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Ailin Zhang

Publications and source records attributed to Ailin Zhang.

At least 55 records · Page 3Linked to original sources
arXiv2009

D and D_s in mass loaded flux tube

Heavy-light hadrons are studied in a mass loaded flux tube model. The study indicates that the dynamics of mesons and baryons containing a $c$ quark is well described by the mass loaded flux tube. The hypothesis of good diquark-antiquark degeneracy is found reasonable in heavy-light quark systems. The spectrum of charmed ($D$) and charmed strange ($D_s$) mesons is systematically computed. $D$ and $D_s$ in 1D multiplets are predicted to have lower masses in comparison with other theoretical predictions. The predicted masses of the $1^-(1^3D_1)$ and the $3^-(1^3D_3)$ $D_s$ agree well with those of recently observed $D_{s1}(2700)^{\pm}$ and $D_{sJ}(2860)$, respectively.

hep-ph↗
arXiv2007

Exotica possibility of new observations by BES

The employment of interpolating currents of existed studies of four-quark state and glueball with QCD sum rule approach is analyzed. In terms of suitable currents, the masses of the lowest lying scalar and pseudo-scalar glueball were determined. The masses of some tetraquark states and their first orbital excitations were obtained through a combination of the sum rule with the constituent quark model. Exotica possibility of the new observations by BES is discussed.

hep-ph↗
arXiv2007

Charmonium possibility of X(3872)

Properties of Regge trajectories for charmonium are studied. Possible interpretations and their implications to newly observed X(3872) are examined. It is found that the mass of X(3872) is consistent with the 1^{++} 2^3P_1 and the 2^{-+} 1^1D_2 charmonium states.

hep-ph↗
arXiv2007

Diquark and light four-quark states

Four-quark states with different internal clusters are discussed within the constituent quark model. It is pointed out that the diquark concept is not meaningful in the construction of a tetraquark interpolating current in the QCD sum rule approach, and hence existing sum-rule studies of four-quark states are incomplete. An updated QCD sum-rule determination of the properties of diquark clusters is then used as input for the constituent quark model to obtain the masses of light $0^{++}$ tetraquark states ({\it i.e.\} a bound state of two diquark clusters). The results support the identification of $σ(600)$, $f_0(980)$ and $a_0(980)$ as the $0^{++}$ light tetraquark states, and seem to be inconsistent with the tetraquark state interpretation of the new BES observations of the near-threshold $p\bar p$ enhancements, X(1835) and X(1812), with the possible exception that X(1576) may be an "exotic" first orbital excitation of $f_0(980)$ or $a_0(980)$.

hep-ph↗
arXiv2007

Charmonium spectrum and new observed states

The linearity and parallelism of Regge trajectories is combined with a hyperfine splitting relation in multiplet to study charmonium spectrum. It is found that predictions to the spectrum of 1D multiplet could be made once another 1D state is confirmed. The newly observed X(3872), Y(3940), X(3940), Y(4260) and Z(3930) are studied within the charmonium framework.

hep-ph↗
arXiv2007

Light Four-quark States and New Observations by BES

Four-quark states are discussed within the constituent quark model. Incompleteness of existed studies of four-quark state with QCD sum rule is analyzed. The masses of diquark cluster were determined by QCD sum rules, and light four-quark states masses were obtained in terms of the diquark. The four-quark state possibility of the newly observed near-threshold p\bar p enhancement, X(1835), X(1812) and X(1576) by BES is discussed.

hep-ph↗
arXiv2006

Improvement of Renormalization-Scale Uncertainties Within Empirical Determinations of the b-Quark Mass

Accurate determinations of the MS-bar b-quark mass $m_b(m_b)$ from $σ(e^+e^-\to{\rm hadrons})$ experimental data currently contain three comparable sources of uncertainty; the experimental uncertainty from moments of this cross-section, the uncertainty associated with $α_s(M_z)$, and the theoretical uncertainty associated with the renormalization scale. Through resummation of all logarithmic terms explicitly determined in the perturbative series by the renormalization-group (RG) equation, it is shown that the renormalization-scale dependence is virtually eliminated as a source of theoretical uncertainty in $m_b(m_b)$. This resummation also reduces the estimated effect of higher-loop perturbative contributions, further reducing the theoretical uncertainties in $m_b(m_b)$. Furthermore, such resummation techniques improve the agreement between the values of the MS-bar b-quark mass extracted from the various moments of $R(s)=σ(e^+e^-\to{\rm hadrons})/σ_{pt}$ [$σ_{pt}=4πα^2/(3s)$], obviating the need to choose an optimummoment for determining $m_b(m_b)$. Resummation techniques are also shown to reduce renormalization-scale dependence in the relation between b-quark MS-bar and pole mass and in the relation between the pole and $1S$ mass.

hep-ph↗
arXiv2006

Regge Trajectories Analysis to DsJ(2317), DsJ(2460) and DsJ(2632) Mesons

Status of investigations of the new observed charmed strange mesons DsJ(2317), DsJ(2460) and DsJ(2632) is simply listed. A systemic classification to these states with Regge trajectories was made. We found that DsJ(2317) and DsJ(2460) are reasonable to be arranged as (0^+,1^+), but DsJ(2632) seems not possible to be an orbital excited tensor particle. As a byproduct, the non-strange charmed mesons including D'1(2427) and D*(2637) were analyzed also.

