Theoretical uncertainties for measurements of alpha_s from electroweak observables

One of the most precise measurements of the strong coupling constant alpha_s(MZ) is obtained in the context of global analyses of precision electroweak data. This article reviews the sensitivity of different electroweak observables to alpha_s and describes the perturbative uncertainties related to missing higher orders. The complete renormalisation scale dependence for the relevant observables is calculated at next-to-next-to-leading order and a new method is presented to determine the corresponding perturbative uncertainty for measurements of alpha_s based on these observables.Comment: v4: Revised version with new tables and figure

Strong and Weak Phases from Time-Dependent Measurements of B→ππB \to \pi \pi

Time-dependence in $B^0(t) \to \pi^+ \pi^-$ and \ob(t) \to \pi^+ \pi^- is utilized to obtain a maximal set of information on strong and weak phases. One can thereby check theoretical predictions of a small strong phase $\delta$ between penguin and tree amplitudes. A discrete ambiguity between $\delta \simeq 0$ and $\delta \simeq \pi$ may be resolved by comparing the observed charge-averaged branching ratio predicted for the tree amplitude alone, using measurements of $B \to \pi l \nu$ and factorization, or by direct comparison of parameters of the Cabibbo-Kobayashi-Maskawa (CKM) matrix with those determined by other means. It is found that with 150 fb$^{-1}$ from BaBar and Belle, this ambiguity will be resolvable if no direct CP violation is found. In the presence of direct CP violation, the discrete ambiguity between $\delta$ and $\pi - \delta$ becomes less important, vanishing altogether as $|\delta| \to \pi/2$. The role of measurements involving the lifetime difference between neutral $B$ eigenstates is mentioned briefly.Comment: 14 pages, LaTeX, 5 figures, to be published in Phys. Rev. D. Updated version with one reference change

Constraint on the CKM angle alpha from the experimental measurements of CP violation in B_d^0 --> pi^+ pi^- decay

In this paper, we study and try to find the constraint on the CKM angle alpha from the experimental measurements of CP violation in B_d^0 --> pi^+ pi^- decay, as reported very recently by BaBar and Belle Collaborations. After considering uncertainties of the data and the ratio r of penguin over tree amplitude, we found that strong constraint on both the CKM angle alpha and the strong phase delta can be obtained from the measured CP asymmetries S_{pi pi} and A_{pi pi}: (a) the ranges of 87 degrees <= alpha <= 131 degrees and 36 degrees <= delta <= 144 degrees are allowed by 1 sigma of the averaged data for r = 0.31; (b) for Belle's result alone, the limits on alpha and delta are 104 degrees <= alpha <= 139 degrees and 42 degrees <= delta <= 138 degrees for 0.32 <= r <= 0.41; and (c) the angle alpha larger than 90 degrees is preferred.Comment: Revtex, 17 pages with 6 ps/eps figure files, new Babar data Reported at ICHEP 2002 considere

Determination of the angle γ\gamma from nonleptonic Bc→DsD0B_c \to D_s D^0 decays

We note that the two body nonleptonic pure tree decays $B_c^\pm \to D_s^\pm D^0(\bar D^0)$ and the corresponding vector-vector modes $B_c^\pm \to D_s^{* \pm} D^{*0}(\bar D^{* 0})$ are well suited to extract the weak phase $\gamma$ of the unitarity triangle. The CP violating phase $\gamma$ can be determined cleanly as these decay modes are free from the penguin pollutions.Comment: 12 pages, LaTeX, 2 references added, Minor changes in the text, to appear in Phys. Rev.

Possibility of extracting the weak phase γ\gamma from Λb→ΛD0\Lambda_b \to \Lambda D^0 decays

We explore the possibility of extracting the weak phase $\gamma$ from pure tree decays $\Lambda_b \to \Lambda (D^0, \bar{D^0}, D^0_{CP})$ in a model independent way. The CP violating weak phase $\gamma$ can be determined cleanly, without any hadronic uncertainties, as these decay modes are free from the penguin pollutions. Furthermore, neither tagging nor time dependent studies are required to extract the angle $\gamma$ with these modes.Comment: 12 pages, LaTex, Minor changes in the text, version to appear in Phys. Rev.

Weak Phase γ\gamma from Bs(t)→K+K−B_s(t) \to K^+ K^-

We re-examine the time-dependent rates of \bs(t) \to K^+ K^- and \obs(t) \to K^+ K^-, including a lifetime difference between neutral \bs mass eigenstates. The two rates, normalized by the rate of \bs \to \ko \ok, are used to obtain ambiguity-free information on a strong phase and on the weak phase $\gamma$. We discuss the sensitivity of extracting $\gamma$ to the measured quantities, and find that an error of $\pm 10^\circ$ in $\gamma$ is possible for a sample of several thousand \bs(t) \to K^+ K^- decays. This study is complementary to a recent similar analysis of the U-spin related decays \bo(t) \to \pi^+\pi^- and \ob(t) \to \pi^+\pi^-.Comment: 12 pages, LaTeX, 3 figures, revised version submitted to Phys. Rev.

