Heavy quarkonia from classical SU(3) Yang-Mills configurations

A generalized Cho-Faddeev-Niemi ansatz for SU(3) Yang-Mills is investigated. The corresponding classical field equations are solved for its simplest parametrization. From these solutions it is possible to define a confining non-relativistic central potential used to study heavy quarkonia. The associated spectra reproduces the experimental spectra with an error of less than 3% for charmonium and 1% for bottomonium. Moreover, the recently discovered new charmonium states can be accomodate in the spectra, keeping the same level of precision. The leptonic widths show good agreement with the recent measurements. The charmonium and bottomonium E1 electromagnetic transitions widths are computed and compared with the experimental values.     

Bottomonium Spectrum with Screened Potential

As a sister work of [Phys. Rev. D 79 (2009) 094004], we incorporate thecolor-screening effect due to light quark pair creation into theheavy quark-antiquark potential, and investigate the effects ofscreened potential on the spectrum of bottomonium. We calculate themasses, electromagnetic decays, and E1 transitions of bottomoniumstates. We find that the fine splittings between χ_bJ (J=0,1,2) states are in good agreement with experimental data, and the E1 transition rates of \Upsilon(2S) → γχ _bJ (1P) and \Upsilon(3S) → γχ _bJ(2P) (J=0,1,2) all agree with data within experimental errors. In particular, the mass of \Upsilon(6S) is lowered down to match that of the \Upsilon(11020), which issmaller than the predictions of the linear potential models by morethan 100~MeV. Comparison between charmonium and bottomonium in somerelated problems is also discussed.     

Heavy quarkonia spectra and their decays in a relativistic quark model

Using the phenomenological relativistic harmonic model (RHM) for quarks, we have obtained the masses of S wave charmonium and bottomonium states. The full Hamiltonian used in the investigation has Lorentz scalar plus vector confinement potential, along with the confined one gluon exchange potential (COGEP). A good agreement with the experimental masses for the ground and the radially excited states is obtained both for the triplet and singlet S wave mesons. The decay properties of the ground state charmonium and bottomonium are investigated.     

Testing static quark-antiquark potentials with bottomonium

We investigate the question of whether experimental data on the energy levels of bottomonium can discriminate between quark-antiquark potentials which are motivated by what we know about QCD and potentials which are purely phenomenological. We restrict ourselves to bottomonium because, of all the quarkonia observed thus far, bottomonium is the least relativistic and therefore the best testing ground for the static quarkonium potential. We consider two potentials whose functional form is motivated from perturbative QCD at short quark-antiquark separations and from nonperturbative lattice QCD at large separations. We also consider three strictly phenomenological potentials. We find that the best of the three phenomenological potentials, which has never been previously used, fits the spin-averaged data at least as well as the best of the QCD-motivated potentials. We propose further measurements on bottomonium energy levels to provide additional tests.     

Analysis of Vector Meson Transitions Among Heavy Quarkonium States

In this article,we study the vector meson transitions among the charmonium and bottomonium states with the heavy quark effective theory in a systematic way,and make predictions for the ratios among the vector meson decay widths of a special multiplet to another multiplet.The predictions can be confronted with the experimental data in the future.     

Quarkonium spectral functions with complex potential

We study quarkonium spectral functions at high temperatures using a potential model with complex potential. The real part of the potential is constrained by the lattice QCD data on static quark anti-quark correlation functions, while the imaginary part of the potential is taken from perturbative calculations. We find that the imaginary part of the potential has significant effect on quarkonium spectral functions, in particular, it leads to the dissolution of the 1S charmonium and excited bottomonium states at temperatures about 250 MeV and melting of the ground state bottomonium at temperatures slightly above 450 MeV.     

Charmonium and bottomonium in heavy-ion collisions

We review the present status in the theoretical and phenomenological understanding of charmonium and bottomonium production in heavy-ion collisions. We start by recapitulating the basic notion of “anomalous quarkonium suppression” in heavy-ion collisions and its recent amendments involving regeneration reactions. We then survey in some detail concepts and ingredients needed for a comprehensive approach to utilize heavy quarkonia as a probe of hot and dense matter. The theoretical discussion encompasses recent lattice QCD computations of quarkonium properties in the Quark-Gluon Plasma, their interpretations using effective potential models, inelastic rate calculations and insights from analyses of electromagnetic plasmas. We illustrate the powerful techniques of thermodynamic Green functions (T-matrices) to provide a general framework for implementing microscopic properties of heavy quarkonia into a kinetic theory of suppression and regeneration reactions. The theoretical concepts are tested in applications to heavy-ion reactions at SPS, RHIC and LHC. We outline perspectives for future experiments on charmonium and bottomonium production in heavy-ion collisions over a large range of energies (FAIR, RHIC-II and LHC). These are expected to provide key insights into hadronic matter under extreme conditions using quarkonium observables.     

