arXiv subjects

Guo-Li Wang

Publications and source records attributed to Guo-Li Wang.

At least 73 records · Page 4Linked to original sources

arXiv2019

The study of light invisible particles in $B_c$ decays

In this paper, we study the light scalar and pseudoscalar invisible particles in the flavor changing neutral current processes of the $B_c$ meson. Effective operators are introduced to describe the couplings between quarks and light invisible particles. The Wilson coefficients are extracted from the experimental results of the $B$ and $D$ mesons, which are used to predict the upper limits of the branching fractions of the similar decay processes for the $B_c$ meson. The hadronic transition matrix element is calculated with the instantaneously approximated Bethe-Salpeter method. The upper limits of the branching fractions when $m_χ$ taking different values are presented. It is found that at some region of $m_χ$, the channel $B_c\to D_s^{(\ast)}χχ$ has the largest upper limit which is of the order of $10^{-6}$, and for $B_c\to D_s^\astχχ^\dagger$, the largest value of the upper limits can achieve the order of $10^{-5}$. Other decay modes, such as $B_c\to D^{(*)}χχ^{(\dagger)}$ and $B_c\to B^{(*)}χχ^{(\dagger)}$, are also considered.

hep-ph↗

arXiv2018

Semi-leptonic decays of $B^\ast$, $B_s^\ast$, and $B_c^\ast$ with the Bethe-Salpeter method

In this paper we study the semileptonic decays of $B^\ast$, $B_s^\ast$, and $B_c^\ast$ by using the Bethe-Salpeter method with instantaneous approximation. Both the $V\to Pl^-\barν_l$ and $V\to Vl^-\barν_l$ cases are considered. The largest partial width of these channels is of the order of $10^{-14}$ GeV. The branching ratios of these semileptonic decays are also estimated by using the partial width of the one photon decay channel to approximate the total width. For $B^{\ast-}\to D^{(\ast)0}e^-\barν_e$ and $B_s^{\ast0}\to D_s^{(\ast)+}e^-\barν_e$, the branching ratios are of the order of $10^{-8}$ and $10^{-7}$, respectively. For $B_c^{\ast-}$, the $J/ψe^-\barν_e$ and $B_s^{\ast0}e^-\barν_e$ channels have the largest branching ratio, which is of the order of $10^{-6}$.

hep-ph↗

arXiv2018

Relativistic effects in the semileptonic $B_c$ decays to charmonium with the Bethe-Salpeter method

Relativistic effects are important in the rigorous study of heavy quarks. In this paper, we study the relativistic corrections of semileptonic $B_c$ decays to charmonium with the instantaneous Bethe-Salpeter method. Within the Bethe-Salpeter framework, we use two methods to study the relativistic effects. One of them is to expand the transition amplitude in powers of $\vec{q}$ which is the relative momentum between the quark and antiquark, and the other is to expand the amplitude base on the wave functions. In the level of decay width, the results show that, for the transition of $B_c\to η_c$, the relativistic correction is about $22\%$; for $B_c\to J/ψ$, it is about $19\%$; the relativistic effects of $1P$ final states are about $14\sim46\%$ larger than those of $1S$ final states; for $2S$ final states, they are about $19\sim 28\%$ larger than those of $1S$ final states; for $3S$ final states, they are about $12\sim13\%$ larger than those of $2S$ final states; for $2P$ final states, they are about $10\sim14\%$ larger than those of $1P$ final states; for $3P$ final states, they are about $7\sim12\%$ larger than those of $2P$ final states. We conclude that the relativistic corrections of the $B_c$ decays to the orbitally or radially excited charmonium (2S, 3S, 1P, 2P, 3P) are quite large.

hep-ph↗

arXiv2018

Strong Decays of the Orbitally Excited Scalar $D^{*}_{0}$ Mesons

We calculate the two-body strong decays of the orbitally excited scalar mesons $D_0^*(2400)$ and $D_J^*(3000)$ by using the relativistic Bethe-Salpeter (BS) method. $D_J^*(3000)$ was observed recently by the LHCb Collaboration, the quantum number of which has not been determined yet. In this paper, we assume that it is the $0^+(2P)$ state and obtain the transition amplitude by using the PCAC relation, low-energy theorem and effective Lagrangian method. For the $1P$ state, the total widths of $D_0^*(2400)^{0}$ and $ D_0^*(2400)^+$ are 226 MeV and 246 MeV, respectively. With the assumption of $0^+(2P)$ state, the widths of $D_J^*(3000)^0$ and $D_J^*(3000)^+$ are both about 131 MeV, which is close to the present experimental data. Therefore, $D_J^*(3000)$ is a strong candidate for the $2^3P_0$ state.

