Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Chiral string theories as an interpolation between strings and particles   A new set of boundary conditions for string propagators is proposed in this
paper. The boundary conditions are parametrized by a complex number $\lambda$.
Under these new boundary conditions, the left-moving and right-moving modes are
treated unequally. Thus, we called them chiral string theories. If $\lambda =
-1$, the spectrum of such theory truncates to a finite number, and therefore it
becomes a different description of supergravity. We found the spectrum of
chiral string theories by requiring that the vertex operators are conformally
invariant. In addition, we also calculate the amplitudes for arbitrary
$\lambda$. The amplitudes are expressed as a product of open string amplitudes
which are similar to the KLT relation. The unitarity of these theories are
investigated. However, we found out that except for $\lambda = \pm 1$, all
other theories are not unitary; i.e., only the supergravity and ordinary
strings are unitary. Although most of the chiral strings are not physical, they
still serve as a valuable tool in studying the relation between particle
theories and string theories.

36
The categories of this paper are: cmp-lg
29
The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph
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The categories of this paper are: chem-ph
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
2
The categories of this paper are: math
5
The categories of this paper are: gr-qc
6
The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat