Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Why is LaMET an effective field theory for partonic structure?   Partons are effective degrees of freedom describing the structure of hadrons
involved in high-energy collisions. Familiar theories of partons are QCD
light-front quantization and soft-collinear effective theory, both of which are
intrinsically Minkowskian and appear unsuitable for classical Monte Carlo
simulations. A ``new'' form of the parton theory has been formulated in term of
the old-fashioned, Feynman's infinite momentum frame, in which the parton
degrees of freedom are filtered through infinite-momentum external states. The
partonic structure of hadrons is then related to the matrix elements of static
(equal-time) correlators in the state $|P^z=\infty\rangle$. This representation
lays the foundation of large-momentum effective theory (LaMET) which
approximates parton physics through a systematic $M/P^z$ expansion of the
lattice QCD matrix elements at a finite but large momentum $P^z$, and removes
the residual logarithmic-$P^z$ dependence by the standard
effective-field-theory matching and running.

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The categories of this paper are: cond-mat
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The categories of this paper are: hep-ex
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The categories of this paper are: dg-ga
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The categories of this paper are: nlin
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The categories of this paper are: econ
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The categories of this paper are: acc-phys
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The categories of this paper are: astro-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: q-alg
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The categories of this paper are: gr-qc
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The categories of this paper are: atom-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: q-bio
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The categories of this paper are: math-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: cs