arXiv subjects

Ya-Dong Yang

Publications and source records attributed to Ya-Dong Yang.

99 records · Page 6Linked to original sources

arXiv2005

Polarizations in decays B_{u,d}\to VV and possible implications for R-parity violating SUSY

Recently BABAR and Belle have measured anomalous large transverse polarizations in some pure penguin $B \to VV$ decays, which might be inconsistent with the Standard Model expectations. We try to explore its implications for R-parity violating (RPV) supersymmetry. The QCD factorization approach is employed for the hadronic dynamics of B decays. We find that it is possible to have parameter spaces solving the anomaly. Furthermore, we have derived stringent bounds on relevant RPV couplings from the experimental data, which is useful for further studies of RPV phenomena.

hep-ph↗

arXiv2004

Polarization Anomaly in $B\to ϕK^{*}$ and Probe of Tensor Interactions

The pure penguin process $B\to ϕK^*$ is one of the most important probes of physics beyond the Standard Model. Recently BaBar and Belle have measured the unexpectedly large transverse polarization in the decays $B\to ϕK^*$, which may single out new physics effects beyond the Standard model. We study the possibility that the phenomenon could serve as an important probe of anomalous tensor interactions. We find that a spin flipped tensor interaction with a small strength and a phase could give a possible solution to the polarization puzzle.

hep-ph↗

arXiv2004

Radiative decays $J/Ψ\toη^{(\prime)}γ$ in perturbative QCD

With the recent investigations of $g^{\ast}g^{\ast}-η^{(\prime)}$ transition form factor and $η-η^{\prime}$ mixing scheme, we present an updated study of the radiative decays $J/Ψ\toη^{(\prime)}γ$ in perturbative QCD. The decays are taken as a test ground for the $g^{\ast}g^{\ast}-η^{(\prime)}$ transition form factors and the $η-η^{\prime}$ mixing scheme. The form factors are found to be working for glunic $η^{(\prime)}$ productions and the mixing angle is constrained to be $ϕ=35.1^{\circ}\pm0.8^{\circ}$.

hep-ph↗

arXiv2002

$B\to ϕπ$ and $B^0 \to ϕϕ$ in the Standard Model and new bounds on R parity violation

We study the pure penguin decays $B \to ϕπ$ and $B^0 \to ϕϕ$. Using QCD factorization, we find ${\cal B}(B^\pm \toϕπ^{\pm} )=2.0^{+0.3}_{-0.1}\times 10^{-8}$. For the pure penguin annihilation process $B^0 \to ϕϕ$, analyzed here for the first time, ${\cal B}(B^0 \toϕϕ)=2.1^{+1.6}_{-0.3}\times 10^{-9}$. The smallness of these decays in the Standard Model makes them sensitive probes for new physics. From the upper limit of $B\to ϕπ$,we find constraints on R parity violating couplings, $| λ{''}_{i23}λ{''}_{i21}|<6\times10^{-5}$, $| λ'_{i23}λ'_{i21}|<4\times10^{-4}$ and $| λ'_{i32}λ'_{i12}|<4\times10^{-4}$ for $i=1,2,3$. Our new bounds on $|λ{''}_{i23}λ{''}_{i21}|$ are one order of magnitude stronger than before. Within the available upper bounds for $| λ{''}_{i23}λ{''}_{i21}|$, $|λ'_{i23}λ'_{i21}|$ and $|λ'_{i32}λ'_{i12}|$, we find that ${\cal B}(B\toϕϕ)$ could be enhanced to $10^{-8}\sim 10^{-7}$. Experimental searches for these decays are strongly urged.

hep-ph↗

arXiv2001

Study of B0-->J/Psi D() and etac D() in Perturbative QCD

Motivated by recent interest in soft $J/Ψ$ production in B decays, we investigate ${B}^0 \to J/ΨD^{(\star)}$ and $η_c D^{(\star)}$ decays in perturbative QCD. We find that, within that framework, these decays are calculable since the heavy $c\bar{c}$ pair in the final states is created by a hard gluon. The branching ratios are estimated to be around $10^{-7}\sim 10^{-8}$, too small to be consistent with the data, suggesting that other mechanism(s) contribute to the observed excess of soft $J/Ψ$ in ${B}^0 \to J/Ψ+ X$ decays. The possibility of the production of a hybrid $s{\bar d}g$ meson with mass about 2 GeV is briefly entertained.

hep-ph↗

arXiv2001

Study of Semileptonic Decays $B^\pm \to η^{(\prime)} l ν$

We study semileptonic decays $B^\pm \to η^{(\prime)} l ν$, which are suggested to be used to extract the hadronic form factors of $B$ meson decays to $η(η^{\prime})$ and the angle of $η-η^{\prime}$ mixing. This would be of great benefit to theoretical studies of $B$ nonleptonic decays involving $η$ and $η^{\prime}$, and could lead to a reliable and complementary determination of $V_{ub}$. The branching ratios are estimated to be ${\cal B}(B^\pm \toη^{(\prime)} l ν)=4.32 \pm 0.83 (2.10 \pm 0.40) \times 10^{-5}$, which could be extensively studied experimentally at $BaBar$ and Belle.

hep-ph↗

arXiv2001

Revisiting Charmless Two-Body B Decays involving $η^{\prime}$ and $η$

We have studied charmless two-body B decays involving $η$ and $η'$ in the framework of QCD improved factorization appraoch. The spectator hard scattering mechanism for $η'$ production have been re-examined and extended, which contributions are incorporated consistently into the factorizable leading contributions. It is found that the conventional mechanism would give $Br(B\to η' K)\sim 30\times 10^{-6}$ which agrees with predictions based on naive factorization approaches. With the incorporation of spectator hard scattering mechanism contributions, theoretical predictions are improved much and the bulk of $Br(B\to η' K)$ are accommodated in the reasonable parameter space. We have also presented calculations of $g^{\ast}g^{\ast}-η^{(\prime)}$ transition form factors within the standard hard scattering approach. It is shown that the new contributions in the modes such as $B\to η' +vector$ and $B\to η+ π, ρ, K^{(\ast)}$ are small. Direct CP-violation in those decay modes are predicted. It is shown that the prospects for measuring direct CP-violation effects in $B^{\pm} \to$ $η' K^{\pm}$, $η' π^{\pm}$, $ηπ^{\pm}$, and $ηK^{\pm}$ are promising at B factories in the near future.

hep-ph↗

arXiv2000

$B\to ππ, K π$ Decays in QCD Improved Factorization Approach

Motivated by recent measurements, we investigate $B\to ππ, K π$ decay modes in the framework of QCD improved factorization, which was recently proposed by Beneke $et al$. We find that all the measured branching ratios are well accommodated in the reasonable parameter space except for $B\to K^0 π^0 $. We also discuss in detail the strong penguin contributions and the ${\cal O}(α_s)$ corrections to the chirally enhanced terms. We find that the weak phase $γ$ lies in the region $120^{\circ}<γ<240^{\circ}$, which is mainly constrained by $B\to π^- π^+ $.

hep-ph↗

arXiv2000

B ->PV Decays in the QCD Improved Factorization Approach

Motivated by recent CELO measurements and the progress of the theory of B decays, we investigate $B\to P V(P=π,K. V= K^{*},ρ,ω)$ decay modes in the framework of QCD improved factorization. We find that all the measured branching ratios are well accommodated in the reasonable parameter space and predictions for the other decay modes are well below the experimental upper limits. We also have calculated CP asymmetries in these decay modes.

hep-ph↗