arXiv subjects

Junfeng Sun

Publications and source records attributed to Junfeng Sun.

At least 37 records · Page 2Linked to original sources

arXiv2021

Study of $C$ parity violating and strangeness changing $J/ψ$ ${\to}$ $PP$ weak decays

The $J/ψ$ weak decays are rare but possible within the standard model of elementary particles. Inspired by the potential prospects at the future intensity frontier, the $C$ parity violating $J/ψ$ ${\to}$ $πη^{({\prime})}$, $ηη^{\prime}$ decays and the strangeness changing $J/ψ$ ${\to}$ $πK$, $Kη^{({\prime})}$ decays are studied with the perturbative QCD approach. It is found that the $J/ψ$ ${\to}$ $ηη^{\prime}$ decays have relatively large branching ratios, about the order of $10^{-11}$, which might be within the measurement capability and sensitivity of the future STCF experiment.

hep-ph↗

arXiv2021

Reinvestigating the $B$ ${\to}$ $PP$ decays by including the contributions from $ϕ_{B2}$

Considering the $B$ mesonic distribution amplitude $ϕ_{B2}$, we reinvestigated the $B$ ${\to}$ $PP$ (where $P$ $=$ $π$ and $K$) decays with the perturbative QCD (pQCD) approach based on the $k_{T}$ factorization for three scenarios. It is found that the contributions of $ϕ_{B2}$ to formfactors $F_{0}^{B{\to}P}(0)$ and branching ratios are comparable with those from the NLO corrections. The $B$ ${\to}$ $Kπ$ decays could be well explained by considering the $ϕ_{B2}$. Hence, when the nonleptonic $B$ decays are studied withe the pQCD approach, the $ϕ_{B2}$ should be taken into account seriously.

hep-ph↗

arXiv2021

Study of the $Υ(1S)$ ${\to}$ $DP$ decays

Inspired by the potential prospects of high-luminosity dedicated colliders and the high enthusiasms in searching for new physics in the flavor sector at the intensity frontier, the $Υ(1S)$ ${\to}$ $D^{-}π^{+}$, $\overline{D}^{0}π^{0}$ and $D_{s}^{-}K^{+}$ weak decays are studied with the perturbative QCD approach. It is found within the standard model that the branching ratios for the concerned processes are tiny, about ${\cal O}(10^{-18})$, and far beyond the detective ability of current experiments unless there exists some significant enhancements from a noval interaction.

hep-ph↗

arXiv2021

The study of $η_{c}(1S)$ ${\to}$ $PP^{\prime}$ decays

The $η_{c}(1S)$ ${\to}$ $PP^{\prime}$ decays are the parity violation modes. These decays can be induced by the weak interactions within the standard model, and have been searched for based on the available experimental data. To meet the needs of experimental investigation, the $η_{c}(1S)$ ${\to}$ $PP^{\prime}$ decays are studied with the perturbative QCD approach. It is found that branching ratios are the order of $10^{-15}$ and less, which offers a ready reference for future analyses.

hep-ph↗

arXiv2019

Contributions from $Φ_{B2}$ to the $B$ ${\to}$ $PP$ decays within the QCD factorization

With the potential for the improvements of measurement precision,the refinement of theoretical calculation on hadronic $B$ weak decays is necessary. In this paper, we study the contributions of $B$ mesonic distribution amplitude $Φ_{B2}$ within the QCD factorization approach, and find that $Φ_{B2}$ contributes to only the nonfactorizable annihilation amplitudes for the $B$ ${\to}$ $PP$ decays ($P$ denotes the ground $SU(3)$ pseudoscalar mesons). Although small, the $Φ_{B2}$ contributions might be helpful for improving the performance of the QCD factorization approach, especially for the pure annihilation $B_{d}$ ${\to}$ $K^{+}K^{-}$ and $B_{s}$ ${\to}$ $π^{+}π^{-}$ decays.

hep-ph↗

arXiv2018

$B_{u}$ ${\to}$ $ψM$ decays and $S$-$D$ wave mixing effects

The $B_{u}$ ${\to}$ $ψM$ decays are studied with the perturbative QCD approach, where the psion $ψ$ $=$ $ψ(2S)$, $ψ(3770)$, $ψ(4040)$ and $ψ(4160)$, and the light meson $M$ $=$ $π$, $K$, $ρ$ and $K^{\ast}$. The factorizable and nonfactorizable contributions, and the $S$-$D$ wave mixing effects on the psions are considered in the calculation. With appropriate inputs, the branching ratios for the $B_{u}$ ${\to}$ $ψK$ decays are generally coincident with the experimental data within errors. However, due to the large theoretical and experimental errors, it is impossible for the moment to give a severe constraint on the $S$-$D$ wave mixing angles.

hep-ph↗

arXiv2018

Study of the $B_{s}$ ${\to}$ $ϕf_{0}(980)$ ${\to}$ $ϕ\,π^{+}π^{-}$ decay with perturbative QCD approach

