Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Scale Invariance plus Unitarity Implies Conformal Invariance in Four
  Dimensions   We give a non-perturbative proof that any 4D unitary and Lorentz-invariant
quantum field theory with a conserved scale current is in fact conformally
invariant. We show that any scale invariant theory (unitary or not) must have
either a vanishing anomaly for global scale transformations or an operator of
spin 2 and dimension 2. Neither of these possibilities is allowed for unitary
theories, proving the result. This is also a strong constraint on non-unitary
Euclidean theories with scale but not conformal invariance, suggesting the
conjecture that all such theories are free field theories.

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The categories of this paper are: chem-ph
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The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
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The categories of this paper are: cmp-lg
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The categories of this paper are: ao-sci
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The categories of this paper are: comp-gas
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The categories of this paper are: atom-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: quant-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: nucl-th
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The categories of this paper are: supr-con
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The categories of this paper are: hep-ph
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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-fin