相关论文: b to d d s bar transition and constraints on new p…
The $\Delta S = 2$ $b \to \bar d ss$ transition proceeds via the box - diagram in the Standard Model with a branching ratio calculated to be below $10^{-11}$, thus providing an appropriate testing ground for physics beyond the Standard…
The $\Delta S = 2$ transition $b \to s s \bar d$ is extremely small in the standard model, proceeding only via box diagrams. Such decays are thus an appropriate ground for searching new physics. We present a study of several two-body and…
Latest Lattice results on $D$ form factors evaluation from first principles show that the standard model (SM) branching ratios prediction for the leptonic $D_s \to \ell \nu_\ell$ decays and the semileptonic SM branching ratios of the $D^0$…
Recent experimental results for the ratio of the branching fractions of $\bar B \to D^{(*)}\tau \nu_\tau$ and $B\to D^{(*)} \mu \nu_\mu$ decays came as a surprise and lead to a discussion of possibility to constraining new physics through…
We investigate new physics effects on $B\to D^{(*)}\tau\nu$ decays in a general and model-independent way. The $\chi^2$ fits for fractions of the branching ratios $R(D^{(*)})$ and other polarization parameters are implemented. We…
Rare decays mediated by $b \to s \nu \bar \nu$ transitions have been reported by the Belle II experiment. The branching ratio of the decay $B^+ \to K^+ \nu \bar \nu$ is found to be enhanced with respect to the standard model value. If taken…
We present an analysis of the rare exclusive $B$ decays $B\to K\nu\bar\nu$ and $B\to K^{*}\nu\bar\nu$ within the Standard Model (SM), in a model-independent manner, and in a number of new physics (NP) models. Combining new form factor…
Recent experimental results for the ratio of the branching fractions of $\bar B\to D^{(*)}\tau\bar \nu_\tau$ and $\bar B\to D^{(*)}\mu\bar \nu_\mu$ decays came as a surprise and lead to a discussion of possibility to constraining New…
We report the results of a study of neutral B meson decays to the D^0 pi+ pi- final state, where the D^0 is fully reconstructed. The results are obtained from an event sample containing 388 million BB-bar -meson pairs collected in the Belle…
The rare decays $B_{s(d)} \to \mu^+\mu^-$ play a key role for the testing of the Standard Model. An overview of the most recent theoretical predictions of the corresponding branching ratios is given, emphasizing that the sizable decay width…
The rare Bc->Ds l^+ l^- decay is investigated by using the most general model independent effective Hamiltonian. The general expressions of longitudinal, normal and transversal polarization asymmetries for l^- and l^+ and the combined…
In this work, a comprehensive analysis for processes related to $b\to c\bar{u}q~(q=d, s)$ transitions are carried out, including new physics contributions. In light of a recent tension between branching fractions for $B_{(s)}\to…
The baryonic $b\to s$ transition $\Lambda_b\to\Lambda^{(*)}\nu{\bar\nu}$ is analyzed. We combine the mesonic counterpart $B^+\to K^+\nu{\bar\nu}$ and $B^0\to K^{*0}\nu{\bar\nu}$ as well as other observables involving $B$ mesons like…
We report a measurement of the exclusive $B^+$ meson decay to the final state $D_s^- K^+\pi^+$ using $520 \times 10^{6} B\bar{B}$ pairs collected near the $\Upsilon(4S)$ resonance, with the Belle detector at the KEKB asymmetric-energy…
A new way of probing new physics in the $B$ meson system is provided. We define double ratios for the observables of $B_{d,s}$-$\Bbar_{d,s}$ mixings and $B_{d,s}\to\mu^+\mu^-$ decays, and find simple relations between the observables. By…
We reconstruct B0bar -> D_s^-D^+ decays using a sample of 275 million BBbar pairs recorded by the Belle experiment, and we measure the branching fraction to be [7.42 +- 0.23(stat) +- 1.36(syst)] x 10^(-3). We also search for the related…
We analyze the rare decay mode $B \to \phi \pi $, which is a pure penguin induced process, receiving dominant contribution from the electroweak penguins. Thus the standard model branching ratio is expected to be very small, which makes it…
We study the loop induced rare decays $B_s(B_d)\to\gamma\nu\bar\nu$ within the standard model. Both constituent quark model and pole model are used and the branching ratios turn out to be of the orders of $10^{-8}$ for $B_s\to \gamma \nu…
We reconstruct B0bar --> Ds-D+ decays using a sample of 449 x 10^6 BBbar pairs recorded by the Belle experiment, and measure the branching fraction to be Br(B0bar --> Ds-D+)=[7.5 +- 0.2(stat) +- 0.8(syst) +- 0.8(Br's)] x 10^(-3). A search…
After incorporating all the available experimental data and the most up-to-date Lattice and light cone sum rule (LCSR) inputs on the form factors, we analyze the exclusive $b\to u\ell\nu_{\ell}$ and $b\to d\ell \ell$ decays simultaneously.…