Quantisation of the string fragmentation model

We quantise the classical Artru-Mennessier string model with a Feynman sum over histories method. This procedure yields both propagation amplitudes and a Veneziano mass spectrum for mesons, with resonance poles for unstable states. Applied to the processe ⁺ e ^?→hadrons our amplitudes justify previous applications of string models and in particular the relative amplitudes for different string configurations are in agreement with a recent conjecture of Andersson and Hofmann which can account for the observed Bose-Einstein correlations ine ⁺ e ^? annihilation.     

Hadrons from jets

A dynamical ansatz on the nature of the interaction that binds the constituents into physical hadrons makes it possible to compute perturbatively the spectrum and the quantum numbers of hadrons near the phase space boundary of a QCD jet. Nonperturbative effects are important for less extreme values of the momentum of the detected hadrons. They can be incorporated in the model using the algorithm of the jet calculus.     

Critical behavior and resonance excitation in the thermodynamics of extended hadrons

A system of spatially extended non-interacting hadrons generally leads at sufficiently high density to a phase transition from “gas” to “solid”. Here we study the effect of interaction, in form of an exponential resonance excitation spectrum (dual resonance model, statistical bootstrap model), on this phenomenon. While the presence of resonances significantly lowers the critical temperature, the finite size of the hadrons prevents the occurrence of the thermodynamic singularity associated with an exponential resonance spectrum in the case of point-like constituents.     

Qualitative features of the glueball spectrum

The low-energy meson spectrum is investigated. Quantum numbers of the lightest glueballs are obtained by studying low-dimension, gauge invariant, colorless operators. A general shell model of hadrons is formulated and its predictions are specified. A comparison and criticism of existing glueball models is included.     

Statistical quantities in particle collisions

Statistical quantities for particle collisions are defined using the analogy between the phase-space integral in multiparticle collisions and that in relativistic quantum statistical mechanics. The analogs of thermodynamic quantities are computed for the uncorrelated jet model. A relativistic derivation for the mass spectrum of hadrons is given and thermodynamic quantities are calculated for a system with this spectrum.     

STATIC PHYSICAL PROPORTIES OF HADRONS CALCULATED IN THE SOLITON BAG MODEL

In this paper,the Mean-Field Approximation is applied to the soliton bag model to calculate static physical proporties of hadrons of hadrons numerically.After taking account of the quark masses and the corrections of the center of mass the g_A/g_V value is improved evidently and the hadron mass spectrum,the r.m.s charge radius and the magnetic moments of the hadrons are basically in agreement with their experimental values.A preliminary derivation of the mass differencs between the d and u guarks is presented.     

Yang-Mills potentials and the van der Waals force between hadrons

The colour-induced magnetic dipole interaction between hadrons is discussed. Fermion motion in a gauge field obtained by solving the classical Yang-Mills equations is considered. It is shown that the spectrum of stationary fermion states is discrete and bound states are colourless. The long range asymptotic behaviour of the gauge potential results in the van der Waals interaction of hadrons.     

A phenomenological quark matter equation of state

Both the MIT bag model and potential models are able to reproduce static properties of hadrons (e.g. their mass spectrum) with reasonable accuracy. However, while the extrapolation of the MIT bag model from hadrons to dense matter is rather straightforward, it is not the same for potential models. To deal with this problem, in this paper, the methods of relativistic quantum many-body theory are applied to the study of quark matter interacting through an instantaneous potential at zero temperature. It is shown that under some conditions, the quark plasma undergoes a first order transition from a massive state at low density to a gas of particles of decreasing mass at high density—as one expects from perturbative QCD. In addition, immediately after the transition, the quarks are in a collective bound state, which might perhaps be interpreted as the fact that they just start to leave the inside of hadrons.     

Correspondances between the Symmetric Lund Model and the Dual Resonance Model

The Symmetric Lund Model is formulated in a manifestly forward-backward symmetric way and generalized to include transverse momenta and finite width resonances. It is shown to possess multiregge behaviour and inclusive-exclusive connection. It's characteristic exp (?area) damping factor is shown to occur also in dual amplitudes, if the Regge slope is given an imaginary part. The introduction of an infinite family of resonances described by a continuous mass spectrum is advocated; it realizes the synthesis of the Symmetric Lund Model with the Bowler and the Artru-Mennessier models, and improves the connection with the Dual Resonance Model.     

