Speaker
Simonetta Liuti
(University of Virginia)
Description
We propose a physically motivated parametrization for the unpolarized Generalized Parton Distributions (GPDs), H and E, valid at both zero and non-zero values of the skewness variable, zeta. We start from a detailed study of the zeta = 0 case where H and E are determined using constraints from simultaneous fits of experimental data on both the nucleon elastic form factors and the deep inelastic structure functions [1]. Lattice calculations of the higher moments of GPDs [2,3] allow us in principle to constrain the parametrization at zeta > 0. Since lattice calculations are at present limited to large quark masses, we extrapolate to the chiral limit by using the technique devised in [4] to obtain the nucleon form factor dipole masses. We then perform a reconstruction of the GPDs using Bernstein polynomials. The inclusion in our fit, of recent precise Jefferson Lab data on Deeply Virtual Compton Scattering [5] is also discussed. Our method provides an alternative to the mathematical ansatz of double distributions in that GPDs are generated from direct constraints from experimental data combined with lattice calculations.
[1] S. Ahmad, H. Honkanen, S. Liuti and S. K. Taneja, submitted to Phys.Rev. D, arXiv:hepph/ 0611046.
[2] M. Gockeler et al. [QCDSF Collaboration], Phys. Lett. B 627, 113 (2005).
[3] P. Hagler, J. Negele, D. B. Renner, W. Schroers, T. Lippert and K. Schilling [LHPC collaboration], Phys. Rev. D 68, 034505 (2003).
[4] J. D. Ashley, D. B. Leinweber, A. W. Thomas and R. D. Young, Eur. Phys. J. A 19, 9 (2004)
[5] C. Munoz Camacho et al. [Jeㄦson Lab Hall A Collaboration], arXiv:nucl-ex/0607029.
[6] F. J. Yndurain, Phys. Lett. B 74, 68 (1978).
Author
Simonetta Liuti
(University of Virginia)
