An ultraviolet divergence comes from arbitrarily large loop momentum, equivalently from singular short-distance behavior. Locality makes its regulator dependence cancellable by local counterterms in a renormalizable theory.
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Ultraviolet (UV) divergence is a concept in quantum field theory and quantum mechanics that refers to the phenomenon where certain integrals, especially those that arise in the calculation of particle interactions and vacuum fluctuations, yield infinite results when evaluated at high energy (or short distance) scales. This is particularly relevant in theories like quantum electrodynamics (QED) and quantum chromodynamics (QCD), where loop diagrams (representing virtual particles) can produce divergences.