arXiv subjects

Zheng-Yi Wei

Publications and source records attributed to Zheng-Yi Wei.

4 recordsLinked to original sources

arXiv2022

Time-reversal asymmetries in $Λ_b \to Λ(\to p π^-)\ell^+\ell^-$

We study the decays of $Λ_b \to Λ(\to p π^-) \ell ^+ \ell^-$ with $\ell = (e, μ, τ)$. In particular, we examine the full angular distributions with polarized $Λ_b$ and identify the time-reversal asymmetries or T-odd observables. By using the homogeneous bag model, we find that the decay branching fractions of $Λ_b \to Λ\ell^+\ell^-$ are $(9.1\pm 2.5,7.9\pm 1.8, 2.1\pm 0.2)\times 10^{-7}$ for $\ell =(e, μ,τ)$, respectively. In addition, we obtain that $A_{FB}^{\ell} = -0.369\pm 0.007$ and $A_{FB}^{h}=-0.333\pm 0.004$, averaged in the range of $15 \leq q^2 \leq 20~ \text{GeV}^2$. These results are well consistent with the current experimental data. We also explore the T-odd observables in $Λ_b \to Λ(\to p π^-) μ^+ μ^-$, which are sensitive to new physics~(NP). Explicitly, we illustrate that the current experimental measurement from one of the T-odd observables favors the existence of NP, such as the extra $Z$-boson model.

hep-ph↗

arXiv2022

New extraction of CP violation in b-baryon decays

We study CP violation in b-baryon decays of $Ξ_b^- \to Ξ^- D$ with $D = D^0, \bar{D}^0$ and $D_i~(i=1,2)$. We find that these baryonic decay processes provide an ideal opportunity to measure the weak phase due to the absence of the relative strong phase. Explicitly, we relate $\barρ$ and $\barη$ the CKM elements with the decay rate ratios of $R_i= Γ(Ξ_b^- \to Ξ^-D_{i} ) / Γ( Ξ_b^- \to Ξ^-D^0 )$ without the charge conjugate states. As a complementary, we also examine the decay distributions of $Λ_b \to Λ(\to p π^- ) D$. There are in total 32 decay observables, which can be parameterized by 9 real parameters, allowing the experiments to extract the angle $γ\equiv \arg(-V_{ud}V_{ub}^*/V_{cd}V_{cb}^*)$ in the CKM unitarity triangle. In addition, the feasibilities of the experimental measurements are discussed. We find that $\barρ$ and $\barη$ can be extracted at LHCb Run3 from $Ξ_b^- \to Ξ^- D$, and a full analysis of $Λ_b \to Λ(\to p π^-)D$ is available at LHCb Run4.

hep-ph↗

arXiv2022

Weak Radiative Decays of Anti-triplet Bottomed Baryons in Light-Front Quark Model

We study the weak radiative decays of ${\bf B}_b \to {\bf B}_n γ$ with ${\bf B}_{b(n)} $ the anti-triplet-bottom (octet) baryons in the light front quark model. We obtain that ${\cal B}(Λ_b \to Λγ)= (7.1 \pm 0.3 )\times 10 ^{-6}$, which agrees well with the current experimental value of $(7.1 \pm 1.7 )\times 10 ^{-6}$. We predict that ${\cal B}(Ξ_b^0 \to Ξ^0 γ)= (1.0 \pm 0.1 )\times 10 ^{-5}$ and ${\cal B}(Ξ_b^- \to Ξ^- γ) = (1.1 \pm 0.1) \times 10^{-5}$, which are consistent with the latest upper limits set by the LHCb collaboration. In addition, we find that the $SU(3)_F$ flavor symmetry breaking effects for the modes related to the $b\to d γ$ transition can be as large as $20\%$.

hep-ph↗

arXiv2021

Analysis of three-body charmed B meson decays under the factorization-assisted topological-amplitude approach

We analyze the quasi-two-body charmed $B$ decays $B^{+,0}_{(s)} \to D_{(s)}^* P_2 \to D_{(s)} P_1 P_2$ with $P_{1,2}$ as a pion or kaon. The intermediate processes $B_{(s)} \to D_{(s)}^* P_2 $ are calculated with the factorization-assisted topological-amplitude approach and the resonant effects are calculated with the Breit-Wigner formalism. Taking all p-wave resonance states $ \bar D_{(s)}^*$ into consideration, we present the related branching fractions, calculate the Breit-Wigner-Tail effects, and investigate the flavor $SU(3)$ breaking effects. Most of our branching fractions are consistent with the perturbative QCD approach's predictions as well as the current experimental data. With more precision calculation of the intermediate two body charmed B meson decays, our quasi-two-body B decays calculation has significantly less theoretical uncertainty than the perturbative QCD approach. Many of those channels without any experimental data will be confronted with the future more accurate experiment measurements. Our results of the Breit-Wigner-tail effects also agree with the experimental very well. In $B^0$ decays this effect can reach approximately to $5\%$. It is also found that the Breit-Wigner-tail effects are not sensitive to the widths of their corresponding resonances. The flavor $SU(3)$ symmetry breaking effect is also investigated.

hep-ph↗