Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Limits on Lorentz violation from charged-pion decay   Charged-pion decay offers many opportunities to study Lorentz violation.
Using an effective field theory approach, we study Lorentz violation in the
lepton, W-boson, and quark sectors and derive the differential pion-decay rate,
including muon polarization. Using coordinate redefinitions we are able to
relate the first-generation quark sector, in which no bounds were previously
reported, to the lepton and W-boson sector. This facilitates a tractable
calculation, enabling us to place bounds on the level of $10^{-4}$ on
first-generation quark parameters. Our expression for the pion-decay rate can
be used to constrain Lorentz violation in future experiments.

2
The categories of this paper are: math
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
12
The categories of this paper are: nucl-th
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
31
The categories of this paper are: ao-sci
4
The categories of this paper are: cond-mat
19
The categories of this paper are: eess
3
The categories of this paper are: physics
29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg
34
The categories of this paper are: chem-ph