A general two Higgs doublet model (2HDM) is adopted to study the signature of flavor changing neutral Higgs (FCNH) decay $phi^0 to tbar{c}+bar{t}c$, where $phi^0$ could be a CP-even scalar ($H^0$) or a CP-odd pseudoscalar ($A^0$). Measurement of the
light 125 GeV neutral Higgs boson ($h^0$) couplings at the Large Hadron Collider (LHC) favor the decoupling limit or the alignment limit of a 2HDM, in which gauge boson and diagonal fermion couplings of $h^0$ approach Standard Model values. In such limit, FCNH couplings of $h^0$ are naturally suppressed by a small mixing parameter $cos(beta-alpha)$, while the off-diagonal couplings of heavier neutral scalars $phi^0$ are sustained by $sin(beta-alpha) sim 1$. We study physics background from dominant processes with realistic acceptance cuts and tagging efficiencies. Promising results are found for the LHC running at 13 or 14 TeV collision energies.
LHC-7 has narrowed down the mass range of the light Higgs boson. This result is consistent with the supergravity unification framework, and the current Higgs boson mass window implies a rather significant loop correction to the tree value pointing to
a relatively heavy scalar sparticle spectrum with universal boundary conditions. It is shown that the largest value of the Higgs boson mass is obtained on the Hyperbolic Branch of radiative breaking. The implications of light Higgs boson in the broader mass range of 115 GeV to 131 GeV and a narrower range of 123 GeV to 127 GeV are explored in the context of the discovery of supersymmetry at LHC-7 and for the observation of dark matter in direct detection experiments.
With the aim of uncovering viable regions of parameter space in deflected mirage mediation (DMM) models of supersymmetry breaking, we study the landscape of particle mass hierarchies for the lightest four non-Standard Model states for DMM models and
compare the results to that of minimal supergravity/constrained MSSM (mSUGRA/CMSSM) models, building on previous studies of Feldman, Liu, and Nath. Deflected mirage mediation is a string-motivated scenario in which the soft terms include comparable contributions from gravity mediation, gauge mediation, and anomaly mediation. DMM allows a wide variety of phenomenologically preferred models with light charginos and neutralinos, including novel patterns in which the heavy Higgs particles are lighter than the lightest superpartner. We use this analysis to motivate two DMM benchmark points to be used for more detailed collider studies. One model point has a higgsino-dominated lightest superpartner and a compressed yet heavy spectrum, while the other has a stau NLSP and similar features to mSUGRA/CMSSM models, but with a slightly less stretched spectrum.
We carry out an analysis of the potential of the Large Hadron Collider (LHC) to discover supersymmetry in runs at $sqrt s=7$ TeV with an accumulated luminosity of (0.1--2) fb$^{-1}$ of data. The analysis is done both with minimal supergravity (mSUGRA
) and supergravity (SUGRA) models with non-universal soft breaking. Benchmarks for early discovery with (0.1--2) fb$^{-1}$ of data are given. We provide an update of b-tagging efficiencies in PGS 4 appropriate for LHC analyses. A large number of signature channels are analyzed and it is shown that each of the models exhibited are discoverable at the 5$sigma$ level or more above the standard model background in several signature channels which would provide cross checks for a discovery of supersymmetry (SUSY). It is shown that some of the benchmarks are discoverable with 0.1 fb$^{-1}$ of data again with detectable signals in several channels.
