurements of SUSY particle masses at the LHC is introduced. The technique involves kinematic fitting of events with two fully identified decay chains. We incorporate both event ETmiss constraints and independent constraints provided by kinematic end-points in experiment invariant mass distributions of SUSY decay products. Incorporation of the event specific information maximises the information used in the fit and is shown to reduce the mass measurement uncertainites by ~30% compared to conventional fitting of experiment end-point constraints for the SPS1a benchmark model.Comment: 10 pages, 2 .eps figures, JHEP3 styl

    Comparison of ground and aerial application of fungicide for control of Ascochyta blight in chickpeas

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    Non-Peer ReviewedAscochyta rabiei control from aerial and ground application was assessed near Saskatoon in 2003 and 2004. Each year, a site of about 12 ha was seeded to kabuli (cv. CDC Xena) chickpeas. At the first sign of disease, applications of fungicide were commenced and maintained at approximately 10-day intervals. In 2003, four applications (two with Headline (pyraclostrobin), two with Lance (boscalid)) were conducted. In 2004, the last Lance application was not done. Aerial application was made using a Cessna AgTruck applying 37 L/ha using CP nozzles emitting a spray with a VMD of approximately 271 μm. Ground applications were conducted using a Melroe SpraCoupe applying 100 L/ha using XR8003 nozzles with a VMD of approximately 246 μm. Disease ratings were done throughout the season, and seed yields were taken at crop maturity. Disease incidence progressed to 80 to 90% in the untreated plots, and fungicide application reduced disease incidence (to 20 to 30%) and increased seed yield in both years. Disease incidence and seed yield were not affected by application method in either season

    Renormalization group parameter evolution of the minimal supersymmetric standard model with R-parity violation

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    A comparison of spectra obtained using the 1-loop MSSM and 2-loop R-parity violating MSSM renormalization group equations is presented. Influence of higher loop corrections and R-parity violating terms is discussed. Some numerical constraints on the R-parity violating parameters are also given.Comment: 4 pages, 1 figure, using RevTE

    Supersymmetric particle mass measurement with invariant mass correlations

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    The kinematic end-point technique for measuring the masses of supersymmetric particles in R-Parity conserving models at hadron colliders is re-examined with a focus on exploiting additional constraints arising from correlations in invariant mass observables. The use of such correlations is shown to potentially resolve the ambiguity in the interpretation of quark+lepton end-points and enable discrimination between sequential two-body and three-body lepton-producing decays. The use of these techniques is shown to improve the SUSY particle mass measurement precision for the SPS1a benchmark model by at least 20-30% compared to the conventional end-point technique.Comment: 29 pages, 23 .eps figures, JHEP3 style; v2 adds some references and small clarifications to text; v3 adds some more clarifications to the tex

    Naturalness Priors and Fits to the Constrained Minimal Supersymmetric Standard Model

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    We examine the effect of a prior that favours low values of fine-tuning on Bayesian multi-dimensional fits of the constrained minimal supersymmetric standard model (CMSSM or mSUGRA) to current data. The dark matter relic density, the anomalous magnetic moment of the muon and the branching ratio of b->s gamma are all used to constrain the model via a Markov Chain Monte Carlo sampler. As a result of the naturalness prior, posterior probability distributions skew towards lighter higgs and sparticle masses, the effect being most pronounced in the gaugino sector. Interestingly, slepton masses are an exception and skew towards heavier masses. The lightest CP-even Higgs h^0-pole region becomes allowed at the 2 sigma level for the latest combination of measurements of m_t=172.7+/-2.9 GeV, provided we allow for a theoretical error in the prediction of its mass m_{h^0}. m_{h^0} is constrained to be less than 120 GeV at the 95% C.L. Probing the branching ratio of B_s->mu^+ mu^- to the level of 2 x 10^{-8}, as might be achieved by the Tevatron experiments, would cover 32% of the probability density, irrespective of which of the two priors is used.Comment: 15 pages, 5 figures. Ref adde

