Sechul Oh

Supersymmetric Grand Unified Theory Contributions and Model Independent Extractions of CP Phases.

We consider the origin of new phases in supersymmetric grand unification model, and show how significant new contributions arise from the gluino mediated diagram. We then present a more general model independent analysis of various modes of B-decays suggested previously for measurement of the CKM phases and point out what they really measure. It is in principle possible to separate out all the phases.

An extension of tribimaximal lepton mixing

Harrison, Perkins and Scott have proposed simple charged lepton and neutrino mass matrices that lead to the tribimaximal mixing UTBM. We consider in this work an extension of the mass matrices so that the leptonic mixing matrix becomes UPMNS = V l† L UTBMW, where V l L is a unitary matrix needed to diagonalize the charged lepton mass matrix and W measures the deviation of the neutrino mixing matrix from the bimaximal form. Hence, corrections to UTBM arise from both charged lepton and neutrino sectors. Following our previous work to assume a Qin-Malike parametrization VQM for the charged lepton mixing matrix V l

Anomalous CP-Violation in

Abstract The recent measurement of the like-sign dimuon charge asymmetry in semileptonic b -hadron decays by the D0 Collaboration is about three sigmas away from the standard-model prediction, hinting at the presence of CP -violating new physics in the mixing of B s mesons. We consider the possibility that this anomalous result arises from the contribution of a light spin-1 particle. Taking into account various experimental constraints, we find that the effect of such a particle with mass below the b -quark mass can yield a prediction consistent with the anomalous D0 measurement within its one-sigma range.

B_s-\bar{B}_s

We consider the branching ratio of b{r_arrow}s{gamma} in gauge-mediated supersymmetry-breaking theories. Useful bounds on the parameter space of these models are derived from the experimental bounds on b{r_arrow}s{gamma}. Constraints on masses of the next to lightest supersymmetric particle are presented as a function of tan{beta} and M/{Lambda} for {mu}{lt}0 and {mu}{gt}0. {copyright} {ital 1997} {ital The American Physical Society}

Mixing Due to a Light Spin-One Particle

Abstract We analyze the CP asymmetries of B → ϕ K and B → η ( ′ ) K modes in the QCD improved factorization framework. The phenomenological parameters are determined from the global fit for the available B → P P and VP modes (without the subprocess b → s s ¯ s ). The large negative sin ( 2 ϕ 1 ) ϕ K s and the large branching ratio for B ± → η ′ K ± can be simultaneously explained in the context of R-parity conserving SUGRA models and R-parity violating SUSY models satisfying all possible experimental data. The SUSY models are also consistent with the available data on the CP asymmetries for different B ± ( 0 ) → ϕ K ± ( 0 ) and B ± ( 0 ) → η ( ′ ) K ± ( 0 ) modes.

Constraints from b{r_arrow}s{gamma} on gauge-mediated supersymmetry-breaking models

In light of recent experimental information from the CLEO, BaBar, KTeV, and Belle collaborations, we investigate some consequences of the possibility that a light spin-one particle is responsible for the three Σ+ → pμ+μ− events observed by the HyperCP experiment. In particular, allowing the new particle to have both vector and axial-vector couplings to ordinary fermions, we systematically study its contributions to various processes involving b-flavored mesons, including

CP Asymmetries of

B - \bar B

B \to \phi K

mixing as well as leptonic, inclusive, and exclusive B decays. Using the latest experimental data, we extract bounds on its couplings and subsequently estimate upper limits for the branching ratios of a number of B decays with the new particle. This can serve to guide experimental searches for the particle in order to help confirm or refute its existence.

and

Abstract We present a method to measure the CKM phase α and the tree and penguin (strong and electroweak) amplitudes in B → ππ decays, based on isospin consideration and the weak assumption that all tree amplitudes have a common strong phase and all penguin amplitudes have a different common phase. The method needs only the time-independent measurements of the relevant decay rates in B → ππ . We also propose a method to experimentally examine the validity of the assumption that all penguin amplitudes have the same strong phases, and to extract detailed informations about the hadronic matrix elements.

B \to \eta^{(\prime)} K

We study the influence of penguin (especially, electroweak penguin) effects on some methods of measuring the angles α, β, and γ in the CKM unitarity triangle. We use next-to-leading order effective Hamiltonian, and present numerical estimates based on the factorization approximation. We find that some techniques suggested in the literature, especially for α determination, are not workable in light of the electroweak penguin effects. Nevertheless, there are methods that would work for each angle determination. For angle β we consider B →D+D∼ - mode and estimate the penguin contamination. For angle γ we consider a method based on SU(3) symmetry and carefully consider SU(3) breaking effects. We point out regions in the parameter space where this method could be used reliably.