Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observation and superselection in quantum mechanics   We attempt to clarify the main conceptual issues in approaches to
`objectification' or `measurement' in quantum mechanics which are based on
superselection rules. Such approaches venture to derive the emergence of
classical `reality' relative to a class of observers; those believing that the
classical world exists intrinsically and absolutely are advised against reading
this paper. The prototype approach (Hepp) where superselection sectors are
assumed in the state space of the apparatus is shown to be untenable. Instead,
one should couple system and apparatus to an environment, and postulate
superselection rules for the latter. These are motivated by the locality of any
observer or other (actual or virtual) monitoring system. In this way
`environmental' solutions to the measurement problem (Zeh, Zurek) become
consistent and acceptable, too. Points of contact with the modal interpretation
are briefly discussed. We propose a minimal value attribution to observables in
theories with superselection rules, in which only central observables have
properties. In particular, the eigenvector-eigenvalue link is dropped. This is
mainly motivated by Ockham's razor.

37
The categories of this paper are: supr-con
33
The categories of this paper are: plasm-ph
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn
19
The categories of this paper are: eess
15
The categories of this paper are: nucl-ex
25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
17
The categories of this paper are: q-fin
36
The categories of this paper are: cmp-lg
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th