Bernoulli Potential, Hall Constant and Cooper Pairs Effective Masses in Disordered BCS Superconductors

It is analyzed what fundamental new information for the properties of the superconductors can be obtained by systematic investigation of the Bernoulli effect. It is shown that it is a tool to determine the effective mass of Cooper pairs, the volume density of charge carriers, the temperature dependence of the penetration depth and condensation energy. The theoretical results for disordered and anisotropic gap superconductors are systematized for this aim. For clean-anisotropic-gap superconductors is presented a simple derivation for the temperature dependence of the penetration depthComment: 13 pages, 3 figures, LaTeX 2e, New figure and reference

High Precision Measurement of the Thermal Exponent for the Three-Dimensional XY Universality Class

Simulations results are reported for critical point of the two-component $\phi^4$ field theory. The correlation length exponent is measured to high precision with the result $\nu=0.6717(3)$. This value is in agreement with recent simulation results [Campostrini \textit{et al}., Phys. Rev. B \textbf{63}, 214503 (2001)], and marginally agrees with the most recent space-based measurements of the superfluid transition in $^4$He [Lipa \textit{et al}., Phys. Rev. B \textbf{68}, 174518 (2003)].Comment: a reference adde

a Unified Chiral Approach to Meson-Nucleon Interaction

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The Recurrent Eclipse of an Unusual Pre--Main-Sequence Star in IC 348

The recurrence of a previously documented eclipse of a solar-like pre--main-sequence star in the young cluster IC 348 has been observed. The recurrence interval is 4.7 $\pm 0.1$ yr and portions of 4 cycles have now been seen. The duration of each eclipse is at least 3.5 years, or $\sim 75$% of a cycle, verifying that this is not an eclipse by a stellar companion. The light curve is generally symmetric and approximately flat-bottomed. Brightness at maximum and minimum have been rather stable over the years but the light curve is not perfectly repetitive or smooth and small variations exist at all phases. We confirm that the star is redder when fainter. Models are discussed and it is proposed that this could be a system similar to KH 15D in NGC 2264. Specifically, it may be an eccentric binary in which a portion of the orbit of one member is currently occulted during some binary phases by a circumbinary disk. The star deserves sustained observational attention for what it may reveal about the circumstellar environment of low-mass stars of planet-forming age.Comment: Accepted for publication in ApJ (Letters