4,971 research outputs found
Non-leptonic B-decays, CP violation & the UT
We study the implication of the time-dependent CP asymmetry in
decays on the extraction of weak phases taking into account
the precise measurement of , obtained from the ``gold-plated''mode
. Predictions and uncertainties for the hadronic parameters
are investigated in QCD factorization. Furthermore, independent theoretical and
experimental tests of the factorization framework are briefly discussed.
Finally, a model-independent bound on the unitarity triangle from CP violation
in and is derived.Comment: 4 pages; 4 figures (requires epsfig, psfrag); To appear in the
proceedings of the 11th International Conference on Quantum Chromodynamics
(QCD 04), Montpellier, France, 5--10th July 200
Large electroweak penguin contribution in B -> K pi and pi pi decay modes
We discuss about a possibility of large electroweak penguin contribution in B
-> K pi and pi pi from recent experimental data. The experimental data may be
suggesting that there are some discrepancies between the data and theoretical
estimation in the branching ratios of them. In B -> K pi decays, to explain it,
a large electroweak penguin contribution and large strong phase differences
seem to be needed. The contributions should appear also in B -> pi pi. We show,
as an example, a solution to solve the discrepancies in both B -> K pi and B ->
pi pi. However the magnitude of the parameters and the strong phase estimated
from experimental data are quite large compared with the theoretical
estimations. It may be suggesting some new physics effects are including in
these processes. We will have to discuss about the dependence of the new
physics. To explain both modes at once, we may need large electroweak penguin
contribution with new weak phases and some SU(3) breaking effects by new
physics in both QCD and electroweak penguin type processes.Comment: 23 pages, 9 figure
Exploring the Unitarity Triangle through CP violation observables in
We discuss the determination of the CKM parameters from the forthcoming
violation observables in decays. Combining the information on
mixing induced CP violation in , with the
precision observable and the -- mixing phase
, we propose a determination of the unitarity triangle . Computing the penguin parameters within QCD
factorization yield precise determination of , reflected
by a weak dependence on the which is shown as a second order effect.
The impact of the direct CP violation observable on the penguin
parameters are investigated and a lower bound on is extracted. We also
discuss the effect of the -- new physics mixing phase on
the penguin parameters and . Using the SU(3)-flavour
symmetry argument and the current -factories data provided by the modes, we complement the CP-violating
observables in a variety of ways, in particular we find that .
Finally we analyze systematically the SU(3)-symmetry breaking factor within QCD
factorization.Comment: 22 pages, 6 figures, typos corrected, reference and some remarks
adde
Obtaining CKM Phase Information from B Penguin Decays
We discuss a method for extracting CP phases from pairs of B decays which are
related by flavor SU(3). One decay (B0 -> M1 M2) receives a significant bbar ->
dbar penguin contribution. The second (B' -> M1' M2') has a significant bbar ->
sbar penguin contribution, but is dominated by a single amplitude. CP phase
information is obtained using the fact that the B' -> M1' M2' amplitude is
related by SU(3) to a piece of the B0 -> M1 M2 amplitude. The leading-order
SU(3)-breaking effect (~25%) responsible for the main theoretical error can be
removed. For some decay pairs, it can be written in terms of known decay
constants. In other cases, it involves a ratio of form factors. However, this
form-factor ratio can either be measured experimentally, or eliminated by
considering a double ratio of amplitudes. In all cases, one is left only with a
second-order effect, ~5%. We find twelve pairs of B decays to which this method
can be applied. Depending on the decay pair, we estimate the total theoretical
error in relating the B' -> M1' M2' and B0 -> M1 M2 amplitudes to be between 5%
and 15%. The most promising decay pairs are Bd -> pi+ pi- and Bu+ -> K0 pi+,
and Bd -> D+ D- and Bd -> Ds+ D- or Bu+ -> Ds+ D0bar.Comment: 38 pages, JHEP format, no figures. Comments added to text regarding
most promising decay pairs; references added; conclusions unchange
Charm production in nonresonant e(+)e(-) annihilations at âs =10.55 GeV
