QCD inequalities

We review the subject of QCD inequalities, using both a Hamiltonian variational approach, and a rigorous Euclidean path integral approach.     

Supersymmetric QCD

We demonstrate the existence of a well-defined vacuum state in supersymmetric QCD with finite vacuum expectation values (VEVs) for scalars. Our results differ from those of several authors who find that a supersymmetric vacuum state exists only at infinite VEVs for the scalar fields. Our analysis is an application of previous results obtained using instantons in conjunction with the anomalous supersymmetry transformation laws found by Konishi.     

Lattice QCD

Possibilities that are provided by a lattice regularization of QCD for studying nonperturbative properties of QCD are discussed. A review of some recent results obtained from computer calculations in lattice QCD is given. In particular, the results for the QCD vacuum structure, the hadron mass spectrum, and the strong coupling constant are considered.     

QCD exotics

I review first some theoretical motivations for violation of Lorentz and/or CPT Invariance. Although the latter symmetries may be violated in a quantum gravity setting, nevertheless there are situations in which these violations are due to a given classical background geometry that may characterised early epochs of our Universe, and in fact be responsible for the observed dominance of matter over antimatter in the Universe. In this way I estimate some of the coefficients of the Standard Model Extension (SME), which is a framework for a field theoretic study of such a breakdown of fundamental symmetries. Then I describe briefly some tests of these symmetries, giving emphasis in low-energy antiproton physics and electric dipole moment measurements, of interest to this conference. I also mention the rôle of entangled states of neutral mesons in providing independent measurements of T(ime reversal) and CP Violation, thus providing independent tests of CPT symmetry, as well as novel (“smoking-gun” type) tests of decoherence-induced CPT violation, which may characterise some models of quantum gravity.     

Testing QCD

QCD is used to predict that the ratio of up to down quarks → 5 as x → 1 and the rigor of the proof and the underlying assumptions are discussed. Measuring $\text{σ}{}^{\mathrm{<mtext>v</mtext><mtext>?</mtext>}}\text{P}\text{σ}{}^{\mathrm{v}}\text{P}\text{as}\text{x → 1}$ gives the best experimental test of this prediction.     

Fairy QCD

We discuss QCD at nonstandard values of parameters (quark masses, vacuum angle θ, the number of colors and flavors) and/or at nonstandard physical conditions (when the system is essentially heated and/or squezed. Studying these “fairy” version of the theory provides a broader perspective and allows one to understand better the dynamics of actual QCD.     

Thermal QCD

By the methbd of the gauge field theory at finite temperature, the static thermodynamic properties in quark-gluon plasma are studied in detail. According to the renormalization group equation, an analytic expression of the running coupling constant g(T, p) with the temperature T is obtained.     

Generating QCD antennas

An extension of the SARGE algorithm of van Hameren, Kleiss and Draggiotis is introduced, which includes the incoming momenta in the kinematical pole structure of the density with which the momenta are generated. The algorithm is compared with RAMBO in the integration of QCD amplitudes in the SPHEL approximation, and the computing times are extrapolated to those for the calculation with exact matrix elements. Received: 11 August 2000 / Published online: 23 October 2000     

High-precision nonperturbative QCD

Recent advances in lattice QCD have resulted in the first simulations with realistic quark vacuum polarization. Consequently a wide variety of high-precision (few percent) nonperturbative calculations are possible now. This paper reviews the recent developments that make this possible, and presents early evidence that the era of high-precision nonperturbative QCD is at hand. It also discusses the future impact of lattice QCD on experiments, and particularly for heavy-quark physics.     

One flavor QCD

One flavor QCD is a rather intriguing variation on the underlying theory of hadrons. In this case quantum anomalies remove all chiral symmetries. This paper discusses the qualitative behavior of this theory as a function of its basic parameters, exploring the non-trivial phase structure expected as these parameters are varied. Comments are made on the expected changes to this structure if the gauge group is made larger and the fermions are put into higher representations.     

The dynamical holographic QCD method for hadron physics and QCD matter

In this paper we present a short overview on the dynamical holographic QCD (DhQCD) method for hadron physics and QCD matter. The five-dimensional DhQCD model is constructed in the graviton-dilaton-scalar framework with the dilaton background field Φ and the scalar field X dual to the gluon condensate and the chiral condensate operator thus can represent the gluodynamics (linear confinement) and chiral dynamics (chiral symmetry breaking), respectively. The dilaton background field and the scalar field are a function of the 5th dimension, which plays the role of the energy scale, in this way, the DhQCD model can resemble the renormalization group from ultraviolet (UV) to infrared (IR). By solving the Einstein equation, the metric structure at IR is automatically deformed by the nonperturbative gluon condensation and chiral condensation in the vacuum. We review the results on the hadron spectra including the glueball spectra, the light/heavy meson spectra, as well as on QCD phase transitions, and thermodynamical as well as transport properties in the framework of the DhQCD model.     

Vacuum condensates of QCD

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