Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the Possibility and Consequences of Negative Mass   We investigate the possibility and consequences of the existence of particles
having negative relativistic masses, and show that their existence implies the
existence of faster- than-light particles (tachyons). Our proof requires only
two postulates concerning such particles: that it is possible for particles of
any (positive, negative or zero) relativistic mass to collide inelastically
with 'normal' (i.e. positive relativistic mass) particles, and that
four-momentum is conserved in such collisions.

7
The categories of this paper are: hep-th
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The categories of this paper are: quant-ph
30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
8
The categories of this paper are: hep-ex
4
The categories of this paper are: cond-mat
1
The categories of this paper are: cs
22
The categories of this paper are: chao-dyn
18
The categories of this paper are: econ
29
The categories of this paper are: funct-an
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The categories of this paper are: hep-ph
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
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The categories of this paper are: astro-ph
21
The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys