arXiv subjects

Ying-Ying Fan

Publications and source records attributed to Ying-Ying Fan.

23 records · Page 2Linked to original sources

arXiv2013

Revisiting $Kπ$ puzzle in the pQCD factorization approach

In this paper, we calculated the branching ratios and direct CP violation of the four $B\to Kπ$ decays with the inclusion of all currently known next-to-leading order (NLO) contributions by employing the perturbative QCD (pQCD) factorization approach. We found that (a) Besides the 10% enhancement from the NLO vertex corrections, the quark-loops and magnetic penguins, the NLO contributions to the form factors can provide an additional $\sim 15%$ enhancement to the branching ratios, and lead to a very good agreement with the data; (b) The NLO pQCD predictions are $\acp^{dir}(B^0\to K^+π^-)=(-6.5\pm 3.1)%$ and $\acp^{dir}(B^+\to K^+ π^0)=(2.2\pm 2.0)%$, become well consistent with the data due to the inclusion of the NLO contributions.

hep-ph↗

arXiv2013

Anatomy of $B \to K η^{(\prime)}$ decays in different mixing schemes and effects of next-to-leading order contributions in the perturbative QCD approach

In this paper we perform a comprehensive study of the four $B \to K \etap$ decays in the pQCD factorization approach. We calculate the CP-averaged branching ratios and CP-violating asymmetries of $B \to K\etap$ decays in the ordinary $η$-$\etar$, the $η$-$\etar$-$G$, and the $η$-$\etar$-$G$-$η_c$ mixing schemes. Besides the full LO contributions, all currently known NLO contributions to $B \to K \etap$ decays in the pQCD approach are taken into account. From our calculations and phenomenological analysis, we find the following. (a) The NLO contributions in general can provide significant enhancements to the LO pQCD predictions for the decay rates of the two $B \to K \etar$ decays, around $70%-89%$ in magnitude, but result in relatively small changes to $Br(B \to K η)$. (b) Although the NLO pQCD predictions in all three considered mixing schemes agree well with the data within one standard deviation, those pQCD predictions in the $η$-$\etar$-$G$ mixing scheme provide the best interpretation for the measured pattern of $Br(B \to K \etap)$: $Br(B^0 \to K^0 η) \approx 1.13\times 10^{-6}$, $Br(B^0 \to K^0 \etar) \approx 66.5 \times 10^{-6}$, $Br(B^\pm \to K^\pm η) \approx 2.36\times 10^{-6}$, and $Br(B^\pm \to K^\pm \etar) \approx 67.3 \times 10^{-6}$, which agree perfectly with the measured values. (c) The NLO pQCD predictions for the CP-violating asymmetries for the four considered decays are also in good consistent with the data. (d) The newly known NLO contribution to the relevant form factors $\calm_{FF}$ can produce about a 20% enhancement to the branching ratios $Br(B \to K \etar)$, which plays an important role in closing the gap between the pQCD predictions and the relevant data. (e) The general expectations about the relative strength of the LO and NLO contributions from different sources are examined and confirmed by explicit numerical calculations.

hep-ph↗

arXiv2013

Semileptonic decays $B/B_s \to (η,\etar, G)(l^+l^-,l\barν,ν\barν)$ in the perturbative QCD approach beyond the leading order

In this paper we make a systematic study of the semileptonic decays $B/B_s \to (η,\etar, G)(l^+l^-,l\barν,ν\barν)$ by employing the perturbative QCD (pQCD) factorization approach. The next-to-leading-order (NLO) contributions to the relevant form factors are included, and the ordinary $η$-$\etar$ mixing scheme and the $η$-$\etar$-$G$ mixing scheme are considered separately, where $G$ denotes a pseudoscalar glueball. The numerical results and the phenomenological analysis indicate that (a) the NLO contributions to the relevant form factors provide 25% enhancement to the leading-order pQCD predictions for the branching ratios $Br(B^-\to η^{(')} l^-\barν_l)$, leading to a good agreement between the predictions and the data; (b) for all considered decays, the pQCD results are basically consistent with those from other different theoretical models; (c) the pQCD predictions in the two considered mixing schemes agree well with each other within theoretical errors. The outcomes presented here can be tested by LHCb and forthcoming Super-$B$ experiments.

hep-ph↗

arXiv2013

Semileptonic decays $B_c\to(η_c,J/Ψ)lν$ in the perturbative QCD approach

In this paper we study the semileptonic decays of $B_c^- \to (η_c,J/ψ)l^-\barν_l$. We firstly evaluate the $B_c \to (η_c,J/Ψ)$ transition form factors $F_0(q^2)$, $F_+(q^2)$, $V(q^2)$ and $A_{0,1,2}(q^2)$ by employing the pQCD factorization approach, and then we calculate the branching ratios for all considered semileptonic decays. Based on the numerical results and the phenomenological analysis, we find that: (a) the pQCD predictions for the values of the $B_c \to η_c$ and $B_c \to J/Ψ$ transition form factors agree well with those obtained by using other methods; (b) the pQCD predictions for the branching ratios of the considered decays are $Br\left(B_c^- \toη_c e^-\barν_e(μ^-\barν_μ)\right) =(4.41^{+1.22}_{-1.09})\times10^{-3}$, $Br\left(B_c^- \toη_cτ^-\barν_τ\right) =(1.37^{+0.37}_{-0.34})\times10^{-3}$, $Br(B_c^- \to J/Ψe^-\barν_e(μ^-\barν_μ)) =(10.03^{+1.33}_{-1.18})\times10^{-3}$, and $Br\left(B_c^- \to J/Ψτ^-\barν_τ\right) =(2.92^{+0.40}_{-0.34})\times10^{-3}$; and (c) we also define and calculate two ratios of the branching ratios $R_{η_c}$ and $R_{J/Ψ}$, which will be tested by LHCb and the forthcoming Super-B experiments.

hep-ph↗

arXiv2010

Lepton Flavor Violating $τ$ Decays in Two Higgs Doublet Model III

We study the lepton flavor violating processes of $τ^-\toμ^-PP$ decays with $PP=K^+K^-,K^0\bar{K}^0,π^+π^-,π^0π^0$ in the framework of two Higgs doublet model III by virtue of the Chiral Perturbation Theory. In this model, only three neutral Higgs bosons contribute to these decays. With the current experimental constraints, we show that (a) the contributions of $|λ_{uu(dd)}|$ term are very small for these four decays; (b) we get the correlation between $|λ_{ss}|$ and $|λ_{τμ}|$. For $|λ_{τμ}| \sim 10-400$, one has $|λ_{ss}|\sim 40-1$; (c) in the existing model parameter space, $Br(τ^- \to μ^- K^+K^-)$ could reach the order of ${\cal O}(10^{-8})$, but $Br(τ\to μ^- π^+π^-/π^0π^0)$ are too small to be observed.

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