Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Covariant Hamiltonian boundary term: Reference and quasi-local
  quantities   The Hamiltonian for dynamic geometry generates the evolution of a spatial
region along a vector field. It includes a boundary term which determines both
the value of the Hamiltonian and the boundary conditions. The value gives the
quasi-local quantities: energy-momentum, angular-momentum and center-of-mass.
The boundary term depends not only on the dynamical variables but also on their
reference values; the latter determine the ground state (having vanishing
quasi-local quantities). For our preferred boundary term for Einstein's GR we
propose 4D isometric matching and extremizing the energy to determine the
reference metric and connection values.

25
The categories of this paper are: patt-sol
30
The categories of this paper are: q-alg
21
The categories of this paper are: adap-org
24
The categories of this paper are: dg-ga
28
The categories of this paper are: alg-geom
0
The categories of this paper are: hep-ph
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
1
The categories of this paper are: cs
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph