A Dynamical Scheme for a Large CP-Violating Phase

A dynamical scheme where the third generation of quarks plays a distinctive role is implemented. New interactions with a $\theta$ term induce the breaking of the electroweak symmetry and the top-bottom mass splitting. A large CP-violating phase naturally follows from the latter.Comment: 10 pages, LaTe

Final State Interaction Phases in B→Kπ B \to K \pi Decay Amplitudes

A simple Regge pole model for $K\pi$ scattering explains the large $e^{i \delta}$ between isospin amplitudes which is observed at the D meson mass ($\delta \approx \pi/2$). It predicts $\delta \approx 14^{\circ}- 20^{\circ}$ at the B mass. Implications for ($B \to K \pi$) decays and extensions of the model to other two-body decay channels are briefly discussed.Comment: 8pages,late

Improvements to the Method of Dispersion Relations for B Nonleptonic Decays

We bring some clarifications and improvements to the method of dispersion relations in the external masses variables, that we proposed recently for investigating the final state interactions in the B nonleptonic decays. We first present arguments for the existence of an additional term in the dispersion representation, which arises from an equal-time commutator in the LSZ formalism and can be approximated by the conventional factorized amplitude. The reality properties of the spectral function and the Goldberger-Treiman procedure to perform the hadronic unitarity sum are analyzed in more detail. We also improve the treatment of the strong interaction part by including the contributions of both t and u-channel trajectories in the Regge amplitudes. Applications to the $B^0\to \pi^+\pi^-$ and $B^+\to \pi^0 K^+$ decays are presented.Comment: 16 pages, 4 new figures. modifications of the dispersion representatio

Long-range two-body final-state interactions and direct CP asymmetry in {B}^{+}\to{\pi}^{+} {K}^{0} decay

We present a calculation of the direct CP asymmetry, $A_{CP}^{dir}$, for the process $B^+ \to \pi^+ K^0$ including the effects of long-range inelastic final-state interactions (FSI). We admit three channels in our calculation: $B^+ \to (\pi^+ K^0), (\eta K^+)$, and $(D_s^+ \bar{D}^0)$. The strong scattering is described in terms of Pomeron and Regge exchanges. We find that the direct CP asymmetry is enhanced by a factor of $\sim 3$ as a result of FSI, but remains well short of the claims of (10 - 20)% in recent literature. A critical assessment of papers claiming large CP asymmetries is also presented.Comment: 21 pages, latex, no figures. Added the charge-exchange channel {B}^{+}\to {\pi}^{0} {K}^{+}. Expanded the discussion section. To be published in Phys. Rev.

Combining CP Asymmetries in B→KπB \to K \pi Decays

We prove an approximate relation, to leading order in dominant terms, between CP-violating rate differences in $B^0/\bar{B}^0 \to K^{\pm}\pi^{\mp}$ and $B^{\pm} \to K^{\pm}\pi^0$. We show how data from these two processes may be combined in order to enhance the significance of a nonzero result.Comment: 9 pages, latex, no figures, submitted to Phys. Rev. Letters, revise

Taming the Penguin in the B0(t) -> Pi+Pi- CP-asymmetry: Observables and Minimal Theoretical Input

Penguin contributions, being not negligible in general, can hide the information on the CKM angle alpha coming from the measurement of the time-dependent B0(t) -> pi+pi- CP-asymmetry. Nevertheless, we show that this information can be summarized in a set of simple equations, expressing alpha as a multi-valued function of a single theoretically unknown parameter, which conveniently can be chosen as a well-defined ratio of penguin to tree amplitudes. Using these exact analytic expressions, free of any assumption besides the Standard Model, and some reasonable hypotheses to constrain the modulus of the penguin amplitude, we derive several new upper bounds on the penguin-induced shift |2alpha-2alpha_eff|, generalizing the recent result of Grossman and Quinn. These bounds depend on the averaged branching ratios of some decays (pi0pi0, K0K0bar, K+-pi-+) particularly sensitive to the penguin. On the other hand, with further and less conservative approximations, we show that the knowledge of the B+- -> Kpi+- branching ratio alone gives sufficient information to extract the free parameter without the need of other measurements, and without knowing |V_td| or |V_ub|. More generally, knowing the modulus of the penguin amplitude with an accuracy of ~30% might result in an extraction of alpha competitive with the experimentally more difficult isospin analysis. We also show that our framework allows to recover most of the previous approaches in a transparent and simple way, and in some cases to improve them. In addition we discuss in detail the problem of the various kinds of discrete ambiguities.Comment: LaTeX2e, 44 pages, 9 figures (from 18 postscript files) included with epsf. Minor changes, references updated. New CLEO results from ICHEP'98 are taken into account. To appear in Phys. Rev.

Rescattering Information from B→KKˉB \to K \bar K Decays

Rescattering effects can modify the dependence on the weak phase $\gamma = -{\rm Arg}(V^*_{ub}V_{ud}/V^*_{cb} V_{cd})$ of the ratio of rates for $B^{\pm} \to K \pi^\pm$ and $B \to K^\pm \pi^\mp$. A test for these effects based on the processes $B^\pm \to K^\pm K$ has been suggested. It is pointed out that the rates for the processes $B \to K^+ K^-$, which are expected to be {\it dominated} by rescattering and for which considerably better experimental bounds exist, are likely to provide a more stringent constraint on these effects.Comment: 22 pages, latex, 7 figures, to be published in Phys. Rev. D. Minor corrections and addition

On Large Final-State Phases in Heavy Meson Decays

An attempt is made to identify circumstances under which the weak decays of $D$ and $B$ mesons may display large differences between eigenphases of strong final-state interactions. There are several cases in which rescattering from other final states appears to enhance decay rates with respect to estimates based on the factorization hypothesis.Comment: 24 pages, latex, 4 figures, to be submitted to Phys. Rev.

Final-State Phases in Charmed Meson Two-Body Nonleptonic Decays

Observed decay rates indicate large phase differences among the amplitudes for the charge states in $D \to \bar K \pi$ and $D \to \bar K^* \pi$ but relatively real amplitudes in the charge states for $D \to \bar K \rho$. This feature is traced using an SU(3) flavor analysis to a sign flip in the contribution of one of the amplitudes contributing to the latter processes in comparison with its contribution to the other two sets. This amplitude may be regarded as an effect of rescattering and is found to be of magnitude comparable to others contributing to charmed particle two-body nonleptonic decays.Comment: 19 pages, latex, 4 figures, to be submitted to Phys. Rev.

Bounding the penguin effects on determinations of α\alpha from B0(t)→π+π−B^0(t)\to\pi^+\pi^- decays

In the absence of the QCD penguin contributions a measurement of the time-dependent asymmetry in the decay $B^0(t)\to \pi^+\pi^-$ gives directly the weak angle $\alpha$. Several bounds have been proposed in the literature on the magnitude of the penguin effects on this determination, the prototype of which is the isospin bound of Grossman and Quinn. It is pointed out that large strong final state interactions could cause these bounds to overestimate the real penguin effect. A new flavor SU(3) bound is proposed, requiring only the charge-averaged branching ratios for $B^0\to \pi^+\pi^-$ and $B_s\to K^+K^-$, which exactly takes into account all relevant amplitudes and electroweak penguin effects. This bound on the penguin-induced error on the determination of the weak phase $\alpha$ holds even without a knowledge of the direct CP asymmetry in the $\pi^+\pi^-$ channel.Comment: 10 pages ReVTeX with 3 included eps figure