The role of transverse momentum on the nuclear valence and sea quark distribution functions
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Regular Article - Theoretical Physics
The role of transverse momentum on the nuclear valence and sea quark distribution functions H. Nematollahia Faculty of physics, Shahid Bahonar University of Kerman, Kerman, Iran
Received: 22 November 2019 / Accepted: 6 February 2020 © The Author(s) 2020
Abstract We investigate the transverse momentum dependence of valence and sea quark distribution functions of light asymmetric nuclei (3 H e and 7 Li). To this end, we first calculate the valence and sea distributions of these nuclei applying a parametrization method in which the parton distribution functions (PDFs) of nucleus are related to those of free nucleon via a weight function that contains the nuclear modifications. Then we obtain the unpolarized transverse momentum dependent (TMD) PDFs of the nucleus using the covariant parton model (CPM) approach. We also compute the valence and sea quark distributions ratios of 3 H e and 7 Li to those of deuteron and present the results with respect to x (Bjorken variable) at fixed values of transverse momentum. It is found that these ratios shift to the larger values of x by increasing the transverse momentum value as expected and they are not transverse momentum dependent in large x region.
1 Introduction The investigation of the parton distribution functions of the nucleons and nuclei has been performed by analysing the deep inelastic scattering (DIS) processes of different targets. These processes have provided the detailed knowledge about internal structure of the nucleons and nuclei. The European Muon Collaboration (EMC) group found the difference between the bound state nucleon structure and that of free one, for the first time in 1983 [1]. They observed that a significant effect appeared in the nucleon structure while changing the target from deuteron to the heavy nuclei which is the so called EMC effect [2–4]. In fact the EMC effect originates from an essential difference between the PDFs of free nucleons and those of the bounded ones in nucleus. Several theoretical models, such as [5,6]: the pion excess model [7–12], the deconfinement model [7,13], the a e-mail:
quark exchange model (QEM) [14,15], the cluster model [7,16,17] and the rescaling model [7,18–21], have been suggested to study the nuclear PDFs and describe the EMC effect, which has been measured [6] in the Drell-Yan process [7,22–26], charged lepton-nucleus scattering [27–32] and neutrino-nucleus scattering processes [33–38]. We have already probed the structure of light nuclei applying the chiral quark exchange model [39] and also investigated the role of nuclear corrections on the structure function and the EMCratio of deuteron [40]. The usual PDFs do not have transverse momentum dependence. They describe the probability for finding a parton with longitudinal momentum fraction x of the parent hadron integrated over the transverse momentum of the parton. Since the transverse momentum of parton is not negligible especially at small values of x and the description of some experimental observations is not poss
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