Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Neutron matter at next-to-next-to-next-to-leading order in chiral
  effective field theory   Neutron matter presents a unique system for chiral effective field theory
(EFT), because all many-body forces among neutrons are predicted to
next-to-next-to-next-to-leading order (N3LO). We present the first complete
N3LO calculation of the neutron matter energy. This includes the subleading
three-nucleon (3N) forces for the first time and all leading four-nucleon (4N)
forces. We find relatively large contributions from N3LO 3N forces. Our results
provide constraints for neutron-rich matter in astrophysics with controlled
theoretical uncertainties.

4
The categories of this paper are: cond-mat
37
The categories of this paper are: supr-con
13
The categories of this paper are: quant-ph
3
The categories of this paper are: physics
34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
11
The categories of this paper are: hep-lat
30
The categories of this paper are: q-alg
14
The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
21
The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th