Inclusion of Z->b b-bar vertex corrections in Precision Electroweak Tests on the Sp(6)_L X U(1)_Y Model

We extend our previous work on the precision electroweak tests in the Sp(6)_L X U(1)_Y family model to include for the first time the important Z->b b-bar vertex corrections encoded in a new variable epsilon_b, utilizing all the latest LEP data. We include in our analysis the one loop EW radiative corrections due to the new bosons in terms of epsilon_1, epsilon_b and $\Delta\Gamma_Z$. We find that the correlation between epsilon_1 and epsilon_b makes the combined constraint much stronger than the individual ones. The model is consistent with the recent CDF result of m_t=174\pm 10^{+13}_{-12}\GeV, but it can not accomodate m_t\gsim 195\GeV.Comment: Latex, 16 pages+4 figures(not included but available as uuencoded or PS files from [email protected]), PURD-TH-94-08, SNUTP-94-4

Precision Electroweak Tests on the Sp(6)L×U(1)YSp(6)_L \times U(1)_Y Model

We perform precision electroweak tests on the $Sp(6)_L \times U(1)_Y$ model. The purpose of the analysis is to delineate the model parameters such as the mixing angles of the extra gauge bosons present in this model. We find that the model is already constrained considerably by the present LEP data.Comment: 14 pages+2 figures(not included), PURD-TH-93-13, to appear in Phys. Rev. D(figures available upon request by regular mail

Density Expansion for the Mobility in a Quantum Lorentz Model

We consider the mobility of electrons in an environment of static hard-sphere scatterers, which provides a realistic description of electrons in Helium gas. A systematic expansion in the scatterer density is carried to second order relative to the Boltzmann result, and the analytic contribution at this order is derived, together with the known logarithmic term in the density expansion. It is shown that existing experimental data are consistent with the existence of the logarithmic term in the density expansion, but more precise experiments are needed in order to unambiguously detect it. We show that our calculations provide the necessary theoretical information for such an experiment, and give a detailed discussion of a suitable parameter range.Comment: 17pp., REVTeX, 7 figure attached as 8 postscript files, db/94/

The Solar pp and hep Processes in Effective Field Theory

The strategy of modern effective field theory is exploited to pin down accurately the flux $S$ factors for the $pp$ and $hep$ processes in the Sun. The technique used is to combine the high accuracy established in few-nucleon systems of the "standard nuclear physics approach" (SNPA) and the systematic power counting of chiral perturbation theory (ChPT) into a consistent effective field theory framework. Using highly accurate wave functions obtained in the SNPA and working to \nlo3 in the chiral counting for the current, we make totally parameter-free and error-controlled predictions for the $pp$ and $hep$ processes in the Sun.Comment: 5 pages, aipproc macros are included. Talk given at International Nuclear Physics Conference 2001, Berkeley, California, July 30 - August 3, 200

How to look for supersymmetry under the lamppost at the LHC

We apply a model-independent, agnostic approach to the collider phenomenology of supersymmetry (SUSY), in which all mass parameters are taken as free inputs at the weak scale. We consider the gauginos, higgsinos, and the first two generations of sleptons and squarks, and analyze all possible mass hierarchies among them ($4\times 8!=161,280$ in total) in which the lightest superpartner is neutral, leading to missing energy. In each case, we identify the full set of the dominant (i.e. least suppressed by phase space, small mixing angles or Yukawa couplings) decay chains originating from the lightest colored superpartner. Our exhaustive search reveals several quite dramatic yet unexplored multilepton signatures with up to 8 isolated leptons (plus possibly up to 2 massive gauge or Higgs bosons) in the final state. Such events are spectacular, background-free for all practical purposes, and may lead to a discovery of SUSY in the very early stage ($\sim 10\ {\rm pb}^{-1}$) of LHC operations at 7 TeV.Comment: 4 pages, 4 figure

Erratum: Dynamics and scaling in a quantum spin chain material with bond randomness

Follow-up neutron measurements, performed on a sample much larger than the one used in the original study, show that in the energy range 0.5-45 meV the magnetic excitations in BaCu2SiGeO7 are indistinguishable from those in conventional (disorder-free) quantum S=1/2 chains. Scrutinizing the previous data, we found that the analysis was affected by a poorly identified structured background and an additional technical mistake in the data reduction.Comment: This is a complete withdrawal of the original paper, also published as in Phys. Rev. Lett 93, 077206 (2004). One page, one figur

Anisotropy of in-plane magnetization due to nodal gap structure in the vortex state

We examine the interplay between anisotropy of the in-plane magnetization and the nodal gap structure on the basis of the approximate analytic solution in the quasiclassical formalism. We show that a four-fold oscillation appears in the magnetization, and its amplitude changes sign at an intermediate field. The high-field oscillation originates from the anisotropy of the upper critical field, while the low-field behavior can be understood by the thermally activated quasiparticles near nodes depending on the applied field angles. The temperature dependence of the magnetization also shows a similar sign change. The anisotropy of the magnetization offers a possible measurement to identify the gap structure directly for a wide class of type II superconductors.Comment: 4 pages, 4 figure