CP Violation in B Decays within QCD Factorization

We analyze the extraction of weak phases from CP violation in $B\to\pi^+\pi^-$ decays. By combining the information on mixing induced CP violation in $B\to\pi^+\pi^-$, namely $S_{\pi\pi}$, with the precision observable $\sin 2\beta$ obtained from the ``gold-plated''mode $B\to\psi K_S$, we propose the determination of the unitarity triangle. We also discuss alternative ways to analyze $S_{\pi\pi}$ which can be useful if new physics affects $B_d$--$\bar B_d$ mixing. Predictions and uncertainties for $r$ and $\phi$ in QCD factorization are examined in detail. It is pointed out that a simultaneous expansion in $1/m_b$ and $1/N_C$ leads to interesting simplifications. At first order infrared divergences are absent, while the most important effects are retained. Independent experimental tests of the factorization framework are briefly discussed.Comment: 3 pages; 2 figures; To appear in the proceedings of International Europhysics Conference on High-Energy Physics (HEP 2003), Aachen, Germany, 17-23 Jul 200

CKM matrix from non-leptonic B-decays

We analyze the impact of the forthcoming CP-violating observables in the $B_s\to K^+ K^-$ system, combined with the precise measurement of $\sin2\beta$ , in the extraction of the CKM matrix. Computing the penguin parameters $(r, \theta)$ within QCD factorization yields a precise determination of $(\bar\rho, \bar\eta)$, reflected by a weak dependence on $\theta$, which is shown to be a second order effect. Using the SU(3)-flavour symmetry argument and the current $B$-factories data provided by the $B_d \to \pi^+ \pi^-$ modes, we complement the $B_s \to K^+ K^-$ CP-violating observables in a variety of ways, in particular we find that $S_{KK}>0$. Finally, we investigate systematically the SU(3)-symmetry breaking factor within QCD factorization.Comment: 4 pages; 4 figures (requires epsfig, psfrag); To appear in the proceedings of 32nd International Conference on High-Energy Physics (ICHEP 04), Beijing, China, 16-22 Aug 200

Phenomenological study of the double radiative decay B−>KγγB ->K\gamma\gamma

Using the operator product expansion (OPE) technique, we study the rare double radiative decay $B\to K \gamma\gamma$ in the Standard Model (SM) and beyond. We estimate the short-distance (SD) contribution to the decay amplitude in a region of the phase space which is around the point where all decay products have energy $\sim m_b/3$ in the rest frame of the $B$-meson. At lowest order in $1/m_b$, the $B\to K \gamma\gamma$ matrix element is then expressed in terms of the usual $B\to K$ form factors known from semileptonic rare decays. The integrated SD branching ratio in the SM in the OPE region turns out to be $\Delta {\cal{B}}(B \to K \gamma \gamma)_{SM}^{OPE} \simeq 1 \times 10^{-9}$. We work out the di-photon invariant mass distribution with and without the resonant background through $B\to K \{\eta_c,\chi_{c0}\}\to K\gamma \gamma$. In the SM, the resonance contribution is dominant in the region of phase space where the OPE is valid. On the other hand, the present experimental upper limit on $B_s \to \tau^+ \tau^-$ decays, leaves considerable room for New Physics (NP) in the one-particle-irreducible contribution to $B\to K \gamma \gamma$ decays. In this case, we find that the SD $B\to K \gamma \gamma$ branching ratio can be enhanced by one order of magnitude with respect to its SM value and the SD contribution can lie outside of the resonance peaks.Comment: 4 pages, 2 figures (requires epsfig, psfrag), To appear in the proceedings of the International Europhysics Conference on High Energy Physics, 21-27 July 2005, Lisboa, Portuga

The Unitarity Triangle through Bd→ρ±π∓B_d\to \rho^{\pm} \pi^{\mp} decays

We analyze the impact of the CP-violating observables in the $B_d\to \rho^{\pm} \pi^{\mp}$ system, combined with the precise measurement of $\sin2\beta$, in the extraction of the CKM matrix. We explore two strategies for determining the Unitarity Triangle in these modes. Computing the penguin parameters $(r_{\pm}, \phi_{\pm})$ and the ratio of two trees $(r_{t}, \phi_{t})$ within QCD factorization yields a precise determination of $(\bar\rho, \bar\eta)$, reflected by a weak dependence on $\phi_{\pm}$, which is shown to be a second order effect, as in the $B_d \to \pi^+ \pi^-$ system. Moreover, we find that the dependence on penguin amplitudes $r_{\pm}$ in $B_d\to \rho^{\pm} \pi^{\mp}$ is less pronounced than in the $B_d \to \pi^+ \pi^-$ case, since penguin contributions $r_{\pm}\approx r_{\pi\pi}/3$, implying an important simplification in our analysis. Independent experimental tests of the factorization framework are proposed and discussed, using $B_d \to \pi^+ \pi^-$ and $B_d \to \rho^{\pm} \rho^{\mp}$ modes.Comment: 4 pages, 2 figures (requires epsfig, psfrag), To appear in the proceedings of the International Europhysics Conference on High Energy Physics, 21-27 July 2005, Lisboa, Portuga

