1,500 research outputs found
Charmless two-body B decays: A global analysis with QCD factorization
In this paper, we perform a global analysis of and decays
with the QCD factorization approach. It is encouraging to observe that the
predictions of QCD factorization are in good agreement with experiment. The
best fit is around . The penguin-to-tree ratio of decays is preferred to be larger than 0.3.
We also show the confidence levels for some interesting channels: , and , . For decays, they are expected to have smaller branching ratios with
more precise measurements.Comment: 20 pages, 4 figures, version to appear in Phys. Rev.
Charming penguin contributions to B => K \pi
We present calculations of the charming-penguin long-distance contributions
to B => K \pi decays due to intermediate charmed meson states. Our calculation
is based on the Chiral Effective Lagrangean for light and heavy mesons,
corrected for the hard pion and kaon momenta. We find that the charming-penguin
contributions increase significantly the B => K \pi decay rates in comparison
with the short-distance contributions, giving results in better agreement with
experimental data.Comment: 13 pages LaTeX (uses RevTeX and epsfig), 3 figures. Corrected typos.
To appear in Physical Review
Testing QCD factorisation and charming penguins in charmless
We try a global fit of the experimental branching ratios and CP-asymmetries
of the charmless decays according to QCD factorisation. We find it
impossible to reach a satisfactory agreement, the confidence level (CL) of the
best fit is smaller than .1 %.
The main reason for this failure is the difficulty to accomodate several
large experimental branching ratios of the strange channels. Furthermore,
experiment was not able to exclude a large direct CP asymmetry in , which is predicted very small by QCD factorisation.
Trying a fit with QCD factorisation complemented by a charming-penguin inspired
model we reach a best fit which is not excluded by experiment (CL of about 8 %)
but is not fully convincing.
These negative results must be tempered by the remark that some of the
experimental data used are recent and might still evolve significantly.Comment: 21 pages, 4 figures; several typos corrected, added one footnote and
two references, comments added about PQCD. To appear in Phys.Rev.
On the Singlet Penguin in B --> K eta' decay
New contributions to the short-distance b --> s eta' transition are
considered. They correspond to the quark and gluon content of eta'. Although
substantially larger than the referent QCD anomaly tail, they still cannot
account for the observed eta' enhancement.Comment: 5 pages, 3 figures, to appear in Proceedings of 9th Adriatic Meetin
Studies of the decays D^0 \rightarrow K_S^0K^-\pi^+ and D^0 \rightarrow K_S^0K^+\pi^-
The first measurements of the coherence factor R_{K_S^0K\pi} and the average
strong--phase difference \delta^{K_S^0K\pi} in D^0 \to K_S^0 K^\mp\pi^\pm
decays are reported. These parameters can be used to improve the determination
of the unitary triangle angle \gamma\ in B^- \rightarrow
decays, where is either a D^0 or a D^0-bar meson decaying to
the same final state, and also in studies of charm mixing. The measurements of
the coherence factor and strong-phase difference are made using
quantum-correlated, fully-reconstructed D^0D^0-bar pairs produced in e^+e^-
collisions at the \psi(3770) resonance. The measured values are R_{K_S^0K\pi} =
0.70 \pm 0.08 and \delta^{K_S^0K\pi} = (0.1 \pm 15.7) for an
unrestricted kinematic region and R_{K*K} = 0.94 \pm 0.12 and \delta^{K*K} =
(-16.6 \pm 18.4) for a region where the combined K_S^0 \pi^\pm
invariant mass is within 100 MeV/c^2 of the K^{*}(892)^\pm mass. These results
indicate a significant level of coherence in the decay. In addition, isobar
models are presented for the two decays, which show the dominance of the
K^*(892)^\pm resonance. The branching ratio {B}(D^0 \rightarrow
K_S^0K^+\pi^-)/{B}(D^0 \rightarrow K_S^0K^-\pi^+) is determined to be 0.592 \pm
0.044 (stat.) \pm 0.018 (syst.), which is more precise than previous
measurements.Comment: 38 pages. Version 3 updated to include the erratum information.
Errors corrected in Eqs (25), (26), 28). Fit results updated accordingly, and
external inputs updated to latest best known values. Typo corrected in Eq(3)-
no other consequence
Branching ratios and CP-violating asymmetries of decays in the general two-Higgs doublet models
Based on the low-energy effective Hamiltonian with the generalized
factorization, we calculate the new physics contributions to branching ratios
and CP-violating asymmetries of the charmless hadronic decays
in the standard model and the general two-Higgs doublet models (models I, II,
and III). Within the considered paramter space, we find the following. (a) In
models I and II, the new physics corrections are always small in size and will
be masked by other larger known theoretical uncertainties. (b) In model III,
the new physics corrections to the branching ratios of those QCD
penguin-dominated decays \ov B_s \to K^0\etapp, K^+ K^{-*}, etc., are large
in size and insensitive to the variations of \mhp and \nceff. For tree- or
electroweak penguin-dominated decay modes, however, the new physics corrections
are very small in size. (c) For \ov B_s \to K^+ K^{-*} and other seven decay
modes, the branching ratios are at the level of and will
be measurable at the future hadron colliders with large production. (d)
Among the studied thirty nine meson decay modes, seven of them can have a
CP-violating asymmetry larger than 20% in magnitude. The new
physics corrections are small or moderate in magnitude. (e) Because of its
large and \nceff stable branching ratio and CP violating asymmetry, the decay
\ov B_s \to K^+ K^{-*} seems to be the "best" channel to find CP violation of
system through studies of two-body charmless decays of meson.Comment: 39 pages, Revtex, 9 eps figures, final version accepted for
publication in Phys.Rev.
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