Purchasing Power Parity and Country Characteristics: Evidence from Time Series Analysis

This paper investigates the relationships between country characteristics and the validity of PPP. We use three alternative time series methods to test for the stationarity of real exchange rates for each of the 72 countries over the period from 1976 to 2005. Our result shows that the evidence of PPP exhibits geographic difference. It is most likely to find stationary real exchange rates for European countries, whereas it is least likely to obtain the result of supporting PPP for Asian countries. We then use a probit regression model to examine if county characteristics are related to the validity of PPP. The probit regression result reveals that the validity of PPP decreases with inflation rate and increases with nominal exchange rate volatility.Purchasing power parity, Country characteristics, Unit root tests

Penguin-Induced Radiative Baryonic B Decays

Weak radiative baryonic B decays B\to\B_1\ov \B_2\gamma mediated by the electromagnetic penguin process $b\to s\gamma$ have appreciable rates larger than their two-body counterparts B\to\B_1\ov \B_2. The branching ratios for $B^-\to\Lambda\bar p\gamma$ and $B^-\to\Xi^0\bar\Sigma^-\gamma$ are sizable, falling into the range of $(1\sim 6)\times 10^{-6}$ with the value preferred to be on the large side, and not far from the bottom baryon radiative decays $\Lambda_b\to\Lambda\gamma$ and $\Xi_b\to\Xi\gamma$ due to the large short-distance enhancement for $b\to s\gamma$ penguin transition and the large strong coupling of the anti-triplet bottom baryons with the B meson and the light baryon. These penguin-induced radiative baryonic B decay modes should be accessible by B factories.Comment: 8 pages, 1 figure. Branching ratios are corrected as previous values are too large by a factor of 2 and a new reference is adde