Flavor Constraints on Split Fermion Models

We examine the contributions to rare processes that arise in models where the Standard Model fermions are localized at distinct points in compact extra dimensions. Tree-level flavor changing neutral current interactions for the Kaluza-Klein (KK) gauge field excitations are induced in such models, and hence strong constraints are thought to exist on the size of the additional dimensions. We find a general parameterization of the model which does not depend on any specific fermion geography and show that typical values of the parameters can reproduce the fermion hierarchy pattern. Using this parameterization, we reexamine the contributions to neutral meson mixing, rare meson decays, and single top-quark production in $e^+e^-$ collisions. We find that is it possible to evade the stringent bounds for natural regions of the parameters, while retaining finite separations between the fermion fields and without introducing a new hierarchy. The resulting limits on the size of the compact dimension can be as low as TeV$^{-1}$.Comment: 29 pages, 8 figures, uses bibtex, expanded discussion on rare B decays, references adde

Constraints on Higgs Properties and SUSY Partners in the pMSSM

Direct searches for superpartners and precision measurements of the properties of the $\sim 126$ GeV Higgs boson lead to important inter-dependent constraints on the underlying parameter space of the MSSM. The 19/20-parameter p(henomenological)MSSM offers a flexible framework for the study of a wide variety of both Higgs and SUSY phenomena at the LHC and elsewhere. Within this scenario we address the following questions: `What will potentially null searches for SUSY at the LHC tell us about the possible properties of the Higgs boson?' and, conversely, `What do precision measurements of the properties of the Higgs tell us about the possible properties of the various superpartners?' Clearly the answers to such questions will be functions of both the collision energy of the LHC as well as the accumulated integrated luminosity. We address these questions employing several sets of pMSSM models having either neutralino or gravitino LSPs, making use of the ATLAS SUSY analyses at the 7/8 TeV LHC as well as planned SUSY and Higgs analyses at the 14 TeV LHC and the ILC. Except for theoretical uncertainties that remain to be accounted for in the ratios of SUSY and SM couplings, we demonstrate that Higgs coupling measurements at the 14 TeV LHC, and particularly at the 500 GeV ILC, will be sensitive to regions of the pMSSM model space that are not accessible to direct SUSY searches.Comment: 23 pages, 9 figures. Contributed to the Community Summer Study 2013, Minneapolis, MN July 29 - August 6, 201

Up Sector of Minimal Flavor Violation: Top Quark Properties and Direct D meson CP violation

Minimal Flavor Violation in the up-type quark sector leads to particularly interesting phenomenology due to the interplay of flavor physics in the charm sector and collider physics from flavor changing processes in the top sector. We study the most general operators that can affect top quark properties and $D$ meson decays in this scenario, concentrating on two CP violating operators for detailed studies. The consequences of these effective operators on charm and top flavor changing processes are generically small, but can be enhanced if there exists a light flavor mediator that is a Standard Model gauge singlet scalar and transforms under the flavor symmetry group. This flavor mediator can satisfy the current experimental bounds with a mass as low as tens of GeV and explain observed $D$-meson direct CP violation. Additionally, the model predicts a non-trivial branching fraction for a top quark decay that would mimic a dijet resonance.Comment: 27 pages, 7 figure

Signatures of long-lived gluinos in split supersymmetry

We examine the experimental signatures for the production of gluinos at colliders and in cosmic rays within the split supersymmetry scenario. Unlike in the MSSM, the gluinos in this model are relatively long-lived due to the large value of the squark masses which mediate their decay. Searches at colliders are found to be sensitive to the nature of gluino fragmentation as well as the gluino-hadron interactions with nuclei and energy deposition as it traverses the detector. We find that the worst-case scenario, where a neutral gluino-hadron passes through the detector with little energy deposition, is well described by a monojet signature. For this case, using Run I data we obtain a bound of $m_{\tilde g} > 170$ GeV; this will increase to 210(1100) GeV at Run II(LHC) if no excess events are observed. In the opposite case, where a charged gluino-hadron travels through the detector, a significantly greater reach is obtained via stable charged particle search techniques. We also examine the production of gluino pairs in the atmosphere by cosmic rays and show they are potentially observable at IceCube; this would provide a cross-check for observations at hadron colliders.Comment: 18 pages, 7 figure

Symmetry Restored in Dibosons at the LHC?

A number of LHC resonance search channels display an excess in the invariant mass region of 1.8 - 2.0 TeV. Among them is a $3.4\,\sigma$ excess in the fully hadronic decay of a pair of Standard Model electroweak gauge bosons, in addition to potential signals in the $HW$ and dijet final states. We perform a model-independent cross-section fit to the results of all ATLAS and CMS searches sensitive to these final states. We then interpret these results in the context of the Left-Right Symmetric Model, based on the extended gauge group $SU(2)_L\times SU(2)_R\times U(1)'$, and show that a heavy right-handed gauge boson $W_R$ can naturally explain the current measurements with just a single coupling $g_R \sim 0.4$. In addition, we discuss a possible connection to dark matter.Comment: 25 pages, 12 figures, V2: references added, extended discussion of Minimal Left-Right Dark Matter, small correction to decay width - conclusions unchanged, V3: expanded discussion of input parameters and statistical procedure, V4: matches published versio

Discovery Potential for New Phenomena

We examine the ability of future facilities to discover and interpret non-supersymmetric new phenomena. We first explore explicit manifestations of new physics, including extended gauge sectors, leptoquarks, exotic fermions, and technicolor models. We then take a more general approach where new physics only reveals itself through the existence of effective interactions at lower energy scales. [Summary Report of the New Phenomena Working Group. To appear in the Proceedings of the 1996 DPF/DPB Summer Study on New Directions for High Energy Physics - Snowmass96, Snowmass, CO, 25 June - 12 July 1996.]Comment: 18 pages, LaTex2