arXiv subjects

Guo-Li Wang

Publications and source records attributed to Guo-Li Wang.

At least 109 records · Page 6Linked to original sources

arXiv2012

The $B_c$ Decays to $P$-wave Charmonium by Improved Bethe-Salpeter Approach

We re-calculate the exclusive semileptonic and nonleptonic decays of $B_c$ meson to a $P$-wave charmonium in terms of the improved Bethe-Salpeter (B-S) approach, which is developed recently. Here the widths for the exclusive semileptonic and nonleptonic decays, the form factors, and the charged lepton spectrums for the semileptonic decays are precisely calculated. To test the concerned approach by comparing with experimental measurements when the experimental data are available, and to have comparisons with the other approaches the results obtained by the approach and those by some approaches else as well as the original B-S approach, which appeared in literature, are comparatively presented and discussed.

hep-ph↗

arXiv2011

Lepton-Number Violating Decays of Heavy Mesons

The experimental observation of lepton-number violating processes would unambiguously indicate the Majorana nature of neutrinos. Various $ΔL$ = 2 processes for pseudoscalar meson $M_1$ decays to another pseudoscalar meson $M_2$ and two charged leptons $\ell_1$, $\ell_2$ ($M_1^+\to \ell_1^+\ell_2^+M_2^-$) have been studied extensively. Extending the existing literature on the studies of these kinds of processes, we consider the rare decays of heavy mesons to a vector meson or a pseudoscalar meson. These processes have not been searched for experimentally, while they may have sizable decay rates. We calculate their branching fractions and propose to search for these decay modes in the current and forthcoming experiments, in particular at the LHCb.

hep-ph↗

arXiv2011

Probing Non-leptonic Two-body Decays of $B_c$ meson

Rates and CP asymmetries of the non-leptonic two-body decay of $B_c$ are calculated based on the low energy effective Hamiltonian. We concentrate on such $b$ quark decays of the processes with $0^-$ and $1^-$ S-wave particles and/or $0^+$ and $1^+$ P-wave particles in the final states. The Salpeter method, which is the relativistic instantaneous approximation of the original Bethe-Salpeter equation, is used to derive hadron transition matrix elements. Based on the calculation, it is found that the best decay channels to observe CP violation are $B_c^-\rightarrow η_c +D^-(D^{*-}_0)$, which need about $\sim10^7$ $B_c$ events in experiment. Decays to $ η_c +D^{*-}(D_s^-), h_c+D^-(D^{*-})(D^{*-}_0), J/Ψ+D^{*-}$ are also hopeful channels.

hep-ph↗

arXiv2011

Radiative E1 decays of X(3872)

Radiative E1 decay widths of $\rm X(3872)$ are calculated through the relativistic Salpeter method, with the assumption that $\rm X(3872)$ is the $χ_{c1}$(2P) state, which is the radial excited state of $χ_{c1}$(1P). We firstly calculated the E1 decay width of $χ_{c1}$(1P), the result is in agreement with experimental data excellently, then we calculated the case of $\rm X(3872)$ with the assignment that it is $χ_{c1}$(2P). Results are: $Γ({\rm X(3872)}\rightarrow γ\sl J/ψ)=33.0$ keV, $Γ({\rm X(3872)}\rightarrow γψ(2S))=146$ keV and $Γ({\rm X(3872)}\rightarrow γψ(3770))=7.09$ keV. The ratio ${{\rm Br(X(3872)}\rightarrowγψ(2{\rm S}))}/{{\rm Br(X(3872)}\rightarrow γ{\sl J}/ψ)}=4.4$ agrees with experimental data by BaBar, but larger than the new up-bound reported by Belle recently. With the same method, we also predict the decay widths: $Γ(χ_{b1}(1\rm P))\rightarrow γΥ(1\rm S))=30.0$ keV, $Γ(χ_{b1}(2\rm P))\rightarrow γΥ(1\rm S))=5.65$ keV and $Γ(χ_{b1}(2\rm P))\rightarrow γΥ(2S))=15.8$ keV, and the full widths: $Γ(χ_{b1}(1\rm P))\sim 85.7$ keV, $Γ(χ_{b1}(2\rm P))\sim 66.5$ keV.