Model Independent Bound on the Unitarity Triangle from CP Violation in B-> pi+ pi- and B-> psi K_S

We derive model independent lower bounds on the CKM parameters (1-rhobar) and etabar as functions of the mixing-induced CP asymmetry S in B-> pi+ pi- and sin(2 beta) from B->psi K_S. The bounds do not depend on specific results of theoretical calculations for the penguin contribution to B-> pi+ pi-. They require only the very conservative condition that a hadronic phase, which vanishes in the heavy-quark limit, does not exceed 90 degrees in magnitude. The bounds are effective if -sin(2 beta) < S < 1. Dynamical calculations indicate that the limits on rhobar and etabar are close to their actual values.Comment: 5 pages, 2 figure

Theoretical studies of exclusive rare B decays in the Standard Model and Supersymmetric theories

We calculate the independent helicity amplitudes in the decays $B \to K^* \ell^+ \ell^-$ and $B \to \rho \ell \nu_\ell$ in the so-called Large-Energy-Effective-Theory (LEET). Taking into account the dominant $O(\alpha_s)$ and SU(3) symmetry-breaking effects, we calculate various Dalitz distributions in these decays making use of the presently available data and decay form factors calculated in the QCD sum rule approach. Differential decay rates in the dilepton invariant mass and the Forward-Backward asymmetry in $B \to K^* \ell^+ \ell^-$ are worked out. We also present the decay amplitudes in the transversity basis which has been used in the analysis of data on the resonant decay $B \to K^* J/\psi (\to \ell^+ \ell^-)$. Measurements of the ratios $R_i(s) \equiv d \Gamma_{H_i}(s)(B \to K^* \ell^+ \ell^-)/ d \Gamma_{H_i}(s)(B \to \rho \ell \nu_\ell)$, involving the helicity amplitudes $H_i(s)$, $i=0,+1, -1$, as precision tests of the standard model in semileptonic rare B-decays are emphasized. We argue that $R_0(s)$ and $R_{-}(s)$ can be used to determine the CKM ratio $| V_{ub}|/| V_{ts} |$ and search for new physics, where the later is illustrated by supersymmetry.Comment: Ph.D. Thesis, 126 pages, 41 figures (requires epsfig, psfrag

Helicity analysis of the decays B --> K^* ell^+ ell^- and B --> rho ell nu_ell in the large Energy Effective Theory

We calculate the independent helicity amplitudes in the decays B --> K^* ell^+ ell^- and B --> rho ell nu_ell in the so-called Large-Energy-Effective-Theory (LEET). Taking into account the dominant O(alpha_s) and SU(3) symmetry-breaking effects, we calculate various Dalitz distributions in these decays making use of the presently available data and decay form factors calculated in the QCD sum rule approach. Differential decay rates in the dilepton invariant mass and the Forward-Backward asymmetry in B --> K^* ell^+ ell^- are worked out. We also present the decay amplitudes in the transversity basis which has been used in the analysis of data on the resonant decay B --> K^* J/psi (--> ell^+ ell^-). Measurements of the ratios R_i(s) equivalent to d Gamma_{H_i}(s)(B --> K^* ell^+ ell^-)/ d Gamma_{H_i}(s)(B --> rho ell nu_ell), involving the helicity amplitudes H_i(s), i = 0,+1, -1, as precision tests of the standard model in semileptonic rare B-decays are emphasized. We argue that R_0(s) and R_{-}(s) can be used to determine the CKM ratio |V_{ub}|/|V_{ts}| and search for new physics, where the later is illustrated by supersymmetry.Comment: 42 pages, 30 figures (requires epsfig,psfrag), corrected sections 6 and 7, compared the results with data and other model estimates, added several reference

Branching ratio for B -> K_1 gamma decay in next-to-leading order in LEET

Branching ratio for B -> K_1 gamma at next-to-leading order of alpha_s has been calculated in Large Energy Effective Theory. By incorporating the higher twist effects in light cone decay amplitude for axial K-meson, it is shown that the form factor is not sensitive to these twists.Comment: 9 postscript figures, text 9 page

Non-leptonic B-decays, CP violation & the UT

We study the implication of the time-dependent CP asymmetry in $B\to\pi^+\pi^-$ decays on the extraction of weak phases taking into account the precise measurement of $\sin 2\beta$, obtained from the ``gold-plated''mode $B\to J/\psi K_S$. Predictions and uncertainties for the hadronic parameters are investigated in QCD factorization. Furthermore, independent theoretical and experimental tests of the factorization framework are briefly discussed. Finally, a model-independent bound on the unitarity triangle from CP violation in $B\to\pi^+\pi^-$ and $B\to J/\psi K_S$ is derived.Comment: 4 pages; 4 figures (requires epsfig, psfrag); To appear in the proceedings of the 11th International Conference on Quantum Chromodynamics (QCD 04), Montpellier, France, 5--10th July 200