    Sparticle Spectra and LHC Signatures for Large Volume String Compactifications

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    We study the supersymmetric particle spectra and LHC collider observables for the large-volume string models with a fundamental scale of 10^{11} GeV that arise in moduli-fixed string compactifications with branes and fluxes. The presence of magnetic fluxes on the brane world volume, required for chirality, perturb the soft terms away from those previously computed in the dilute-flux limit. We use the difference in high-scale gauge couplings to estimate the magnitude of this perturbation and study the potential effects of the magnetic fluxes by generating many random spectra with the soft terms perturbed around the dilute flux limit. Even with a 40% variation in the high-scale soft terms the low-energy spectra take a clear and predictive form. The resulting spectra are broadly similar to those arising on the SPS1a slope, but more degenerate. In their minimal version the models predict the ratios of gaugino masses to be M_1 : M_2 : M_3=(1.5 - 2) : 2 : 6, different to both mSUGRA and mirage mediation. Among the scalars, the squarks tend to be lighter and the sleptons heavier than for comparable mSUGRA models. We generate 10 fb^{-1} of sample LHC data for the random spectra in order to study the range of collider phenomenology that can occur. We perform a detailed mass reconstruction on one example large-volume string model spectrum. 100 fb^{-1} of integrated luminosity is sufficient to discriminate the model from mSUGRA and aspects of the sparticle spectrum can be accurately reconstructed.Comment: 42 pages, 21 figures. Added references and discussion for section 3. Slight changes in the tex

    Discriminating Electroweak-ino Parameter Ordering at the LHC and Its Impact on LFV Studies

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    Current limit on the dark matter relic abundance may suggest that μ|\mu| should be smaller than prediction in the minimal supergravity scenario (mSUGRA) for moderate m0m_0 and m1/2m_{1/2}. The electroweak-ino parameter M1,M2M_1, M_2 and μ|\mu| are then much closer to each other. This can be realized naturally in the non-universal Higgs mass model (NUHM). Since the heaviest neutralino (χ~40\tilde\chi^0_4) and chargino (χ~2±\tilde\chi^\pm_2) have significant gaugino components, they may appear frequently in the left-handed squark decay and then be detectable at the LHC. In such a case, we showed that the hierarchy of M1,M2M_1, M_2 and μ|\mu| can be determined. In the light slepton mass scenario with non-vanishing lepton-flavor violation (LFV) in the right-handed sector, NUHM with small μ|\mu| corresponds to region of parameter space where strong cancellation among leading contributions to Br(μeγ)Br(\mu\to e\gamma) can occur. We showed that determination of electroweak-ino hierarchy plays a crucial role in resolving cancellation point of Br(μeγ)Br(\mu\to e\gamma) and determination of LFV parameters. We also discussed test of the universality of the slepton masses at the LHC and the implications to SUSY flavor models.Comment: 34 pages, 16 figure

    Measuring superparticle masses at hadron collider using the transverse mass kink

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    We present a detailed study of the collider observable mT2m_{T2} applied for pair-produced superparticles decaying to visible particles and a pair of invisible lightest supersymmetric particles (LSPs). Analytic expressions of the maximum of mT2m_{T2} over all events (mT2maxm_{T2}^{\rm max}) are derived. It is noticed that if the decay product of each superparticle involves more than one visible particles, mT2maxm_{T2}^{\rm max} being a function of the {\it trial} LSP mass mχ{m}_\chi has a kink structure at mχ={m}_\chi= true LSP mass, which can be used to determine the mother superparticle mass and the LSP mass simultaneously. To see how well mT2maxm_{T2}^{\rm max} can be constructed from collider data, a Monte-Carlo analysis of the gluino mT2m_{T2} is performed for some superparticle spectra.Comment: Typos corrected. A few references added. Figures update

    Magnetic Branes in Gauss-Bonnet Gravity

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    We present two new classes of magnetic brane solutions in Einstein-Maxwell-Gauss-Bonnet gravity with a negative cosmological constant. The first class of solutions yields an (n+1)(n+1)-dimensional spacetime with a longitudinal magnetic field generated by a static magnetic brane. We also generalize this solution to the case of spinning magnetic branes with one or more rotation parameters. We find that these solutions have no curvature singularity and no horizons, but have a conic geometry. In these spacetimes, when all the rotation parameters are zero, the electric field vanishes, and therefore the brane has no net electric charge. For the spinning brane, when one or more rotation parameters are non zero, the brane has a net electric charge which is proportional to the magnitude of the rotation parameter. The second class of solutions yields a spacetime with an angular magnetic field. These solutions have no curvature singularity, no horizon, and no conical singularity. Again we find that the net electric charge of the branes in these spacetimes is proportional to the magnitude of the velocity of the brane. Finally, we use the counterterm method in the Gauss-Bonnet gravity and compute the conserved quantities of these spacetimes.Comment: 17 pages, No figure, The version to be published in Phys. Rev.
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