UC Davis Particle Physics Seminars

Baumgart explores the relation between eternal inflation and de Sitter holography.

Many models for Supersymmetry (SUSY) predict strong coupling to third-generation Standard Model particles. As part of a broad program of complementary searches for SUSY, CMS has two recent analyses requiring b-jets in the final state. I will present these latest results, each performed with 1.1 fb^-1 of data.

David Sanford discusses the direct detection of dark matter through its elastic scattering off nucleons as among the most promising methods for establishing the particle identity of dark matter.

Rob Forrest describes recent SUSY searches at CDF, emphasizing direct searches for weakly produced Charginos and Neutralinos including many recent results using the dilepton and trilepton signatures. The results represent the final and most stringent limits placed on Chargino and Neutralino mass from CDF through the end of the life of the Tevatron.

Jason Evans discuss the implications of the excesses in LHC Higgs boson searches on the gauge mediated supersymmetric standard model, for the mass range 120-140 GeV. A relatively heavy lightest Higgs boson mass in this range can be reconciled with light SUSY particles, if there are additional fields which couple directly to the Higgs boson. The mass of this extra matter can be predicted rather precisely in gauge mediation for a given Higgs boson and gluino mass.

Yang Bai argues that dark matter particles that have strong interactions with the Standard Model particles are not excluded by current astrophysical constraints. These dark matter particles have unique signatures at colliders; instead of missing energy, the dark matter particles produce jets. We propose a new search strategy for such strongly interacting particles by looking for a signal of two trackless jets. We show that suitable cuts can plausibly allow us to find these signals at the LHC even in early data.

The AdS/CFT correspondence relates bulk Einstein geometries to boundary conformal geometry. We show that bulk geometry can also be described in terms of conformal geometry. This description yields a solution generating algebra in the bulk that controls solutions to very general bulk boundary problems. Using this algebra we present a boundary conformal calculus for conformally compact manifolds.

Jason Gallicchio discusses a new class of observables that aims to characterize the superstructure of an event, that is, features such as color flow, which are not determined by the jet four-momenta alone.

Jiji Fan discusses a broad class of supersymmetric models that preserve R-parity but lack missing energy signatures. These models have new light particles with weak-scale supersymmetric masses that feel SUSY breaking only through couplings to the MSSM. This small SUSY breaking leads to nearly degenerate fermion/boson pairs, with small mass splittings and hence small phase space for decays carrying away invisible energy. The simplest scenario has low-scale SUSY breaking, with missing energy only from soft gravitinos.

An emergent or accidental supersymmetry is used to address the little hierarchy problem in Randall-Sundrum models by naturally generating a hierarchy between the IR scale and the electroweak scale. Supersymmetry is broken on the UV brane which triggers the stabilization of the warped extra dimension at an IR scale of order 10 TeV. This causes the first two sparticle generations to decouple, thereby avoiding the supersymmetric flavour and CP problems, while an accidental R-symmetry protects the gaugino mass. The resulting low-energy sparticle spectrum consists of stops, gauginos and Higgsinos which are sufficient to stabilize the little hierarchy between the IR scale and the electroweak scale. Introducing a singlet Higgs field on the IR brane, ameliorates the supersymmetric little hierarchy problem, and allows Higgs masses up to 300 GeV.