hep-ph↗

arXiv2018

Doubly-charged scalar in four-body decays of neutral flavored mesons

In this paper, we study the four-body decay processes of neutral flavored mesons, including $\bar K^0$, $D^0$, $\bar B^0$, and $\bar B_s^0$. These processes, which induced by a hypothetical doubly-charged scalar particle, violate the lepton number. The quantity $Br\times\left(\frac{s_Δh_{ij}}{m_Δ^2}\right)^{-2}$ of different channels are calculated, where $s_Δ$, $h_{ij}$, and $M_Δ$ are parameters related to the doubly-charged scalar. For $\bar K^0\rightarrow h_1^+h_2^+l_1^-l_2^-$, $D^0\rightarrow h_1^-h_2^-l_1^+l_2^+$, and $\bar B_{d,s}^0\rightarrow h_1^+h_2^+l_1^-l_2^-$, it is of the order of $10^{-13}\sim 10^{-11}$ ${\rm GeV^4}$, $10^{-17}\sim 10^{-10}$ ${\rm GeV^4}$, and $10^{-17}\sim 10^{-10}$ ${\rm GeV^4}$, respectively. Based on the experimental results for the $D^0\rightarrow h_1^-h_2^-l_1^+l_2^+$ channels, we also set the upper limit for $\frac{s_Δh_{ij}}{M_Δ^2}$.

hep-ph↗

arXiv2018

The Strong Decays of $P-$wave Mixing Heavy-Light $1^+$ States

Many $P-$wave mixing heavy-light $1^+$ states have not been discovered by experiment, some of them have been discovered but without the information of width, or with large uncertainty widths. In this paper, we study the strong decays of $P-$wave mixing heavy-light $1^+$ states $D^0$, $D^\pm$, $D_s^\pm$, $B^0$, $B^\pm$ and $B_s$ by the improved Bethe-Salpeter(B-S) method in two conditions of mixing angle $θ$: one is $θ=35.3^\circ$; another is considering the correction to mixing angle $θ=35.3^\circ+θ_1$. And we get some valuable predictions of the strong decay widths: $Γ(D_1^{\prime0})=232$ MeV, $Γ(D_1^0)=21.5$ MeV, $Γ(D_1^{\prime\pm})=232$ MeV, $Γ(D_1^\pm)=21.5$ MeV, $Γ(D_{s1}^{\prime\pm})=0.0101$ MeV, $Γ(D_{s1}^{\pm})=0.950$ MeV, $Γ(B_1^{\prime\pm})=263$ MeV, $Γ(B_1^{\pm})=16.8$ MeV, $Γ(B_{s1}^{\prime})=0.01987$ MeV and $Γ(B_{s1})=0.412$ MeV. We find that the decay widths of $D_{s1}^{\pm}$ and $B_{s1}$ are very sensitive to the mixing angle. And our results will provide the theoretical assistance by the future experiments.

hep-ph↗

arXiv2018

Strong decays of $D_J(3000)$ and $D_{sJ}(3040)$

In this paper, we systematically calculate two-body strong decays of newly observed $D_J(3000)$ and $D_{sJ}(3040)$ with 2P$(1^+)$ and 2P$(1^{+\prime})$ assignments in an instantaneous approximation of the Bethe-Salpeter equation method. Our results show that both resonances can be explained as the 2P$(1^{+'})$ with broad width via $^3P_1$ and $^1P_1$ mixing in $D$ and $D_s$ families. For $D_J(3000)$, the total width is 229.6 MeV in our calculation, close to the upper limit of experimental data, and the dominant decay channels are $D_2^*π$, $D^*π$, and $D^*(2600)π$. For $D_{sJ}(3040)$, the total width is 157.4 MeV in our calculation, close to the lower limit of experimental data, and the dominant channels are $D^*K$ and $D^*K^*$. These results are consistent with observed channels in experiments. Given the very little information that has been obtained from experiments and the large error bars of the total decay widths, we recommend the detection of dominant channels in our calculation.

hep-ph↗

arXiv2018

Doubly-charged scalar in rare decays of $B_c$ meson

In this paper, we study the lepton number violation processes of $B_c$ meson induced by possible doubly-charged scalars. Both the three-body decay channels and the four-body decay channels are considered. For the former, $Br\times\left(\frac{s_Δh_{ij}}{M_Δ^2}\right)^{-2}$ is of the order of $10^{-7}\sim 10^{-9}$, and for the later channels, $Br\times\left(\frac{s_Δh_{ij}}{M_Δ^2}\right)^{-2}$ is of the order of $10^{-12}\sim 10^{-20}$, where $s_Δ$, $h_{ij}$, $M_Δ$ are the constants related to the doubly-charged boson.

hep-ph↗

arXiv2017

Testing the nature of neutrinos from four-body $τ$ decays

This paper is designed to discuss four-body lepton number violating tau decay. We study the processes $τ^+ \to e^+ e^+ π^- ν_τ$ and $τ^+ \to e^+ e^+ π^- ν_e$ to determine the nature of neutrino. The first process violates lepton number by two units which can only happen through an internal Majorana. The second one conserves lepton number but violates lepton flavor which can take place with both Majorana neutrino and Dirac neutrino. We calculate their branching ratio $Br$ and differential branching ratio $dBr/dE_π$ to distinguish Majorana neutrino vs. Dirac neutrino. We also propose the possibility of experiment to perform this detection.

hep-ph↗

arXiv2017

Four-body decays of $B$ meson with lepton number violation

This paper is designed to calculate the branching ratio of four-body decays of $B$ meson with lepton number changed by 2. With the new experimental data limit to lepton-number violation processes, we update the upper limits of mixing parameters between heavy Majorana neutrino and charged leptons. Afterwards, we calculate the branching ratio of $B^0(P)\rightarrow D^{*-}(P_1)\ell^+_1(P_2)\ell^+_2(P_3)M_2^-(P_4)$ using the updated parameters. It is found that the most hopeful decay channel is $B^0(P)\rightarrow D^{*-}(P_1)e^+_1(P_2)e^+_2(P_3)ρ^-(P_4)$ or $B^0(P)\rightarrow D^{*-}(P_1)e(μ)^+_1(P_2)μ(e)^+_2(P_3)ρ^-(P_4)$, whose branching ratio can reach about $10^{-4}$ with heavy Majorana neutrino mass range around $2~\mathrm{GeV}$.

hep-ph↗

arXiv2017

Study of the excited $1^-$ charm and charm-strange mesons

We give a systematical study on the recently reported excited charm and charm-strange mesons with potential $1^-$ spin-parity, including the $D^*_{s1}(2700)^+$, $D^*_{s1}(2860)^+$, $D^*(2600)^0$, $D^*(2650)^0$, $D^*_1(2680)^0$ and $D^*_1(2760)^0$. The main strong decay properties are obtained by the framework of Bethe-Salpeter (BS) methods. Our results reveal that the two $1^-$ charm-strange mesons can be well described by the further $2^3\!S_1$-$1^3\!D_1$ mixing scheme with a mixing angle of $8.7^{+3.9}_{-3.2}$ degrees. The predicted decay ratio $\frac{\mathcal{B}(D^*K)}{\mathcal{B}(D~K)}$ for $D^*_{s1}(2860)$ is $0.62^{+0.22}_{-0.12}$.~$D^*(2600)^0$ can also be explained as the $2^3\!S_1$ predominant state with a mixing angle of $-(7.5^{+4.0}_{-3.3})$ degrees. Considering the mass range, $D^*(2650)^0$ and $D^*_1(2680)^0$ are more likely to be the $2^3\!S_1$ predominant states, although the total widths under both the $2^3\!S_1$ and $1^3\!D_1$ assignments have no great conflict with the current experimental data. The calculated width for LHCb $D^*_1(2760)^0$ seems about 100 \si{MeV} larger than experimental measurement if taking it as $1^3\!D_1$ or $1^3\!D_1$ dominant state $c\bar u$. The comparisons with other calculations and several important decay ratios are also present. For the identification of these $1^-$ charm mesons, further experimental information, such as $\frac{\mathcal{B}(Dπ)}{\mathcal{B}(D^*π)}$ are necessary.

