The Radiative rare decays B→K∗∗γB\to K^{**}\gamma in the light-cone QCD sum rule approach

We predict contributions of higher $K$-resonances to the radiative rare decays $b\to s\gamma$, in the framework of the QCD sum rules on the light cone, which combines the traditional QCD sum rule method with the description of final state mesons in terms of the light-cone wave functions of increasing twist. Our calculations are restricted to the leading twist-two operators for $K^*(892)$ and to the asymptotic wave function for the other $K^{**}$-mesons. Using experimental data on the semileptonic $\tau\to K^{**}\nu_{\tau}$ decays, we extract the corresponding decay constants for vector and axial-vector $K^{**}$-mesons. Based on our estimate of the transition form factor $F_1^{K^*(892)}(0)=0.32 \pm 0.06$ and the $K_2^*(1430)$ decay constant $f_{K_2^*(1430)}=(160\pm 20) MeV$, we find good agreement with experimental results. The two largest fractions of the inclusive $b\to s\gamma$ branching ratio are found to be $(10.0\pm 4.0)$ for $B\to K^*(892) \gamma$ and $(5.0\pm 2.0)$ for $B\to K_2^*(1430)\gamma$ decays. We also compare our results with the existing theoretical predictions.Comment: 29 pages, 20 figures, to be submitted to European Physical Journal

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

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

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

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

Branching Ratio and CP-asymmetry for B-> 1^{1}P_{1}gamma decays

We calculate the branching ratios for B_{d}^{0}->(b_{1},h_{1})gamma at next-to-leading order (NLO) of alpha_{s} where b_{1} and h_{1} are the corresponding radially excited axial vector mesons of rho and omega respectively. Using the SU(3)symmetry for the form factor, the branching ratio for B_{d}^{0}->(b_{1},h_{1})gamma is expressed in terms of the branching ratio of the B_{d}^{0}-> K_{1}gamma and it is found to be B(B_{d}^{0}->b_{1}gamma)=0.71* 10^{-6} and B(B_{d}^{0}-> h_{1}gamma) =0.74*10^{-6}. We also calculate direct CP asymmetry for these decays and find, in confirmity with the observations made in the literature, that the hard spectator contributions significantely reduces the asymmetry arising from the vertex corrections alone. The value of CP-asymmetry is 10% and is negative like rho and omega in the Standard Model.Comment: 10 pages, 2 figure