Speaker
Carlo Ewerz
(ExtreMe Matter Institute EMMI, GSI, and Heidelberg University)
Description
From the new measurement of F_L at HERA we derive fixed-Q^2 averages <F_L/F_2>. We compare these with bounds which are rigorous in the framework of the standard dipole picture. The bounds are sharpened by including information on the charm structure function F_2^(c). Within the experimental errors the bounds are respected by the data. But for 3.5 GeV^2 <= Q^2 <= 20 GeV^2 the central values of the data are close to and in some cases even above the bounds. Data on F_L/F_2 significantly exceeding the bounds would rule out the standard dipole picture at these kinematic points. We discuss, furthermore, what can be learned from data respecting the bounds but coming close to them.
Author
Carlo Ewerz
(ExtreMe Matter Institute EMMI, GSI, and Heidelberg University)
