Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Instantons on Noncommutative R^4 and Projection Operators   I carefully study noncommutative version of ADHM construction of instantons,
which was proposed by Nekrasov and Schwarz. Noncommutative ${\bf R}^4$ is
described as algebra of operators acting in Fock space. In ADHM construction of
instantons, one looks for zero-modes of Dirac-like operator. The feature
peculiar to noncommutative case is that these zero-modes project out some
states in Fock space. The mechanism of these projections is clarified when the
gauge group is U(1). I also construct some zero-modes when the gauge group is
U(N) and demonstrate that the projections also occur, and the mechanism is
similar to the U(1) case. A physical interpretation of the projections in IIB
matrix model is briefly discussed.

27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
24
The categories of this paper are: dg-ga
16
The categories of this paper are: stat
10
The categories of this paper are: q-bio
8
The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg
18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
36
The categories of this paper are: cmp-lg
21
The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys