arXiv subjects
Publications and source records attributed to Junfeng Sun.
The $Υ(nS)$ ${\to}$ $B_{c}D_{s}$, $B_{c}D_{d}$ weak decays are studied with the pQCD approach firstly. It is found that branching ratios ${\cal B}r(Υ(nS){\to}B_{c}D_{s})$ ${\sim}$ ${\cal O}(10^{-10})$ and ${\cal B}r(Υ(nS){\to}B_{c}D_{d})$ ${\sim}$ ${\cal O}(10^{-11})$, which might be measurable in the future experiments.
With the potential prospects of the $Υ(1S)$ at high-luminosity dedicated heavy-flavor factories, the bottom-changing $Υ(1S)$ ${\to}$ $B_{c}π$, $B_{c}K$ weak decays are studied with the pQCD approach. It is found that branching ratio for the color-favored and CKM-favored $Υ(1S)$ ${\to}$ $B_{c}π$ decay can reach up to ${\cal O}(10^{-11})$. So the $Υ(1S)$ ${\to}$ $B_{c}π$ decay might be measured promisingly by the future experiments.
With anticipation of abundant Upsilons data sample at high-luminosity heavy-flavor experiments in the future, we studied nonleptonic two-body weak decays of $Υ(nS)$ below the open-bottom threshold with $n$ $=$ $1$, $2$ and $3$. It is found that branching ratios for $Υ(1S,2S,3S)$ ${\to}$ $B_{c}ρ$ decays are relatively large among upsilons decay into $B_{c}M$ final states ($M$ $=$ $π$ $ρ$, $K$ and $K^{\ast}$) and can reach up to $10^{-10}$, which is promisingly detected by experiments at the running LHC and forthcoming SuperKEKB.
Motivated by the prospects of the potential $Υ(1S)$ particle at high-luminosity heavy-flavor experiments, we studied the $Υ(1S)$ ${\to}$ $B_{c}M$ weak decays, where $M$ $=$ $π$, $ρ$, $K^{(\ast)}$. The nonfactorizable contributions to hadronic matrix elements are taken into consideration with the QCDF approach. It is found that the CKM-favored $Υ(1S)$ ${\to}$ $B_{c}ρ$ decay has branching ratio of ${\cal O}(10^{-10})$, which might be measured promisingly by the future experiments.
Besides the traditional strong and electromagnetic decay modes, $Υ(nS)$ meson can also decay through the weak interactions within the standard model of elementary particle. With anticipation of copious $Υ(nS)$ data samples at the running LHC and coming SuperKEKB experiments, the two-body nonleptonic bottom-changing $Υ(nS)$ ${\to}$ $B_{c}^{\ast}π$, $B_{c}^{\ast}K$ decays ($n$ $=$ 1, 2, 3) are investigated with perturbative QCD approach firstly. The absolute branching ratios for $Υ(nS)$ ${\to}$ $B_{c}^{\ast}π$ and $B_{c}^{\ast}K$ decays are estimated to reach up to about $10^{-10}$ and $10^{-11}$, respectively, which might possibly be measured by the future experiments.
With the potential prospects of the $Υ(1S)$ data samples at the running LHC and upcoming SuperKEKB, the $Υ(1S)$ ${\to}$ $B_{c}ρ$ weak decays are studied with the pQCD approach. It is found that (1) the lion's share of branching ratio comes from the longitudinal polarization helicity amplitudes; (2) branching ratio for the $Υ(1S)$ ${\to}$ $B_{c}ρ$ decay can reach up to ${\cal O}(10^{-9})$, which might be hopefully measurable.
