Bob McElrath

Accurate Mass Determinations in Decay Chains with Missing Energy

Many beyond the standard model theories include a stable dark matter candidate that yields missing or invisible energy in collider detectors. If observed at the CERN Large Hadron Collider, we must determine if its mass and other properties (and those of its partners) predict the correct dark matter relic density. We give a new procedure for determining its mass with small error.

Probing NMSSM Scenarios with Minimal Fine-Tuning by Searching for Decays of the Upsilon to a Light CP-Odd Higgs Boson

Completely natural electroweak symmetry breaking is easily achieved in supersymmetric models if there is a SM-like Higgs boson, h, with m{sub h} 0.7, and if m{sub a}<2m{sub b}, then the LEP constraints are satisfied even if m{sub h} < or approx. 100 GeV. In this paper, we show that in the next-to-minimal supersymmetric model the above h and a properties (for the lightest CP-even and CP-odd Higgs bosons, respectively) imply a lower bound on Br({upsilon}{yields}{gamma}a) that dedicated runs at present (and future) B factories can explore.

Invisible quarkonium decays as a sensitive probe of dark matter

We examine in a model-independent manner the measurements that can be performed at B factories with sensitivity to dark matter. If a singlet scalar, pseudoscalar, or vector is present and mediates the standard model-dark matter interaction, it can mediate invisible decays of quarkonium states such as the {upsilon}, J/{psi}, and {eta}. Such scenarios have arisen in the context of supersymmetry, extended Higgs sectors, solutions of the supersymmetric {mu} problem, and extra U(1) gauge groups from grand unified theories and string theory. Existing B factories running at the {upsilon}(4S) can produce lower {upsilon} resonances by emitting an initial state radiation (ISR) photon. Using a combination of ISR and radiative decays, the initial state of an invisibly decaying quarkonium resonance can be tagged, giving sensitivity to the spin and CP nature of the particle that mediates standard model-dark matter interactions. These measurements can discover or place strong constraints on dark matter scenarios where the dark matter is approximately lighter than the b quark. For the decay chains {upsilon}(nS){yields}{pi}{sup +}{pi}{sup -}{upsilon}(1S) (n=2,3) we analyze the dominant backgrounds and determine that with 400 fb{sup -1} collected at the {upsilon}(4S), the B factories can limit BR({upsilon}(1S){yields}invisible) < or approx. 0.1%.

Higgs sector in a U ( 1 ) ′ extension of the minimal supersymmetric standard model

We consider the Higgs sector in an extension of the MSSM with extra SM singlets, involving an extra

The Higgs sector in a U(1)-prime extension of the MSSM

U(1)^\prime

Signatures of Extra Dimensions from Upsilon Decays with a Light Gaugephobic Higgs Boson

gauge symmetry, in which the domain-wall problem is avoided and the effective

Measuring neutrino mass with radioactive ions in a storage ring

\mu

Gaugephobic Higgs signals at the LHC

parameter is decoupled from the new gauge boson

Higgs sector in a U(1){sup '} extension of the minimal supersymmetric standard model

Z^\prime

Mass determination in SUSY-like events with missing energy

mass. The model involves a rich Higgs structure very different from that of the MSSM. In particular, there are large mixings between Higgs doublets and the SM singlets, significantly affecting the Higgs spectrum, production cross sections, decay modes, existing exclusion limits, and allowed parameter range. Scalars considerably lighter than the LEP2 bound (114 GeV) are allowed, and the range