This is the publisher's version also available electronically from http://journals.aps.org/prd/abstract/10.1103/PhysRevD.37.1719We report results on the differential and total cross sections for inclusive production of the charmed particles D*+, D*(0), D(0), D(+), D(s), and Îc in e(+)e(-) annihilations at âs=10.55 GeV. Widely used quark fragmentation models are discussed and compared with the measured charmed-particle momentum distributions. This comparison, as well as that with measurements at other center-of-mass energies, shows the need to take QCD corrections into account and their importance for a correct interpretation of the model parameters. The observed rate of D(0) and D(+) production is compared to the expected total charm production cross section. We measure the probability of a charmed meson being produced as a vector meson and the D*(+) decay branching fraction into D(0)Ï+
Recommended from our members
Measurement of B(B-->X_s {\gamma}), the B-->X_s {\gamma} photon energy spectrum, and the direct CP asymmetry in B-->X_{s+d} {\gamma} decays
The photon spectrum in B --> X_s {\gamma} decay, where X_s is any strange
hadronic state, is studied using a data sample of (382.8\pm 4.2) \times 10^6
e^+ e^- --> \Upsilon(4S) --> BBbar events collected by the BABAR experiment at
the PEP-II collider. The spectrum is used to measure the branching fraction B(B
--> X_s \gamma) = (3.21 \pm 0.15 \pm 0.29 \pm 0.08)\times 10^{-4} and the
first, second, and third moments = 2.267 \pm 0.019 \pm 0.032 \pm
0.003 GeV,, )^2> = 0.0484 \pm 0.0053 \pm 0.0077 \pm
0.0005 GeV^2, and )^3> = -0.0048 \pm 0.0011 \pm 0.0011
\pm 0.0004 GeV^3, for the range E_\gamma > 1.8 GeV, where E_{\gamma} is the
photon energy in the B-meson rest frame. Results are also presented for
narrower E_{\gamma} ranges. In addition, the direct CP asymmetry A_{CP}(B -->
X_{s+d} \gamma) is measured to be 0.057 \pm 0.063. The spectrum itself is also
unfolded to the B-meson rest frame; that is the frame in which theoretical
predictions for its shape are made.Comment: 37 pages, 19 postscript figures, submitted to Phys. Rev. D. No
analysis or results have changed from previous version. Some changes to
improve clarity based on interactions with Phys. Rev. D referees, including
one new Figure (Fig. 13), and some minor wording/punctuation/spelling
mistakes fixe
Differential branching fraction and angular analysis of the decay B0âKâ0ÎŒ+ÎŒâ
The angular distribution and differential branching fraction of the decay B 0â K â0 ÎŒ + ÎŒ â are studied using a data sample, collected by the LHCb experiment in pp collisions at sâ=7 TeV, corresponding to an integrated luminosity of 1.0 fbâ1. Several angular observables are measured in bins of the dimuon invariant mass squared, q 2. A first measurement of the zero-crossing point of the forward-backward asymmetry of the dimuon system is also presented. The zero-crossing point is measured to be q20=4.9±0.9GeV2/c4 , where the uncertainty is the sum of statistical and systematic uncertainties. The results are consistent with the Standard Model predictions
Observation of an Excited Bc+ State
Using pp collision data corresponding to an integrated luminosity of 8.5 fb-1 recorded by the LHCb experiment at center-of-mass energies of s=7, 8, and 13 TeV, the observation of an excited Bc+ state in the Bc+Ï+Ï- invariant-mass spectrum is reported. The observed peak has a mass of 6841.2±0.6(stat)±0.1(syst)±0.8(Bc+) MeV/c2, where the last uncertainty is due to the limited knowledge of the Bc+ mass. It is consistent with expectations of the Bcâ(2S31)+ state reconstructed without the low-energy photon from the Bcâ(1S31)+âBc+Îł decay following Bcâ(2S31)+âBcâ(1S31)+Ï+Ï-. A second state is seen with a global (local) statistical significance of 2.2Ï (3.2Ï) and a mass of 6872.1±1.3(stat)±0.1(syst)±0.8(Bc+) MeV/c2, and is consistent with the Bc(2S10)+ state. These mass measurements are the most precise to date
Measurements of Flavour Dependent Fragmentation Functions in Z^0 -> qq(bar) Events
Fragmentation functions for charged particles in Z -> qq(bar) events have
been measured for bottom (b), charm (c) and light (uds) quarks as well as for
all flavours together. The results are based on data recorded between 1990 and
1995 using the OPAL detector at LEP. Event samples with different flavour
compositions were formed using reconstructed D* mesons and secondary vertices.
The \xi_p = ln(1/x_E) distributions and the position of their maxima \xi_max
are also presented separately for uds, c and b quark events. The fragmentation
function for b quarks is significantly softer than for uds quarks.Comment: 29 pages, LaTeX, 5 eps figures (and colour figs) included, submitted
to Eur. Phys. J.
- âŠ