hep-ph↗

arXiv2010

Annihilation Rates of Heavy $1^{--}$ S-wave Quarkonia in Salpeter Method

The annihilation rates of vector $1^{--}$ charmonium and bottomonium $^3S_1$ states $V \rightarrow e^+e^-$ and $V\rightarrow 3γ$, $V \rightarrow γgg$ and $V \rightarrow 3g$ are estimated in the relativistic Salpeter method. We obtained $Γ(J/ψ\rightarrow 3γ)=6.8\times 10^{-4}$ keV, $Γ(ψ(2S)\rightarrow 3γ)=2.5\times 10^{-4}$ keV, $Γ(ψ(3S)\rightarrow 3γ)=1.7\times 10^{-4}$ keV, $Γ(Υ(1S)\rightarrow 3γ)=1.5\times 10^{-5}$ keV, $Γ(Υ(2S)\rightarrow 3γ)=5.7\times 10^{-6}$ keV, $Γ(Υ(3S)\rightarrow 3γ)=3.5\times 10^{-6}$ keV and $Γ(Υ(4S)\rightarrow 3γ)=2.6\times 10^{-6}$ keV. In our calculations, special attention is paid to the relativistic correction, which is important and can not be ignored for excited $2S$, $3S$ and higher excited states.

hep-ph↗

arXiv2010

$B_s$ Semileptonic Decays to $D_s$ and $D_s^*$ in Bethe-Salpeter Method

Using the relativistic Bethe-Salpeter method, the electron energy spectrum and the semileptonic decay widths of $B^0_s\to D^-_s \ell^+{ν_\ell}$ and $B^0_s\to D_s^{*-}\ell^+{ν_\ell}$ are calculated. We obtained large branching ratios, $Br(B_s\to D_seν_e)=(2.85\pm0.35)% $ and $Br (B_s\to D_s^*eν_e)=(7.09\pm0.88)%$, which can be easily detected in the future experiment.

hep-ph↗

arXiv2010

Spectrum for Heavy Quankonia and Mixture of the Relevant Wave Functions within the Framework of Bethe-Salpeter Equation

Considering the fact that some excited states of the heavy quarkonia (charmonium and bottomonium) still missing in experimental observations and potential applications of the relevant wave functions of the bound states, we re-analyze the spectrum and the relevant wave functions of the heavy quarkonia within the framework of Bethe-Salpeter (B.S.) equation with a proper QCD-inspired kernel. Such a kernel for the heavy quarkonia, relating to potential of non-relativistic quark model, is instantaneous, so we call the corresponding B.S. equation as BS-In equation throughout the paper. Particularly, a new way to solve the B.S. equation, which is different from the traditional ones, is proposed here, and with it not only the known spectrum for the heavy quarkonia is re-generated, but also an important issue is brought in, i.e., the obtained solutions of the equation `automatically' include the 'fine', 'hyperfine' splittings and the wave function mixture, such as $S-D$ wave mixing in $J^{PC}=1^{--}$ states, $P-F$ wave mixing in $J^{PC}=2^{++}$ states for charmonium and bottomonium etc. It is pointed out that the best place to test the wave mixture probably is at $Z$-factory ($e^+e^-$ collider running at $Z$-boson pole with extremely high luminosity).

hep-ph↗

arXiv2010

The magnetic dipole transitions in the $(c\bar{b})$ binding system

The magnetic dipole transitions between the vector mesons $B_c^*$ and their relevant pseudoscalar mesons $B_c$ ($B_c$, $B_c^*$, $B_c(2S)$, $B_c^*(2S)$, $B_c(3S)$ and $B_c^*(3S)$ etc, the binding states of $(c\bar{b})$ system) of the $B_c$ family are interesting. To see the `hyperfine' splitting due to spin-spin interaction is an important topic for understanding the spin-spin interaction and the spectrum of the the $(c\bar{b})$ binding system. The knowledge about the magnetic dipole transitions is also very useful for identifying the vector boson $B_c^*$ mesons experimentally, whose masses are just slightly above the masses of their relevant pseudoscalar mesons $B_c$ accordingly. Considering the possibility to observe the vector mesons via the transitions at $Z^0$ factory and the potentially usages of the theoretical estimate on the transitions, we fucus our efforts on calculating the magnetic dipole transitions, i.e. precisely to calculate the rates for the transitions such as decays $B_c^*\to B_cγ$ and $B_c^*\to B_c e^+e^-$, and particularly work in the Behte-Salpeter framework. In the estimate, as a typical example, we carefully investigate the dependance of the rate $Γ(B_c^*\to B_cγ)$ on the mass difference $ΔM=M_{B_c^*}-M_{B_c}$ as well.

