6,022 research outputs found
Effect of sea quarks on the single-spin asymmetries in polarized pp collisions at RHIC
We calculate the single-spin asymmetries of
bosons produced in polarized pp collisions with the valence part of the up and
down quark helicity distributions modeled by the light-cone
quark-spectator-diquark model while the sea part helicity distributions of the
up and down quarks treated as parametrization. Comparing our results with those
from experimental data at RHIC, we find that the helicity distributions of sea
quarks play an important role in the determination of the shapes of
. It is shown that is sensitive to , while to intuitively. The experimental
data of the polarized structure functions and the sum of helicities are also
important to constrain the sizes of quark helicity distributions both for the
sea part and the valence part of the nucleon.Comment: 19 latex pages, 5 figures, final version for publicatio
Revisiting B\to\pi K, \pi K^{\ast} and \rho K decays: CP violations and implication for New Physics
Combining the up-to-date experimental information on and decays, we revisit the decay rates and CP asymmetries of
these decays within the framework of QCD factorization. Using an infrared
finite gluon propagator of Cornwall prescription, we find that the time-like
annihilation amplitude could contribute a large strong phase, while the
space-like hard spectator scattering amplitude is real. Numerically, we find
that all the branching ratios and most of the direct CP violations, except
, agree with the current experimental data
with an effective gluon mass . Taking the unmatched
difference in direct CP violations between and
decays as a hint of new physics, we perform a
model-independent analysis of new physics contributions with a set of
(q=u,d) operators. Detail
analyses of the relative impacts of the operators are presented in five cases.
Fitting the twelve decay modes, parameter spaces are found generally with
nontrivial weak phases. Our results may indicate that both strong phase from
annihilation amplitude and new weak phase from new physics are needed to
resolve the puzzle. To further test the new physics hypothesis, the
mixing-induced CP violations in and are
discussed and good agreements with the recent experimental data are found.Comment: Version published in JHE
mixing within minimal flavor-violating two-Higgs-doublet models
In the "Higgs basis" for a generic 2HDM, only one scalar doublet gets a
nonzero vacuum expectation value and, under the criterion of minimal flavor
violation, the other one is fixed to be either color-singlet or color-octet,
which are named as the type-III and type-C models, respectively. In this paper,
the charged-Higgs effects of these two models on mixing are
studied. Firstly, we perform a complete one-loop computation of the
electro-weak corrections to the amplitudes of mixing.
Together with the up-to-date experimental measurements, a detailed
phenomenological analysis is then performed in the cases of both real and
complex Yukawa couplings of charged scalars to quarks. The spaces of model
parameters allowed by the current experimental data on
mixing are obtained and the differences between type-III and type-C models are
investigated, which is helpful to distinguish between these two models.Comment: 19 pages, 3 figures, 2 tables; More references and discussions added,
final version published in the journa
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