Motivated by the powerful capability of measurement for the $b$-flavored hadron rare decays at LHC and SuperKEKB/Belle-II, the nonleptonic $\bar{B}^{\ast}$ ${\to}$ $D\bar{D}^{\ast}$, $D{ρ^-}$, $DK^{\ast-}$, $πD^{\ast}$ and $KD^{\ast}$ weak decays are studied in detail. With the amplitudes calculated with factorization approach and the form factors of $B^{\ast}$ transition into pseudoscalar meson evaluated with the BSW model, branching fractions and polarization fractions are firstly presented. Numerically, the CKM-favored $\bar{B}_{q}^{\ast}$ ${\to}$ $D_{q}D_{s}^{{\ast}-}$ and $D_{q}ρ^{-}$ decays have large branching fractions, $\sim$ $10^{-8}$, which should be sought for with priority and firstly observed by LHC and Belle-II experiments. The $\bar{B}^{\ast}_q$ ${\to}$ $D_qK^{\ast}$ and $D_qρ$ decays are dominated by the longitudinal polarization states. While, the parallel polarization fractions of $\bar{B}^{\ast}_q$ ${\to}$ $D_q\bar{D}^{\ast}$ decays are comparable with the longitudinal ones, numerically, $f_{\parallel}$ $+$ $f_{L}$ ${\simeq}$ 95\% and $f_{L}:f_{\parallel}$ $\simeq$ $5:4$. Some comparisons between $\bar{B}^{*0}_q$ $\to$ $D_q V$ and their corresponding $\bar{B}^{0}_q$ $\to$ $D^*_q V$ decays are performed, and the relation $ f_{L,\parallel}(\bar{B}^{\ast 0}\to D V)\simeq f_{L,\parallel}(\bar{B}^0\to D^{\ast +} V^-) $ is presented. Besides, with the implication of $SU(3)$ flavor symmetry, some useful ratios $ R_{\rm du}$ and $ R_{\rm ds}$ are discussed in detail, and suggested to be verified experimentally.
The $Υ(1S)$ ${\to}$ $B_{c}D_{s}^{\ast}$ weak decay is studied with the perturbative QCD approach firstly. It is found that (1) main contributions to branching ratio come from the longitudinal and parallel helicity amplitudes, (2) branching ratio, longitudinal and parallel polarization fractions are sensitive to the wave functions of the $Υ(1S)$ meson, (3) branching ratio for the $Υ(1S)$ ${\to}$ $B_{c}D_{s}^{\ast}$ decay can reach up to $10^{-9}$, which might be promisingly measured by the future experiments.
In this paper the properties of right invertible row operators, i.e., of 1X2 surjective operator matrices are studied. This investigation is based on a specific space decomposition. Using this decomposition, we characterize the invertibility of a 2X2 operator matrix. As an application, the invertibility of Hamiltonian operator matrices is investigated.
Inspired by the recent measurements on the $J/ψ(1S)$ ${\to}$ $D_{s}ρ$, $D_{u}K^{\ast}$ weak decays at BESIII and the potential prospects of the charmonium at the high-luminosity heavy-flavor experiments, we study $ψ(1S,2S)$ and $η_{c}(1S,2S)$ weak decays into final states including one charmed meson plus one light meson, considering the QCD corrections to hadronic matrix elements with the QCD factorization. It is found that the Cabibbo favored $ψ(1S,2S)$ ${\to}$ $D_{s}^{-}ρ^{+}$, $D_{s}^{-}π^{+}$, $\overline{D}_{u}^{0}\overline{K}^{{\ast}0}$ decays have branching ratios ${\gtrsim}$ $10^{-10}$, which might be accessible at the future experiments.
Motivated by the recent measurements on nonleptonic $J/ψ$ weak decays at BESIII and the potential prospects of $J/ψ$ meson at the high-luminosity heavy-flavor experiments, the branching ratios of the two-body nonleptonic $J/ψ$ ${\to}$ $DP$, $DV$ decays are estimated quantitatively by considering the QCD radiative corrections to hadronic matrix elements with the QCD factorization approach. It is found that the Cabibbo favored $J/ψ$ ${\to}$ $D_{s}^{-}ρ^{+}$, $D_{s}^{-}π^{+}$, $\overline{D}_{u}^{0}\overline{K}^{{\ast}0}$ decays have branching ratios ${\gtrsim}$ $10^{-10}$, which might be promisingly detectable in the near future.
Motivated by the recent LHCb measurements on $\bar{B}_{s}$ $\to$ $π^{-}K^{*+}$ and $\bar{B}_{s}$ $\to$ $K^{\pm}K^{*\mp}$ decay modes, we revisit the $B_{s}$ $\to$ $PV$ decays within QCD factorization framework. The effects of hard-spectator scattering and annihilation corrections are studied in detail. After performing a $χ^2$-fit on the end-point parameters $X_A^{i,f}$ ($ρ_A^{i,f}$, $ϕ_A^{i,f}$) and $X_H$ ($ρ_H$, $ϕ_H$) with available data, it is found that although some possible mismatches exist, the universalities of $X_A^{i,f}$ and $X_H$ in $B_s$ and $B_{u,d}$ systems are still allowed within theoretical uncertainties and experimental errors. With the end-point parameters gotten from $B_{u,d}$ $\to$ $PV$ decays, the numerical results and detailed analyses for the observables of $\bar{B}_{s}$ ${\to}$ $πK^{\ast}$, $ρK$, $πρ$, $πϕ$ and $Kϕ$ decay modes are presented. In addition, we have identified a few useful observables, especially the ones of $\bar{B}_{s}$ $\to$ $π^{0}ϕ$ decay for instance, for probing hard-spectator scattering and annihilation contributions.
