The Higgs Mass and the Stueckelberg Mechanism in Supersymmetry

We investigate a class of theories where the mass of the lightest Higgs boson of the Minimal Supersymmetric Standard Model (MSSM) can be larger than the Z gauge boson mass at tree level. In this context the MSSM fields feel a new force, whose corresponding gauge boson attains its mass through the Stueckelberg mechanism. We show how one can achieve a Higgs mass around 126 GeV without assuming a heavy stop spectrum or a large stop trilinear term. The application of this class of models to the conservation of R-parity is also discussed.Comment: to appear in Physical Review

Supersymmetry at the LHC and The Theory of R-parity

We discuss the possible signatures at the Large Hadron Collider in models where R-parity is spontaneously broken. In the context of the minimal gauge theory for R-parity, we investigate signals with multileptons which can provide an unique test of this theory. The possible impact of these ideas for the search of supersymmetry at the Large Hadron Collider is discussed. We also discuss the constraints coming from cosmology due to the existence of two light sterile neutrinos in the theory

On the Higgs Mass and Perturbativity

The predictions for the Higgs mass in extensions of the Minimal Supersymmetric Standard Model are discussed. We propose a simple theory where the Higgs mass is modified at tree-level and one can achieve a mass around 125 GeV without assuming heavy stops or large left-right mixing in the stop sector. All the parameters in the theory can be perturbative up to the grand unified scale, and one predicts the existence of new colored fields at the TeV scale. We refer to this model as Adjoint MSSM. We discuss the main phenomenological aspects of this scenario and the possible signatures at the Large Hadron Collider.Comment: title and format changed, new plot, to appear in Physics Letters

The upside of minimal left-right supersymmetric seesaw in deflected anomaly mediation

The state of the standard model of particle physics is reviewed focusing on two of it's major issues: the hierarchy problem and its inconsistency with observed neutrino masses. Supersymmetry, an elegant solution to the former, and the seesaw mechanism in left-right models, a natural solution to the latter, are then introduced. The work then focuses on a specific supersymmetric left-right models, which has an additional discrete symmetry allowing a prediction of the seesaw scale at around 1011 GeV--consistent with neutrino oscillation data. It also solves the μ problem and guarantees automatic R-parity conservation and a pair of light doubly-charged Higgses which can be searched for at the LHC. This model has interesting properties in the context of anomaly mediated supersymmetry breaking (AMSB). After a brief introduction to this topic, it is shown that this model is an instance of the Pomarol Rattazzi model of deflected AMSB. The tachyonic slepton problem of AMSB is solved in a combination of two ways: the right-handed sleptons are saved by their couplings to the low energy doubly-charged fields while the left-handed sleptons receive positive contributions from the partially decoupled D-terms. The resulting phenomenology is similar to that of mimimal AMSB due to the gaugino spectrum; however, same generation mass differences in the sfermion sector are much larger than that of mAMSB and the right-handed selectron can be as massive as the squarks. Finally, this model also contains a mechanism for solving the EWSB problem of AMSB and a dark matter candidate

The Minimal SUSY B−LB-L Model: From the Unification Scale to the LHC

This paper introduces a random statistical scan over the high-energy initial parameter space of the minimal SUSY $B-L$ model--denoted as the $B-L$ MSSM. Each initial set of points is renormalization group evolved to the electroweak scale--being subjected, sequentially, to the requirement of radiative $B-L$ and electroweak symmetry breaking, the present experimental lower bounds on the $B-L$ vector boson and sparticle masses, as well as the lightest neutral Higgs mass of $\sim$125 GeV. The subspace of initial parameters that satisfies all such constraints is presented, shown to be robust and to contain a wide range of different configurations of soft supersymmetry breaking masses. The low-energy predictions of each such "valid" point - such as the sparticle mass spectrum and, in particular, the LSP - are computed and then statistically analyzed over the full subspace of valid points. Finally, the amount of fine-tuning required is quantified and compared to the MSSM computed using an identical random scan. The $B-L$ MSSM is shown to generically require less fine-tuning.Comment: 65 pages, 18 figure

Spontaneous R-Parity Breaking, Stop LSP Decays and the Neutrino Mass Hierarchy

The MSSM with right-handed neutrino supermultiplets, gauged B-L symmetry and a non-vanishing sneutrino expectation value is the minimal theory that spontaneously breaks R-parity and is consistent with the bounds on proton stability and lepton number violation. This minimal B-L MSSM can have a colored/charged LSP, of which a stop LSP is the most amenable to observation at the LHC. We study the R-parity violating decays of a stop LSP into a bottom quark and charged leptons--the dominant modes for a generic "admixture" stop. A numerical analysis of the relative branching ratios of these decay channels is given using a wide scan over the parameter space. The fact that R-parity is violated in this theory by a vacuum expectation value of a sneutrino links these branching ratios directly to the neutrino mass hierarchy. It is shown how a discovery of bottom-charged lepton events at the LHC can potentially determine whether the neutrino masses are in a normal or inverted hierarchy, as well as determining the theta_23 neutrino mixing angle. Finally, present LHC bounds on these leptoquark signatures are used to put lower bounds on the stop mass.Comment: 13 pages, 2 figures, upgraded stop lower bound analysis, version accepted by PL

TeV Scale Spontaneous R-Parity Violation

Understanding the origin or absence of the R-parity violating interactions in the minimal supersymmetric Standard Model is a vital and open issue. Here we show that in the minimal B-L models, R-parity and B-L are spontaneously broken at the TeV scale. We also briefly discuss the phenomenological and cosmological aspects of these scenarios.Comment: Based on a plenary talk given by P.F.P. at PPC09, OU, May 2009 and talk given by S.S. at SUSY09, Northeastern Univ., Boston, June 200