Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Power counting for three-body decays of a near-threshold state   We propose a new power counting for the effective field theory describing a
near-threshold state with unstable constituents, such as the X(3872) meson. In
this counting, the momenta of the heavy particles, the pion mass and the
excitation energy of the unstable constituent -- the D* in the case of the X --
are treated as small scales, of order Q. The difference, delta, between the
excitation energy of the D* and the pion mass is smaller than either by a
factor ~20. We therefore assign delta an order Q^2 in our counting. This
provides a consistent framework for a double expansion in both delta/m_pi and
the ratio of m_pi to the high-energy scales in this system. It ensures that
amplitudes have the correct behaviour at the three-body threshold. It allows us
to derive, within an effective theory, various results which have previously
been obtained using physically-motivated approximations.

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The categories of this paper are: supr-con
13
The categories of this paper are: quant-ph
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
5
The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
32
The categories of this paper are: atom-ph
8
The categories of this paper are: hep-ex
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
20
The categories of this paper are: acc-phys
16
The categories of this paper are: stat
21
The categories of this paper are: adap-org