Strong QCD corrections of the wave function in S-wave quarkonium decays

The first non-leading QCD corrections to the coulombic wave function of an S-state in quarkonium have been computed. The result is presented for general principal quantum number n of the decaying state. The corrections increase with n; in most cases, they dominate by far the decay corrections in the simplest example, the leptonic decay of quarkonium.     

相对论夸克模型对重夸克偶素质量谱的研究

介绍了量子场论中基于准势途径的一个相对论夸克模型,并使用这个相对论夸克模型计算了重夸克偶素的质量谱.显示这个相对论夸克模型可较好地拟合实验上肯定的质量谱数据. A relativistic quark model based on the quasipotential approach in quantum field theory is briefly introduced, and by using this model, heavy quarkonium mass spectra are calculated in detail. It is shown that such a model can give results which are in agreement with the observed experimental data on the mass spectra.     

Quarkonia with a variational method

A variational method, based in independent minimization of energy levels, is applied to quantum mechanical quarkonium systems. A discussion is presented of the method, with emphasis on quark mass dependence of energy levels (Feynman-Hellman theorem), on the behaviour of wave functions at the origin (Martin's theorem) and on the ordering of energy levels. The potential used in the applications is the Coulomb (4-vector) + Linear (4-scalar) potentials, the fine and hyperfine splittings being included by means of the Fermi-Breit hamiltonian. An attempt is made for an overall treatment of the known splittings (radials-wave, hyperfine and fine splittings) for all quarkonium systems, using an approximately flavour independent potential. Thep-wave splittings, as well as the hyperfine splittings, are shown to be particularly sensitive to the nature and mass dependence of the potential. In particular, asymptotic freedom can be more easily tested there. On the other hand, radial excitations provide the place where the set up of short range potential effects should be first detected. Some results concerning the ordinary mesons are presented, and it is specifically pointed out that strong restrictions exist for the masses of the ρ′ and theA ₁. Predictions for the toponium family are also presented.     

Entropic destruction of heavy quarkonium in a rotating hot and dense medium from holography

Previous studies have indicated that the peak of the quarkonium entropy at the deconfinement transition can be related to the entropic force, which would induce the dissociation of heavy quarkonium. In this study, we investigated the entropic force in a rotating hot and dense medium using AdS/CFT correspondence. It was found that the inclusion of angular velocity increases the entropic force, thus enhancing quarkonium dissociation, while chemical potential has the same effect. The results imply that the quarkonium dissociates easier in rotating medium compared with the static case.     

Heavy quarkonium production in the regge limit of quantum chromodynamics

Heavy quarkonium \((c\bar c,b\bar b)\) hadronic production at Tevatron (run I and run II) and LHC energies is considered in the framework of nonrelativistic quantum chromodynamics in the leading order with respect to α _s and v using the quasi-multi-Regge kinematics approach. Fitting of p _T spectra of different S and P wave heavy quarkonium states at Tevatron (run I and run II) energies is carried out. The obtained set of octet nonperturbative matrix elements is used for prediction of heavy quarkonium production at LHC energies. The results obtained in the framework of quasi-multi-Regge kinematics are compared with predictions of the collinear parton model.     

Translation invariant calculation of nonperturbative quarkonium mass shifts

The mass shifts of $\text{q}\text{q}$ bound states in the nonperturbative QCD vacuum are calculated by applying field theoretic perturbation theory as derived within the formalism of the Bethe-Salpeter equation. We obtain corrections to heavy quarkonium masses of the order of, but somewhat smaller than those of previous authors, who employed ordinary perturbation theory of nonrelativistic quantum mechanics.     

Melting temperature of heavy quarkonium with a holographic potential up to sub-leading order

A calculation of the melting temperatures of heavy quarkonium states with the holographic potential was introduced in a previous work.In this paper,we consider the holographic potential at sub-leading order,which permits finite coupling corrections to be taken into account.It is found that this correction lowers the dissociation temperatures of heavy quarkonium.     

库仑加线性位基态解析解

应用新发展的单一轨迹积分方法求解库仑加线性位的基态量子波函数,得到基态能量和波函数的一般解析表达式,并讨论了解的收敛性.应用此方法讨论了重夸克偶素系统.     

Hadronic collisions: A quarkonium factory

Hadronic collisions are quite efficient in producing new quark flavours due to the large gluon content of ordinary hadrons. In particular, one may expect sizable yields of heavy quark-antiquark bound states with various spin and orbital quantum numbers. Using perturbative QCD in combination with the nonrelativistic quarkonium model we present a fairly complete and detailed picture of charmonium and bottomonium production. We compare our results on inclusiveJ/ψ and γ distributions with high energypp data and make predictions onη _c and χ production.     

自旋相关相对论修正对重夸克偶素性质的研究

自旋相关的相对论修正对有限温度下重夸克偶素的结合和分解的影响进行了讨论,结果表明精细和超精细相互作用特影响对重夸克偶素性质的预言,特别是对ηc和J/ψ起着明显的作用.     

Quarkonium suppression

I discuss quarkonium suppression in equilibrated strongly interacting matter. After a brief review of basic features of quarkonium production I discuss the application of recent lattice data on the heavy quark potential to the problem of quarkonium dissociation as well as the problem of direct lattice determination of quarkonium properties in finite temperature lattice QCD.     

