9,757 research outputs found
Implications of new data in charmless B decays
Based on the latest experimental data of and modes, a
model-independent analytical analysis is presented. The CP-averaged branching
ratio difference in decays with and
is reduced though it remains larger than the prediction from the standard
model(SM) as both measured and are enhanced, which indicates that a
room for new physics becomes smaller. The present data of decay reduce
the ratio from the previous value of to , which is still larger than the theoretical estimations based on
QCD factorization and pQCD. Within SM and flavor SU(3) symmetry, the current
data also diminish the ratio from the previous value to with a large strong phase , while its value remains much larger than the one extracted from
the modes. The direct CP violation is
predicted to be , which is consistent
with the present data. Two kinds of new effects in both strong and weak phases
of the electroweak penguin diagram are considered. It is found that both cases
can reduce the ratio to and lead to roughly the same
predictions for CP violation in .Comment: 13 pages, 4 figure
Charmless decays B->pipi, piK and KK in broken SU(3)symmetry
Charmless B decay modes and aresystematically
investigated with and without flavor SU(3) symmetry. Independent analyses on
and modes both favor a large ratio between color-suppressed
tree () and tree ( diagram, which suggests that they are more likely to
originate from long distance effects. The sizes of QCD penguin diagrams
extracted individually from , and modes are found to
follow a pattern of SU(3) breaking in agreement with the naive factorization
estimates. Global fits to these modes are done under various scenarios of
SU(3)relations. The results show good determinations of weak phase in
consistency with the Standard Model (SM), but a large electro-weak penguin
(P_{\tmop{EW}}) relative to with a large relative strong phase are
favored, which requires an big enhancement of color suppressed electro-weak
penguin (P_{\tmop{EW}}^C) compatible in size but destructively interfering
with P_{\tmop{EW}} within the SM, or implies new physics. Possibility of
sizable contributions from nonfactorizable diagrams such as -exchange (),
annihilation() and penguin-annihilation diagrams() are investigated.
The implications to the branching ratios and CP violations in modes are
discussed.Comment: 27 pages, 9 figures, reference added, to appear in Phy.Rev.
Searching for Dark Matter Signals in the Left-Right Symmetric Gauge Model with CP Symmetry
We investigate singlet scalar dark matter (DM) candidate in a left-right
symmetric gauge model with two Higgs bidoublets (2HBDM) in which the
stabilization of the DM particle is induced by the discrete symmetries P and
CP. According to the observed DM abundance, we predict the DM direct and
indirect detection cross sections for the DM mass range from 10 GeV to 500 GeV.
We show that the DM indirect detection cross section is not sensitive to the
light Higgs mixing and Yukawa couplings except the resonance regions. The
predicted spin-independent DM-nucleon elastic scattering cross section is found
to be significantly dependent on the above two factors. Our results show that
the future DM direct search experiments can cover the most parts of the allowed
parameter space. The PAMELA antiproton data can only exclude two very narrow
regions in the 2HBDM. It is very difficult to detect the DM direct or indirect
signals in the resonance regions due to the Breit-Wigner resonance effect.Comment: 24 pages, 8 figures. minor changes and a reference added, published
in Phys. Rev.
The separability of tripartite Gaussian state with amplification and amplitude damping
Tripartite three mode Gaussian state undergoes parametric amplification and
amplitude damping as well as thermal noise is studied. In the case of a state
totally symmetrically interacting with the environment, the time dependent
correlation matrix of the state in evolution is given. The conditions for fully
separability and fully entanglement of the final tripartite three mode Gaussian
state are worked out.Comment: 9 pages, 3 figure
Quark deconfinement phase transition in nuclear matter for improved quark mass density-dependent model
The improved quark mass density-dependent (IQMDD) model, which has been
successfully used to describe the properties of both infinite nuclear matter
and finite nuclei, is applied to investigate the properties of quark
deconfinement phase transition. By using the finite-temperature quantum field
theory, we calculate the finite temperature effective potential and extend the
IQMDD model to finite temperature and finite nuclear matter density. The
critical temperature and the critical density of nuclear matter are given and
the QCD phase diagram is addressed. It is shown that this model can not only
describe the saturation properties of nuclear matter, but also explain the
quark deconfinement phase transition successfully
Overexpression AtNHX1 confers salt-tolerance of transgenic tall fescue
Saline soil is a serious problem worldwide, and it is necessary to improve the salt tolerance of plants so as to avoid the progressive deterioration of saline soil. Here we report that over-expression of AtNHX1 improves salt tolerance in transgenic tall fescue. The AtNHX1 gene driven with CaMV35S promoter wasconstructed into the plant expression vector pGreen0229, and introduced into the embryonic calli of hypocotyls of tall fescue (Festuca arundinacea ) by particle bombardment. Regenerated plantlets were obtained by screening of herbicide (PPT, 2 mg/L), and the putative transformants were assayed by PCRand western blot analysis. 29 transgenic plants were obtained. The results indicated that the exogenous genes had been integrated into the genomes of transgenic plants, and AtNHX1 is expressed in the plants. There was remarkable salt tolerance in transgenic plants compared to control plant
Heavy Quark Expansion in 1/\hat{m}_Q and |V_{cb}| Extraction
The dressed heavy quark mass \hat{m}_Q=m_Q+\bar{{\Lambda}} with
\bar{{\Lambda}} being the binding energy is introduced to characterize the
heavy hadrons containing a single heavy quark. A heavy quark expansion in terms
of the inverse of the dressed heavy quark mass 1/\hat{m}_Q is presented with a
complete decomposition of the full field and integrating out the small
components. The heavy quark-antiquark coupling effects are included in the
finite mass corrections. It is shown that the 1/\hat{m}_Q expansion is more
favorable in application. The extraction of |V_{cb}| from exclusive B decays is
studied by using such a new expansion approach.Comment: 21 pages, 11 figure
Implication of from global fit and
The measurement of is discussed within and beyond the standard
model. In the presence of new physics, the angle extracted from the
global fit(denoted by ) and the one extracted from (denoted by ) are in general all different from the
'true' angle which is the weak phase of CKM matrix element .
Possible new physics effects on the ratio is studied and parameterized in a most general form. It is
shown that the ratio may provide a useful tool in probing new
physics. The experimental value of is obtained through an update of
the global fit of the unitarity triangle with the latest data and found to be
less than unity at 1 level. The new physics effects on from
the models with minimum flavor violation (MFV) and the standard model with
two-Higgs-doublet (S2HDM) are studied in detail. It is found that the MFV
models seem to give a relative large value . With the current
data, this may indicate that this kind of new physics may be disfavored and
alternative new physics with additional phases appears more relevant. As an
illustration for models with additional phase beyond CKM phase, the S2HDM
effects on are studied and found to be easily coincide with the
data due to the flavor changing neutral Higgs interaction.Comment: 19 pages, ReVtex, 5 figures, published version, latest result on sin
(2 beta) from BaBar was considered and more references adde
Met promotes the formation of double minute chromosomes induced by Sei-1 in NIH-3T3 murine fibroblasts
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