Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Zero Mode Divergence Problem in String Theory   For $2D$ string theory, the perturbative $S$-matrices are not well-defined
due to a zero mode divergence. Although there exist formal procedures to make
the integral convergent, their physical meanings are unclear. We describe a
method to obtain finite $S$-matrices physically to justify the formal schemes.
The scheme uses asymptotic states by wave packets which fall faster than
exponentials. It is shown that the scheme gives well-defined $S$-matrices and
justifies the formal shifted Virasoro-Shapiro amplitude for simple processes.
The tree-level unitarity for these processes is also shown. We point out a
problem in this scheme.

13
The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph
35
The categories of this paper are: mtrl-th
26
The categories of this paper are: bayes-an
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The categories of this paper are: patt-sol
27
The categories of this paper are: comp-gas
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The categories of this paper are: alg-geom
33
The categories of this paper are: plasm-ph
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The categories of this paper are: supr-con
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The categories of this paper are: econ
32
The categories of this paper are: atom-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: dg-ga
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The categories of this paper are: gr-qc
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The categories of this paper are: q-fin
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The categories of this paper are: astro-ph