Quantization of the First-Order Two-Dimensional Einstein-Hilbert Action

A canonical analysis of the first-order two-dimensional Einstein-Hilbert action has shown it to have no physical degrees of freedom and to possess an unusual gauge symmetry with a symmetric field $\xi_{\mu\nu}$ acting as a gauge function. Some consequences of this symmetry are explored. The action is quantized and it is shown that all loop diagrams beyond one-loop order vanish. Furthermore, explicit calculation of the one-loop two-point function shows that it too vanishes, with the contribution of the ghost loop cancelling that of the ``graviton'' loop

Realistic calculations of nuclear disappearance lifetimes induced by neutron-antineutron oscillations

Realistic calculations of nuclear disappearance lifetimes induced by neutron-antineutron oscillations are reported for oxygen and iron, using antineutron nuclear potentials derived from a recent comprehensive analysis of antiproton atomic X-ray and radiochemical data. A lower limit of 3.3 x 10E8 s on the neutron-antineutron oscillation time is derived from the Super-Kamiokande I new lower limit of 1.77 x 10E32 yr on the neutron lifetime in oxygen. Antineutron scattering lengths in carbon and nickel, needed in trap experiments using ultracold neutrons, are calculated from updated antinucleon optical potentials at threshold, with results shown to be largely model independent.Comment: version matching PRD publication, typos and references correcte

Theory of a large thermoeffect in superconductors doped with magnetic impurities

We argue that parametrically strong enhancement of a thermoelectric current can be observed in conventional superconductors doped by magnetic impurities. This effect is caused by violation of the symmetry between electron-like and hole-like excitations due to formation of subgap Andreev bound states in the vicinity of magnetic impurities. We develop a quantitative theory of this effect and demonstrate that it can be detected in modern experiments.Comment: 5 pages, 4 figure