关于Reggeon的结构

从强子组分夸克具有结构的观点出发，根据高能强作用软过程中的最大非微扰强作用反应假定,提出了关于Reggeon(IR)的结构模型.高能时对撞强子中的一对组分夸克-反夸克在最大反应下有一定的几率先分解为非微扰胶子和旋量团(反旋量团).此旋量团对将进一步演化而放射出一系列的非微扰胶子(和夸克对)并最终湮没.将这种过程与其逆向(厄米共轭)过程并合,就可得出有关的IR的场论结构图象.它是以旋量团为竖线,胶子为横线的一系列切割梯形图之和所代表.本文在系统能量大而动量转移很小的多重Regge运动学区间和只保留Ins的领头阶近似下,计算了这组切割梯形图相应的散射振幅,求出了它们的总和,得出了与轻夸克介子对应的典型Regge极点轨迹的简洁表达式,对结果进行了简单的讨论.     

关于软玻密子的结构

本文修改了Landshoff-Nachtmann的软玻密子(Pomeron P)场论模型.从强子组分夸克具有结构的观点出发,根据高能强作用软过程中的最大非微扰强作用反应假定,提出了有关软P新的结构图像.对撞强子中的一对组分夸克被分解为裸夸克和一系列非微扰胶子(和夸克对).与此相应,软P的结构是由胶子形成的一系列切割梯形图之和所代表.在系统能量s很大而动量转移|t|很小的多重雷吉(Regge)运动学区间,并在保留lns的领头阶近似下,计算了这组切割梯形图之和所对应的散射振幅和总截面.它们的表达式出现了对s的Regge型幂次因子,得出了软P轨迹的简洁表达式.简单说明了按本文提出的方案可以讨论那些相关的强作用过程.     

High energy,large momentum transfer amplitudes: The sum of ladder diagrams inΦ 3 theory

We perform summation of ladder diagrams in the high energy, large momentum limit. This leads to new results for both perturbative and non-perturbative approaches. In particular, an explicit expression for any diagram's contribution is given, the non-perturbative form of asymptotically non-analytic terms is found and representation of amplitude as a series of Regge poles is presented.Supported in part by Polish Ministery of National Education, grant no. CPBP 01.03     

Quasi-confinement in theSU(3)-gluon plasma

We investigate a phenomenological equation of state for the gluon plasma, which differs from the ideal gluon gas equation of state in three aspects: (a) it is assumed that gluons withlow momentum are subject to confining interactions anddo not contribute to the energy spectrum of free gluons; (b)only gluons withhigh momentum are considered as an ideal gas with perturbative corrections of orderO(α_s); (c) a non-perturbative vacuum pressure is included. We show that feature (a) allows for a reasonable perturbative treatment of the interaction between gluons with high momentum. The equation of state reproduces lattice data for the thermodynamical functions of theSU(3) pure gauge theory above the deconfinement transition temperatureT _c. This result suggests that a possible way to describe the gluon plasma is in terms of perturbatively interacting gluons and non-perturbative “glueball” states.     

On the importance of low-energy beta beams for supernova neutrino physics

We argue that isotropization and, consequently, thermalization of the system of gluons and quarks produced in an ultrarelativistic heavy-ion collision does not follow from Feynman diagram analysis to any order in the coupling constant. We conclude that the apparent thermalization of quarks and gluons, leading to success of perfect fluid hydrodynamics in describing heavy-ion collisions at RHIC, can only be attributed to the non-perturbative QCD effects not captured by Feynman diagrams. We proceed by modeling these non-pertrubative thermalization effects using viscous hydrodynamics. We point out that matching Color Glass Condensate inital conditions with viscous hydrodynamics leads to a continuous evolution of all the components of the energy-momentum tensor and, unlike the case of ideal hydrodynamics, does not give rise to a discontinuity in the longitudinal pressure. An important consequence of such a matching is a relationship between the thermalization time and shear viscosity: we observe that small viscosity leads to short thermalization time.     

Dynamics of Many-Body Correlation Green's Functions Ⅲ Truncation with Respect to Crder

All of the main non-perturbative results in the standard Green's function theory are obtained naturally and explicitly from the set of dynamic equations of the many-body correlation Green's functions by means of truncation up to lower correlations.The two-body correlation Green's function dynamics includes both ladder diagrams for short-range correlations and ring diagrams for long-range correlations in a unified way.     

