Universal modified function in conjunction with the short range correlation effect to extract the nuclear $xF_3^A$ structure function

TL;DR

The paper tackles nuclear modifications of parton distributions by linking the EMC effect to short-range correlations (SRC) via a universal modification framework for the nonsinglet ratio $xF_3^A$ in neutrino-nucleus DIS. It introduces a universal modified function $R_f^u$ and a corresponding weight $R_m$ to capture SRC-driven changes across nuclei, and demonstrates universality by examining $xF_3^A$ against nPDF benchmarks such as $nCTEQ15$ and $EPPS21$. The authors show that an EMC-based weight derived from $R_f^u$ can reproduce $xF_3^A$ for Fe and Pb, with results that agree with experimental data and that are consistent across different parameterizations. The framework provides a physically motivated, nucleus-scale predictive tool for separating nuclear effects from possible beyond-Standard-Model contributions in neutrino scattering, and points to future work on extracting SRC parameters from cross-section data.

Abstract

Parton distribution functions (PDFs) are comprehensive and not reliant on the process. They are affected by nuclear matter during nuclear scattering process. As a recent approach, in order to study the nuclear PDFs (nPDFs), the nucleon pair PDFs are utilized to describe parton distributions in the nucleon pair which are confined to a nucleus. Nucleon pair PDFs stem from nucleon-nucleon correlation which is called short range correlation (SRC) and are proportional to common nucleon PDFs. In this regard a modified universal function is constructed which provides a test for SRC in (neutrino)-nucleus scattering. In fact we can show that the modification of the structure function of nucleons bound in atomic nuclei (known as the EMC effect) are consistently accounted for within the frame work of a universal modification of nucleons in SRC pairs. In this article, based on the strategy which was introduced in Ref.\cite{nature}, we are investigating to find the universality behaviour for the ratio of nonsinglet $xF_3^A$ nuclear structure function. The numerical calculations performed within the CTEQ framework confirm the universality feature of the concerned ratio, as has been established for the ratio of the structure function $F^A_2$ in Ref. \cite{nature}. Following that we reformulate the $R_{EMC}$ nuclear weight function which relates the free and bound structure function in terms of modified universal function. It makes us a possibility to achieve $R_{EMC}$ and finally $xF_3^A$ nuclear structure function for each nucleus only by considering the specified feature of nucleus.The results are compared with the nuclear $xF_3$ structure function which are computing from bound PDFs, based on some parameterizations models. The findings, considering the SRC effect, demonstrating qualitative agreement with nCTEQ15 and EPPS21 parametrization models and also the available experimental data.

Figures (10)

• Figure 1: A schematic diagram for neutrino charged-current DIS process, quoted from Dia.
• Figure 2: Weight functions for different carbon, iron and lead nuclei, resulted from EPPS21 parametrization EPPS21.
• Figure 3: Modified weight functions for different carbon. iron and lead nuclei, based on Eq.( \ref{['Mod-Wei']}).
• Figure 4: Improved weight functions for different carbon, iron and lead nuclei, based on Eq.( \ref{['use_of_uni_function']}).
• Figure 5: The ratio of $xF^A_3/xF^d_3$ with respect to $x$-Bjorken scale for different nuclei at $Q^2=10$ GeV$^2$.