We studied the nonleptonic $B_{c}$ ${\to}$ $BP$, $BV$ decay with the QCD factorization approach. It is found that the Cabibbo favored processes of $B_{c}$ ${\to}$ $B_{s}π$, $B_{s}ρ$, $B_{u}\bar{K}$ are the promising decay channels with branching ratio larger than 1\%, which should be observed earlier by the LHCb Collaboration.
In this paper, we investigate the contributions of hard spectator scattering and annihilation in $B\to PV$ decays within the QCD factorization framework. With available experimental data on $B\to πK^{\ast}$, $ρK$, $πρ$ and $Kϕ$ decays, comprehensive $χ^2$ analyses of the parameters $X_{A,H}^{i,f}(ρ_{A,H}^{i,f},ϕ_{A,H}^{i,f})$ are performed, where $X_A^f$ ($X_A^i$) and $X_H$ are used to parameterize the endpoint divergences of the (non)factorizable annihilation and hard spectator scattering amplitudes, respectively. Based on $χ^2$ analyses, it is observed that (1) The topology-dependent parameterization scheme is feasible for $B\to PV$ decays; (2) At the current accuracy of experimental measurements and theoretical evaluations, $X_H=X_A^i$ is allowed by $B\to PV$ decays, but $X_{H}\neq X_A^f$ at $68%$ C. L.; (3) With the simplification $X_H=X_A^i$, parameters $X_A^f$ and $X_A^i$ should be treated individually. The above-described findings are very similar to those obtained from $B\to PP$ decays. Numerically, for $B\to PV$ decays, we obtain $(ρ_{A,H}^i,ϕ_{A,H}^i[^{\circ}]) =(2.87^{+0.66}_{-1.95}, -145^{+14}_{-21})$ and $(ρ_A^f,ϕ_A^f[^{\circ}]) = (0.91^{+0.12}_{-0.13}, -37^{+10}_{-9})$ at $68%$ C. L.. With the best-fit values, most of the theoretical results are in good agreement with the experimental data within errors. However, significant corrections to the color-suppressed tree amplitude $α_2$ related to a large $ρ_H$ result in the wrong sign for $A^{dir}_{CP}(B^- \to π^0 K^{{\ast}-})$ compared with the most recent BABAR data, which presents a new obstacle in solving "$ππ$" and "$πK$" puzzles through $α_2$. A crosscheck with measurements at Belle (or Belle II) and LHCb, which offer higher precision, is urgently expected to confirm or refute such possible mismatch.
Motivated by the possible large annihilation contributions implied by recent CDF and LHCb measurements on nonleptonic annihilation B meson decays, and the refined experimental measurements on hadronic B meson decays, we study the strength of annihilation contributions within QCD factorization (QCDF) in this paper. With the available measurements of two-body B_{u,d,s} -> pi pi, pi K, K K decays, a comprehensive fit on the phenomenological parameters X_A^{i,f} (or rho_A^{i,f} and phi_A^{i,f}) which are used to parameterize the endpoint singularity in annihilation amplitudes is performed with the statistical chi^2 approach. It is found that (1) flavor symmetry breaking effects are hardly to be distinguished between X_{A,s}^i and X_{A,d}^i due to the large experimental errors and theoretical uncertainties, where X_{A,s}^i and X_{A,d}^i are related to the nonfactorization annihilation contributions in B_s and B_{u,d} decays, respectively. So X_{A,s}^i = X_{A,d}^i is a good approximation by now. (2) In principle, parameter X_{A}^f which is related to the factorization annihilation contributions and independent of the initial state can be regarded as the same variable for B_{u,d,s} decays. (3) Numerically, two solutions are found, one is (rho_A^i, phi_A^i) = (2.98^+1.12_-0.86,-105^+34_-24) and (rho_A^f, phi_A^f) = (1.18^+0.20_-0.23,-40^+11_-8), the other is (rho_A^i, phi_A^i) = (2.97^+1.19_-0.90,-105^+32_-24) and (rho_A^f, phi_A^f) = (2.80^+0.25_-0.21,165^+4_-3). Obviously, nonfactorization annihilation parameter X_A^i is generally unequal to factorization annihilation parameter X_A^f, which differ from the traditional treatment. With the fitted parameters, all results for observables of B_{u,d,s} ->pi pi, pi K, K K decays are in good agreement with experimental data.