hep-ph↗

arXiv2016

Decays of $B$, $B_s$ and $B_c$ to $D$-wave heavy-light mesons

We study the weak decays of $\bar{B}_{(s)}$ and $B_c$ into $D$-wave heavy-light mesons, including $J^P=2^-$ ($D_{(s)2},D'_{(s)2},B_{(s)2}, B'_{(s)2}$) and $3^-$~($D^*_{(s)3}, B^*_{(s)3}$) states. The weak decay hadronic matrix elements are achieved based on the instantaneous Bethe-Salpeter method. The branching ratios for $\bar{B}$ decays are $\mathcal{B}[\bar{B}\to D_{2}e\barν_e] = 1.1^{-0.3}_{+0.3} \times 10^{-3}$, $\mathcal{B}[\bar{B}\to D'_2e\barν_e]=4.1^{-0.8}_{+0.9} \times 10^{-4}$, and $\mathcal{B}[\bar{B}\to D^*_3e\barν_e]=1.0^{-0.2}_{+0.2} \times 10^{-3}$, respectively. For semi-electronic decays of $\bar B_s$ to $D_{s2}$, $D'_{s2}$, and $D^*_{s3}$, the corresponding branching ratios are $1.7^{-0.5}_{+0.5}\times 10^{-3}$, $5.2^{-1.5}_{+1.6}\times 10^{-4}$, and $1.5^{-0.4}_{+0.4}\times 10^{-3}$, respectively. The branching ratios of semi-electronic decays of $B_c$ to $D$-wave $D$ mesons are in the order of $10^{-5}$. We also achieved the forward-backward asymmetry, angular spectra, and lepton momentum spectra. In particular the distribution of decay widths for $2^-$ states $D_2$ and $D'_2$ varying along with mixing angle are presented.

hep-ph↗

arXiv2016

The Strong Decays of X(3940) and X(4160)

The new mesons $X(3940)$ and $X(4160)$ have been found by Belle Collaboration in the processes $e^+e^-\to J/ψD^{(*)}\bar D^{(*)}$. Considering $X(3940)$ and $X(4160)$ as $η_c(3S)$ and $η_c(4S)$ states, the two-body open charm OZI-allowed strong decay of $η_c(3S)$ and $η_c(4S)$ are studied by the improved Bethe-Salpeter method combine with the $^3P_0$ model. The strong decay width of $η_c(3S)$ is $Γ_{η_c(3S)}=(33.5^{+18.4}_{-15.3})$ MeV, which is closed to the result of $X(3940)$, therefore, $η_c(3S)$ is a good candidate of $X(3940)$. The strong decay width of $η_c(4S)$ is $Γ_{η_c(4S)}=(69.9^{+22.4}_{-21.1})$ MeV, considering the errors of the results, it's closed to the lower limit of $X(4160)$. But the ratio of the decay width $\frac{Γ(D\bar D^*)}{Γ(D^*\bar D^*)}$ of $η_c(4S)$ is larger than the experimental data of $X(4160)$. According to the above analysis, $η_c(4S)$ is not the candidate of $X(4160)$, and more investigations of $X(4160)$ is needed.

hep-ph↗

arXiv2016

Strong decays of $2^+$ charm and charm-strange mesons

In this paper, we calculate the strong decays of $2^+$ heavy-light states, namely, the charmed $D^*_2(2460)^0$ meson and the charm-strange $D^*_{s2}(2573)^+$ meson. The method we adopt is the reduction formula, PCAC relation and low energy theorem, following which, the transition amplitudes are calculated. The wave functions of the heavy mesons involved are achieved by solving the instantaneous Bethe-Salpeter equation. As the OZI-allowed two-body strong decays give the dominant contribution, they can be used to estimate to total widths of mesons. Our results are: $Γ[D^*_2(2460)^0]=51.3$ MeV and $Γ[D^*_{s2}(2573)^+]=19.6$ MeV. The ratios of branching ratios of two main channels are $Br[D^*_2(2460)^0\rightarrow D^+π^-]/Br[D^*_2(2460)^0\rightarrow D^{\ast+}π^-]=2.13$ and $Br[D^*_{s2}(2573)^+\rightarrow D^{\ast 0} K^+]/Br[D^*_{s2}(2573)^+\rightarrow D^0K^+]=0.08$, respectively.

