Phase-sensitive tests of the pairing state symmetry in Sr2RuO4

Exotic superconducting properties of Sr$_{2}$RuO$_{4}$ have provided strong support for an unconventional pairing symmetry. However, the extensive efforts over the past decade have not yet unambiguously resolved the controversy about the pairing symmetry in this material. While recent phase-sensitive experiments using flux modulation in Josephson junctions consisting of Sr$_{2}$RuO$_{4}$ and a conventional superconductor have been interpreted as conclusive evidence for a chiral spin-triplet pairing, we propose here an alternative interpretation. We show that an overlooked chiral spin-singlet pairing is also compatible with the observed phase shifts in Josephson junctions and propose further experiments which would distinguish it from its spin-triplet counterpart.Comment: 4 pages, 1 figur

Determination of critical current density from arbitrary flux relaxation process

The current-carrying ability of a type-II superconductor is generally represented by its critical current density. This can be determined by measuring a flux relaxation process starting with a testing current density that is greater than or equal to the critical value. Here we show that a flux relaxation process starting with an intermediate current density can be converted into a process starting with the critical current density by introducing a virtual time interval. Therefore, one may calculate the critical current density from the flux relaxation process starting with a current density below the critical value. The exact solutions of the time dependence of current density in the flux relaxation process were also discussed.Comment: 5 page

Calculation of gluon and four-quark condensates from the operator expansion

The magnitudes of gluon and four-quark condensates are found from the analysis of vector mesons consisting of light quarks (the families of $\rho$ and $\omega$ mesons) in the 3 loops approximation. The QCD model with infinite number of vector mesons is used to describe the function $R(s)$. This model describes well the experimental function $R(s)$. Polarization operators calculated with this model coincide with the Wilson operator expansion at large $Q^2$. The improved perturbative theory, such that the polarization operators have correct analytical properties, is used. The result is $<0 | (\alpha_s/\pi) G^2 | 0 > = 0.062 \pm 0.019 GeV^4$. The electronic widths of $\rho(1450)$ and $\omega(1420)$ are calculated.Comment: 18 pages, latex, changed content slightl