The 2HDM-X and Large Hadron Collider Data

We study the consistency of two Higgs doublet models in light of the new bosonic particle discovery at the LHC. We work within a general setup that we call the 2HDM-X, in which the quarks couple to both scalar doublets with aligned couplings such that flavor-changing neutral currents are absent at tree level. The 2HDM-X encompasses the traditional Type I, Type II, lepton specific, and flipped models, but also provides for more general possibilities. The best fit to the current data with a suppressed tau tau signal and a b bbar signal of Standard Model strength is given by the 2HDM-X with specific parameter choices; however, very good fits are also obtained within the lepton-specific model and a democratic model, the 2HDM-D, in which both the up-type and down-type quarks couple to each doublet with equal strengths. The approach provides a general framework in which to interpret future LHC Higgs data within extensions of the Standard Model with two Higgs doublets.Comment: 5 pages, 4 figure

Flat Directions in Three-Generation Free-Fermionic String Models

In quasi-realistic string models that contain an anomalous U(1) the non-zero Fayet-Iliopoulos term triggers the shifting of the original vacuum to a new one along some flat direction, so that SUSY is preserved but the gauge group is partially broken. The phenomenological study of these models thus requires as a first step the mapping of the space of flat directions. We investigate F- and D-flat directions in several three-generation SU(3)_C x SU(2)_L x U(1)_Y free-fermionic string models and discuss the typical scenarios that generically arise. When they exist, we systematically construct the flat directions that preserve hypercharge, only break Abelian group factors, and can be proven to remain F-flat to all orders in the non-renormalizable superpotential.Comment: 59 page

Mirage Models Confront the LHC: III. Deflected Mirage Mediation

We complete the study of a class of string-motivated effective supergravity theories in which modulus-induced soft supersymmetry breaking is sufficiently suppressed in the observable sector so as to be competitive with anomaly-mediated supersymmetry breaking. Here we consider deflected mirage mediation (DMM), where contributions from gauge mediation are added to those arising from gravity mediation and anomaly mediation. We update previous work that surveyed the rich parameter space of such theories, in light of data from the CERN Large Hadron Collider (LHC) and recent dark matter detection experiments. Constraints arising from LHC superpartner searches at $\sqrt{s} = 8\,{\rm TeV}$ are considered, and discovery prospects at $\sqrt{s} = 14\,{\rm TeV}$ are evaluated. We find that deflected mirage mediation generally allows for SU(3)-charged superpartners of significantly lower mass (given current knowledge of the Higgs mass and neutralino relic density) than was found for the `pure' mirage mediation models of Kachru et al. Consequently, discovery prospects are enhanced for many combinations of matter multiplet modular weights. We examine the experimental challenges that will arise due to the prospect of highly compressed spectra in DMM, and the correlation between accessibility at the LHC and discovery prospects at large-scale liquid xenon dark matter detectors

Moduli Stabilization and Supersymmetry Breaking in Deflected Mirage Mediation

We present a model of supersymmetry breaking in which the contributions from gravity/modulus, anomaly, and gauge mediation are all comparable. We term this scenario "deflected mirage mediation," which is a generalization of the KKLT-motivated mirage mediation scenario to include gauge mediated contributions. These contributions deflect the gaugino mass unification scale and alter the pattern of soft parameters at low energies. In some cases, this results in a gluino LSP and light stops; in other regions of parameter space, the LSP can be a well-tempered neutralino. We demonstrate explicitly that competitive gauge-mediated terms can naturally appear within phenomenological models based on the KKLT setup by addressing the stabilization of the gauge singlet field which is responsible for the masses of the messenger fields. For viable stabilization mechanisms, the relation between the gauge and anomaly contributions is identical in most cases to that of deflected anomaly mediation, despite the presence of the Kahler modulus. Turning to TeV scale phenomenology, we analyze the renormalization group evolution of the supersymmetry breaking terms and the resulting low energy mass spectra. The approach sets the stage for studies of such mixed scenarios of supersymmetry breaking at the LHC.Comment: 33 pages, 8 figures. Published version in Journal of High Energy Physic

Phenomenological Implications of Supersymmetric Family Non-universal U(1)-prime Models

We construct a class of anomaly-free supersymmetric U(1)' models that are characterized by family non-universal U(1)' charges motivated from E_6 embeddings. The family non-universality arises from an interchange of the standard roles of the two SU(5) 5* representations within the 27 of E_6 for the third generation. We analyze U(1)' and electroweak symmetry breaking and present the particle mass spectrum. The models, which include additional Higgs multiplets and exotic quarks at the TeV scale, result in specific patterns of flavor-changing neutral currents in the b to s transitions that can accommodate the presently observed deviations inthis sector from the SM predictions.Comment: 25 pages, 3 figure