A φ4-TYPE BAG MODEL OF HADRONS——THE “RUBBER BAG”MODEL Ⅱ.THE MASS SPECTRA OF HADRONS

The mass spectrum of the J/ψ meson family can't be explained by the MIT bagmodel.Based on the theory of our Rubber Bag model of hadrons,the mass spectrumof the ordinary hadrons and that of the J/ψ family (ψ(3772) included) are calcula-ted in a unified way in this paper.The results so obtained conform well to experi-mental data.     

袋模型进展

本文回顾了强子结构袋模型几年来所取得进展,着重介绍近两年来的进展。总结是沿以下三个方面进行的,(一)理论描述的进一步完善,包括半定量地介绍了R.L.Jaffe等人最近提出的,考虑到手征对称的混合袋模型。(二)袋模型对强子静态性质的应用,包括轻夸克强子和重夸克强子的质量谱,以及对π介子质量的重新考虑。(三)多夸克强子,分析了它们分类情况,并估计了它们的质量。袋模型对于强子衰变,强子碰撞等动态过程,以及对原子核的应用成就不多,进展不大,而且篇幅有限,未作定量介绍。     

Kaon-pion ratio derived from dynamical model and the spectral shape of the muon spectrum

The kaon-pion ratio, estimated from the theoretical model based on the structural aspects of hadrons, has been applied to the diffusion model ofBull et al. The derived spectral shape of the sea level muon spectrum is in accord with the magnetic spectrograph data of Kiel and Durham Groups.     

MASSES OF THE LIGHT HADRONS AND SELF-ENERGIES IN THE BAG MODEL

The masses of the light hadrons are calculated in terms. of the cloudy bag model with use of pion-energies due to both gluon and pion exchange. By use of a type of pion-guark interaction which incorporates the finite extent of the pion the convergent self-energy due to pion exchange is obtained. The difficulties in the bag models which only include one type of the self-energies can be removed by. taking account of both and the baryon spectrum is reproduced well. It is found that these self-energies are large but have opposite effect on the masses of the hadrons.     

Dynamical models of hadrons based on the string model and the behavior of strongly interacting matter at high density

We propose dynamical models of hadrons, the nucleation model and the free-decay model, in which results of the string model are used to represent interactions. The string model is examined by comparing its predictions with experimental data and parameters are fitted. The equilibrium properties of hadrons at high density are investigated in terms of the nucleation model; we find a singular behavior at energy density 3–5 GeV/fm³, where hadrons coalesce and create highly excited states. We argue that this singular behavior corresponds to the phase transition to quark-gluon plasma. The possibility of observing the production of high-density strongly interacting matter in collider experiments is discussed using the free-decay model, which produces pion distributions as decay products of resonances. We show that our free-decay model recovers features of hadron distributions obtained in hadron collison experiments. Finally, perspectives and extensions of the models are discussed.     

Pionic corrections to the masses of heavier hadrons in the bag model

The influence of pionic corrections to the masses of heavier hadrons is investigated in the cloudy bag model. After determining the bag parameters from ordinary baryons and mesons the heavier hadron mass spectrum is calculated. A sizable amount of pionic correction is observed which has improved the masses favourably.     

THE VIRTUAL EXCHANGE OF PSEUDOSCALAR MESONS IN THE MIT BAG MODEL

In this paper the virtual exchange effect of pseudoscalar mesons in the MZT bag model is discussed and the mass spectrum of hadrons,the magnetic moment's and the mean square values of charge radius are calculated. It is pointed out that our model can pre-serve and improve the static properties of the MIT bag model and provide an explanation for the origin of the meson cloud outside.     

How to solve the problem of the knee in the cosmic ray spectrum

It is shown that recent experimental data in the region of the knee in the cosmic ray spectrum are somewhat contradictory and new approaches are needed to solve the so-called knee problem. The RRISMA project that we propose is based on the simple idea of giving priority to detecting and studying hadrons as the major EAS component. Special detectors are therefore developed. The experiment should be conducted high in the mountains (the higher the better), where the number of hadrons is higher. We therefore proposed combining PRISMA and the LHAASO (Large High Altitude Air Shower Observatory) now under construction in Tibet 4300 m above sea level.     

Physics on lattice

A short review of physical results obtained recently in lattice gluodynamics and lattice QCD is given. The topics are: formation and breaking of the confining string, spectrum of hadrons, QCD at finite temperature, monopoles and vortices in Abelian and non-Abelian gauge theories.