Nuclear Shadowing at Low Q

In the light of a recent claim that models of nuclear shadowing which incorporate a vector meson dominance component at low Q2 are incompatible with nuclear deep inelastic scattering data, we compare the predictions of such a model with high precision data on the Q2 dependence of nuclear shadowing. Contrary to this claim, we find that models which incorporate both vector meson and partonic mechanisms are indeed consistent with both the magnitude and the Q2 slope of the shadowing data. In a recent note [1] Zeller, McFarland et al. have suggested that the nuclear shadowing model of Ref. [2] “is not supported by charged-lepton deep inelastic scattering (DIS) data”, and predicts the wrong Q dependence for nuclear shadowing in the NuTeV kinematic region (1 < Q < 140 GeV). This assertion was used to cast doubt on the suggestion by Miller and Thomas [3] — see also Kovalenko et al. [4] — that a difference between the nuclear shadowing in neutral and charged current interactions may account for the apparent discrepancy between the value of sin θW extracted from neutrino–nucleus scattering [5] and its value within the Standard Model. In view of the importance of this issue we carefully examine the predictions of Ref. [2] in comparison with the Q dependence of the best available data on nuclear shadowing [6–8]. An extensive review of both data and models of nuclear shadowing was given recently by Piller and Weise [9]. We shall concentrate on the model which we published just before the release of the final NMC data [8]. Whereas that model was based on a two-phase picture of nuclear shadowing [10,11], similar to that pioneered by Kwiecinski and Badelek [12–14], Zeller et al. misidentify it as “a specific vector meson dominance shadowing model” [1]. To clarify the confusion apparent in Ref. [1], we briefly review this model.