The effects of configuration mixing on excited charmonium decays

Configuration mixing betwenn ψ, ψ′ and ψ″ is considered in two models. In one model the confining potential consists of a scalar and a vector part; in the other model the vector confining potential interacts with a colour anomalous magnetic moment. It is shown that strong configuration mixing affects theEl transition rate and electronic decay widths of the vector mesons considerably.     

Confinement of infrared radiation to nanometer scales through metallic slit arrays

One-dimensional metallic slit array has been intensively studied in the spectral range from ultraviolet to near-infrared due to its enhanced transmission for transverse magnetic waves. However, the transmission enhancement is sensitive to the wavelength of incident radiation because of resonance characteristics. In this paper, we theoretically demonstrate that confining mid-infrared radiation to nanometer scales with a large transmission enhancement can be achieved from an aluminum slit array in a wavelength-insensitive manner, for potential applications in localized heating and nanothermal patterning. The Poynting vector and energy density calculated from the rigorous coupled-wave analysis (RCWA) are used to explain the strong localization of electromagnetic energy in the near-field regime. Furthermore, the localization of energy is also studied when a dielectric substrate is used to support the slit array in practical applications.     

Electromagnetic scattering by a time reversal symmetry broken topological insulator sphere

An exact solution of electromagnetic wave scattering by a time reversal symmetry broken topological insulator sphere is researched. According to the constitute relations of topological insulator, we modified magnetic vector potential and electric vector potential of standard Mie theory and derived scattered electromagnetic fields and scattered coefficients. Numerical results show that, when the time reversal symmetry is broken, the extinction efficiencies and the scattering efficiencies are influenced by topological magneto-electric polarizability.     

The Pion Electromagnetic Form Factor in a QCD-Inspired Model

We present detailed numerical results for the pion space-like electromagnetic form factor obtained within a recently proposed model of the pion electromagnetic current in a confining light-front QCD-inspired model. The model incorporates the vector meson dominance mechanism at the quark level, where the dressed photon with q⁺ > 0 decays in an interacting quark-antiquark pair, which absorbs the initial pion and produces the pion in the final state.     

Electromagnetic properties of relativistic quarks in confining potentials

We investigate electromagnetic properties of the quark core of nucleons in a model with massless quarks in confining potentials. We find quark core rms radii of 0.6 fm or smaller to be compatible with form factor data corrected for pion cloud effects. Relations between the magnetic form factor and the axial vector or pseudoscalar form factors will also be discussed.     

The Anomalous Gyromagnetic Ratio

With this approach we endeavour to bring about the justification of the Zero Point Field (ZPF) and its feasible nature. We commence our work by combining the vector potential associated with the ZPF electromagnetic vector potential, thereby modifying the elctromagnetic field. This modification explains certain phenomena regarding the spin of a slowly moving electron in the electromagnetic field and the observed electron g-factor including Schwinger’s corrections.     

NUCLEON PROPERTIES IN A QUARK BAG MODEL WITH WOODS-SAXON TYPE CONFINING POTENTIAL

A quark bag model with Woods-Saxon type confining potential is suggested. This model is used to examine three well-nown characteristic quantities of the nucleon and the proton electromagnetic form factors are evaluated by considering the quark core contributions. It is found that our model employing a confinement of W-S potential can improve the fit with the experimental values and can give good results for the form factors.     

Nonperturbative determination of the QCD potential at O(1/m)

The relativistic correction to the QCD static interquark potential at O(1/m) is investigated nonperturbatively for the first time by using lattice Monte Carlo QCD simulations. The correction is found to be comparable with the Coulombic term of the static potential when applied to charmonium, and amounts to one-fourth of the Coulombic term for bottomonium.     

在非拓扑孤立子模型中核子的电磁形状因子

从Friedberg-李政道的非拓扑孤立子模型出发得到一个新的夸克禁闭势.利用这个新的禁闭势,预言了核子的静态性质,并与实验数据进行了比较.理论很好地解释了实验结果.     

An exact argument against an effective vector exchange for the confining quark-antiquark potential

We derive an exact inequality involving the tensor and spin-spin potentials. It is in contradiction with an effective vector exchange for the confining potential while trivially fulfilled by a scalar.     

Molecular and compact four-quark states

We study charmonium (c(c)n(n)), bottomonium (b(b)n(n)) and exotic (cc(n)(n) and bb(n)(n)) four-quark states by means of a standard non-relativistic quark potential model. We look for possible bound states. Among them we are able to distinguish between meson-meson molecules and compact four-quark states.