Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Limits on new long range nuclear spin-dependent forces set with a K-3He
  co-magnetometer   A magnetometer using spin-polarized K and $^3$He atoms occupying the same
volume is used to search for anomalous nuclear spin-dependent forces generated
by a separate $^3$He spin source. We measure changes in the $^3$He spin
precession frequency with a resolution of 18 pHz and constrain anomalous spin
forces between neutrons to be less than $2 \times 10^{-8}$ of their magnetic or
less than $2\times 10^{-3}$ of their gravitational interactions on a length
scale of 50 cm. We present new limits on neutron coupling to light pseudoscalar
and vector particles, including torsion, and constraints on recently proposed
models involving unparticles and spontaneous breaking of Lorentz symmetry.

9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
37
The categories of this paper are: supr-con
1
The categories of this paper are: cs
4
The categories of this paper are: cond-mat
22
The categories of this paper are: chao-dyn
12
The categories of this paper are: nucl-th
11
The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
17
The categories of this paper are: q-fin
15
The categories of this paper are: nucl-ex
29
The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom