No abstract

New sum rules for B → π, K and B → ρ, K * form factors are derived from the correlation functions expanded near the light-cone in terms of B-meson distribution amplitudes. The contributions of quark-antiquark and quark-antiquark-gluon components in the B meson are taken into account. Models for the B-meson three-particle distribution amplitudes are suggested, based on QCD sum rules in HQET. Employing the new light-cone sum rules we calculate the form factors at small momentum transfers, including SU (3)-violation effects. The results agree with the predictions of the conventional light-cone sum rules.

We reconsider and update the QCD light-cone sum rules for B → π form factors. The gluon radiative corrections to the twist-2 and twist-3 terms in the correlation functions are calculated. The M S b-quark mass is employed, instead of the one-loop pole mass used in the previous analyses. The light-cone sum rule for f + Bπ (q 2 ) is fitted to the measured q 2 -distribution in B → πlν l , fixing the input parameters with the largest uncertainty: the Gegenbauer moments of the pion distribution amplitude. For the B → π vector form factor at zero momentum transfer we predict f + Bπ (0) = 0.26 +0.04 −0.03 . Combining it with the value of the product |V ub f + Bπ (0)| extracted from experiment, we obtain |V ub | = (3.5 ± 0.4 ± 0.2 ± 0.1) × 10 −3 . In addition, the scalar and penguin B → π form factors f 0 Bπ (q 2 ) and f T Bπ (q 2 ) are calculated.

We employ the B ! form factors obtained from QCD light-cone sum rules and calculate the B ! ' ' width (' ¼ e, ) in units of 1=jV ub j 2 , integrated over the region of accessible momentum transfers, 0 q 2 12:0 GeV 2 . Using the most recent BABAR Collaboration measurements we extract jV ub j ¼ ð3:50 þ0:38 À0:33 j th AE 0:11j exp Þ Â 10 À3 . The sum rule results for the form factors, taken as an input for a z-series parametrization, yield the q 2 shape in the whole semileptonic region of B ! ' ' . We also present the charged lepton energy spectrum in this decay. Furthermore, the current situation with B ! is discussed from the QCD point of view. We suggest using the ratio of the B ! and B ! ' ' ð' ¼ ; eÞ widths as an additional test of the standard model. The sensitivity of this observable to new physics is illustrated by including a charged Higgs-boson contribution in the semileptonic decay amplitude.

No abstract

In the past decade, one of the major challenges of particle physics has been to gain an in-depth understanding of the role of quark flavor. In this time frame, measurements and the theoretical interpretation of their results have advanced tremendously. A much broader understanding of flavor particles has been achieved; apart from their masses and quantum numbers, there now exist detailed measurements of the characteristics of their interactions allowing stringent tests of Standard Model predictions. Among the most interesting phenomena of flavor physics is the violation of the CP symmetry that has been subtle and difficult to explore. In the past, observations of CP violation were confined to neutral K mesons, but since the early 1990s, a large number of CP-violating processes have been studied in detail in neutral B mesons. In parallel, measurements of the couplings of the heavy quarks and the dynamics for their decays in large samples of K, D, and B mesons have been greatly improved in accuracy and the results are being used as probes in the search for deviations from the Standard Model. In the near future, there will be a transition from the current to a new generation of experiments; thus a review of the status of quark flavor physics is timely. This report is the result of the work of physicists attending the 5th CKM workshop, hosted by the University of Rome "La Sapienza", September 9-13, 2008. It summarizes the results of the current generation of experiments that are about to be completed and it confronts these results with the theoretical understanding of the field which has greatly improved in the past decade. (C) 2010 Elsevier B.V. All rights reserved

No abstract

No abstract