nLab
QCD

under construction

Context

Physics

physics, mathematical physics, philosophy of physics

Surveys, textbooks and lecture notes


theory (physics), model (physics)

experiment, measurement, computable physics

Quantum Field Theory

algebraic quantum field theory (perturbative, on curved spacetimes, homotopical)

Introduction

Concepts

field theory:

Lagrangian field theory

quantization

quantum mechanical system, quantum probability

free field quantization

gauge theories

interacting field quantization

renormalization

Theorems

States and observables

Operator algebra

Local QFT

Perturbative QFT

Contents

Idea

Quantum chromodynamics (“QCD”) is the quantum field theory of Yang-Mills theory: it describes the quantum theory of gluons and quarks.

The corresponding effective field theory that describes confined bound states such as protons is quantum hadrodynamics.

Properties

Confinements

See at confinement.

Asymptotic freedom

See at asymptotic freedom.

Trace anomaly

See at QCD trace anomaly.

Phase diagram

QCD has an intricate phase diagram (e.g. Shuryak 96 Hands 01, Schaefer 05), phases including

References

General

Introductions:

Textbooks:

with emphasis on phenomenology:

On QCD’s running coupling constant:

Rigorous construction as a perturbative quantum field theory via causal perturbation theory is discussed in

Survey with emphasis on non-perturbative effects:

Discussion of on-shell methods in QCD perturbation theory includes

See also

As thermal field theory:

Phase diagram

On the phase diagram of QCD:

Via lattice QCD:

History

Lattice QCD checks

Due to confinement, the fundamental degrees of freedom in terms of which QCD is formulated, namely the quarks, are actually not the low-energy bound states of the theory, which instead are the hadrons. This leaves room to speculate that QCD is not really the fundamental theory of the strong nuclear force.

However, brute-force computation in lattice QCD shows that the quark-model does reproduce these hadron bound states somehow (even if the real understanding of how it does so remains open, this is the mass gap problem):

our study strongly suggests that QCD is the theory of the strong interaction, at low energies as well