hep-ph↗

arXiv2010

The Decays of $B^{+}\to{\bar{D}^0}+D^{+}_{sJ}(2S)$ and $B^{+}\to\bar{D}^{0}+D^{+}_{sJ}(1D)$

We analyzed the decays of $B^{+}\to {\bar {D}^0}+D^{+}_{sJ}(2S)$ and $B^{+}\to\bar D^{0}+D^{+}_{sJ}(1D)$ by naive factorization method and model dependent calculation based on the Bethe-Salpeter method, the branching ratios are $Br({\bar {D}^0}D^{+}_{sJ}(2S))=(0.72\pm0.12)%$ and $Br({\bar {D}^0}D^{+}_{sJ}(1D))=(0.027\pm0.007)%$. The branching ratio of decay $B^{+}\to {\bar {D}^0}D^{+}_{sJ}(2S)\to {\bar {D}^0}D^0 K^+$ consist with the data of Belle Collaboration, so we conclude that the new state $D^{+}_{sJ}(2700)$ is the first excited state $D^{+}_{sJ}(2S)$.

hep-ph↗

arXiv2010

Strong Decays of the Radial Excited States $B(2S)$ and $D(2S)$

The strong OZI allowed decays of the first radial excited states $B(2S)$ and $D(2S)$ are studied in the instantaneous Bethe-Salpeter method, and by using these OZI allowed channels we estimate the full decay widths: $Γ_{B^0(2S)}=24.4$ MeV, $Γ_{B^+(2S)}=23.7$ MeV, $Γ_{D^0(2S)}=11.3$ MeV and $Γ_{D^+(2S)}=11.9$ MeV. We also predict the masses of them: $M_{B^0(2S)}=5.777$ GeV, $M_{B^+(2S)}=5.774$ GeV, $M_{D^0(2S)}=2.390$ GeV and $M_{D^+(2S)}=2.393$ GeV.

hep-ph↗

arXiv2009

Annihilation Rate of $2^{++}$ Charmonium and Bottomonium

Two-photon annihilation rates of $2^+$ tensor charmonium and bottomonium up to third radial excited states are estimated in the relativistic Salpeter method. Full Salpeter equation for $2^+$ tensor state is solved with a well defined relativistic wave function and we calculated the annihilation amplitude using the Mandelstam formalism. Our estimates of the decay widths are: $Γ(χ_{c2} \to 2γ)=501$ eV, $Γ(χ'_{c2} \to 2γ)=534$ eV, $Γ(χ_{b2} \to 2γ)=7.4$ eV and $Γ(χ'_{b2} \to 2γ)=7.7$ eV. We also give total decay widths of the lowest states estimated by the two-gluon decay rates, and the results are: $Γ_{tot}(χ_{c2})=2.64$ MeV, $Γ_{tot}(χ_{b2})=0.220$ MeV and $Γ_{tot}(χ'_{b2})=0.248$ MeV.

hep-ph↗

arXiv2007

Annihilation Rate of Heavy 0^{++} P-wave Quarkonium in Relativistic Salpeter Method

Two-photon and two-gluon annihilation rates of P-wave scalar charmonium and bottomonium up to third radial excited states are estimated in the relativistic Salpeter method. We solved the full Salpeter equation with a well defined relativistic wave function and calculated the transition amplitude using the Mandelstam formalism. Our model dependent estimates for the decay widths: $Γ(χ_{c0} \to 2γ)=3.78$ keV, $Γ(χ'_{c0} \to 2γ)=3.51$ keV, $Γ(χ_{b0} \to 2γ)=48.8$ eV and $Γ(χ'_{b0} \to 2γ)=50.3$ eV. We also give estimates of total widths by the two-gluon decay rates: $Γ_{tot}(χ_{c0})=10.3$ MeV, $Γ_{tot}(χ'_{c0})=9.61$ MeV, $Γ_{tot}(χ_{b0})=0.887$ MeV and $Γ_{tot}(χ'_{b0})=0.914$ MeV.

hep-ph↗

arXiv2007

Decay constants of $P$-wave mesons

Decay constants of $P$-wave mesons are computed in the framework of instantaneous Bethe-Salpeter method (Salpeter method). By analyzing the parity and possible charge conjugation parity, we give the relativistic configurations of wave functions with definite parity and possible charge conjugation parity. With these wave functions as input, the full Salpeter equations for different $P$-wave states are solved, and the mass spectra as well as the numerical values of wave functions are obtained. Finally we compute the leptonic decay constants of heavy-heavy and heavy-light $^3P_0$, $^3P_1$ and $^1P_1$ states.

