# Status of the Experimental Studies on DVMP and Transversity GPDs

## TL;DR

This paper reports on experimental measurements of exclusive meson electroproduction at Jefferson Lab, providing new insights into transversity GPDs and their flavor decomposition, including the first demonstration of this decomposition for certain GPDs.

## Contribution

It presents the first direct extraction and flavor decomposition of transversity GPDs from experimental data on $
ho^0$ and $
ho^+$ meson production, advancing understanding of nucleon spin structure.

## Key findings

- Transversity GPDs dominate at low momentum transfer.
- First direct extraction of generalized form factors for transversity GPDs.
- Demonstration of flavor decomposition of transversity GPDs.

## Abstract

The cross section of the exclusive $\pi^0$ and $\eta$ electroproduction reaction $ep\to e^\prime p^\prime \pi^0/\eta$ was measured at Jefferson Lab with a 5.75-GeV electron beam and the CLAS detector. Differential cross sections $d^4\sigma/dtdQ^2dx_Bd\phi$ and structure functions $\sigma_U = \sigma_T+\epsilon\sigma_L, \sigma_{TT}$ and $\sigma_{LT}$, as functions of $t$ were obtained over a wide range of $Q^2$ and $x_B$. At low $t$, both $\pi^0$ and $\eta$ are described reasonably well by Generalized Parton Distributions (GPDs) in which chiral-odd transversity GPDs are dominant. Generalized form factors of the transversity GPDs $\langle H_T \rangle^{\pi,\eta}$ and $\langle \bar{E}_T \rangle^{\pi,\eta}$ were directly extracted from the experimental observables. The combined $\pi^0$ and $\eta$ data opens the way for the flavor decomposition of the transversity GPDs. The first ever demonstration of this decomposition was done for the transversity GPDs $H_T$ and $\bar E_T$. GPD $\bar E_T$ is connected with the density of the polarized quarks in an unpolarized nucleon in the impact parameter space. The spin density of polarized $u$ and $d$-quarks was evaluated for different values of Feynman $x$ from the GPD model tuned to described the experimental data.