Vacuum condensates of QCD

We study the properties of QCD vacuum state in this paper. The values of various local quark vacuum condensates, quark-gluon mixed vacuum condensates, and the structure of non-local quark vacuum condensate are predicted by the solution of Dyson-Schwinger Equations in "rainbow" approximation with three sets of different parameters for effective gluon propagator. The light quark virtuality is also obtained in a consistent way. Our all theoretical results here are in good agreement with the empirical values used widely in literature and many other theoretical calculations.     

Vacuum condensates of QCD

We study the properties of QCD vacuum state in this paper. The     

Vacuum alignment in supersymmetric gauge theories

The vacuum alignment problem is analyzed in the context of supersymmetric gauge theories with dynamical symmetry breaking. Three cases are distinguished, depending on whether the vacuum expectation value of the weak gauge current superfield in vacuum characterized by the orientation Ω is zero for all Ω, for some Ω, or for no Ω. In the first case, a non-renormalization theorem is proved to all orders in the weak coupling, showing that the usual criterion of minimizing the vacuum energy density is insufficient to determine the alignment, and possible resolutions of the problem are discussed. The second case is similar, except that the possible alignments are resricted to the range of Ω giving a vanishing VEV and the weak gauge group may then be broken non-minimally. In the third case, supersymmetry is itself broken at the tree level by the weak interactions. The supersymmetric generalization of the Schwinger mechanism for dynamical mass generation is described.     

Vacuum condensates in the bag model

The consequences of having quark and gluon condensates inside a MIT bag are investigated. We show that one naturally expects a state dependent bag constant and a colour-magnetic interaction term ～R². This gives the possibility of having a small strong coupling constant α_s inside the bag.     

Vacuum energies in dimensionally reduced supersymmetric theories

We demonstrate how supersymmetric theories cancel the appearance of unwanted cosmological constants that arise when considering the quantum behaviour of dimensionallu reduced theories. However the cancellation only works in standard supersymmetric theories if the dimensional reduction is over circular “extra” dimensions.     

Vacuum fluctuations of the supersymmetric field in curved background

We study a supersymmetric model in curved background spacetime. We calculate the effective action and the vacuum expectation value of the energy momentum tensor using a covariant regularization procedure. A soft supersymmetry breaking induces a nonzero contribution to the vacuum energy density and pressure. Assuming the presence of a cosmic fluid in addition to the vacuum fluctuations of the supersymmetric field an effective equation of state is derived in a self-consistent approach at one loop order. The net effect of the vacuum fluctuations of the supersymmetric fields in the leading adiabatic order is a renormalization of the Newton and cosmological constants.     

Instantons and condensates in supersymmetric CPN−1 models

The partition function in the multi-instanton background for the supersymmetric CP^N?1 model is calculated and is shown to be supersymmetry invariant. This is used to calculate Green's function involving N pairs of $\text{ψ}\text{ψ(x}{}_{\mathrm{i}}\text{)}$, and this turns out to be independent of the positions. A possible interpretation is that the composite field $\text{ψ}\text{ψ}$ acquires a vacuum expectation value. The results are in agreement with those obtained in the 1/N expansion.     

Dilaton effective lagrangian in gluodynamics

The lagrangian of gluodynamics does not contain dimensional parameters. As a consequence, there emerges an infinite set of Ward identities connecting n-point functions induced by the operator σ = θ_μμ, where θ_μv stands for the regularized energy-momentum tensor. We construct an effective (tree) lagrangian which includes one scalar meson field and saturates automatically all the Ward identities.     

Sum rules for SUSY gluodynamics

The sum rules analysis for SU(N) SUSY gluodynamics is presented, concerning scalar, pseudoscalar and spinor channels. The spectrum obtained is characterized by a relatively dense disposition of excitations. The applicability of the effective lagrangian method to the study of resonance properties is thus made doubtful. Some new non-trivial relations between condensates in the SUSY vacuum are also presented.     

Monopoles in gluodynamics and blocking from continuum to lattice

We review the method of blocking of topological defects from continuum to lattice as a nonperturbative tool to construct effective actions for these defects. The actions are formulated in the continuum limit, while the couplings of these actions can be derived from simple observables calculated numerically on lattices with a finite lattice spacing. We demonstrate the success of the method in deriving the effective actions for Abelian monopoles in the pure SU(2) gauge models in an Abelian gauge. In particular, we discuss the gluodynamics in three and four spacetime dimensions at zero and nonzero temperatures. Besides the action, the quantities of our interest are the monopole density, the magnetic Debye mass, and the monopole condensate.     

