A Perspective on Hadron Physics

Abstract

Detailed investigations of the structure of hadrons are essential for understanding how matter is constructed from the quarks and gluons of Quantum chromodynamics (QCD), and amongst the questions posed to modern hadron physics, three stand out. What is the rigorous, quantitative mechanism responsible for confinement? What is the connection between confinement and dynamical chiral symmetry breaking? And are these phenomena together sufficient to explain the origin of more than 98% of the mass of the observable universe? Such questions may only be answered using the full machinery of nonperturbative relativistic quantum field theory.This contribution provides a perspective on progress toward answering these key questions. In so doing it will provide an overview of the contemporary application of Dyson-Schwinger equations in Hadron Physics, additional information on which may be found in Refs. [1,2,3,4,5,6]. The presentation assumes that the reader is familiar with the concepts and notation of relativistic quantum mechanics, with the functional integral formulation of quantum field theory and with regularisation and renormalisation in its perturbative formulation. For these topics, in order of appearance, Refs. [7,8,9,10] are useful. In addition, Chaps. 1 and 2 of Ref.[5] review the bulk of the necessary concepts.Hadron physics is a key part of the international effort in basic science. For example, in the USA we currently have the Thomas Jefferson National Accelerator Facility (JLab) and the Relativistic Heavy Ion Collider (RHIC) while in Europe hadron physics is studied at the Frascati National Laboratory and is an important part of a forthcoming pan-European initiative; namely, the Facility for Antiproton and Ion Research (FAIR) at GSI-Darmstadt. Progress in this field is gauged via the successful completion of precision measurements of fundamental properties of hadrons; e.g., the pion, proton and neutron, and simple nuclei, for comparison with theoretical calculations to provide a quantitative understanding of their quark substructure.

Impact of Different Combinations of Water Treatment Processes on the Concentration of Disinfection Byproducts and Their Precursors in Swimming Pool Water

“…The concentration of bromate was determined in the BFA stock solution, the HAs, and the filling water according to DIN 15061 (2001) . The concentration of bromate in the NaOCl stock solution was analyzed by iodometric titration of bromate after reduction of the hypochlorite as described by Höll …”

Single-particle spectral function for the classical one-component plasma

“…The many-particle Green function approach [1] allows for a systematic study of macroscopic properties of correlated systems. Green functions know a long history of applications in solid state theory [2], nuclear [3], and hadron physics [4], and also in the theory of strongly coupled plasmas [5]. In the latter case, optical and dielectric properties [6,7] have been studied using the Green function approach, as well as transport properties like conductivity [8] and stopping power [9,10], and the equation of state [11].…”

“…Therefore, the perturbation expansion of the self-energy has to be replaced by a non-perturbative approach, accounting for the dynamical screening of the interparticle potential.A non-perturbative approach to the many-particle problem is given by the theory of Dyson [14] and Schwinger [15,16] generalized to finite temperature and finite density [17]. An excellent introduction to Dyson-Schwinger equations can also be found in [4]. The Dyson-Schwinger equation for the self-energy Σ contains the full Green function G, the screened interaction W and the proper vertex Γ.…”