CP Violation and the CKM Matrix

Abstract

Our knowledge of quark-flavor physics and CP violation increased tremendously over the past five years. It is confirmed that the Standard Model correctly describes the dominant parts of the observed CP -violating and flavorchanging phenomena. Not only does CP violation provide some of the most precise constraints on the flavor sector, but several measurements performed at the B-factories achieved much better precision than had been expected. We review the present status of the Cabibbo-Kobayashi-Maskawa matrix and CP violation, recollect the relevant experimental and theoretical inputs, display the results from the global CKM fit, and discuss their implications for the Standard Model and some of its extensions.

Measuring V ub and probing SUSY with double ratios of purely leptonic decays of B and D mesons

“…A measurement of the double ratio involving B u → τ ν, D → µν, D s → µν/τ ν and B s → µ + µ − would enable a complementary measurement of the CKM matrix element V ub [5,7,8] with a theoretical error which is much smaller than that present in the conventional approaches to measure |V ub | (which utilize inclusive and exclusive semi-leptonic decays of B mesons). We quantified the experimental error in a possible future measurement of |V ub | using the above double ratio, and showed that it can be competitive with the anticipated precision from the conventional approaches.…”

“…A complementary technique for which the theoretical error is known to be small is particularly attractive. In this regard, the use of double ratios of leptonic decays to measure |V ub | was proposed in [5,7,8]. One such double ratio is defined by:…”

“…see [4]). Therefore, as emphasized in [5][6][7][8][9] it is important to consider alternative methods of measuring |V ub | for which the theoretical error is known to be very small, even if the experimental error for such a method is currently large.…”

“…1 The decay constants in this double ratio appear as (f Bs /f B )/(f Ds /f D ), and such a quantity is numerically very close to 1, with a very small error. Hence such a double ratio can be used to obtain a measurement of |V ub | with a small theoretical error [7,8]. At the time of writing of [5], only one of the four decays had been measured (D s → µν/τ ν).…”

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…”