Search results for "Mixing"

A plausible explanation of ϒ(10860)

2019

We show that a good description of the ¿(10860) properties, in particular the mass, the e + e ¿ leptonic widths and the ¿ + ¿ ¿ ¿(ns) (n=1,2,3) production rates, can be obtained under the assumption that ¿(10860) is a mixing of the conventional ¿(5s) quark model state with the lowest P¿ wave hybrid state. © 2019 The Author(s)

mixing in the weak-gauged U(4)L⊗U(4)R chiral lagrangian model

1998

Abstract The D0– D 0 mixing is analyzed in a weak gauged U(4)L⊗U(4)R chiral lagrangian model where the electroweak interaction is introduced as a gauge theory over the meson degrees of freedom. This model allows a particular realization of the G.I.M. mechanism and then could be useful in the study of processes where G.I.M. suppression is effective. As a test of the model we have also analyzed the K0– K 0 mixing. We find ΔmK in good agreement with the experimental result and we show that the D0– D 0 mixing is very much suppressed in agreement with previous estimates in the Heavy Quark expansion framework.

Measurement of $B_d$ mixing using opposite-side flavor tagging

2006

We report on a measurement of the $B^0_d$ mixing frequency and the calibration of an opposite-side flavor tagger in the D{\O}experiment. Various properties associated with the $b$ quark on the opposite side of the reconstructed $B$ meson were combined using a likelihood-ratio method into a single variable with enhanced tagging power. Its performance was tested with data, using a large sample of reconstructed semileptonic $B \to \mu \dzero X$ and $B \to \mu \dst X$ decays, corresponding to an integrated luminosity of approximately 1 fb$^{-1}$. The events were divided into groups depending on the value of the combined tagging variable, and an independent analysis was performed in each group. …

D–D¯ mixing and new physics: General considerations and constraints on the MSSM

2007

Abstract Combining the recent experimental evidence of D – D ¯ mixing, we extract model-independent information on the mixing amplitude and on its CP-violating phase. Using this information, we present new constraints on the flavour structure of up-type squark mass matrices in supersymmetric extensions of the Standard Model.

Confusing nonzero theta(13) with nonstandard interactions in the solar neutrino sector

2009

Solar and KamLAND data are in slight tension when interpreted in the standard two-flavor oscillations framework and this may be alleviated allowing for a non-zero value of the mixing angle theta_13. Here we show that, likewise, non-standard flavor-changing interactions (FCI), possibly intervening in the propagation of solar neutrinos, are equally able to alleviate this tension and therefore constitute a potential source of confusion in the determination of theta_13. By performing a full three-flavor analysis of solar and KamLAND data in presence of FCI we provide a quantitative description of the degeneracy existing between theta_13 and the vectorial coupling eps_e\tau^dV characterizing the…

Scalar quark searches in $e^+ e^-$ collisions at $\sqrt{s}$ = 181-184 GeV

1998

Searches for scalar top, scalar bottom and degenerate scalar quarks have been performed with data collected with the ALEPH detector at LEP. The data sample consists of 57 pb^-1 taken at sqrt{s} = 181-184 GeV. No evidence for scalar top, scalar bottom or degenerate scalar quarks was found in the channels tilde{t} --> c chi, tilde{t} --> b l snu, tilde{b} --> b chi, and tilde{q} --> q chi. From the channel tilde{t} --> c chi a limit of 74 GeV/c^2 has been set on the scalar top quark mass, independent of the mixing angle. This limit assumes a mass difference between the stop and the chi in the range 10-40 GeV/c^2. From the channel tilde{t} --> b l snu the mixing-angle-indepen…

Experimental Determination of Weak Quark Mixing Angles in the Eight Quark Scheme

1989

Weak Mixing, CP Violation and Rare Decays

1989

This review summarizes experimental information on weak couplings of quark flavours from weak decays and weak production of heavy flavours and the relation of the observed direct CP violation to a non-trivial phase in the quark mixing matrix. The interest in this field is twofold: on the one side, we can measure precisely the parameters of the standard model in its own framework; on the other side, any inconsistency amongst these measurements or evidence for any process forbidden in the standard model will lead beyond that model.

Comment On The Lepton Mixing Matrix

1980

The problem of finding a suitable parametrization for a nontrivial lepton mixing matrix is considered in the framework of the ''sequential'' Weinberg-Salam theory. It is noted that in the case of n lepton generations there are in fact n+1 different theories, corresponding to different numbers m of right-handed neutrino fields present in the Lagrangian. These (n,m) models conserve CP for leptonic couplings naturally only for m=0 or 1 when n > or = 3. These models would seem to be useful as self-consistent approximations for reducing the number of parameters in the experimental analysis of lepton mixing matrices.

The effect of hyperfine mixing in electromagnetic and semileptonic decays of doubly heavy baryons

2010

We consider the role played by hyperfine mixing in electromagnetic and semileptonic decays of doubly heavy baryons, which give rise to large corrections to the decay widths in both cases.