hep-ph↗

arXiv2006

Study on the Form Factors at Effective Vertices of Diqarks Interacting with Gauge Bosons

The diquark structure in baryons is commonly accepted as a reasonable approximation which can much simplify the picture and reduce the length of calculations. However, a diquark by no means is a point-like particle, even though it is treated as a whole object. Therefore, to apply the diquark picture to the phenomenological calculations, at the effective vertices for the diquark-gauge boson interactions, suitable form factors must be introduced to compensate the effects caused by the inner structure of the diquark. It is crucial to derive the appropriate form factors for various interactions. In this work, we use the Bethe-Salpeter equation to derive such form factors and numerically evaluate their magnitudes.

hep-ph↗

arXiv2006

Study on Strong Decays of $D_{sJ}(2632)$

The resonance $D_{sJ}(2632)$ observed by SELEX, has attracted great interests and meanwhile brought up serious dispute. Its spin-parity, so far has not finally determined and if it exists, its quark-structure might be exotic. Following the previous literature where $D_{sJ}(2632)$ is assumed to be a radial-excited state of $1^-$, we consider the possibilities that it might be a $q\bar q$ ground state of $2^+$ or the first radial-excited state of $0^+$ $D_{sJ}(2317)$ and re-calculate its strong decay widths in terms of the Bethe-Salpeter equation. Our results indicate that there still is a sharp discrepancy between the theoretical evaluation and data.

hep-ph↗

arXiv2006

Spectra of Free Diquark in the Bethe-Salpeter Approach

In this work, we employ the Bethe-Salpeter (B-S) equation to investigate the spectra of free diquarks and their B-S wave functions. We find that the B-S approach can be consistently applied to study the diqaurks with two heavy quarks or one heavy and one light quarks, but for two light-quark systems, the results are not reliable. There are a few free parameters in the whole scenario which can only be fixed phenomenologically. Thus, to determine them, one has to study baryons which are composed of quarks and diquarks.

hep-ph↗

arXiv2006

Average Kinetic Energy of Heavy Quark ($μ_π^2$) inside Heavy Meson of $0^-$ State by Bethe-Salpeter Method

The average kinetic energy of the heavy quark inside $B$ or $D$ meson is computed by means of the instantaneous Bethe-Salpeter method. We first solve the relativistic Salpeter equation and obtain the relativistic wave function and mass of $0^{-}$ state, then we use the relativistic wave function to calculate the average kinetic energy of the heavy quark inside heavy meson of $0^{-}$ state. We find that the relativistic corrections to the average kinetic energy of the heavy quark inside $B$ or $D$ meson are quite large and cannot be ignored. We estimate $μ^2_π~ (= - λ_1)~ \approx~ 0.35~ (B^0,B^\pm)$, $~0.28~(D^0,D^\pm)$, $~ 0.43~(B_s)$, $~0.34~(D_s)$, $~0.96~(B_c)$ and $0.62~(η_c)$ GeV$^2$.

hep-ph↗

arXiv2005

Decay Constants of Heavy Vector Mesons in Relativistic Bethe-Salpeter Method

In a previous letter, we computed the decay constants of heavy pseudoscalar mesons in the framework of relativistic (instantaneous) Bethe-Salpeter method (full $0^-$ Salpeter equation), in this letter, we solve the full $1^-$ Salpeter equation and compute the leptonic decay constants of heavy-heavy and heavy-light vector mesons. The theoretical estimate of mass spectra of these heavy-heavy and heavy-light vector mesons are also presented. Our results for the decay constants and mass spectra include the complete relativistic contributions. We find $F_{D^*_s} \approx 375 \pm 24 $, $F_{D^*} \approx 340 \pm 23 (D^{*0},D^{*\pm})$, $F_{B^*_s} \approx 272 \pm 20 $, $F_{B^*} \approx 238 \pm 18 (B^{*0},B^{*\pm})$, $F_{B^*_c} \approx 418 \pm 24 $, $F_{J/Ψ} \approx 459 \pm 28 $, $F_{Ψ(2S)} \approx 364 \pm 24 $, $F_Υ \approx 498 \pm 20 $ and $F_{Υ(2S)} \approx 366 \pm 27 $ MeV.

math-ph↗