In this paper, we make a comprehensive determination of the Hubble constant H 0 by using two parameters-the B − V color and the rate of decline ∆m 15 -to simultaneously standardize the luminosities of all nearby Cepheid-calibrated type Ia supernovae (SNe Ia) and those of a larger, more distant sample of 29 SNe Ia. Each group is treated in as similar a manner as possible in order to avoid systematic effects. A simultaneous χ 2 minimization yields a standardized absolute luminosity of the Cepheid-calibrated supernovae as well as the Hubble constant obtained from the more distant sample. We find H 0 = 62 km s −1 Mpc −1 and a standardized absolute magnitude of -19.46. The sensitivity of H 0 to a metallicity dependence of the Cepheid-determined distances is investigated. The total uncertainty δH 0 , dominated by uncertainties in the primary Cepheid distance indicator, is estimated to be 5 km s −1 Mpc −1 .Subject headings: cosmology: distance scale-supernovae: general * means the distance is inferred from association with other galaxies with the distance uncertainty increased by the projected distance.
Limits are reported on charged right-handed currents, based on precise measurement of the endpoint e+ spectrum in ~+ decay. Highly polarized ~+ from the TRIUMF "surface" muon beam were stopped in high purity metal foils and liquid He targets selected to minimize depolarization effects. Decay e+ emitted within 160 mrad of the beam direction were momentum-analyzed to 0.15%. Muons were stopped within either a spin-precessing transverse field (70-G or 110-G) or a spin-holding longitudinal field (0.3-T or 1.1-T). Data collected with the spin-precessing field were used for the momentum calibration of the spectrometer. The spin-held data were used to measure the relative e+ rate at the endpoint. An extrapolation was made to + extract the endpoint rate opposite to the ~ spin. In terms of the standard muon decay parameters this rate is given by (1-~P~o/p) where P~ is muon polarization. The result for ~P~o/p was consistent with the V-A prediction of 1. It is quoted as a 90% confidence lower
The correction to our result for { P p 6 / p due to muon depolarization in scattering with unpolarized electrons was computed incorrectly. This mistake was caused by an error' in a calculation published by Ford and ~u 1 l i n . l Their Eq. (21) for the laboratory muon fractional kinetic-energy loss w should read rather thanHere 0 is the center-of-momentum scattering angle and pc is the laboratory muon velocity. Equation (1) is larger than Eq.(2) by a factor of 4 / D 2 , where 8 <0.27.Since the correction we applied ( 7 . 3 x l o p 4 ) is inversely proportional to w, the true correction is more than 50 times smaller and therefore is negligible. Correspondingly, slight modifications to our quantitative results are required. The corrected combined result from all stopping targets is Although this central value is not as close to the V -A prediction of unity as before (2.4 vs 1.6 standard deviations), the various possible upward corrections to { P , 6 / p discussed in Secs. V C, V I A , and VI B would tend to bring it closer to the predicted value. With the unphysical region i { P , 6 / p > 1 ) excluded, the 90% confidence limit becomes Since our central value for { P , 6 / p obtained by means of the muon-spin-rotation technique3 was also affected by the same error, the combined 90% confidence limit from 0 0 05 0 1 0 15 € = M' (W,) / M2(w2) FIG. 1. Experimental 90% confidence limits on the masssquared ratio E and mixing angle { for the gauge bosons W , and W,.237
An analysis has been made of 64600 events of the type K p + K p-0 and 22 800 events of the type K p + K n in the Berkeley 25-inch hydrogen bubble chamber. Differential cross sections have been measured in intervals of 10 MeV/c over the momentum range 220 to 470 MeV/c. Legendre polynomial fits to the distributions have been made,and the coefficients show structure from the resonant D-wave A(1520) and background Sand P-waves. No new structure is observed. The total K-p cross section determined from measurements of all final states seen in this exposure is also presented. 'I
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