Yong-Yeon Keum

Penguin enhancement and

We compute branching ratios of B → Kπ decays in the framework of perturbative QCD factorization theorem. Decay amplitudes are classified into the topologies of tree, penguin and annihilation, all of which contain both factorizable and nonfactorizable contributions. These contributions are expressed as the convolutions of hard b quark decay amplitudes with universal meson wave functions. It is shown that (1) matrix elements of penguin operators are dynamically enhanced compared to those employed in the factorization assumption; (2) annihilation diagrams are not negligible, contrary to common belief; (3) annihilation diagrams contribute large strong phases; (4) the uncertainty of current data of the ratio R = Br(B0 d → Kπ)/Br(B → K0π±) and of CP asymmetries is too large to give a constraint of φ3. Assuming φ3 = 90 o which is extracted from the best fit to the data of R, predictions for the branching ratios of the four B → Kπ modes are consistent with data.

B \to K \pi

Abstract We investigate the effect of supersymmetric CP violating phases on the B → X s γ and B → X s l + l − decays in the minimal supergravity model. We show that the phase of the trilinear scalar coupling constant for top squarks is strongly suppressed and aligned to that of the gaugino mass due to a renormalization effect from the Planck scale to the electroweak scale. As a result, the effect of supersymmetric CP violating phases on the B → X s γ and B → X s l + l − decays are small taking into account the neutron and the electron electric dipole moment constraints. For the B → X s γ decay, the amplitude has almost no new CP violating phase and the direct CP asymmetry is less than 2%. For the B → X s l + l − decay, the branching ratio can be sizably different from that in the standard model only when the sign of the B → X s γ amplitude is opposite to that in the standard model.

decays in perturbative QCD

We derive a new parton-like formula, which establishes a simple connection between the electroweak decay rate

Effect of supersymmetric CP phases on the B→Xsγ and B→Xsl+l− decays in the minimal supergravity model

\Gamma (\bar B \to X_s\gamma

The Nonperturbative corrections to the anti-B ---> X(s) gamma photon spectrum in a parton - like model

) and the rate of a free b-quark decay. The main features of our approach are the treatment of the b-quark as an on-mass-shell particle and the inclusion of the effects arising from the b-quark transverse motion in the

Penguin diagrams in the Δ I = 1 / 2 rule and ε ′ / ε with σ models

\bar B

Penguins diagrams in Delta I=1/2 rule and \epsilon'/\epsilon with \sigma models

-meson. Using various b-quark light-front (LF) distribution functions, both phenomenological one and the ones derived from current constituent quark models, and neglecting perturbative corrections we compute the photon energy spectra and the moments of the shape function. It is shown that the parton-like approach is fully consistent with the Heavy Quark Effective Theory (HQET) provided the b-quark constituent mass is redefined in the way similar to that used in HQET to define the pole mass of the b quark. In this way the correction to first order in

Penguin diagrams in theΔI=1/2rule andε′/εwith σ models

1/m_b

Penguin diagrams in the Delta I = 1/2 rule and epsilon-prime epsilon with sigma models

can be eliminated from the total width in agreement with the general statement of HQET. We have also found that the photon energy spectra calculated in the LF approach agree well with the ones obtained in the ACM model, provided the same distribution function is used as input in both cases. In spite of the simplicity of the model our results show a fair good agreement both with the HQET predictions and available experimental data.Abstract We derive a new parton-like formula, which establishes a simple connection between the electroweak decay rate Γ( B →X s γ ) and the rate of a free b -quark decay. The main features of our approach are the treatment of the b -quark as an on-mass-shell particle and the inclusion of the effects arising from the b -quark transverse motion in the B -meson. Using various b -quark light-front (LF) distribution functions, both phenomenological one and the ones derived from current constituent quark models, and neglecting perturbative corrections we compute the photon energy spectra and the moments of the shape function. It is shown that the parton-like approach is fully consistent with the Heavy Quark Effective Theory (HQET) provided the b -quark constituent mass is redefined in the way similar to that used in HQET to define the pole mass of the b quark. In this way the correction to first order in 1/ m b can be eliminated from the total width in agreement with the general statement of HQET. We have also found that the photon energy spectra calculated in the LF approach agree well with the ones obtained in the ACM model, provided the same distribution function is used as input in both cases. In spite of the simplicity of the model our results show a fair good agreement both with the HQET predictions and available experimental data.

Factorization and Decay Constants

We study the correlation between