The rare cascade $B_{s}$ ${\to}$ $ϕf_{0}(980)$ ${\to}$ $ϕ\,π^{+}π^{-}$ decay is studied with the perturbative QCD approach based on the formula for the quasi two-body decay, where the two-pion pair originates from the $S$-wave resonant $f_{0}(980)$ state. It is found that with the introduction of the nonperturbative two-pion distribution amplitudes and the Flatté parameterization of the scalar form factor for the $f_{0}(980)$ resonance, the branching ratio in the mass range 400 MeV $<$ $m(π^{+}π^{-})$ $<$ 1600 MeV is ${\cal B}_{\rm theo}(B_{s}^{0}\, {\to}\,ϕ\,f_{0}(980)\,{\to}\,ϕ\,π^{+}\,π^{-})$ $=$ $[1.31_{-0.31}^{+0.40}(a_{ππ}){}_{-0.16}^{+0.19}(m_{b}) {}_{-0.09}^{+0.10}(\text{CKM})]{\times}10^{-6}$, where the uncertainties come from the parameter $a_{ππ}$ of the two-pion distribution amplitudes, the $b$ quark mass $m_{b}$, the Cabibbo-Kobayashi-Maskawa (CKM) factors, respectively. This result agrees with the recent LHCb measurement within uncertainties, ${\cal B}_{\rm exp}(B_{s}^{0}\,{\to}\,ϕ\, f_{0}(980)\,{\to}\,ϕ\,π^{+}\,π^{-})$ $=$ $(1.12{\pm}0.16^{+0.09}_{-0.08}{\pm}0.11){\times}10^{-6}$, where the errors are statistical, systematic and from the normalization, respectively.

hep-ph↗

arXiv2017

$Υ(nS)$ ${\to}$ $B_{c}ρ$, $B_{c}K^{\ast}$ decays with perturbative QCD approach

Inspired by the potential prospects of $Υ(nS)$ data samples ($n$ $=$ $1$, $2$, $3$) at LHC and SuperKEKB, $Υ(nS)$ ${\to}$ $B_{c}ρ$, $B_{c}K^{\ast}$ decays are studied phenomenologically with pQCD approach. Branching ratios for $Υ(nS)$ ${\to}$ $B_{c}ρ$ and $B_{c}K^{\ast}$ decays are estimated to reach up to ${\cal O}(10^{-11})$ and ${\cal O}(10^{-12})$, respectively. Given the identification and detection efficiency of final states, searching for these weak decay modes should be fairly challenging experimentally in the future.

hep-ph↗

arXiv2017

Study of $J/ψ$ ${\to}$ $D_{s,d}V$ decays with perturbative QCD approach

Inspired by the recent measurements on two-body nonleptonic $J/ψ$ weak decay at BESIII, the charm-changing $J/ψ$ ${\to}$ $D_{s,d}V$ weak decays are studied with perturbative QCD approach, where $V$ denotes $ρ$ and $K^{\ast}$ vector mesons. It is found that branching ratio for $J/ψ$ ${\to}$ $D_{s}ρ$ decay can reach up to ${\cal O}(10^{-9})$, which is within the potential measurement capability of the future high-luminosity experiments.

hep-ph↗

arXiv2017

$J/ψ$ ${\to}$ $D_{s,d}π$, $D_{s,d}K$ decays with perturbative QCD approach

Besides the conventional strong and electromagnetic decay modes, the $J/ψ$ particle can also decay via the weak interaction in the standard model. In this paper, nonleptonic $J/ψ$ ${\to}$ $D_{s,d}π$, $D_{s,d}K$ weak decays, corresponding to the externally emitted virtual $W$ boson process, are investigated with the perturbative QCD approach. It is found that branching ratio for the Cabibbo-favored $J/ψ$ ${\to}$ $D_{s}π$ decay can reach up to ${\cal O}(10^{-10})$, which might be potentially measurable at the future high-luminosity experiments.

hep-ph↗

arXiv2017

$Υ(nS)$ ${\to}$ $B_{c}^{\ast}D$ decays with perturbative QCD approach

The $Υ(nS)$ ${\to}$ $B_{c}^{\ast}D$ weak decays ($n$ $=$ $1$, $2$, $3$) are investigated with perturbative QCD approach. It is found that the CKM-favored $Υ(nS)$ ${\to}$ $B_{c}^{\ast}D_{s}$ decays have branching ratio of ${\cal O}(10^{-10})$, which might be potentially accessible to the future LHC and SuperKEKB experiments.

hep-ph↗

arXiv2017

$B^{\ast}$ ${\to}$ $\bar{D}D$ decays with perturbative QCD approach

The nonleptonic two-body $B^{\ast}$ ${\to}$ $\bar{D}D$ weak decays are studied phenomenologically with the perturbative QCD factorization approach. It is found that the $B_{s}^{{\ast}0}$ ${\to}$ $D_{s}^{-}D_{s}^{+}$, $B_{d}^{{\ast}0}$ ${\to}$ $D_{d}^{-}D_{s}^{+}$, and $B_{u}^{{\ast}+}$ ${\to}$ $\bar{D}_{u}^{0}D_{s}^{+}$ decays have branching ratios ${\gtrsim}$ $10^{-9}$, and might be promisingly measurable at the running LHC and forthcoming SuperKEKB experiments in the future.