Charmless hadronic decays B→PP,PV,VVB \to PP, PV, VV and new physics effects in the general two-Higgs doublet models

Based on the low-energy effective Hamiltonian with the generalized factorization, we calculate the new physics contributions to the branching ratios of the two-body charmless hadronic decays of $B_u$ and $B_d$ mesons induced by the new gluonic and electroweak charged-Higgs penguin diagrams in the general two-Higgs doublet models (models I, II and III). Within the considered parameter space, we find that: (a) the new physics effects from new gluonic penguin diagrams strongly dominate over those from the new $\gamma$- and $Z^0$- penguin diagrams; (b) in models I and II, new physics contributions to most studied B meson decay channels are rather small in size: from -15% to 20%; (c) in model III, however, the new physics enhancements to the penguin-dominated decay modes can be significant, $\sim (30 -200)$, and therefore are measurable in forthcoming high precision B experiments; (d) the new physics enhancements to ratios {\cal B}(B \to K \etap) are significant in model III, $\sim (35 -70)$, and hence provide a simple and plausible new physics interpretation for the observed unexpectedly large B \to K \etap decay rates; (e) the theoretical predictions for ${\cal B}(B \to K^+ \pi)$ and ${\cal B}(B \to K^0 \pi^+)$ in model III are still consistent with the data within $2\sigma$ errors; (f) the significant new physics enhancements to the branching ratios of $B \to K^0 \pi^0, K^* \eta, K^{*+} \pi^-, K^+ \phi, K^{*0} \omega, K^{*+} \phi$ and $K^{*0} \phi$ decays are helpful to improve the agreement between the data and the theoretical predictions; (g) the theoretical predictions of ${\cal B}(B \to PP, PV, VV)$ in the 2HDM's are generally consistent with experimental measurements and upper limits ($90$)Comment: 55 pages, Latex file, 17 PS and EPS figures. With minor corrections, final version to be published in Phys.Rev. D. Repot-no: PKU-TH-2000-4

Convention-independent study of CP-violating asymmetries in B→ππB \to \pi \pi

CP-violating asymmetries in the decay $B^0(t)\to \pi^+ \pi^-$ are a potentially rich source of information about both strong and weak phases. In a previous treatment by the present authors use was made of an assumption about the relative magnitude of tree and penguin amplitudes contributing to this process. This assumption involved an ambiguity in relating the tree amplitude to the amplitude for $B \to \pi \ell \nu$. It is shown here that one can avoid this assumption, which adopted a particular convention for tree and penguin amplitudes, and that the results are convention-independent.Comment: 14 pages, LaTeX, 2 figures, revised version submitted to Phys. Rev. D. Further references and text adde

Exploring flavor structure of supersymmetry breaking from rare B decays and unitarity triangle

We study effects of supersymmetric particles in various rare B decay processes as well as in the unitarity triangle analysis. We consider three different supersymmetric models, the minimal supergravity, SU(5) SUSY GUT with right-handed neutrinos, and the minimal supersymmetric standard model with U(2) flavor symmetry. In the SU(5) SUSY GUT with right-handed neutrinos, we consider two cases of the mass matrix of the right-handed neutrinos. We calculate direct and mixing-induced CP asymmetries in the b to s gamma decay and CP asymmetry in B_d to phi K_S as well as the B_s--anti-B_s mixing amplitude for the unitarity triangle analysis in these models. We show that large deviations are possible for the SU(5) SUSY GUT and the U(2) model. The pattern and correlations of deviations from the standard model will be useful to discriminate the different SUSY models in future B experiments.Comment: revtex4, 36 pages, 10 figure

ATP synthase: from single molecule to human bioenergetics

ATP synthase (FoF1) consists of an ATP-driven motor (F1) and a H+-driven motor (Fo), which rotate in opposite directions. FoF1 reconstituted into a lipid membrane is capable of ATP synthesis driven by H+ flux. As the basic structures of F1 (α3β3γδε) and Fo (ab2c10) are ubiquitous, stable thermophilic FoF1 (TFoF1) has been used to elucidate molecular mechanisms, while human F1Fo (HF1Fo) has been used to study biomedical significance. Among F1s, only thermophilic F1 (TF1) can be analyzed simultaneously by reconstitution, crystallography, mutagenesis and nanotechnology for torque-driven ATP synthesis using elastic coupling mechanisms. In contrast to the single operon of TFoF1, HFoF1 is encoded by both nuclear DNA with introns and mitochondrial DNA. The regulatory mechanism, tissue specificity and physiopathology of HFoF1 were elucidated by proteomics, RNA interference, cytoplasts and transgenic mice. The ATP synthesized daily by HFoF1 is in the order of tens of kilograms, and is primarily controlled by the brain in response to fluctuations in activity