46 research outputs found
Analysis of the B --> \pi \ell^+ \ell^- Decay in the Standard Model with Fourth Generation
We investigate the influence of the fourth generation quarks on the branching
ratio and the CP-asymmetry in B -->\pi \ell^+ \ell^- decay. Taking the
|V_{t'd}V_{t'b}| ~ 0.001 with phase about 10 degree, which is consistent with
the sin2\phi_1 of the CKM and the B_d mixing parameter \Delta m_{B_d}, we
obtain that for both muon and tau channels the branching ratio, the magnitude
of CP-asymmetry and lepton polarization depict strong dependency on the 4th
generation quarks mass and mixing parameters. These results can serve as a good
tool to search for new physics effects, precisely, to search for the fourth
generation quarks( via its indirect manifestations in loop diagrams.Comment: 17 pages, 8 figure
The Pattern of CP Asymmetries in Transitions
New CP violating physics in transitions will modify the CP
asymmetries in B decays into final CP eigenstates (, , , , and ) from their
Standard Model values. In a model independent analysis, the pattern of
deviations can be used to probe which Wilson coefficients get a significant
contribution from the new physics. We demonstrate this idea using several
well-motivated models of new physics, and apply it to current data.Comment: 20 pages, 3 figures, 6 tables. v3: Discussion of higher order
corrections extended; Version appearing in JHE
Constraint of B_{d,s}-bar{B}_{d,s} mixing on warped extra-dimension model
Recent CDF measurement of the Bs-Bs oscillation frequency, at the Tevatron
imposes significant constraint on various models for new physics. A warped
extra-dimension model with custodial isospin symmetry accommodates the Bd-Bd
mixing at tree level mainly through the Kaluza-Klein gluons. This is due to the
misalignment between the bulk gauge eigenstates and the localized Yukawa
eigenstates of the bulk fermions. We adopt the universal 5D Yukawa coupling
model where all Yukawa couplings are of order one. The SM fermion mass spectra
and mixings are controlled by the bulk Dirac mass parameters. With two versions
of the hadronic parameter values, we investigate the implication of the
observed BB mixings on this model. The CP-violating effects on the Bd system is
shown to provide very strong constraint: The first Kaluza-Klein mass of a gluon
has its lower bound about 3.7 TeV with 1 sigma uncertainty.Comment: published version in JHEP, CP-violating effects include
Flavor SU(3) analysis of charmless B meson decays to two pseudoscalar mesons
Global fits to charmless B --> PP decays in the framework of flavor SU(3)
symmetry are updated and improved without reference to the \sin2\beta measured
from the charmonium decay modes. Fit results directly constrain the
(\bar\rho,\bar\eta) vertex of the unitarity triangle, and are used to predict
the branching ratios and CP asymmetries of all decay modes, including those of
the B_s system. Different schemes of SU(3) breaking in decay amplitude sizes
are analyzed. The major breaking effect between strangeness-conserving and
strangeness-changing decays can be accounted for by including a ratio of decay
constants in tree and color-suppressed amplitudes. The possibility of having a
new physics contribution to K \pi decays is also examined from the data fitting
point of view.Comment: 22 pages and 2 figures; some comments and references added; more
references added, version to appear in journa
First ADS analysis of B- -> D0K- decays in hadron collisions
Proceedings of DISCRETE 2010, Symposium on Prospects in the Physics of
Discrete Symmetries, Rome (IT), 6-11 December 2010Comment: 7 pages, 5 figure
A Parameterization Invariant Approach to the Statistical Estimation of the CKM Phase
In contrast to previous analyses, we demonstrate a Bayesian approach to the
estimation of the CKM phase that is invariant to parameterization. We
also show that in addition to {\em computing} the marginal posterior in a
Bayesian manner, the distribution must also be {\em interpreted} from a
subjective Bayesian viewpoint. Doing so gives a very natural interpretation to
the distribution. We also comment on the effect of removing information about
.Comment: 14 pages, 3 figures, 1 table, minor revision; to appear in JHE
Footprints of the Beyond in flavor physics: Possible role of the Top Two Higgs Doublet Model
The B-factories results provide an impressive confirmation of the Standard
Model (SM) description of flavor and CP violation. Nevertheless, as more data
were accumulated, deviations in the 2.5-3.5 sigma range have emerged pointing
to the exciting possibility of new CP-odd phase(s) and flavor violating
parameters in B-decays. Primarily this seems to be the case in the time
dependent CP asymmetries in penguin dominated modes (e.g. B -> phi (eta') Ks).
We discuss these and other deviations from the SM and, as an illustration of
possible new physics scenarios, we examine the role of the Top Two Higgs
Doublet Model. This is a simple extension of the SM obtained by adding second
Higgs doublet in which the Yukawa interactions of the two Higgs doublets are
assigned in order to naturally account for the large top-quark mass.
Of course, many other extensions of the Standard Model could also account for
these experimental deviations. Clearly if one takes these deviations seriously
then some new particles in the 300 GeV to few TeV with associated new CP-odd
phase(s) are needed.Comment: 40 pages, 17 figures (png format), uses pdflate
Composite fermions in Electroweak Symmetry Breaking
If the electroweak symmetry is broken by some unspecified strong dynamics,
composite fermions may exist with definite transformation properties under
SU(2)_L x SU(2)_R/SU(2)_{L+R} and may play a role in giving masses by mixing to
all the standard quarks and leptons. Assuming this to be the case, we analyze
the role of Singlets, Doublets and Triplets in the ElectroWeak Precision Tests
and in Flavour Physics. Doublets and Triplets are generically disfavoured. In
the Singlet case, we specify the breaking patterns of the flavour group that
allow to keep the CKM picture of flavour physics and we discuss the effects of
the mixing between composite and elementary fermions. These mixings affect in
particular the rather peculiar LHC phenomenology of the composite fermions.Comment: 18 pages, 2 figures (v2: minor modifications, published version
Chiral behavior of the B(s,d)-Bbar(s,d) mixing amplitude in the Standard Model and beyond
We compute the chiral logarithmic corrections to the Bd and Bs mixing
amplitudes in the Standard Model and beyond. We then investigate the impact of
the inclusion of the lowest-lying scalar heavy-light states to the decay
constants and bag-parameters and show that this does not modify the pion chiral
logarithms, but it does produce corrections which are competitive in size with
the K- and eta-meson chiral logarithms. This conclusion is highly relevant to
the lattice studies since the pion chiral logarithms represent the most
important effect in guiding the chiral extrapolations of the lattice data for
these quantities. Also important is to stress that the pion chiral logarithmic
corrections are useful in guiding those extrapolations as long as Mpi << Delta,
where Delta is the mass gap between the scalar and pseudoscalar heavy-light
mesons.Comment: 16 pages, 5 figures (published version
Flavor symmetry analysis of charmless B --> VP decays
Based upon flavor SU(3) symmetry, we perform global fits to charmless
B decays into one pseudoscalar meson and one vector meson in the final
states. We consider different symmetry breaking schemes and find that the one
implied by na{\"i}ve factorization is slightly favored over the exact symmetry
case. The vertex of the unitarity triangle (UT)
constrained by our fits is consistent with other methods within errors. We have
found large color-suppressed, electroweak penguin and singlet penguin
amplitudes when the spectator quark ends up in the final-state vector meson.
Nontrivial relative strong phases are also required to explain the data. The
best-fit parameters are used to compute branching ratio and CP asymmetry
observables in all of the decay modes, particularly those in the decays
to be measured at the Tevatron and LHC experiments.Comment: 23 pages and 2 plots; updated with ICHEP'08 data and expanded in
discussions and reference