Abstract: We present a study of the decays B(+) -> DK(+) with D mesons reconstructed in the K(+)pi(-)pi(0) or K(-)pi(+)pi(0) final states, where D indicates a D(0) or a (D) over bar (0) meson. Using a sample of 474 x 10(6) B (B) over bar pairs collected with the BABAR detector at the PEP- II asymmetric- energy e(+)e(-) collider at SLAC, we measure the ratios R +/- equivalent to Gamma(B(+)->[K(-/+)pi(+)pi(0)](D)K(+))/Gamma(B(+)->[K(+)pi(-/+)pi(0)](D) K(+)). We obtain R+ = (5(-10)(+12)(stat)(4)(2)(syst)) X 10(-3) and R(-) = (12(-10)(+12)(stat)(-5)(+3)(syst)) X 10(-3), from which we extract the upper limits at 90% probability: R(+) < 23 X 10(-3) and R- < 29 X 10(-3). Using these measurements, we obtain an upper limit for the ratio r(B) of the magnitudes of the b -> u and b -> c amplitudes r(B) < 0.13 at 90% probability.

Abstract: Gamow-Teller (GT) transitions are the most common weak interaction processes of spin-isospin (sigma tau) type in atomic nuclei. They are of interest not only in nuclear physics but also in astrophysics; they play an important role in supernovae explosions and nucleosynthesis. The direct study of weak decay processes, however, gives relatively limited information about GT transitions and the states excited via GT transitions (GT states); beta decay can only access states at excitation energies lower than the decay Q-value, and neutrino-induced reactions have very small cross-sections. However, one should note that beta decay has a direct access to the absolute GT transition strengths B(GT) from a study of half-lives, Q(beta)-values and branching ratios. They also provide information on GT transitions in nuclei far-from-stability. Studies of M1 gamma transitions provide similar information. In contrast, the complementary charge-exchange (CE) reactions, such as the (p, n) or ((3)He, t) reactions at intermediate beam energies and 0 degrees, can selectively excite GT states up to high excitation energies in the final nucleus. It has been found empirically that there is a close proportionality between the cross-sections at 0 degrees and the transition strengths B(GT) in these CE reactions. Therefore, CE reactions are useful tools to study the relative values of B(GT) strengths up to high excitation energies. In recent ((3)He, t) measurements, one order-of-magnitude improvement in the energy resolution has been achieved. This has made it possible to make one-to-one comparisons of GT transitions studied in CE reactions and beta decays. Thus GT strengths in ((3)He, t) reactions can be normalised by the beta-decay values. In addition, comparisons with closely related M1 transitions studied in gamma decay or electron inelastic scattering [(e, e')1, and furthermore with “spin” M I transitions that can be studied by proton inelastic scattering [(p, p')[ have now been made possible. In these comparisons, the isospin quantum number T and associated symmetry structure in the same mass A nuclei (isobars) play a key role. Isospin symmetry can extend our scope even to the structures of unstable nuclei that are far from reach at present unstable beam factories.

Abstract: We update the phenomenological constraints of the nonstandard neutrino interactions (NSNI) with electrons including in the analysis, for the first time, data from LAMPF, Krasnoyarsk, and the latest Texono observations. We assume that NSNI modify the cross section of elastic scattering of (anti) neutrinos off electrons, using reactor and accelerator data, and the cross section of the electron-positron annihilation, using the four LEP experiments, in particular, new data from DELPHI. We find more restrictive allowed regions for the NSNI parameters: -0.11< epsilon(eR)(ee) < 0.05 and -0.02 < epsilon(eL)(ee) < 0.09 (90% C.L.). We also recalculate the parameters of tauonic flavor obtaining -0.35 < epsilon(eR)(tau tau) < 0.50 and -0.51 < epsilon(eL)(tau tau) < 0.34 (90% C.L.). Although more severe than the limits already present in the literature, our results indicate that NSNI are allowed by the present data as a subleading effect, and the standard electroweak model continues consistent with the experimental panorama at 90% C.L. Further improvement on this picture will deserve a lot of engagement of upcoming experiments.