Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quasi-local gravitational angular momentum and centre of mass from
  generalised Witten equations   Witten's proof for the positivity of the ADM mass gives a definition of
energy in terms of three-surface spinors. In this paper, we give a
generalisation for the remaining six Poincar\'e charges at spacelike infinity,
which are the angular momentum and centre of mass. The construction improves on
certain three-surface spinor equations introduced by Shaw. We solve these
equations asymptotically obtaining the ten Poincar\'e charges as integrals over
the Nester--Witten two-form. We point out that the defining differential
equations can be extended to three-surfaces of arbitrary signature and we study
them on the entire boundary of a compact four-dimensional region of spacetime.
The resulting quasi-local expressions for energy and angular momentum are
integrals over a two-dimensional cross-section of the boundary. For any two
consecutive such cross-sections, conservation laws are derived that determine
the influx (outflow) of matter and gravitational radiation.

13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
4
The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex
3
The categories of this paper are: physics
34
The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
22
The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph
1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an
29
The categories of this paper are: funct-an