Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Neutron-Deuteron System and Photon Polarization Parameter at Thermal
  Neutron Energies   Effective Field Theory(EFT) is, the unique, model independent and systematic
low-energy version of QCD for processes involving momenta below the pion mass.
A low-energy photo-nuclear observable in three-body systems, photon
polarization parameter at thermal neutron energies is calculated by using
pionless EFT up to next-to-next to leading order(N$^2$LO). In order to make a
comparative study of this model, we compared our results for photon
polarization parameter with the realistic Argonne $v_{18}$ two-nucleon and
Urbana IX or Tucson-Melbourne three-nucleon interactions. Three-body currents
give small but significant contributions to some of the observables in the
neutron-deuteron radiative capture cross section at thermal neutron energies.
In this formalism the three-nucleon forces are needed up to N$^2$LO for cut-off
independent results. Our result converges order by order in low energy
expansion and also cut-off independent at this order.

10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
8
The categories of this paper are: hep-ex
21
The categories of this paper are: adap-org
16
The categories of this paper are: stat
18
The categories of this paper are: econ
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas
36
The categories of this paper are: cmp-lg
15
The categories of this paper are: nucl-ex