Status of the experimental studies on DVMP and transversity GPDs
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.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Nuclear Physics (NP)
- Contributing Organization:
- CLAS Collaboration
- DOE Contract Number:
- AC05-06OR23177
- OSTI ID:
- 1574400
- Report Number(s):
- JLAB-PHY-18-2890; DOE/OR/23177-4613; arXiv:1902.02643
- Journal Information:
- Proceedings of Science, SPIN2018, Conference: SPIN2018, 10-14 Sep 2018. Ferrara, Italy
- Country of Publication:
- United States
- Language:
- English
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