arXiv subjects

Yong-Liang Ma

Publications and source records attributed to Yong-Liang Ma.

106 records · Page 6Linked to original sources

arXiv2010

Strong and radiative decays of X(3872) as a hadronic molecule with a negative parity

Properties of X(3872) are studied by regarding it as a $DD^{\ast}$ hadronic molecule with $J^{PC} = 2^{-+}$ in the phenomenological Lagrangian approach. We find that our model with about 97.6% isospin zero component explains the existing data nicely, for example, the ratio $\mathcal{B}(X(3872) \to J/ψπ^+π^-π^0)/\mathcal{B}(X(3872) \to J/ψπ^+π^-)$. We predict the partial widths of the radiative decays of $X(3872) \to γJ/ψ$, $γψ(2S) $ and the strong decays of $X(3872) \to J/ψπ^+ π^-$, $J/ψπ^+π^-π^0$ as well as $X(3872) \to χ_{cJ}π^0$. Our analysis shows that the measurement of the ratio $\mathcal{B}(X(3872) \to χ_{c0}π^0)/\mathcal{B}(X(3872) \to χ_{c1}π^0)$ may signal the nature of X(3872).

hep-ph↗

arXiv2010

Estimates for X(4350) Decays from the Effective Lagrangian Approach

The strong and electromagnetic decays of $X(4350)$ with quantum numbers $J^P =0^{++}$ and $2^{++}$ have been studied by using the effective Lagrangian approach. The coupling constant between $X(4350)$ and $D_s^{\ast}D_{s0}^{\ast}$ is determined with the help of the compositeness condition which means that $X(4350)$ is a bound state of $D_s^{\ast}D_{s0}^{\ast}$. Other coupling constants applied in the calculation are determined phenomenologically. Our numerical results show that, using the present data within the present model, the possibility that $X(4350)$ is a $D_s^{\ast}D_{s0}^{\ast}$ molecule can not be ruled out.

hep-ph↗

arXiv2009

Properties of the Scalar Mesons below 1.0 GeV as Hadronic Molecules

Properties of scalar mesons below 1.0 GeV have been studied by regarding them as hadronic molecular states. Using the effective Lagrangian approach, we have calculated their leptonic decays, strong decays and productions via the $ϕ$ meson radiative decays. Comparing our results with that given in the literature and the data, we conclude that it is difficult to arrange them in the same nonet if some of them are pure hadronic molecules.

hep-ph↗

arXiv2009

Strong and Electromagnetic Decays of X(1835) as a Baryonium State

With the assumption that the recently observed X(1835) is a baryonium state we have studied the strong decays of $X(1835) \to η^{(\prime)} π^+ π^-, η^{(\prime)} π^0 π^0$ and the electromagnetic decay of $X(1835) \to 2γ$ in the framework of effective Lagrangian formalism. In the present investigation we have included the contributions from the iso-singlet light scalar resonances but we have not included the isospin violating effect. Our result for the strong decay of $X(1835) \to η^{\prime} π^+ π^-$ is smaller than the observed data. The decay width for the radiative decay of $X(1835) \to 2γ$ is consistent with the assumption that it decays through the glueball. In addition, the width for the strong decay of $X(1835) \to ηπ^+ π^-$ is larger than that of the strong decay of $X(1835) \to η^{\prime} π^+ π^-$ due to the large phase space and coupling constant $g_{N\bar{N}η}$. From our investigation, it is not possible to interpret X(1835) as a baryonium.

hep-ph↗

arXiv2009

The Lepton-Number-Violating Decays of $B^+, D^+ $ and $D_s^+$ Mesons Induced by the Doubly Charged Higgs Boson

The lepton-number-violating decays of $B^+, D^+$ and $D_s^+$ mesons induced by the doubly charged Higgs boson have been studied. It is found that although the yielded results of the branch ratio are much smaller than the present limits from the data they are consistent with the previous conclusions calculated in the framwork of relativistic quark model where the processes happened via the light Majorana neutrinos.

hep-ph↗

arXiv2008

P Wave Meson Spectrum in a Relativistic Model with Instanton Induced Interaction

On the basis of the phenomenological relativistic harmonic models for quarks we have obtained the masses of P wave mesons. The full Hamiltonian used in the investigation has Lorentz scalar + vector confinement potential, along with one gluon exchange potential (OGEP) and the instanton-induced quark-antiquark interaction (III). A good agreement is obtained with the experimental masses. The respective role of III and OGEP for the determination of the meson masses is discussed.

