Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Compton scattering on the proton, neutron, and deuteron in chiral
  perturbation theory to O(Q^4)   We study Compton scattering in systems with A=1 and 2 using chiral
perturbation theory up to fourth order. For the proton we fit the two
undetermined parameters in the O(Q^4) $\gamma$p amplitude of McGovern to
experimental data in the region $\omega,\sqrt{|t|} \leq 180$ MeV, obtaining a
chi^2/d.o.f. of 133/113. This yields a model-independent extraction of proton
polarizabilities based solely on low-energy data: alpha_p=12.1 +/- 1.1 (stat.)
+/- 0.5 (theory) and beta_p=3.4 +/- 1.1 (stat.) +/- 0.1 (theory), both in units
of 10^{-4} fm^3. We also compute Compton scattering on deuterium to O(Q^4). The
$\gamma$d amplitude is a sum of one- and two-nucleon mechanisms, and contains
two undetermined parameters, which are related to the isoscalar nucleon
polarizabilities. We fit data points from three recent $\gamma$d scattering
experiments with a chi^2/d.o.f.=26.6/20, and find alpha_N=13.0 +/- 1.9 (stat.)
+3.9/-1.5 (theory) and a beta_N that is consistent with zero within sizeable
error bars.

37
The categories of this paper are: supr-con
6
The categories of this paper are: astro-ph
4
The categories of this paper are: cond-mat
29
The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
3
The categories of this paper are: physics
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
7
The categories of this paper are: hep-th
8
The categories of this paper are: hep-ex
33
The categories of this paper are: plasm-ph
28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an