Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Lifetime Asymmetry of Polarized Muons in Flight   Based on the parity violation in Standard Model, we study the dependence of
the lifetime on the polarization of an initial-state fermion in weak
interactions. The fermion lifetime was usually calculated in terms of spin
states. However, after comparing spin states with helicity states and chirality
states, it is pointed out that a spin state is helicity degenerate, and the
spin state and the helicity state are entirely different. Using helicity
states, we calculate the lifetime of polarized muons. The result shows that the
lifetime of right-handed polarized muons is always greater than that of
left-handed polarized muons with the same speed in flight.

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The categories of this paper are: math-ph
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The categories of this paper are: stat
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The categories of this paper are: atom-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: dg-ga
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The categories of this paper are: astro-ph
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The categories of this paper are: supr-con
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The categories of this paper are: econ
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The categories of this paper are: plasm-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: nlin
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The categories of this paper are: q-alg
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The categories of this paper are: solv-int
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The categories of this paper are: q-fin
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The categories of this paper are: mtrl-th
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The categories of this paper are: alg-geom