Derivation of a 1/r2 potential term for Q(Q) in a potential model

We clarify the difference among potential models so far proposed to explain mass spectra of heavylight mesons via transformations of the vacuum.Applying our idea to Q(Q) quarkonium,we obtain the extra term,1/r2 with positive coefficient,other than non-relativistic potential terms expected for quarkonium.     

Towards the experimental clarification of quarkonium polarization

We highlight issues which are often underestimated in the experimental analyses on quarkonium polarization: the relation between the parameters of the angular distributions and the angular momentum composition of the quarkonium, the importance of the choice of the reference frame, the interplay between observed decay and production kinematics, and the consequent influence of the experimental acceptance on the comparison between experimental measurements and theoretical calculations. Given the puzzles raised by the available experimental results, new measurements must provide more detailed information, such that physical conclusions can be derived without relying on model-dependent assumptions. We describe a frame-invariant formalism which minimizes the dependence of the measurements on the experimental acceptance, facilitates the comparison with theoretical calculations, and probes systematic effects due to experimental biases. This formalism is a direct and generic consequence of the rotational invariance of the dilepton decay distribution and is independent of any assumptions specific to particular models of quarkonium production. The use of this improved approach, which exploits the intrinsic multidimensionality of the problem, will significantly contribute to a faster progress in our understanding of quarkonium production, especially if adopted as a common analysis framework by the LHC experiments, which will soon perform analyses of quarkonium polarization in proton-proton collisions.     

Fractals and quantum mechanics

A new application of a fractal concept to quantum physics has been developed. The fractional path integrals over the paths of the Levy flights are defined. It is shown that if fractality of the Brownian trajectories leads to standard quantum mechanics, then the fractality of the Levy paths leads to fractional quantum mechanics. The fractional quantum mechanics has been developed via the new fractional path integrals approach. A fractional generalization of the Schrodinger equation has been discovered. The new relationship between the energy and the momentum of the nonrelativistic fractional quantum-mechanical particle has been established, and the Levy wave packet has been introduced into quantum mechanics. The equation for the fractional plane wave function has been found. We have derived a free particle quantum-mechanical kernel using Fox's H-function. A fractional generalization of the Heisenberg uncertainty relation has been found. As physical applications of the fractional quantum mechanics we have studied a free particle in a square infinite potential well, the fractional "Bohr atom" and have developed a new fractional approach to the QCD problem of quarkonium. We also discuss the relationships between fractional and the well-known Feynman path integral approaches to quantum mechanics. (c) 2000 American Institute of Physics.     

A Test of Color-Octet Heavy Quarkonium Production Mechanism

Using the scale evolution of nuclear parton distributions,the contribution of color-octet heavy quarkonium production mechanism to the P + Fe → J/ψ + γ + X process in calculated and discussed.Comparing our theoretical results with the future experimental data,the color-octet heavy quarkonium production mechanism can be examined.     

Radial excitations and exotic mesons via QCD sum rules

We continue our investigation of $\text{q}\text{qG}$ states via QCD sum rules. Using previous results for the vacuum polarization functions we study both states with equal mass quarks and open flavour states for J = 0 and 1 with all possible combinations for the P and C quantum numbers, including several exotic combinations. Definite predictions are obtained in several channels. As before the resulting mass values come out high, but some of the states found can be connected to radial excitations of ordinary quarkonium states.     

Exclusive decay of 1 heavy quarkonium into photon and two pions

We study the exclusive decay of 1⁻⁻ heavy quarkonium into one photon and two pions in the kinematic region, where the two-pion system has a invariant mass which is much smaller than the mass of heavy quarkonium. Neglecting effects suppressed by the inverse of the heavy quark mass, the decay amplitude can be factorized, in which the nonperturbative effect related to heavy quarkonium is represented by a non-relativistic QCD matrix element, and that related to the two pions is represented by a distribution amplitude of two gluons in the isoscalar pion pair. By taking the asymptotic form for the distribution amplitude and by using chiral perturbative theory we are able to obtain numerical predictions for the decay. Numerical results show that the decay of J/ψ can be observed at BEPC and at CESR. Experiment observation of this process in this kinematic region at BEPC and CESR can provide information about how gluons are converted into the two pions and may supply a unique approach to study I=0 s-wave ππ scattering.     

Inclusive photoproduction of polarized 3P1 quarkonium

We analyse inclusive photoproduction of polarized ³P₁ quarkonium in the framework of QCD. To separate non-perturbative and perturbative parts in the density matrix of the produced quarkonium we use a method, which is equivalent to the diagrammatic expansion widely used in analyzing deeply inelastic scattering. A systematic expansion in a small velocity v, with which a heavy quark moves inside the quarkonium in its rest frame, is performed for the non-perturbative parts, and they are expressed as matrix elements in non-relativistic QCD. At the leading order of v there are four matrix elements representing non-perturbative physics. The perturbative parts are calculated at the leading order of coupling constants. Some numerical results, especially numerical results for HERA, are given.     

Phenomenology of χF Dependence of Quarkonium Production in Proton-Nucleus interactions

We present a phenomenological study of the XF dependence of quarkonium production in high-energy proton-nucleus collisions. The χ_F dependence of comover contributions is introduced to account for the observed quarkonium suppression at low χ_F. Combining comover contributions, nuclear shadowing effect, energy loss mechanism and nuclear absorption together we reproduce the overall χ_F dependence of E772/E789 data.