Optical conductivity of d-wave superconductors

We study theoretically the optical conductivity of d-wave superconductors like in high temperature cuprates in the presence of impurities. We limit ourselves at T=0K and focus on the frequency dependence of both sigma_1(omega) and \omega*\sigma_2(omega) for omega<2Delta. When the impurity scattering is in the unitary limit, we find a peak in sigma_1(omega) with omega/Delta\simeq 0.1\sim 0.5$, which may account for the peak seen by Basov et al. in Zn-substituted YBCO.Comment: 7 pages, 9 figures, submitted to Europhys. Let

Paramagnetic Reentrance Effect in NS Proximity Cylinders

A scenario for the unusual paramagnetic reentrance behavior at ultra-low temperatures in Nb-Ag, Nb-Au, and Nb-Cu cylinders is presented. For the diamagnetic response down to temperatures of the order 15 mK, the standard theory (quasi-classical approximation) for superconductors appears to work very well, assuming that Ag, Au, and Cu remain in the normal state except for the proximity-induced superconductivity. Here it is proposed that these noble metals may become p-wave superconductors with a transition temperature of order 10 mK. Below this temperature, p-wave triplet superconductivity emerges around the periphery of the cylinder. The diamagnetic current flowing in the periphery is compensated by a quantized paramagnetic current in the opposite direction, thus providing a simple explanation for the observed increase in the susceptibility at ultra-low temperatures.Comment: RevTex, 8 pages with 1 eps figur

Asymmetric adjustment of the equilibrium relationship between the nominal interest rate and inflation rate

This paper investigates the equilibrium relationship between the nominal interest rate and inflation rate in Japan using a threshold cointegration test, which allows for asymmetric adjustment. While the Engle-Granger method assuming symmetric adjustment cannot obtain the result of cointegration, a threshold cointegration approach provides clear evidence of the cointegration relationship characterized by asymmetric adjustment toward equilibrium. This shows that the long-run equilibrium relationship between the nominal interest rate and inflation rate is stable with asymmetric adjustment.

A Misguided Tobacco Policy? Public Policy and Consumption Substitutability Between Cigarettes and An Important Smokeless Tobacco Alternative

Snus, Tobacco, Smokeless Tobacco, Agricultural and Food Policy, Health Economics and Policy,

The term structure of interest rates with nonlinear adjustment: Evidence from a unit root test in the nonlinear STAR framework

This paper investigates the term structure of interest rates in Japan using the unit root test in a nonlinear STAR framework. The results provide strong evidence against the unit root of the yield spread between long-term and short-term interest rates, compared with standard unit root tests assuming only linear adjustment. This finding shows that the term structure of interest rates is stable with nonlinear adjustment.