Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: 1-Loop improved lattice action for the nonlinear sigma-model   In this paper we show the Wilson effective action for the 2-dimensional
O(N+1)-symmetric lattice nonlinear sigma-model computed in the 1-loop
approximation for the nonlinear choice of blockspin $\Phi(x)$, $\Phi(x)=
\Cav\phi(x)/{|\Cav\phi(x)|}$,where $\Cav$ is averaging of the fundamental field
$\phi(z)$ over a square $x$ of side $\tilde a$.
  The result for $S_{eff}$ is composed of the classical perfect action with a
renormalized coupling constant $\beta_{eff}$, an augmented contribution from a
Jacobian, and further genuine 1-loop correction terms. Our result extends
Polyakov's calculation which had furnished those contributions to the effective
action which are of order $\ln \tilde a /a$, where $a$ is the lattice spacing
of the fundamental lattice. An analytic approximation for the background field
which enters the classical perfect action will be presented elsewhere.

27
The categories of this paper are: comp-gas
2
The categories of this paper are: math
21
The categories of this paper are: adap-org
29
The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
14
The categories of this paper are: math-ph
3
The categories of this paper are: physics
31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
18
The categories of this paper are: econ
19
The categories of this paper are: eess
33
The categories of this paper are: plasm-ph
32
The categories of this paper are: atom-ph
15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th