Nuclear Corrections in Neutrino-Nucleus Deep Inelastic Scattering and their Compatibility with Global Nuclear Parton-Distribution-Function Analyses

Abstract

We perform a global χ² analysis of nuclear parton distribution functions using data from charged current neutrino-nucleus (νA) deep-inelastic scattering (DIS), charged-lepton-nucleus (ℓ(±)A) DIS, and the Drell-Yan (DY) process. We show that the nuclear corrections in νA DIS are not compatible with the predictions derived from ℓ(±)A DIS and DY data. We quantify this result using a hypothesis-testing criterion based on the χ² distribution which we apply to the total χ² as well as to the χ² of the individual data sets. We find that it is not possible to accommodate the data from νA and ℓ(±)A DIS by an acceptable combined fit. Our result has strong implications for the extraction of both nuclear and proton parton distribution functions using combined neutrino and charged-lepton data sets.

Nuclear PDFs in the beginning of the LHC era

“…Also the work of nCTEQ collaboration [19,20,21] will be commented, although their final pre-LHC parametrization is not yet available. Some characteristics of these NLO fits are summarized in Table 1. )…”

“…The results seemed to point towards nuclear modifications in PDFs different from those obtained in charged-lepton-induced reactions. Later on, it was argued [20] that the these two types of data display clear mutual tension, and, even a breakdown of the collinear factorization was flashed as a possible explanation. Such would have far reaching consequences as the all major free proton groups [9,10,11] do include neutrino data in their fits, thereby silently assuming the validity of the factorization there.…”

Neutrino-nucleus interactions in the few-GeV region

“…1. There, we see nuclear corrections turn out to be small, of the order of 5%, and are successfully described by the nCTEQ analysis [5]. In general, there exist some tension between charged-lepton (l ± A) and the neutrino 11011-p. 3 …”

“…The dashed lines show the result of the nCTEQ [5] analysis of νA (CHORUS [7], CCFR/NuTeV [8]) differential cross sections plotted in terms of the average F Fe 2 divided by the results obtained with the reference fit (free proton) PDFs. For comparison, the solid curve stands for the nCTEQ fit [5] to the charged-lepton data. Right: ν + 12 C cross sections.…”

“…The latter effects account for events where the gauge boson is absorbed by two interacting nucleons (excitation of a 2p2h nuclear component). Up to re-scattering processes which could produce secondary pions, 2p2h events will give rise to only 11011-p. 5 EPJ Web of Conferences one muon in the final state, and thus they are included in the MiniBooNE data-set. Thus, they could be experimentally misidentified as QE events.…”