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 eva
des 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.
We propose a supersymmetric explanation for the anomalously high forward backward asymmetry in top pair production measured by CDF and D0. We suppose that it is due to the t-channel exchange of a right-handed sbottom which couples to d_R and t_R, as
is present in the R-parity violating minimal supersymmetric standard model. We show that all Tevatron and LHC experiments t tbar constraints may be respected for a sbottom mass between 300 and 1200 GeV, and a large Yukawa coupling >2.2, yielding A_{FB} up to 0.18. The non Standard Model contribution to the LHC charge asymmetry parameter is Delta A_C^y=0.017-0.045, small enough to be consistent with current measurements but non-zero and positive, allowing for LHC confirmation in the future within 20 fb^-1. A small additional contribution to the LHC t tbar production cross-section is also predicted, allowing a further test. We estimate that 10 fb^-1 of LHC luminosity would be sufficient to rule out the proposal to 95% confidence level, if the measurements of the t tbar cross-section turn out to be centred on the Standard Model prediction.
We present a set of recommendations for the presentation of LHC results on searches for new physics, which are aimed at providing a more efficient flow of scientific information between the experimental collaborations and the rest of the high energy
physics community, and at facilitating the interpretation of the results in a wide class of models. Implementing these recommendations would aid the full exploitation of the physics potential of the LHC.
Gluinos that result in classic large missing transverse momentum signatures at the LHC have been excluded by 2011 searches if they are lighter than around 800 GeV. This adds to the tension between experiment and supersymmetric solutions of the natura
lness problem, since the gluino is required to be light if the electroweak scale is to be natural. Here, we examine natural scenarios where supersymmetry is present, but was hidden from 2011 searches due to violation of R-parity and the absence of a large missing transverse momentum signature. Naturalness suggests that third generation states should dominate gluino decays and we argue that this leads to a generic signature in the form of same-sign, flavour-ambivalent leptons, without large missing transverse momentum. As a result, searches in this channel are able to cover a broad range of scenarios with some generality and one should seek gluinos that decay in this way with masses below a TeV. We encourage the LHC experiments to tailor a search for supersymmetry in this form. We consider a specific case that is good at hiding: baryon number violation, and estimate that the most constraining existing search from 2011 data implies a lower bound on the gluino mass of 550 GeV.
Recent LHC data significantly extend the exclusion limits for supersymmetric particles, particularly in the jets plus missing transverse momentum channels. The most recent such data have so far been interpreted by the experiment in only two different
supersymmetry breaking models: the constrained minimal supersymmetric standard model (CMSSM) and a simplified model with only squarks and gluinos and massless neutralinos. We compare kinematical distributions of supersymmetric signal events predicted by the CMSSM and anomaly mediated supersymmetry breaking (mAMSB) before calculating exclusion limits in mAMSB. We obtain a lower limit of 900 GeV on squark and gluino masses at the 95% confidence level for the equal mass limit, tan(beta)=10 and mu>0.
The Supersymmetry Les Houches Accord (SLHA) provides a universal set of conventions for conveying spectral and decay information for supersymmetry analysis problems in high energy physics. Here, we propose extensions of the conventions of the first S
LHA to include various generalisations: the minimal supersymmetric standard model with violation of CP, R-parity, and flavour, as well as the simplest next-to-minimal model.
We study the properties of the constrained minimal supersymmetric standard model (mSUGRA) by performing fits to updated indirect data, including the relic density of dark matter inferred from WMAP5. In order to find the extent to which mu < 0 is disf
avoured compared to mu > 0, we compare the Bayesian evidence values for these models, which we obtain straightforwardly and with good precision from the recently developed multi-modal nested sampling (MultiNest) technique. We find weak to moderate evidence for the mu > 0 branch of mSUGRA over mu < 0 and estimate the ratio of probabilities to be P(mu > 0)/P(mu < 0) = 6-61 depending on the prior measure and range used. There is thus positive (but not overwhelming) evidence that mu > 0 in mSUGRA. The MultiNest technique also delivers probability distributions of parameters and other relevant quantities such as superpartner masses. We explore the dependence of our results on the choice of the prior measure used. We also use the Bayesian evidence to quantify the consistency between the mSUGRA parameter inferences coming from the constraints that have the largest effects: (g-2)_mu, BR(b -> s gamma) and cold dark matter (DM) relic density Omega_{DM}h^2.
We consider the case where supersymmetry with broken R-parity is embedded in the minimal supergravity model (mSUGRA). This alters the standard mSUGRA spectrum and opens a wide range in parameter space, where the scalar tau is the lightest supersymmet
ric particle, instead of the lightest neutralino. We study the resulting LHC phenomenology. Promising signatures would be detached vertices from long-lived staus, multi lepton final states and multi-tau final states. We investigate in detail the corresponding cross sections and decay rates in characteristic benchmark scenarios.
