26-30 March 2012
University of Bonn
Europe/Berlin timezone

Physical Interpretation of Chiral Odd Generalized Parton Distributions from Deeply Virtual Meson Production

Not scheduled
Wolfgang Paul Lecture Hall (University of Bonn)

Wolfgang Paul Lecture Hall

University of Bonn

Kreuzbergweg 28, 53115 Bonn, Germany,
Spin physics


Simonetta Liuti (University of Virginia)


Exclusive $\pi^o$ electroproduction from nucleons was suggested in as a method for extracting from experiment the tensor charge, transversity and other quantities related to chiral odd combinations of generalized parton distributions. In this contribution we explain the details of the process: {\it i)} the connection between the helicity description and the cartesian basis; {\it ii)} the dependence on the momentum transfer squared, $Q^2$, and {\it iii)} the angular momentum, parity, and charge conjugation constraints ($J^{PC}$ quantum numbers). We also address the question of the physical interpretation of the chiral-odd GPDs. This issue is at variance with the chiral-even sector where the four chiral even GPDs correspond to a clear physical picture each one being normalized to the nucleon form factors describing its electroweak properties. In the chiral-odd sector, instead, only $H_T$ yields the transversity structure function, $h_1(x)$ in the forward limit, whereas no model independent connection with known form factors or structure functions exists for the other GPDs. While interesting connections to Transverse Momentum Distributions were established within a class of models, in this contribution we discuss a different perspective whereby using Parity transformations, and assuming the validity of the quark-diquark model, we can establish relations between the chiral-even and chiral-odd quark-proton helicity amplitudes.

Primary author

Simonetta Liuti (University of Virginia)

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