hep-ph↗

arXiv2017

Study of the $\bar{B}_{q}^{\ast}$ ${\to}$ $DM$ decays with perturbative QCD approach

The $\bar{B}_{q}^{\ast}$ ${\to}$ $DP$, $DV$ weak decays are studied with the perturbative QCD approach, where $q$ $=$ $u$, $d$ and $s$; $P$ and $V$ denote the ground $SU(3)$ pseudoscalar and vector meson nonet. It is found that the branching ratios for the color-allowed $\bar{B}_{q}^{\ast}$ ${\to}$ $D_{q}ρ^{-}$ decays can reach up to $10^{-9}$ or more, and should be promisingly measurable at the running LHC and forthcoming SuperKEKB experiments in the near future.

hep-ph↗

arXiv2017

Charmless $B_{c} \to VV$ decays in the QCD factorization approach

In this paper, we studied the charmless $B_{c}\to VV$ ($V$ denotes the light ground $\rm SU(3)$ vector meson) decays within the framework of QCD factorization. In the evaluation, two different schemes for regulating the end-point divergence are adopted. One (scheme I) is to use parameterization model, which is usually employed in the QCD factorization approach; the other (scheme II) is based on the infrared finite gluon propagator of Cornwall prescription. It is found that, in the annihilation amplitudes, the end-point divergence appears only in the power-suppressed corrections related to the twist-3 distribution amplitudes of $V$-meson. The strength of annihilation amplitudes evaluated in scheme II is generally larger than the one in scheme I. Numerically, in the decay modes considered in this paper, the CKM-favored $B_{c} \to ρ^{-}ω, K^{*-}K^{*0} $ decays have the relatively large branching fractions, $\sim {\cal{O}}(10^{-7})$, and hence are likely to be the first observed by the future experiments. In addition, all of the decay modes are dominated by the longitudinal polarization state; numerically, $f_{L}(B_{c} \to VV) \gtrsim 99\%$.

hep-ph↗

arXiv2017

Possibility of searching for $B_{c}^{\ast}$ ${\to}$ $B_{u,d,s}V$, $B_{u,d,s}P$ decays

The $B_{c}^{\ast}$ ${\to}$ $B_{u,d,s}V$, $B_{u,d,s}P$ decays are investigated with the QCD factorization approach, where $V$ and $P$ denote the ground $SU(3)$ vector and pseudoscalar mesons, respectively. The $B_{c}^{\ast}$ ${\to}$ $B_{u,d,s}$ transition form factors are calculated with the Wirbel-Stech-Bauer model. It is found that branching ratios for the color-favored and Cabibbo-favored $B_{c}^{\ast}$ ${\to}$ $B_{s}ρ$, $B_{s}π$ decays can reach up to ${\cal O}(10^{-7})$, which might be measurable in the future LHC experiments.

hep-ph↗

arXiv2017

Study on the $Υ(1S)$ ${\to}$ $B_{c}D_{s}$ decay

The branching ratio and direct $CP$ asymmetry of the $Υ(1S)$ ${\to}$ $B_{c}D_{s}$ weak decay are estimated with the perturbative QCD approach. It is found that (1) The direct $CP$-violating asymmetry is close to zero. (2) the branching ratio ${\cal B}r(Υ(1S){\to}B_{c}D_{s})$ ${\gtrsim}$ $10^{-10}$ might be measurable at the future experiments.

hep-ph↗

arXiv2017

Study of $B_{c}^{\ast}$ ${\to}$ $ψ(1S,2S)P$, $η_{c}(1S,2S)P$ weak decays

Motivated by the potential prospects of the $B_{c}^{\ast}$ meson samples at hadron colliders, the bottom-changing $B_{c}^{\ast}$ ${\to}$ $ψ(1S,2S)P$, $η_{c}(1S,2S)P$ weak decays are first studied with the perturbative QCD approach, where $P$ $=$ $π$ and $K$. It is found that branching ratio of the CKM-favored $B_{c}^{\ast}$ ${\to}$ $J/ψπ$ decay is about ${\sim}$ ${\cal O}(10^{-8})$, which might be measurable at the future LHC experiments.

hep-ph↗

arXiv2017

Study of $Υ(nS)$ ${\to}$ $B_{c}P$ decays with perturbative QCD approach

With the potential prospects of the $Υ(nS)$ at high-luminosity dedicated heavy-flavor factories, the color-favored $Υ(nS)$ ${\to}$ $B_{c}π$, $B_{c}K$ weak decays are studied with the pQCD approach. It is found that branching ratios for the $Υ(nS)$ ${\to}$ $B_{c}π$ decay are as large as the order of ${\cal O}(10^{-11})$, which might be measured promisingly by the future experiments.

hep-ph↗