We measure the time dependence of the ratio of decay rates for the rare decay D{0}-->K{+}pi{-} to the Cabibbo-favored decay D{0}-->K{-}pi;{+}. A signal of 12.7x10;{3} D{0}-->K{+}pi{-} decays was obtained using the Collider Detector at Fermilab II detector at the Fermilab Tevatron with an integrated luminosity of 1.5 fb;{-1}. We measure the D0-D[over ]{0} mixing parameters (R_{D},y{'},x{'2}), and find that the data are inconsistent with the no-mixing hypothesis with a probability equivalent to 3.8 Gaussian standard deviations.

The quasielastic scattering of muon neutrinos on oxygen 16 is studied for neutrino energies between 200 MeV and 1 GeV using a relativistic shell model. Final state interactions are included within the distorted wave impulse approximation, by means of a relativistic optical potential, with and without imaginary part, and of a relativistic mean field potential. For comparison with experimental data the inclusive charged-current quasielastic cross section for − 12 C scattering in the kinematical conditions of the LSND experiment at Los Alamos is also presented and briefly discussed. In the past few years the observation of neutrino oscillations at Super-Kamiokande [1] and the subsequent proposal and realization of new experiments, aimed at determining neutrino properties with high accuracy [2], have renovated the interest towards neutrino scattering on complex nuclei. In fact, neutrino detectors usually contain carbon or oxygen nuclei, and for a proper interpretation of the experimental results the description of the -nucleus interaction must be accurate [3].At intermediate neutrino energies, ranging from some hundreds MeV to a few GeV, -nucleus quasielastic scattering has been studied within several approaches [4]. Relativistic and nonrelativistic studies of random phase approximation have shown nuclear structure effects to be relevant only at low momentum transfers, but indications have been found that for future and precise data analyses of, e.g., atmospheric neutrino measurements, more accurate theoretical estimates may be needed. Additionally, very recently attention has been drawn towards final state interaction (FSI) effects, which, contrary to what is often assumed, may still be relevant even at the relatively high energy E =1 GeV [5].In this contribution we study charged-current (CC) neutrino-nucleus quasielastic scattering within the framework of a relativistic shell model (RSM), already successfully employed to study exclusive electron scattering [6] and neutral current neutrino scattering [7]. We compute inclusive - 16O quasielastic cross sections for three values of the incident neutrino energy, namely, 200 MeV, 500 MeV, and 1 GeV, which are representative of the kinematical range where quasielastic scattering gives the main contribution to the inclusive -nucleus process.We describe the CC quasielastic scattering of neutrinos on a nuclear target within the impulse approximation (IA), assuming that the incident neutrino exchanges one vector boson with only one nucleon, which is then emitted, while the remaining ͑A−1͒ nucleons in the target are spectators. The nuclear current is assumed to be the sum of single-nucleon currents, for which we employ the usual free nucleon expression (see Ref.[7]) with the axial form factor parametrized as a dipole with cutoff mass M A =1.026 GeV [8], and the states of the target and residual nuclei to be adequately described by an independent particle model wave function.To describe the bound nucleon states we use relativistic shell model wave functions, obtained as the se...

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A relativistic and quantum mechanical framework to compute nuclear transparencies for pion photoand electroproduction reactions is presented. Final-state interactions for the ejected pions and nucleons are implemented in a relativistic eikonal approach. At sufficiently large ejectile energies, a relativistic Glauber model can be adopted. At lower energies, the framework possesses the flexibility to use relativistic optical potentials. The proposed model can account for the color-transparency (CT) phenomenon and short-range correlations (SRC) in the nucleus. Results are presented for kinematics corresponding to completed and planned experiments at Jefferson Lab. The influence of CT and SRC on the nuclear transparency is studied. Both the SRC and CT mechanisms increase the nuclear transparency. The two mechanisms can be clearly separated, though, as they exhibit a completely different dependence on the hard-scale parameter. The nucleon and pion transparencies as computed in the relativistic Glauber approach are compared with optical-potential and semiclassical calculations. The similarities in the trends and magnitudes of the computed nuclear transparencies indicate that they are not subject to strong model dependences.PHYSICAL REVIEW C 77, 034602 (2008) electroproduction reactions from various target nuclei. Our conclusions are stated in Sec. IV. II. FORMALISMIn this section, the formalism used to describe A(γ, Nπ) and A(e, e Nπ) reactions is presented. A. Pion photoproductionWe use the following notations for the four-momenta in the laboratory frame: q µ (q, q) for the photon, P µ A (E A , p A = 0) for the target nucleus, P µ A−1 (E A−1 , p A−1 ) for the residual nucleus, and P µ N (E N , p N ) and P µ π (E π , p π ) for the ejected nucleon and pion. The missing momentum p m is defined as p m ≡ − p A−1 = p N + p π − q and the outgoing nucleon has spin m s . The fivefold differential cross section in the laboratory frame reads

We present a relativistic and cross-section factorized framework for computing nuclear transparencies extracted from A(\gamma,\pi N) reactions at intermediate energies. The proposed quantummechanical model adopts a relativistic extension to the multiple-scattering Glauber approximation to account for the final state interactions of the ejected nucleon and pion. The theoretical predictions are compared against the experimental ^4He(\gamma,p \pi^-) data from Jefferson Lab. For those data, our results show no conclusive evidence for the onset of mechanisms related to color transparency.Comment: 5 pages, 3 figure