Flavor physics in the quark sector

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

Sterile neutrinos in leptonic and semileptonic decays

“…Lattice QCD computations have allowed to determine the ratio f Ds /f D with a high precision. For instance in [68], one has 33) while in [67], one has 34) f K and f π being the kaon and pion decay constants, whose ratio is given by (world average value, see [69]):…”

“…This is due to the fact that the hadronic parameters taken into our computation (see eqs. (3.34), (3.35)) make use of new values for the ratio of f Ds and f D , determined from Lattice QCD [67], as well as the very precise experimental determination of f K /f π [69]. In view of this, we only present the central values for the experimental results.…”

$$B-S$$ B - S transition form-factors with the light-cone QCD sum rules

“…We can use both the exclusive and inclusive b → u transitions to study the CKM matrix element V ub . Furthermore, the processes induced by the flavor-changing neutral currents b → s(d) provide the most sensitive and stringent test for the standard model at one-loop level and can put powerful constraints on the new physics models, as they are forbidden at the tree-level in the standard model [6][7][8]. So reliable calculations of the transition form-factors are needed to make robust predictions.…”

Prediction of the CP asymmetry C00 in $$ {B}^0\to {D}^0\overline{D^0} $$ decay

“…In this context, study of decays of heavy flavor mesons, especially the B mesons, has played an important role (see refs. [7][8][9][10] for some recent reviews). In our analysis we shall exploit the isospin symmetry, which is known to be a very useful symmetry in the study of various hadronic decays, most notably in many B meson…”