Searcharxiv⌕ Search

arXiv subjects

M. Pierini

Publications and source records attributed to M. Pierini.

42 records · Page 3Linked to original sources
arXiv2004

CKM-Triangle analysis: Updates and Novelties for Summer 2004

Using the most recent determinations of several theoretical and experimental parameters, we update the Unitarity Triangle analysis in the Standard Model. The basic experimental constraints come from the measurements of epsilon_k, Vub/Vcb and Delta m_d, the limit on Delta m_s, and the measurement of the CP asymmetry in the B sector through the J/psi K^0 channel. In addition we also include in our analysis the direct determination of sin 2 alpha, gamma and sin(2 beta + gamma) from the measurements of new CP-violating quantities, recently coming from the B-Factories. We also discuss the opportunities offered by improving the precision of the measurements of the various physical quantities entering in the determination of the Unitarity Triangle parameters. The results and the plots presented in this paper can be also found at http://www.utfit.org, where they are continuously updated with the newest experimental and theoretical results.

hep-ph↗
arXiv2002

Charming Penguins Saga

We briefly recall the main formulae for computing the B -> K pi branching ratios within the "charming penguin" approach, present an updated fit to the data, and explain why we believe that, in general, these fits can hardly be used to extract gamma.

hep-ph↗
arXiv2001

Two Body B Decays, Factorization and LambdaQCD/mb Corrections

By using the recent experimental measurements of B -> pi pi and B -> K pi branching ratios, we find that the amplitudes computed at the leading order of the LambdaQCD/mb expansion disagree with the observed BRs, even taking into account the uncertainties of the input parameters. Beyond the leading order, Charming and GIM penguins allow to reconcile the theoretical predictions with the data. Because of these large effects, we conclude, however, that it is not possible, with the present theoretical and experimental accuracy, to determine the CP violation angle gamma from these decays. We compare our results with those obtained with the parametrization of the chirally enhanced non-perturbative contributions by BBNS. We also predict large asymmetries for several of the particle--antiparticle BRs, in particular BR(B+ -> K+ pi0), BR(Bd -> K+ pi-) and BR(Bd -> pi+ pi-).

hep-ph↗
arXiv2001

Charming Penguins Strike Back

By using the recent experimental measurements of B to pi pi and B to K pi branching ratios, we find that factorization is unable to reproduce the observed BRs even taking into account the uncertainties of the input parameters. Charming and GIM penguins allow to reconcile the theoretical predictions with the data. Because of these large effects, we conclude, however, that it is not possible, with the present theoretical and experimental accuracy, to determine the CP violation angle gamma from these decays. Contrary to factorization, we predict large asymmetries for several of the particle-antiparticle BRs, in particular BR(B^+ to K^+ pi^0), BR(B_d to K^+ pi^-) and BR(B_d to pi^+ pi^-). This opens new perspectives for the study of CP violation in B systems.

hep-ph↗
arXiv2001

Penguin Contractions and Factorization in B -> K pi Decays

We study Lambda_{QCD}/m_B corrections to factorization in B -> K pi decays. First, we analyze these decay channels within factorization, showing that, irrespectively of the value of gamma, it is not possible to reproduce the experimental data. Then, we discuss Lambda_{QCD}/m_B corrections to these processes, and argue that there is a class of doubly Cabibbo enhanced non-factorizable contributions, usually called charming penguins, that cannot be neglected. Including these corrections, we obtain an excellent agreement with experimental data. Furthermore, contrary to what is obtained with factorization, we predict sizable rate asymmetries in B^\pm -> K^\pm π^0 and B -> K^\pm pi^\mp.

hep-ph↗