hep-ph↗

arXiv2016

Strong decays of $D_{3}^{\ast}(2760)$, $D_{s3}^{\ast}(2860)$, $B_{3}^{\ast}$, and $B_{s3}^{\ast}$

In this paper, we study the OZI-allowed two-body strong decays of $3^-$ heavy-light mesons. Experimentally the charmed $D_{3}^{\ast}(2760)$ and the charm-strange $D_{s3}^{\ast}(2860)$ states with these quantum numbers have been discovered. For the bottomed $B(5970)$ state, which was found by the CDF Collaboration recently, its quantum number has not been decided yet and we assume its a $3^-$ meson in this paper. The theoretical prediction for the strong decays of bottom-strange state $B_{s3}^\ast$ is also given. The relativistic wave functions of $3^-$ heavy mesons are constructed and their numerical values are obtained by solving the corresponding Bethe-Salpeter equation with instantaneous approximation. The transition matrix is calculated by using the PCAC and low energy theorem, following which, the decay widths are obtained. For $D_{3}^\ast(2760)$ and $D_{s3}^\ast(2860)$, the total strong decay widths are 72.6 MeV and 47.6 MeV, respectively. For $B_3^\ast$ with $M=5978$ MeV and $B_{s3}^\ast$ with $M=6178$ MeV, their strong decay widths are 22.9 MeV and 40.8 MeV, respectively.

hep-ph↗

arXiv2016

Annihilation Rates of $^3D_2(2^{--})$ and $^3D_3(3^{--})$ Heavy Quarkonia

We calculate the annihilation decay rates of the $^3D_2(2^{--})$ and $^3D_3(3^{--})$ charmonia and bottomonia by using the instantaneous Bethe-Salpeter method. The wave functions of states with quantum numbers $J^{PC}=2^{--}$ and $3^{--}$ are constructed. By solving the corresponding instantaneous Bethe-Salpeter equations, we obtain the mass spectra and wave functions of the quarkonia. The annihilation amplitude is written within Mandelstam formalism and the relativistic corrections are taken into account properly. This is important, especially for high excited states, since their relativistic corrections are large. The results for the $3g$ channel are as follows: $Γ_{^3D_2(c\bar c)\rightarrow ggg} = 9.24$ keV, $Γ_{^3D_3(c\bar c)\rightarrow ggg}=25.0$ keV, $Γ_{^3D_2(b\bar b)\rightarrow ggg}= 1.87$ keV, and $Γ_{^3D_3(b\bar b)\rightarrow ggg}= 0.815$ keV.

hep-ph↗

arXiv2016

The Production of $X(3940)$ and $X(4160)$ in $B_c$ decays

Considering $X(3940)$ and $X(4160)$ as $η_c(3S)$ and $η_c(4S)$, we study the productions of $X(3940)$ and $X(4160)$ in exclusive weak decays of $B_c$ meson by the improved Bethe-Salpeter(B-S) Method. Using the relativistic B-S equation and Mandelstam formalism, we calculate the corresponding decay form factors. The predictions of the corresponding branching ratios are: $Br(B_c^+\to X(3940)e^+ν_e)$$=1.0\times10^{-4}$ and $Br(B_c^+\to X(4160)e^+ν_e)=2.4\times10^{-5}$. That will provide us a new way to observe the $X(3940)$ and $X(4160)$ in the future, as well as to improve the knowledge of $B_c$ meson decay.

hep-ph↗

arXiv2016

Semi-leptonic Production of $D_{sJ}(3040)$ and $D_J(3000)$ in $B_s$ and $B$ Decays

In this paper, we study the productions of the newly detected states $D_{sJ}(3040)$ and $D_J(3000)$ observed by BABAR Collaboration and LHCb Collaboration. We assume these states to be the $D_s(2P)$ and $D(2P)$ states with the quantum number $J^P=1^+$ in our work. The results of improved Bethe-Salpeter method indicate that the semi-leptonic decays via $B_s$ and $B$ into $D_{sJ}(3040)$ and $D_J(3000)$ have considerable branching ratios, for example, Br($\bar{B}_s^0 \rightarrow D{_{sJ}^+}(3040)e^-\barν{_e}$)=$5.79\times10^{-4}$, Br($\bar{B}^0\rightarrow D_{J}^+(3000)e^-\barν{_e}$)=$2.63\times10^{-4}$, which shows that these semi-leptonic decays can be accessible in experiments.

hep-ph↗