Within the framework of the perturbative QCD approach, we study the two-body charmless decays $B\to K_1(1270)(K_1(1400))π(K)$. We find the following results: (i) The decays $\bar B^0\to K_1(1270)^+π^-, K_1(1400)^+π^-$ are incompatible with the present experimental data. There exists a similar situation for the decays $\bar B^0\to a_1(1260)^+K^-, b_1(1235)^+K^-$, which are usually considered that the nonperturbative contributions are needed to explain the data. But the difference is that the nonperturbative contributions seem to play opposite roles in these two groups of decays.(ii) The pure annihilation type decays $\bar B^0\to K_1^{\pm}(1270)K^{\mp}, K_1^{\pm}(1400)K^{\mp}$ are good channels to test whether an approach can be used to calculate correctly the strength of the penguin-annihilation amplitudes. Their branching ratios are predicted at $10^{-7}$ order, which are larger than the QCDF results. (iii) The dependence of the direct CP-violating asymmetries of these decays on the mixing angle $θ_{K_1}$ are also considered.
The large branching ratios for pure annihilation $\bar{B}_s^0$ $\to$ $π^+ π^-$ and $\bar{B}_d^0$ $\to$ $K^+ K^-$ decays reported by CDF and LHCb collaborations recently and the so-called $πK$ and $ππ$ puzzles indicate that spectator scattering and annihilation contributions are important to the penguin-dominated, color-suppressed tree dominated, and pure annihilation nonleptonic $B$ decays. Combining the available experimental data for $B_{u,d}$ ${\to}$ $ππ$, $πK$ and $K \bar{K}$ decays, we do a global fit on the spectator scattering and annihilation parameters $X_H(ρ_H$, $ϕ_H)$, $X_A^i(ρ_A^{i},ϕ_A^{i})$ and $X_A^f(ρ_A^{f},ϕ_A^{f})$, which are used to parameterize the endpoint singularity in amplitudes of spectator scattering, nonfactorizable and factorizable annihilation topologies within the QCD factorization framework, in three scenarios for different purpose. Numerically, in scenario II, we get $(ρ_A^{i},ϕ_A^{i}[^{\circ}])=(2.88^{+1.52}_{-1.30},-103^{+33}_{-40})$ and $(ρ_A^{f},ϕ_A^{f}[^{\circ}])=(1.21^{+0.22}_{-0.25},-40^{+12}_{-8})$ at the $68\%$ confidence level, which are mainly demanded by resolving $πK$ puzzle and confirm the presupposition that $X_A^i\neq X_A^f$. In addition, correspondingly, the $B$-meson wave function parameter $λ_B$ is also fitted to be $0.18^{+0.11}_{-0.08}\, MeV$, which plays an important role for resolving both $πK$ and $ππ$ puzzles. With the fitted parameters, the QCDF results for observables of $B_{u,d}$ $\to$ $ππ$, $πK$ and $K \bar{K}$ decays are in good agreement with experimental measurements. Much more experimental and theoretical efforts are expected to understand the underlying QCD dynamics of spectator scattering and annihilation contributions.
The $B_{c}$ ${\to}$ $B_{s}π$ decay is studied with the perturbative QCD approach. Three types of wave functions for $B_{s}$ meson are considered. The transition form factor $F_{0}^{B_{c}{\to}B_{s}}(0)$ and the branching ratio ${\cal B}r(B_{c}{\to}B_{s}π)$ are sensitive to the model of the $B_{s}$ meson wave functions. With appropriate inputs, our estimate on ${\cal B}r(B_{c}{\to}B_{s}π)$ is comparable with the recent LHCb measurement. A clear signal of $B_{c}$ ${\to}$ $B_{s}π$ decay should be easily observed at the Large Hadron Collider.