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arXiv · 2110.13682

Novel Corrections to the Momentum Sum Rule for Nuclear Structure Functions

Stanley J. Brodsky·Valery E. Lyubovitskij·Ivan Schmidt
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Abstract

We address novel features of deep inelastic lepton scattering on nuclei at small Bjorken variable $x_{Bj}$. In this regime the lepton-nuclear cross section involves the interference between the standard lepton-quark scattering amplitude for the deep inelastic scattering (DIS) process on a single nucleon and a two-step process where diffractive scattering on a first nucleon combines with the amplitude for DIS on a second nucleon. The phases associated with the $t$-channel exchanges to the diffractive amplitude can produce either a destructive or constructive quantum-mechanical interference of the one-step and two-step amplitudes. This provides a mechanism regulating the respective amounts of shadowing suppression and anti-shadowing enhancement at low $x_{Bj}$. Furthermore, the standard leading-twist operator product and handbag diagram analyses of the forward virtual Compton amplitude on the nucleus are inapplicable, barring a conventional probabilistic interpretation. A main observable consequence is the impossibility of extracting momentum and spin sum rules from nuclear structure functions. We present numerical predictions supporting this picture and test them against DIS neutrino-nucleus and charged-lepton-nucleus scattering data.

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Stanley J. Brodsky, Valery E. Lyubovitskij, Ivan Schmidt. 2021-10-26. Novel Corrections to the Momentum Sum Rule for Nuclear Structure Functions. https://doi.org/10.1016/j.physletb.2021.136812

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