Ken Hsieh

Triplet extended supersymmetric standard model

We revisit an extension of the minimal supersymmetric standard model (MSSM) by adding a hypercharge-neutral,

Pseudo-Dirac bino dark matter

SU(2)

Mixed gauge and anomaly mediation from new physics at 10 TeV

-triplet chiral superfield. Similar to the next-to-minimal supersymmetric standard model , the triplet gives an additional contribution to the quartic coupling in the Higgs potential, and the mass of the lightest

Global Analysis of General SU(2) SU(2) U(1) Models with Precision Data

CP

Lone Higgs boson at the CERN LHC

-even Higgs boson can be greater than

Dark matter in universal extra dimension models: Kaluza-Klein photon and right-handed neutrino admixture

{M}_{Z}

Mixed dark matter in Universal Extra Dimension models with TeV scale WR and Z

at tree level. In addition to discussing the perturbativity, fine-tuning, and decoupling issues of this model, we compute the dominant 1-loop corrections to the mass of the lightest

Z to b bbar and Chiral Currents in Higgsless Models

CP

Z→bb¯and chiral currents in Higgsless models

-even Higgs boson from the triplet sector. When the Higgs-Higgs-Triplet coupling in the superpotential is comparable to the top Yukawa coupling, we find that the Higgs mass can be as heavy as 140 GeV even without the traditional contributions from the top--s-top sector, and at the same time consistent with the precision electroweak constraints. At the expense of having Landau poles before the grand unified theory scale, this opens up a previously forbidden region in the MSSM parameter space where both s-tops are light. In addition to having relatively small fine-tuning (about one part in 30), this leads to a gluophilic Higgs boson whose production via gluon-gluon fusion at the CERN LHC can be twice as large as the standard model prediction.

Z-->b bmacr and chiral currents in Higgsless models

While the bino-dominated lightest neutralino of the minimal supersymmetric standard model (MSSM) is an interesting and widely studied candidate of dark matter, the p-wave suppression of its annihilation cross section requires fine-tuning of the MSSM spectra to be consistent with Wilkinson Microwave Anisotropy Probe (WMAP) observations. We propose a pseudo-Dirac bino that arises in theories with D-type supersymmetry breaking as an intriguing alternative candidate of dark matter. The pseudo-Dirac nature of the bino gives a natural mechanism of enhanced coannihilation because these two states are degenerate in the absence of electroweak symmetry breaking. In addition, the lightest state can be consistent with limits of direct-detection experiments because of the lack of vector interactions, as with the case of the MSSM bino.