The preservation of sum rules andpositivity constraints is naturally provided by the kinetic descriptution of QCD evolution equations. It implies the irreversibility manifested in the existence of "scale arrows". The sign change in the course of TMD evolution at $Q \sim Q_T$
is interpreted as change of scale arrow direction. The Burkardt sum rule is related to momentum conservation and equivalence principle by
a sort of analytic continuation. The claimed way of its evolution means its "spontaneous" conservation implied by the boundary condition, analogously to twist-3 contribution to Burkhardt-Cottingam sum rule. It is compatible with its validity separately for each flavour.
Evolution of sum rules and positivity constraints
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Pre-published on:
February 10, 2017
Published on:
March 28, 2017
Abstract
DOI: https://doi.org/10.22323/1.284.0032
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Copyright owned by the author(s) under the term of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.