Speaker
Description
In this study, we have theoretically evaluated the polarized nucleon structure functions $g_{1N,2N}(x,Q^2)$, via longitudinally
polarized charged lepton induced deep inelastic scattering (DIS) off longitudinally polarized nucleon target~\cite{Zaidi:2024obq},
using DSSV14 parameterization~\cite{DeFlorian:2019xxt} for the polarized parton density distribution functions (PPDFs) in the 3-flavor ($u,d,s$) $\overline{\textrm{MS}}$ scheme at next-to-the-leading-order (NLO) incorporating the nonperturbative effects like
target mass correction (TMC) and twist-3 ($\tau=3$) corrections. Furthermore, the unpolarized nucleon structure functions $F_{1N, 2N}(x,Q^2)$ are also evaluated using
the MMHT PDFs parameterization~\cite{Harland-Lang:2014zoa} in the 3-flavor $\overline{\textrm{MS}}$ scheme, and by taking into account
the higher order perturbative evolution of parton densities upto NLO and the nonperturbative QCD corrections viz. TMC
and higher twist (HT: $\tau=4$) effects~\cite{Zaidi:2019mfd}.
These unpolarized structure functions are required to study the nucleon spin asymmetries: {\bf (i)}
$A_{1N}(x,Q^2)\Big(=\frac{g_{1N}(x,Q^2)-\gamma^2\;g_{2N}(x,Q^2)}{F_{1N}(x,Q^2)};\;\gamma=\sqrt{\frac{4M^2 x^2}{Q^2}}\Big)$ which is important to understand the role of valence quarks and
their orbital angular momentum contribution to the proton spin,
and {\bf (ii)} $A_{2N}(x,Q^2)\Big(=\frac{\gamma\;\big(g_{1N}(x,Q^2)+g_{2N}(x,Q^2)\big)}{F_{1N}(x,Q^2)}\Big)$ that is important to obtain the information about
the transverse polarization of quark spins. Moreover, we have studied the model dependence of $g_{1N,2N}(x,Q^2)$ and $F_{1N,2N}(x,Q^2)$ using various PDFs parameterizations available
in the literature as well as analyze the effect of the center of mass energy ($W$) cut required to demarcate the
resonance production and deep inelastic regions. The obtained numerical results for
$g_{1N,2N}(x,Q^2)$ and $A_{1N,2N}(x,Q^2)$ have been compared
with some of the experimental results from SLAC, DESY, JLab and CERN collaborations and will be presented in the
forthcoming DAE High Energy Physics Symposium'2024. This study shed light on how the higher order perturbative and
nonperturbative corrections impact the quark parton model (QPM) results for $g_{1N,2N}(x,Q^2)$ and $A_{1N,2N}(x,Q^2)$. This work may also be useful to
understand the contribution of polarized quarks and antiquarks in consituting the nucleon spin as well as the anticipated
experimental results from JLab, EIC, and CERN collaborations in the wide range of $x$ and $Q^2$.
| Field of contribution | Theory |
|---|
