Top polarization is an important probe of new physics that couples to the top sector, and which may be discovered at the 14 TeV LHC. Taking the example of the MSSM, we argue that top polarization measurements can put a constraint on the soft supersym
metry breaking parameter A_t. In light of the recent discovery of a Higgs-like boson of mass ~125 GeV, a large A_t is a prediction of many supersymmetric models. To this end, we develop a *detector level* analysis methodology for extracting polarization information from hadronic tops using boosted jet substructure. We show that with 100 fb^(-1) of data, left and right 600 GeV stops can be distinguished to 4sigma, and 800 GeV stops can be distinguished to 3sigma.
We propose a method for reconstructing the mass of a particle, such as the Higgs boson, decaying into a pair of tau leptons, of which one subsequently undergoes a 3-prong decay. The kinematics is solved using information from the visible decay produc
ts, the missing transverse momentum, and the 3-prong tau decay vertex, with the detector resolution taken into account using a likelihood method. The method is shown to give good discrimination between a 125 GeV Higgs boson signal and the dominant backgrounds, such as Z decays to tau tau and W plus jets production. As a result, we find an improvement, compared to existing methods for this channel, in the discovery potential, as well as in measurements of the Higgs boson mass and production cross section times branching ratio.
The hierarchy of the Yukawa couplings is an outstanding problem of the standard model. We present a class of models in which the first and second generation fermions are SUSY partners of pseudo-Nambu-Goldstone bosons that parameterize a non-compact K
ahler manifold, explaining the small values of these fermion masses relative to those of the third generation. We also provide an example of such a model. We find that various regions of the parameter space in this scenario can give the correct dark matter abundance, and that nearly all of these regions evade other phenomenological constraints. We show that for gluino mass ~700 GeV, model points from these regions can be easily distinguished from other mSUGRA points at the LHC with only 7 fb^(-1) of integrated luminosity at 14 TeV. The most striking signatures are a dearth of b- and tau-jets, a great number of multi-lepton events, and either an inverted slepton mass hierarchy, narrowed slepton mass hierarchy, or characteristic small-mu spectrum.
