Are not coming out as expected the fact that modern

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Unformatted text preview: ies noted in the experimental data. In particular, it is now being recognized that nucleon-nucleon correlations and two-body exchange currents must be included in order to provide a more accurate description of neutrino-nucleus QE scattering. These effects yield significantly enhanced cross sections (larger than the free scattering case) which, in some cases, appear to better match the experimental data (Aguilar-Arevalo et al., 2010a) at low neutrino energies (Amaro et al., 2011b; Barbaro et al., 2011; Bodek and Budd, 2011; Giusti and Meucci, 2011; Martini, Ericson, and Chanfray, 2011; Nieves, Ruiz-Simo, and Vicente-Vacas, 2011; Sobczyk, 2012). They also produce final states that include multiple nucleons, especially when it comes to scattering off of nuclei. The final state need not just include a single nucleon, hence why one needs to be careful in defining a ‘‘quasielastic’’ event especially when it comes to scattering off nuclei. In hindsight, the increased neutrino QE cross sections and harder Q2 distributions (high MA ) observed in much of the experimental data should probably have not come as a surprise. Such effects were also measured in transverse electronnucleus quasielastic scattering many years prior (Carlson, 2002). The possible connection between electron and neutrino QE scattering observations has only been recently appreciated. Today, the role that additional nuclear effects may play in neutrino-nucleus QE scattering remains the subject of much theoretical and experimental scrutiny. Improved theoretical calculations and experimental measurements are already underway. As an example, the first double differential cross section distributions for  QE scattering were recently reported by the MiniBooNE experiment (Aguilar-Arevalo et al., 2010a). It is generally recognized that such modelindependent measurements are more useful than comparing MA values. Such differential cross section data are also providing an important new testing ground for improved nuclear model calculations (Amaro et al., 2011a; Giusti and Meucci, 2011; Martini, Ericson, and Chanfray, 2011; Nieves, Simo, and Vacas, 2012; Sobczyk, 2012). Moving forward, additional differential cross section measurements, detailed measurements of nucleon emission, and studies of antineutrino QE scattering are needed before a solid description can be secured. So far we have focused on neutrino QE scattering. Figure 12 shows the status of measurements of the corresponding antineutrino QE scattering cross section. Recent results from the NOMAD experiment have expanded the reach out to higher neutrino energies, however, there are currently no existing measurements of the antineutrino QE scattering cross section below 1 GeV. Given that the newly appreciated effects of nucleon-nucleon correlations are expected to be different for neutrinos and antineutrinos, a high priority has been recently given to the study of antineutrino QE scattering at these energies. A precise handle on...
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This document was uploaded on 09/28/2013.

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