Abstract
Many-body correlations in nuclei determine the behavior of Deep-Inelastic-Scattering (DIS) and Quasi-Elastic Scattering (QES) cross section ratios off heavy over light nuclei especially for xBjorken > 1, obtained at Jefferson Lab. They can be described in terms of quark-cluster formation in nuclei due to wave-function overlapping, manifesting itself when the momentum transfer is high so that the partonic degrees of freedom are resolved. In clusters (correlated nucleons) the quark and gluon momentum distributions are softer than in single nucleons and extend to xBjorken > 1. The cluster formation probabilities are computed using a network-defining algorithm in which the initial nucleon density is either standard Woods-Saxon or is input from lower energy data while the critical radius for nucleon merging is an adjustable parameter. The exact choice of critical radius depends on the specific nucleus and it is anti-correlated to the rescaling of the xBjorken needed for bound nucleons. The calculations show that there is a strong dependence of the cross section ratios on the xBjorken in agreement with the data and that four-body correlations are needed to explain the experimental results even in the range 1 xBjorken < 2. The dependence on the specific exponents of parton distributions in high-order clusters is weak.
Highlights
In this work it was shown that many-body correlations in the nucleus are necessary in order to understand Quasi-Elastic Scattering (QES) data
This is in agreement with the need for such effects in Deep Inelastic Scattering (DIS) data
A quark-cluster model has been constructed to account for these correlations. This assumes overlapping of bound-nucleon wave-functions to the extent that they share partons whose momentum distributions are softened compared to those in independent nucleons
Summary
The so called EMC-effect, named after the European Muon Collaboration [1] [2] [3] [4] [5], has shown that in the case of Deep Inelastic Scattering (DIS) of muons off nuclei the cross section does not scale with the number of nucleons and exhibits a strong dependence on the longitudinal momentum fraction carried by the struck quarks This effect has been observed in many other processes involving the electromagnetic and the weak interactions of nuclei with probes at high energies, such as Drell-Yan pair production, neutrino scattering, and charmonium and bottomonium suppression [6] [7] [8] [9] [10] and predicted for direct photon production in hardon-nucleus and nucleus-nucleus collisions [11] [12] [13]. Those probabilities are expressed as functions of a critical distance (radius) between two
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
