# Status of the experimental studies on DVMP and 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.

- Authors:

- Publication Date:

- Research Org.:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

- Sponsoring Org.:
- USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)

- Contributing Org.:
- CLAS Collaboration

- OSTI Identifier:
- 1574400

- Report Number(s):
- JLAB-PHY-18-2890; DOE/OR/23177-4613; arXiv:1902.02643

- DOE Contract Number:
- AC05-06OR23177

- Resource Type:
- Conference

- Journal Name:
- Proceedings of Science, SPIN2018

- Additional Journal Information:
- Conference: SPIN2018, 10-14 Sep 2018. Ferrara, Italy

- Country of Publication:
- United States

- Language:
- English

### Citation Formats

```
Kubarovsky, Valery.
```*Status of the experimental studies on DVMP and transversity GPDs*. United States: N. p., 2019.
Web. doi:10.22323/1.346.0075.

```
Kubarovsky, Valery.
```*Status of the experimental studies on DVMP and transversity GPDs*. United States. doi:10.22323/1.346.0075.

```
Kubarovsky, Valery. Mon .
"Status of the experimental studies on DVMP and transversity GPDs". United States. doi:10.22323/1.346.0075. https://www.osti.gov/servlets/purl/1574400.
```

```
@article{osti_1574400,
```

title = {Status of the experimental studies on DVMP and transversity GPDs},

author = {Kubarovsky, Valery},

abstractNote = {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.},

doi = {10.22323/1.346.0075},

journal = {Proceedings of Science, SPIN2018},

number = ,

volume = ,

place = {United States},

year = {2019},

month = {8}

}