Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spectrum, Scattering Amplitudes, and String Field Theory of 4
  Dimensional Twistor String   The recently introduced anomaly-free twistor string in 4 dimensions is
further explored. The spectrum based on the physical states and its Minkowski
interpretation are examined. Scattering amplitudes with vertex operators
involving gravitons and fermions are computed and are compared with
Einstein-Yang-Mills amplitudes. Tree and one-loop scattering amplitudes are
shown to have proper unitary factorization properties. Finally a string field
theory is proposed.

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The categories of this paper are: atom-ph
12
The categories of this paper are: nucl-th
14
The categories of this paper are: math-ph
3
The categories of this paper are: physics
13
The categories of this paper are: quant-ph
23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
0
The categories of this paper are: hep-ph
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
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The categories of this paper are: acc-phys
27
The categories of this paper are: comp-gas
15
The categories of this paper are: nucl-ex
25
The categories of this paper are: patt-sol
19
The categories of this paper are: eess
6
The categories of this paper are: astro-ph