B_s to K^(*)0 \bar K^(*)0 decays: the golden channels for new physics searches

We point out that time-dependent CP asymmetries in B_s to K^{*0} \bar K^{*0} decays probe the presence of new physics in b to s transitions with an unprecedented theoretical accuracy. We show that, contrary to the case of B_d to phi K_S, it is possible to obtain a model-independent prediction for the coefficient S(B_s to K^{*0} \bar K^{*0}) in the Standard Model. We give an estimate of the experimental precision achievable with the next generation of B physics experiments. We also discuss how this approach can be extended to the case of B_s to \bar K^{*0} K^0, B_s to K^{*0} \bar K^0 and B_s to K^0 \bar K^0 decays and the different experimental challenges for these channels.Comment: 4 pages, 1 figure. v2: Corrected dependence on CKM angles, expanded discussion of multiple polarizations, conclusions strengthened. Final version to appear in PR

Charming Penguins in B decays

Full expressions of the $B^0_d \to \pi^+ \pi^-$ and $B^0_d \to \pi^0 \pi^0$ amplitudes, given in terms of matrix elements of operators of the effective weak Hamiltonian, are used to study the dependence of the relevant branching ratios on the different contributions. The uncertainty in the extraction of the weak phase $\alpha$ from the measurement of the time-dependent asymmetry in $B^0_d \to \pi^+ \pi^-$ decays is also analyzed. We find that, among several effects which may enhance the $B^0_d \to \pi^0 \pi^0$ branching ratio, the most important is due to ``charming penguin" diagrams that have never been studied before. These diagrams easily increase $BR(B^0_d \to \pi^0 \pi^0)$ up to a value of $1-3 \times 10^{-6}$. The same effect produces, however, a large error in the extraction of $\alpha$ from the measurement of the $B^0_d \to \pi^+ \pi^-$ time-dependent asymmetry. We show that it is possible to determine charming-penguin amplitudes from the experimental measurement of many decay rates. Their effect is impressive in $B^+ \to \pi^+ K^0$ and $B^0_d \to K^+ \pi^-$ decays, where charming-penguin contributions easily give values of $BR(B^+ \to \pi^+ K^0)$ and $BR(B^0_d \to K^+ \pi^-)$ of about $1 \times 10^{-5}$. Among other possibilities, we also suggest to use $B^0_d \to K^0 \bar K^0$, the BR of which can be as large as $2-3 \times 10^{-6}$, to determine the size of charming-penguin amplitudes.Comment: LaTeX, 28 pages, 8 figure

b -> s Transitions: A New Frontier for Indirect SUSY Searches

The present unitarity triangle fit, whose essential input is represented by the s to d and b to d transition processes, fully agrees with the SM. However, most of the phenomena involving b to s transitions are still largely unexplored and hence b to s phenomenology still constitutes a place for new physics manifestations, in spite of the tremendous experimental and theoretical progress on B to X_s gamma. We perform a systematic study of the CP conserving and violating SUSY contributions to b to s processes in a generic MSSM. We consider gluino exchange contributions including NLO QCD corrections and lattice hadronic matrix elements for Delta B = 2 and Delta B = 1 processes. We take into account all available experimental information on processes involving b to s transitions (B to X_s gamma, B to X_s l^+ l^- and the lower bound on the B_s - bar B_s mass difference Delta M_s). We study the correlations among the relevant observables under scrutiny at present or in a not too far future: Delta M_s and the amount of CP violation in B to phi K_s, B_s to J/psi phi, B to X_s gamma. In particular we discuss the recent data by BaBar and BELLE on the time-dependent CP asymmetry in the decay B to phi K_s which suggest a deviation from the SM expectation. Our results show that the processes involving b to s transitions represent a splendid opportunity to constrain different MSSM realizations, and, even more important, that they offer concrete prospects to exhibit SUSY signals at B factories and hadron colliders in spite of all the past frustration in FCNC searches of new physics hints.Comment: 20 pages, 8 figures. Bug in the code corrected, figures for RL and RL=RR cases and some conclusions change

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-).Comment: 14 pages 3 figures uses aippro

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 \pi^0 and B -> K^\pm pi^\mp.Comment: 4 pages, 3 figures. Talk given by L. Silvestrini at BCP4, Ise-Shima, Japan, 18-23 Feb 200

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.Comment: Invited talk at FPCP '02 given by M. Ciuchini, uses econfmacros.tex. Final version with minor changes to appear in the proceeding

Worries and Hopes for SUSY in CKM Physics: The b to s Example

We discuss the twofold role of flavor and CP violation as a constraint in model building and as a signal of SUSY. Considering as an example b to s transitions, we analyze present bounds on SUSY parameters, discuss possible deviations from SM predictions in Bd and Bs physics and present strategies to reveal SUSY signals in present and future experiments in the CKM domain.Comment: Invited talks given by A. Masiero and L. Silvestrini at the Workshop on the CKM Unitarity Triangle, IPPP Durham, April 2003 (eConf C0304052). 9 pages, 5 figure

Upper bounds on SUSY contributions to b to s transitions from B_s - B_sbar mixing

We study the constraints on supersymmetric contributions to b to s transitions from the recent allowed range and measurement of Bs-Bsbar mixing obtained by the D0 and CDF collaborations at the Tevatron. We compute the upper bounds on the relevant off-diagonal squark mass terms and compare them with the bounds coming from Delta F=1 decays. We find that the constraints on chirality-flipping mass insertions are unaffected. Conversely, the measurement of Bs-Bsbar mixing is effective in constraining chirality-conserving mass insertions, and it has striking effects in the case in which left- and right-handed insertions have similar size. Finally, we discuss the phase of the Bs-Bsbar mixing amplitude in the presence of SUSY contributions.Comment: 4 pages, 4 figures; v2: CDF measurement include