Central dominance and the confinement mechanism in gluodynamics

New topological objects, which we call center monopoles, naturally arise in the Maximal Center Projection of SU(3) gluodynamics. The condensate of the center monopoles is the order parameter of the theory.     

Towards Abelian-like formulation of the dual gluodynamics

We consider gluodynamics in case when both color and magnetic charges are present. We discuss first short distance physics, where only the fundamental |Q_m|=1 monopoles introduced via the 't Hooft loop can be considered consistently. We show that at short distances the external monopoles interact as pure Abelian objects. This result can be reproduced by a Zwanziger-type Lagrangian with an Abelian dual gluon and ordinary gluons in an adjoint representation. We introduce also an effective dual gluodynamics which might be a valid approximation at distances where the monopoles |Q_m|=2 can be considered as point-like as well. Assuming the monopole condensation we arrive at a model which is reminiscent in some respect of the Abelian Higgs model but, unlike the latter leaves space for the Casimir scaling.     

Hamiltonian reduction of SU(2) gluodynamics

The Hamiltonian reduction of the Yang-Mills theory with the structure group SU(2) to a nonlocal model of a self-interacting 3 × 3 positive semidefinite matrix field is presented. Analysis of the field transformation properties under the action of the Poincaré group is carried out. It is shown that, in the strong coupling limit, the classical dynamics of a reduced system can be described by the local theory of interacting nonrelativistic spin-0 and spin-2 fields. A perturbation theory in powers of the inverse coupling constant g ^−2/3 that allows calculating the corrections to a leading long-wave approximation is suggested.     

Evidence for fine tuning of fermionic modes in lattice gluodynamics

We consider properties of zero and near-zero fermionic modes in lattice gluodynamics. The modes are known to be sensitive to the topology of the underlying gluonic fields in the quantum vacuum state of the gluodynamics. We find evidence that these modes are fine-tuned; that is, they exhibit sensitivity to both physical (one can say, hadronic) scale and to the ultraviolet cutoff. Namely, the density of the states is in physical units, while the localization volume of the modes tends to zero in physical units with the lattice spacing tending to zero. We briefly discuss the possible theoretical implications and also include some general, review-type remarks.     

SU(2) gluodynamics above the deconfinement temperature

A physical model for describing SU(2) gluodynamics above the deconfinement temperature is developed on the basis of the operator-product-expansion method. The properties of the nonperturbative vacuum are parametrized in terms of gauge-invariant gluomagnetic correlation functions. The free energy of the system is calculated for T>T _c. The results obtained within the proposed model for the thermal properties of gluons (energy density, nonideality) are shown to agree with data coming from lattice calculations.     

Calculation of the bulk viscosity in SU(3) gluodynamics

We perform a lattice Monte Carlo calculation of the trace-anomaly two-point function at finite temperature in the SU(3) gauge theory. We obtain the long distance properties of the correlator in the continuum limit and extract the bulk viscosity zeta via a Kubo formula. Unlike the tensor correlator relevant to the shear viscosity, the scalar correlator depends strongly on temperature. If s is the entropy density, we find that zeta/s becomes rapidly small at high T, zeta/s<0.15 at 1.65T(c), and zeta/s<0.015 at 3.2T(c). However, zeta/s rises dramatically just above T(c), with 0.5相似文献   

Naturalnes in supersymmetric GUTS

We propose a resummation of QCD radiative corrections in large transverse momentum hadronic processes, based on the introduction of an infrared cut-off, linked to the confinement radius. An analysis of the inclusive reactionspp → π⁰ X andpp → γX and of γ/π⁰ ratio is presented.     

Novel probe of the vacuum of the lattice gluodynamics

We introduce the notion of a minimal number of negative links on the lattice for a given original configuration of SU(2) fields. Negative links correspond to a large potential, not necessarily to large action. The idea is that the minimal number of negative links is a gauge invariant notion. To verify this hypothesis, we measure the correlator of two negative links, averaged over all the directions, as a function of the distance between the links. The inverse correlation length coincides within the error bars with the lightest glueball mass.