hep-ph↗

arXiv2008

Molecular structure of the Bs0*(5725) and Bs1(5778) bottom-strange mesons

We discuss a possible interpretation of the scalar Bs0*(5725) and axial Bs1(5778) bottom-strange mesons as hadronic molecules - bound states of B K and B* K mesons, respectively. Using a phenomenological Lagrangian approach we analyze the strong Bs0* to Bs pi0, Bs1 to Bs* pi0 and the radiative Bs0* to Bs* gamma, Bs1 to Bs gamma, Bs1 to Bs* gamma, Bs1 to Bs0* gamma decays. We give predictions for the decay properties: effective couplings and decay widths.

hep-ph↗

arXiv2007

D* K molecular structure of the Ds1(2460) meson

We discuss a possible interpretation of the Ds1(2460) meson as a hadronic molecule - a bound state of D* and K mesons. Using a phenomenological Lagrangian approach we determine the strong Ds1 to Ds* pi0 and radiative Ds1 to Ds gamma decays. In order of magnitude our results for the partial strong and radiative decay widths are consistent with previous calculations.

hep-ph↗

arXiv2007

Strong and radiative decays of the Ds0*(2317) meson in the DK-molecule picture

We consider a possible interpretation of the new charm-strange meson Ds0*(2317) as a hadronic molecule - a bound state of D and K mesons. Using an effective Lagrangian approach we calculate the strong Ds0* to Ds pi0 and radiative Ds0* to Ds* gamma decays. A new impact related to the DK molecular structure of the Ds0*(2317) meson is that the presence of u(d) quarks in the D and K mesons gives rise to a direct strong isospin-violating transition Ds0* to Ds pi0 in addition to the decay mechanism induced by eta-pi0 mixing considered previously. We show that the direct transition dominates over the eta-pi0 mixing transition in the Ds0* to Ds pi0 decay. Our results for the partial decay widths are consistent with previous calculations.

hep-ph↗

arXiv2007

On the Radiatively Induced Lorentz and CPT Violating Chern-Simons Term

The radiatively induced Lorentz and CPT violating Chern-Simons terms in QED is calculated based on the recently developed loop regularization method [Y.L. Wu, Int.J.Mod.Phys.A18 (2003) 5363, hep-th/0209021; Y.L. Wu, Mod.Phys.Lett.A19 (2004) 2191, hep-th/0311082] for quantum field theories. It enables us to make general comments on the various results in literature and obtain a consistent result when simultaneously combining the evaluation for the chiral anomaly which has a unique form once the vector current is kept conserved.

hep-ph↗

arXiv2006

Anomaly and Anomaly-Free Treatment of QFTs Based on Symmetry-preserving Loop Regularization

The triangle anomaly in massless and massive QED is investigated by adopting the symmetry-preserving loop regularization method proposed recently in \cite{LR}. The method is realized in the initial dimension of theory without modifying the original lagrangian, it preserves symmetries under non-Abelian gauge and Poincare transformations in spite of the existence of two intrinsic mass scales $M_c$ and $μ_s$ which actually play the roles of UV- and IR-cut off respectively. The axialvector-vector-vector (AVV) triangle diagrams in massless and massive QED are evaluated explicitly by using the loop regularization. It is shown that when the momentum $k$ of external state is soft with $k^2 \ll μ_s^2, m^2 $ ($m$ is the mass of loop fermions) and $ M_c \to \infty$, both massless and massive QED become anomaly free. The triangle anomaly is found to appear as quantum corrections in the case that $ m^2, μ_s^2 \ll k^2 $ and $M_c \to \infty$. Especially, it is justified that in the massless QED with $μ_s =0$ and $M_c\to \infty$, the triangle anomaly naturally exists as quantum effects in the axial-vector current when the ambiguity caused by the trace of gamma matrices with $γ_5$ is eliminated by simply using the definition of $γ_5$. It is explicitly demonstrated how the Ward identity anomaly of currents depends on the treatment for the trace of gamma matrices, which enables us to make a clarification whether the ambiguity of triangle anomaly is caused by the regularization scheme in the perturbation calculations or by the trace of gamma matrices with $γ_5$.