hep-ph↗
arXiv2004

Analysis of Exotic Hybrid eta pion, eta-prime pion Decays

Investigations of the mass and decays of the exotic hybrid are reviewed, including calculation of the pion1 to eta pion, eta-prime pion decay widths within the QCD sum rules technique. In this calculation, the recently-proposed eta, eta-prime quark mixing scheme is employed. The results indicate that the decay width Gamma(pion1 to eta pion) around 250 MeV is large compared with the decay width Gamma(pion1 to eta-prime pion) around 20 MeV. Inspired by these results, some phenomenological approaches are suggested to gain an understanding of the underlying mechanism of eta pion and eta-prime pion hybrid decays.

hep-ph↗
arXiv2003

Instanton and Higher-Loop Perturbative Contributions to the QCD Sum-Rule Analysis of Pseudoscalar Gluonium

Instanton effects and three-loop perturbative contributions are incorporated into QCD sum-rule analyses of pseudoscalar ($J^{PC}=0^{-+}$) gluonium. Gaussian sum-rules are shown to be superior to Laplace sum-rules in optimized predictions for pseudoscalar gluonium states in the presence of instanton contributions. The Gaussian sum-rule analysis yields a pseudoscalar mass of $(2.65\pm 0.33) GeV$ and width bounded by $Γ<530 MeV$. The Laplace sum-rules provide corroborating evidence in support of the $\approx 2.7 GeV$ mass scale.

hep-ph↗
arXiv2003

Can the Mechanism for $π_1\to ηπ,η'π$ Hybrid Decays be Detected?

Two mechanisms for the $π_1$ ($J^{PC}=1^{-+}$) hybrid meson decay processes $π_1\toηπ,η'π$ are investigated. These mechanisms are applied to $ϕ\toηγ,η'γ$ and $J/ψ\toηγ,η'γ$ decays to illustrate the validity of the decay mechanisms and to obtain independent information on the coupling of $η,η'$ to quark and gluonic operators. From this information, we find that $Γ(π_1\toηπ)/Γ(π_1\toη'π)$ is substantially different in the two decay mechanisms, and hence future experimental measurements of this ratio will provide valuable information for substantiating the hybrid nature of these states and for determining the mechanism for these hybrid decays.

hep-ph↗
arXiv2002

Decays of the $\hatρ(1^{-+})$ Exotic Hybrid and $η$-$η'$ Mixing

QCD sum-rules are used to calculate the $\hatρ(1^{-+})\toπη, πη'$ decay widths of the exotic hybrid in two different $η-η'$ mixing schemes. In the conventional flavour octet-singlet mixing scheme, the decay widths are both found to be small, while in the recently-proposed quark mixing scheme, the decay width $Γ_{\hatρ\toηπ}\approx 250 MeV$ is large compared with the decay width $Γ_{\hatρ\toη^\primeπ}\approx 20 MeV$. These results provide some insight into $η$-$η'$ mixing and hybrid decay features.

hep-ph↗
arXiv2001

g-2 in composite models of leptons

Based on the bound state description of the muon and general relativistic covariant quantum field theory, we illustrate with a simple composite model that the observed deviation of (g-2)_μcan be a demonstration of the substructure of the muon and give the constraints on the radius of the muon in different cases of light constituents and heavy constituents.

hep-ph↗
arXiv2001

New interpretation to zitterbewegung

In previous investigations on zitterbewegung(zbw) of electron, it is believed that the zbw results from some internal motion of electron. However, all the analyses are made at relativistic quantum mechanical level. In framework of quantum field theory (QFT), we find that the origin of zbw is different from previous conclusion. Especially, some new interesting conclusions are derived at this level: 1) the zbw arises from the rapid to-and-fro polarization of the vacuum in the range of the Compton wavelength (divided by $4π$) of the electron, which offer the four-dimensional(4D) spin and intrinsic electromagnetic-moment tensor to the electron; 2) Any attempt that attributes spin (rather than double the spin) of the electron to some kind of orbital angular momentum would not be successful; 3) the macroscopic classical speed of the Dirac vacuum medium vanish in all inertial systems.

hep-ph↗
arXiv2000

Excited heavy baryon masses in HQET QCD sum rules

We construct the interpolating currents for the fourteen p-wave excited heavy baryons in the framework of heavy quark effective theory (HQET). At the leading order in the 1/m_Q expansion these interpolating currents do not mix different states with the same J^P with each other. We use QCD sum rule to calculate the masses of the p-wave excited J=1/2 spin doublet heavy baryons in the m_Q~infinity limit. We discuss some implications of our results.

hep-ph↗
arXiv2000

Four-quark state in QCD

The spectra of some 0++ four-quark states, which are composed of \bar qq pairs, are calculated in QCD. The light four-quark states are calculated using the traditional sum rules while four-quark states containing one heavy quark are computed in HQET. For constructing the interpolating currents, different couplings of the color and spin inside the \bar qq pair are taken into account. It is found that the spin and color combination has little effect on the mass of the four-quark states.

hep-ph↗
arXiv2000

A new massive vector field theory

In this paper, we put forth a new massive spin-1 field theory. In contrast to the quantization of traditional vector field, the quantization of the new vector field is carried out in a natural way. The Lorentz invariance of the theory is discussed, where owing to an interesting feature of the new vector field, the Lorentz invariance has a special meaning. In term of formalism analogical to QED(i. e. spinor QED), we develop the quantum electrodynamics concerning the new spin-1 particles, say, vector QED, where the Feynman rules are given. The renormalizability of vector QED is manifest without the aid of Higgs mechanism. As an example, the polarization cross section $σ_{polar}$ for $e^+ e^-\to f^+ f^-$ is calculated in the lowest order. It turns out that $σ_{polar}\sim 0$ and the momentum of $f^+$ and $f^-$ is purely longitudinal.

hep-th↗