关于J/ψ→Gb+γ和J/ψ→e+ē过程

基于J/ψ辐射产生胶球态Gb和湮没为e+ē对两过程的中间态和末态都不涉及任何夸克强子而只与强作用的真空性质密切相关这一特性，从另一种角度讨论了这两个过程.利用高能强作用软过程中修改后的pomeron场论模型和相关的最大非微扰强作用反应假定，并考虑到轻的和重的组分夸克在结构上的差异而在模型参数中作出相应的变更后，提出了这两个过程的另一种物理机制，计算了它们的衰变宽度，定出了胶球态与非微扰胶子间的耦合数值，并就此进行了简单的讨论. 关键词： J/ψ衰变 pomeron 非微扰     

Unusual initial state interactions and Kinoshita diagram identities in perturbative QCD

Unlike in QED, algebraic identities for individual single-cut Kinoshita diagrams with all soft gluons are generally violated by initial state spectator interactions in light-cone time-ordered perturbation theory. At g⁴ order, identities insuring IR cancellation for the real graphs considered by Bodwin, Brodsky and Lepage for ππ→μ⁺μ^?+X when all gluons are soft can be obtained by summing over several of the corresponding single-cut diagrams. Although this fails for the two-loop virtual's diagrams considered by BBL, summing over a larger class of possible two-loop virtual spectator interactions having two Glauber singularities does restore IR finiteness when both gluons are soft.For individual single-cut Kinoshita diagrams with an arbitrary number ladder exchanges, algebraic identities for the (C_F)^n/2 contribution from the initial state are derived.     

Effective potential between two gluons from the scalar glueball

Starting from the 0⁺⁺ glueball mass and wave function computed from lattice QCD, we compute the local potential between two constituent gluons. Since the properties of constituent gluons are still a matter of research, we allow for them to be either massless, or massive with a mass around 0.7GeV. Both pictures are actually used in the literature. When the gluons are massless, the corresponding local potential is shown to be compatible with a Cornell form, that is a linear confinement plus a short-range Coulomb part, with standard values for the flux tube energy density and for the strong coupling constant. When the gluons are massive, the confining potential is a saturating one, commonly used to simulate string-breaking effects. These results fill a gap between lattice QCD and phenomenological models: The picture of the scalar glueball as a bound state of two constituent gluons interacting via a phenomenological potential is shown to emerge from pure gauge lattice QCD computations. Moreover, we show that the allowed potential shape is constrained by the mass of the constituent gluons.     

Meson exchange interactions at low and intermediate energies: colour screening effects

We consider the colour screening effects of constituent quarks and the exchange of effective gluons in the interaction of hadrons. To this end we propose two different processes derived from fundamental properties of the underlying microscopic theory (QCD). Sum rules for diagrams providing colour screening are also given.     

Elastic diffraction and non-perturbative gluons

Zeitschrift für Physik C Particles and Fields - We consider a simple model for the propagator of a non-perturbative gluon and derive the rules determining its coupling to perturbative gluons...     

Compatibility of a model for the QCD-Pomeron and chiral-symmetry breaking phenomenologies

The phenomenology of a QCD-Pomeron model based on the exchange of a pair of non-perturbative gluons, i.e. gluon fields with a finite correlation length in the vacuum, is studied in comparison with the phenomenology of QCD chiral symmetry breaking, based on non-perturbative solutions of Schwinger-Dyson equations for the quark propagator including these non-perturbative gluon effects. We show that these models are incompatible, and point out some possibles origins of this problem.     

Contribution of final-state interaction to the branching ratio of <Emphasis Type="Italic">B</Emphasis>→<Emphasis Type="Italic">J</Emphasis>/<Emphasis Type="Italic">ψ</Emphasis><Emphasis Type="Italic">D</Emphasis>

To test the validity of perturbative QCD (pQCD) and investigate its range of application, one should look for a suitable process. B→J/ψ D is a promising candidate. The linear momentum of the products is relatively small, so that there may exist a region where exchanged gluons are soft and the perturbative treatment may fail, so that the non-perturbative effect would be significant. We attribute such non-perturbative QCD effects to the long-distance final-state interaction (FSI) which is estimated in this work. We find that the contribution from the FSI to the branching ratio is indeed sizable and may span the rather wide range of 10⁻⁶∼10⁻⁵ and cover a region where the pQCD prediction is of the same order. A more accurate measurement of its branching ratio may provide important information about the application region of pQCD and help to clarify the picture of inelastic rescattering (i.e. FSI), which is generally believed to play an important role in B decays.     