hep-ph↗

arXiv2006

Anomalous Action of QCD from the General Quark Propagator

The anomalous action of the chiral effective theory to $\mathcal{O}(p^4)$ is investigated by generalizing the consideration in \cite{ma02} with including the wave function part in the general quark propagator. It is found that the QCD dynamics dependence of the Wess-Zumino term is explicit and this dependence means that the QCD chiral symmetry must be broken dynamically in the low energy region for dynamically generating the Wess-Zumino term. In addition, we found that the next to leading order anomalous action in the momentum expansion of the chiral perturbation theory is gauge invariant and QCD dynamics dependent.

hep-ph↗

arXiv2006

Spin Polarisability of the Nucleon in the Heavy Baryon Effective Field Theory

We have constructed a heavy baryon effective field theory with photon as an external field in accordance with the symmetry requirements similar to the heavy quark effective field theory. By treating the heavy baryon and anti-baryon equally on the same footing in the effective field theory, we have calculated the spin polarisabilities $γ_i, i=1...4$ of the nucleon at third order and at fourth-order of the spin-dependent Compton scattering. At leading order (LO), our results agree with the corresponding results of the heavy baryon chiral perturbation theory, at the next-to-leading order(NLO) the results show a large correction to the ones in the heavy baryon chiral perturbation theory due to baryon-antibaryon coupling terms. The low energy theorem is satisfied both at LO and at NLO. The contributions arising from the heavy baryon-antibaryon vertex were found to be significant and the results of the polarisabilities obtained from our theory is much closer to the experimental data.

hep-ph↗

arXiv2005

Can a Nonsymmetric Metric mimic NCQFT in $e^+e^- \to γγ$ ?

In the nonsymmetric gravitational theory (NGT) the space-time metric $g_{μν}$ departs from the flat-space Minkowski form $η_{μν}$ such that it is no longer symmetric, $i.e.$ $g_{μν} \ne g_{νμ}$. We find that in the most conservative such scenario coupled to quantum field theory, which we call Minimally Nonsymmetric Quantum Field Theory (MNQFT), there are experimentally measurable consequences similar to those from noncommutative quantum field theory (NCQFT). This can be expected from the Seiberg-Witten map which has recently been interpreted as equating gauge theories on noncommutative spacetimes with those in a field dependent gravitational background. In particular, in scattering processes such as the pair annihilation $e^+e^- \to γγ$, both theories make the same striking prediction that the azimuthal cross section oscillates in $ϕ$. However the predicted number of oscillations differs in the two theories: MNQFT predicts between one and four, whereas NCQFT has no such restriction.

hep-ph↗

arXiv2004

Hidden Local Symmetry and Chiral Effective Theory for Vector and Axial-vector Mesons

In this paper, we present the full Lagrangian of mesons (pseudoscalars, vectors and axial-vectors) to $O(p^4)$ by using the explicit global chiral symmetry and hidden local symmetry in the chiral limit. In this approach, we see that there are many other terms besides the usual eleven terms given in the literature from hidden local symmetry approach. Of particular, there are some terms in our full results which are important for understanding the vector meson dominance and $π-π$ scattering and providing consistent predictions on the decay rates of $a_1\toγπ$ and $a_1\toρπ$ as well as for constructing a consistent effective chiral Lagrangian with chiral perturbation theory. It is likely that the structures of the effective chiral Lagrangian for $O(p^4)$ given in the literature by using hidden local symmetry are incomplete and consequently the resulting couplings are not reliable. It is examined that the more general effective chiral Lagrangian given in present paper can provide more consistent predictions for the low energy phenomenology of $ρ-a_1$ system and result in more consistent descriptions on the low energy behavior of light flavor mesons.

hep-ph↗

arXiv2003

Anomalous Action in Gauge Invariant, Nonlocal, Dynamical Quark Model

Anomalous sector of chiral Lagrangian is calculated in a gauge invariant, nonlocal, dynamical quark model. The Wess-Zumino term is proved coming from two kinds of sources, one is independent on and another dependent on dynamical quark self energy $Σ(k^2)$. $p^6$ and more higher order anomalous sectors come only from $Σ(k^2)$ dependent source. After some cancellation, standard Wess-Zumino action is obtained.

hep-ph↗