Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Vanishing of the conformal anomaly for strings in a gravitational wave   Using the non-symmetric-connection approach proposed by Osborn, we
demonstrate that, for a bosonic string in a specially chosen plane-fronted
gravitational wave and an axion background, the conformal anomaly vanishes at
the two-loop level. Under some conditions, the anomaly vanishes at all orders.

32
The categories of this paper are: atom-ph
4
The categories of this paper are: cond-mat
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an
6
The categories of this paper are: astro-ph
18
The categories of this paper are: econ
21
The categories of this paper are: adap-org
9
The categories of this paper are: nlin
16
The categories of this paper are: stat
22
The categories of this paper are: chao-dyn
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The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
17
The categories of this paper are: q-fin
34
The categories of this paper are: chem-ph