Rare B decays and Tevatron top-pair asymmetry

The recent Tevatron result on the top quark forward-backward asymmetry, which deviates from its standard model prediction by 3.4$\sigma$, has prompted many authors to build new models to account for this anomaly. Among the various proposals, we find that those mechanisms which produce $t\bar t$ via $t$- or $u$-channel can have a strong correlation to the rare B decays. We demonstrate this link by studying a model with a new charged gauge boson, $W'$. In terms of the current measurements on $B\to \pi K$ decays, we conclude that the branching ratio for $B^-\to \pi^- \bar K^0$ is affected most by the new effects. Furthermore, using the world average branching ratio for the exclusive B decays at $2\sigma$ level, we discuss the allowed values for the new parameters. Finally, we point out that the influence of the new physics effects on the direct CP asymmetry in B decays is insignificant.Comment: 15 page, 6 figures, typos corrected and references added, final version to appear journa

What can we learn from B+→Ds(∗)−K+π+B^{+}\to D^{(*)-}_{s} K^{+} \pi^{+}, Bd→Ds(∗)−K0π+B_{d}\to D_{s}^{(*)-} K^{0} \pi^{+} and Bd→Ds(∗)−K∗+B_{d}\to D_{s}^{(*)-} K^{*+} decays?

We study the nonresonant three-body decays of $B^{+}\to D^{(*)-}_{s} K^{+} \pi^{+}$ and $B_{d}\to D_{s}^{(*)-} K^{0} \pi^{+}$. We find that these decays can provide the information on the time-like form factors of $D^{(*)}_{s} K$. We also explicitly investigate $B_{d}\to D_{s}^{(*)-} K^{*+}$ decays by discriminating the nonresonant contributions with the unknown $D^{(*)}_{s}$ wave functions being fixed by the measured mode of $B_{d}\to D_{s}^{-} K^{+}$.Comment: 14 pages, 4 figures, Revtex4, version to appear in PL

Non-Leptonic Two Body B Decays in QCD

We review the current status of theoretical study of non-leptonic two body B decays. There are two independent directions for this purpose. One is the so called QCD factorization approach (or BBNS approach), which is based on naive factorization approach. The other one is named perturbative QCD approach. We list the different ideas and applications of the two method, and make a comparison between the two.Comment: 12 pages, including 2 figures, invited talk given at International Conference on Flavor Physics (ICFP 2001), Zhang-Jia-Jie City, Hunan, China, 31 May - 6 Jun 200

Nonuniversal Z′Z^{\prime} couplings in B decays

We study the impacts of nonuniversal $Z^{\prime}$ model, providing flavor changing neutral current at tree level, on the branching ratios (BRs), CP asymmetries (CPAs) and polarization fractions of B decays. We find that for satisfying the current data, the new left- and right-handed couplings have to be included at the same time. The new introduced effective interactions not only could effectively explain the puzzle of small longitudinal polarization in $B\to K^* \phi$ decays, but also provide a solution to the small CPA of $B^{\pm}\to \pi^{0} K^{\pm}$. We also find that the favorable CPA of $B^{\pm}\to \pi^{0} K^{\pm}$ is opposite in sign to the standard model; meanwhile, the CPA of $B_{d}\to \pi^{0}K$ has to be smaller than -10%. In addition, by using the values of parameters which are constrained by $B\to \pi K$, we find that the favorable ranges of BRs, CPAs, longitudinal polarizations, and perpendicular transverse polarizations for $(B^{\pm}\to \rho^{\pm} K^{*}, B_{d}\to \rho^{\mp} K^{*\pm})$ are $(17.1\pm 3.9, 10.0\pm2.0)\times 10^{-6}$, $(3\pm 5, 21\pm 7)$, $(0.66\pm 0.10, 0.44\pm 0.08)$ and $(0.14\pm 0.10, 0.25\pm 0.09)$, respectively.Comment: 28 pages, 9 figures, version revise

Evidence for two-quark content of f0(980)f_{0}(980) in exclusive b→cb\to c decays

Inspired by a large decay branching ratio (BR) of $B^{+}\to f_{0}(980)K^{+}$ measured by Belle recently, we propose that a significant evidence of the component of $n\bar{n}=(u\bar{u}+d\bar{d})/\sqrt{2}$ in $f_{0}(980)$ could be demonstrated in exclusive $b\to c$ decays by the observation of $f_{0}(980)$ in the final states $\bar{B}\to D^{0(*)} \pi^{+} \pi^{-}(KK)$ and $\bar{B}\to J/\Psi \pi^{+} \pi^{-}(KK)$. We predict the BRs of $\bar{B}\to D^{0(*)} (J/\Psi) f_{0}(980)$ to be ${\cal {O}}(10^{-4})$ (${\cal {O}}(10^{-5})$) while the unknown wave functions of $D^{(*)0}$ ($J/\Psi$) are chosen to fit the observed decays of $\bar{B}\to D^{(*)0} \pi^{0} (J/\Psi K^{0(*)})$.Comment: 4 pages, 2 figures, Revtex4, version to appear in PR