Daniel Feldman

Higgs boson mass predictions in supergravity unification, recent LHC-7 results, and dark matter

LHC-7 has narrowed down the mass range of the light Higgs boson. This result is consistent with the supergravity unification framework, and the current Higgs boson mass window implies a rather significant loop correction to the tree value pointing to a relatively heavy scalar sparticle spectrum with universal boundary conditions. It is shown that the largest value of the Higgs boson mass is obtained on the Hyperbolic Branch of radiative breaking. The implications of light Higgs boson in the broader mass range of 115 GeV to 131 GeV and a narrower range of 123 GeV to 127 GeV are explored in the context of the discovery of supersymmetry at LHC-7 and for the observation of dark matter in direct detection experiments.

The Association of Exposure to Lead, Mercury, and Selenium and the Development of Amyotrophic Lateral Sclerosis and the Epigenetic Implications

Metal exposures are an intriguing potential culprit in the cause of sporadic amyotrophic lateral sclerosis (ALS). For one, there are numerous case reports linking different metals to an ALS phenotype. Furthermore, some investigators have demonstrated higher levels of certain metals in the blood, bone, cerebrospinal fluid, urine, or spinal cords of patients with ALS compared to controls. There are also many case-control studies looking at the possible association of certain metals with the development of ALS. We have reviewed the relevant literature regarding metal exposures and the risk of developing ALS. We found that many different metals have been implicated as having a role in ALS, but there is more literature investigating the role of lead than any other metal. Despite many studies, the role, if any, of this metal in the pathogenesis of ALS remains unclear. Similarly, other metals either have inconclusive, conflicting, or insufficient results in order to make a definitive conclusion. One explanation for these findings is that metal exposures alone are insufficient for the development of ALS. Perhaps an interaction between the metal exposure and an individual’s genetic makeup is required to produce epigenetic changes that ultimately lead to ALS.

Multicomponent Dark Matter in Supersymmetric Hidden Sector Extensions

Most analyses of dark matter within supersymmetry assume the entire cold dark matter arising only from weakly interacting neutralinos. We study a new class of models consisting of U(1){sup n} hidden sector extensions of the minimal supersymmetric standard model that includes several stable particles, both fermionic and bosonic, which can be interpreted as constituents of dark matter. In one such class of models, dark matter is made up of both a Majorana dark matter particle, i.e., a neutralino, and a Dirac fermion with the current relic density of dark matter as given by WMAP being composed of the relic density of the two species. These models can explain the PAMELA positron data and are consistent with the antiproton flux data, as well as the photon data from FERMI-LAT. Further, it is shown that such models can also simultaneously produce spin-independent cross sections which can be probed in CDMS-II, XENON-100, and other ongoing dark matter experiments. The implications of the models at the LHC and at the next linear collider (NLC) are also briefly discussed.

Low Mass Neutralino Dark Matter in the MSSM with Constraints from

An analysis of spin independent neutralino-proton cross sections

B_s\to \mu^+\mu^-

{\ensuremath{\sigma}}_{\mathrm{SI}}(\ensuremath{\chi}p)

and Higgs Search Limits

that includes this low mass region is given. The analysis is done in minimal supersymmetric standard model (MSSM) with radiative electroweak symmetry breaking (REWSB). It is found that cross sections as large as

Low Mass Gluino within the Sparticle Landscape, Implications for Dark Matter, and Early Discovery Prospects at LHC-7

{10}^{\ensuremath{-}40}\text{ }\text{ }{\mathrm{cm}}^{2}

Interpreting the First CMS and ATLAS SUSY Results

can be accommodated in MSSM within the REWSB framework. However, inclusion of sparticle mass limits from current experiments, as well as lower limits on the Higgs searches from the Tevatron, and the current experimental upper limit on

A new (string motivated) approach to the little hierarchy problem

{B}_{s}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}

New Constraints on Dark Matter from CMS and ATLAS Data

significantly limit the allowed parameter space reducing