Impact of nuclear dependence of R=\sigma_L/\sigma_T on antishadowing in nuclear structure functions

TL;DR

This paper investigates how the nuclear dependence of the ratio R affects the extraction of nuclear structure functions, revealing that antishadowing is mainly driven by the longitudinal structure function F_L and highlighting the importance of precise measurements for understanding nuclear gluon distributions.

Contribution

It demonstrates that nuclear dependence of R influences the observed antishadowing effect and emphasizes the potential of precise R and F_L measurements to constrain nuclear gluon distributions.

Findings

Antishadowing for F_1^A/F_1^D is reduced or disappears in 0.1<x<0.3.

F_1^A/F_1^D < \sigma^A/\sigma^D extless F_2^A/F_2^D.

Antishadowing is dominated by the longitudinal structure function F_L.

Abstract

We study the impact of the nuclear dependence of R=\sigma_L/\sigma_T on the extraction of the F_2^A/F_2^D and F_1^A/F_1^D structure function ratios from the data on the \sigma^A/\sigma^D cross section ratios. Guided by indications of the nuclear dependence of R from the world data, we examine selected sets of EMC, BCDMS, NMC and SLAC data and find that F_1^A/F_1^D < \sigma^A/\sigma^D \leq F_2^A/F_2^D. In particular, we observe that the nuclear enhancement (antishadowing) for F_1^A/F_1^D in the interval 0.1 < x < 0.3 becomes significantly reduced or even disappears, which indicates that antishadowing is dominated by the longitudinal structure function F_L. We also argue that precise measurements of nuclear modifications of R and F_L^A have the potential to constrain the poorly known gluon distribution in nuclei over a wide range of x.