Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Chiral Perturbation Theory and the Quenched Approximation of QCD   The quenched approximation for QCD is, at present and in the foreseeable
future, unavoidable in lattice calculations with realistic choices of the
lattice spacing, volume and quark masses. In these lectures, I review the
analytic study of the effects of quenching based on chiral perturbation theory.
Quenched chiral perturbation theory leads to quantitative insight into the
difference between quenched and unquenched QCD, and reveals clearly diseases
which plague quenched QCD. A short review of the ideas underlying chiral
perturbation theory is included.

28
The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
6
The categories of this paper are: astro-ph
12
The categories of this paper are: nucl-th
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
25
The categories of this paper are: patt-sol
34
The categories of this paper are: chem-ph
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
21
The categories of this paper are: adap-org
14
The categories of this paper are: math-ph
35
The categories of this paper are: mtrl-th