The magnetic penetration depth in the local limit λ(T) for a high-Tc superconductor has been calculated within the electron pairing induced by holes model proposed by us recently. The derivation of the formula for λ...
The magnetic penetration depth in the local limit λ(T) for a high-Tc superconductor has been calculated within the electron pairing induced by holes model proposed by us recently. The derivation of the formula for λ(T) is based on a new expression for the current-density operator which takes into account the nonparabolic band structure of the conduction electrons. Our numerical results for the temperature dependence of λ(T) when the hole concentration δ=0.263 (which corresponds to 90-K superconductors) are near to the BCS results for a conventional superconductor and also agree qualitatively with the experimental data on the single crystal of YBa2Cu3O7. Our value for the zero-temperature penetration depth is also close to the experimental values for the single crystals of the above material.
Published theoretical L x-ray emission rates based upon a fixed atomic potential cover the atomic number range Z = 4 to 94. However, the presumably more accurate calculations employing different initial- and final-sta...
Published theoretical L x-ray emission rates based upon a fixed atomic potential cover the atomic number range Z = 4 to 94. However, the presumably more accurate calculations employing different initial- and final-state potentials have been done for only 21 values of Z . The ratio of these two rates for each electric dipole transition as a function of Z is fitted using polynomials in piece-wise fashion. The fixed-potential emission rates are then renormalized by these interpolated ratios to provide equivalent two-potential rates. The errors incurred are generally under 0.2%.
Vacuum-ultraviolet continuous emission spectra have been acquired from dense, cold helium gas in the pressure of solid hydrogen during excitation by a 6.5-MeV proton beam. The emission has been identified as the D2Σ+...
Vacuum-ultraviolet continuous emission spectra have been acquired from dense, cold helium gas in the pressure of solid hydrogen during excitation by a 6.5-MeV proton beam. The emission has been identified as the D2Σ+→X Σ+2 radiative dissociation of HeH, based on theoretical potential curves and the qualitative similarities of the continuum to discrete bands previously observed with this experimental technique.
We study the possibility of making precision measurements of W-boson properties with an e-γ collider. We find that the measurements are comparable in sensitivity to W-pair production measurements to be made at the LE...
We study the possibility of making precision measurements of W-boson properties with an e-γ collider. We find that the measurements are comparable in sensitivity to W-pair production measurements to be made at the LEPII e + e − collider. In addition this process will be able to measure the W-photon anomalous magnetic moment, κ γ , independently of the W-Z 0 anomalous magnetic moment, κ Z 0 . This process is potentially a goldmine of W-boson physics and we strongly encourage that serious thought be given to the possibility of building such a collider.
There is yet to be a complete quantum mechanical version of the Fokker-Feynman model for many-particle systems with interactions of electromagnetic origin, because the corresponding Lagrangian is of infinite order. It...
A solution is presented for the outstanding problem of formulating a classical relativistic dynamics for many-particle systems via a Lagrangian. The Fokker-Wheeler-Feynman approach is both modified and generalized to ...
The production of fourth-generation quarks at the Superconducting Super Collider is studied concentrating on event signatures resulting from the single-lepton and two-lepton decay modes. We find that events with multi...
The production of fourth-generation quarks at the Superconducting Super Collider is studied concentrating on event signatures resulting from the single-lepton and two-lepton decay modes. We find that events with multijets (njet≥3) and one or two high-pT leptons are good signals for heavy-quark production for quark masses up to 600 GeV. In addition, we also found that the total transverse energy of an event is useful for distinguishing between heavy-quark production and the top-quark background.
We consider the process e±p→e±γX. In the first section, we look for radiative zeros and find that they are absent in e−p collisions but possibly observable in e+p collisions. In the second section we inves...
We consider the process e±p→e±γX. In the first section, we look for radiative zeros and find that they are absent in e−p collisions but possibly observable in e+p collisions. In the second section we investigate the effects of the exchange of an extra neutral gauge boson on the process at hand. We find that, given appropriate cuts and using expected luminosities at the DESY ep collider HERA, a 2-standard-deviation effect could arise from a light neutral gauge boson. Z’ masses up to ∼300 GeV/c2 could be probed at the 1-standard-deviation level.
The decay of V50 has been studied with a low-background, three-crystal intrinsic Ge detector operating in a salt mine. The partial half-life for electron-capture decay to the first excited state of Ti50 has been estim...
The decay of V50 has been studied with a low-background, three-crystal intrinsic Ge detector operating in a salt mine. The partial half-life for electron-capture decay to the first excited state of Ti50 has been estimated to be (2.05±0.49)×1017 yr, and the partial half-life for β− decay to the first excited state of Cr50 has been estimated to be (8.2−3.1+13.1)×1017 yr.
A generalization of the McMillan-Kobayashi mean-field theory of smectic-A liquid crystals to explicitly include anisotropic hard-core interactions is described. Hard-core effects are incorporated using perturbation ar...
A generalization of the McMillan-Kobayashi mean-field theory of smectic-A liquid crystals to explicitly include anisotropic hard-core interactions is described. Hard-core effects are incorporated using perturbation arguments on a reference system of aligned parallel ellipsoids with effective shape parameters, which is treated by a nonlocal-density-functional approach. The results reveal the necessity of including both anisotropic repulsions and certain ‘‘symmetry-breaking’’ attractive interactions, usually omitted from McMillan-Kobayashi treatments, for obtaining stable smectic-A phases. The theory shows explicitly how the interlayer distance in a smectic phase results, variationally, from incompressibility of the hard cores. Phase diagrams that include nematic, smectic, as well as isotropic liquid and vapor phases are presented, using both temperature and density (or pressure) as independent variables.
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