Ab-initio Hamiltonian approach to light nuclei and to quantum field theory

Nuclear structure physics is on the threshold of confronting several long-standing problems such as the origin of shell structure from basic nucleon-nucleon and three-nucleon interactions. At the same time those interactions are being developed with increasing contact to QCD, the underlying theory of the strong interactions, using effective field theory. The motivation is clear — QCD offers the promise of great predictive power spanning phenomena on multiple scales from quarks and gluons to nuclear structure. However, new tools that involve non-perturbative methods are required to build bridges from one scale to the next. We present an overview of recent theoretical and computational progress with a Hamiltonian approach to build these bridges and provide illustrative results for the nuclear structure of light nuclei and quantum field theory.     

A simple method for evaluating Goldstone diagrams in an angular momentum coupled representation

A simple and convenient method is derived for evaluating linked Goldstone diagrams in an angular momentum coupled representation. Our method is general, and can be used to evaluate any effective interaction and/or effective operator diagrams for both closed-shell nuclei (vacuum to vacuum linked diagrams) and open-shell nuclei (valence linked diagrams). The techniques of decomposing diagrams into ladder diagrams, cutting open internal lines and cutting of one-body insertions are introduced. These enable us to determine angular momentum factors associated with diagrams in the coupled representation directly, without the need for carrying out complicated angular momentum algebra. A summary of diagram rules is given.     

Studying the perturbative Reggeon

We consider the flavour non-singlet Reggeon within the context of perturbative QCD. This consists of ladders built out of “reggeized” quarks. We propose a method for the numerical solution of the integro-differential equation for the amplitude describing the exchange of such a Reggeon. The solution is known to have a sharp rise at low values of Bjorken-x when applied to non-singlet quantities in deep-inelastic scattering. We show that when the running of the coupling is taken into account this sharp rise is further enhanced, although the dependence is suppressed by the introduction of the running coupling. We also investigate the effects of simulating non-perturbative physics by introducing a constituent mass for the soft quarks and an effective mass for the soft gluons exchanged in the t-channel. Received: 30 June 1999 / Published online: 16 November 1999     

Chiral symmetry breaking in Hamiltonian QCD in Coulomb gauge

Spontaneous breaking of chiral symmetry is investigated in the Hamiltonian approach to QCD in Coulomb gauge. The quark wave functional is determined by the variational principle using an ansatz which goes beyond the commonly used BCS-type of wave functionals and includes the coupling of the quarks to the transversal spatial gluons. Using the lattice gluon propagator as input it is shown that the low energy chiral properties of the quarks, like the quark condensate and the constituent quark mass, are substantially increased by the coupling of the quarks to the spatial gluons. Our results compare favorably with the phenomenological values.     

Quark pair production in a rapid chiral phase transition

In very energetic heavy ion collisions it is expected that chiral symmetry is temporarily restored. If the underlying QCD vacuum changes its structure rather suddenly, the transition is accompanied by a spontaneous and nonperturbative production of quark pairs. If gluons are already present they may assist additively to the overall production: As a particularly interesting nonequilibrium phenomena, real gluons are partially decaying during such a chiral transition. The total number of produced quarks is calculated and found to be quite sizeable. For the future collider experiments such effects could give rise to a significant contribution to the total number of quark pairs created in the preequilibrium stage of the reaction.     

On the multipomeron exchange and the BKP equation in the high colour limit

The interaction of reggeized gluons is discussed in the high-colour limit. It is argued that the dominant contributions from the diagrams with a topology of a cylinder sum into a single BFKL pomeron. It is also shown that the BKP equation should be supplemented with terms which change the number of gluons, after which it can be solved in a trivial manner. In the high energy limit the theory reduces to that of noninteracting BFKL pomerons.     

Stability of quark gluon plasma to nielsen-olesen mode

Nielsen and Olesen showed that perturbative vacuum with uniform chromomagnetic field in one space and one color direction is unstable. This instability is called Nielsen-Olesen instability (NOI), and leads to formation of a ‘spaghetti of flux tubes’ as a model for non-perturbative vacuum and confinement. We re-examine this instability in presence of color sources, quarks and gluons, at a finite temperature and find that at sufficiently high temperature NOI is stabilized due to an ‘effective mass’ of gluons arising through plasma effects. This explains how a QGP with no confinement effects may exist at high temperature. As the temperature is lowered, NOI reappears at a valueT=T _c, which is very close to confinement-deconfinement transition from hadrons to QGP..