Scaling function and nucleon momentum distribution

Scaling studies of inclusive quasielastic electron scattering reactions have been used in the past as a basic tool to obtain information on the nucleon momentum distribution in nuclei. However, the connection between the scaling function, extracted from the analysis of cross-section data, and the spectral function only exists assuming very restricted approximations. We revisit the basic expressions involved in scaling studies and how they can be linked to the nucleon momentum distribution. In particular, the analysis applied in the past to the so-called scaling region, that is, negative values of the scaling variable y, is extended here to positive y, as a "universal" superscaling function has been extracted from the analysis of the separated longitudinal data. This leads to results that clearly differ from those based solely on the negative-y scaling region, providing new information on how the energy and momentum are distributed in the spectral function.Programa Consolider-Ingenio CSD2007-00042Junta de AndalucíaMICINN FIS2008-04189 PCI2006-A7-0548INFN-CICYTINFN08-20Ministerio de Ciencia e Innovación (España) FPA2008-03770-E/INF