Search

The $t$-dependence of generalized parton distrbutions for $x\to 1$ is discussed. We argue that constituent quark models, where the $t$-dependence for $x\to 1$ is through the product $(1-x)t$, are inconsistent. Instead we suggest a leading dependence in terms of $(1-x)^n t$, where $n\geq 2$, for $x\to 1$., Comment: 4 pages, revtex

We discuss some constraints on the $x$ and $t$-dependence of $E(x,0,t)$ that arise from positivity bounds in the impact parameter representation. In addition, we show that $E(x,0,0)$ for the nucleon vanishes for $x\to 1$ at least as rapidly as $(1-x)^4$. Finally we provide an inequality that limits the contribution from $E$ to the angular momentum sum rule., Comment: 3 pages

We express the correlation between quark transversity and (total) quark angular momentum in terms of the second moment of chirally odd generalized parton distributions. The resulting relation allows to determine how much quarks of a given transversity contribute to the total angular momentum of the nucleon.

For Nc→∞ the structure function of physical fermions in the Gross-Neveu model is of pure valence type. Nevertheless several strange form factors of u-quarks, including the induced magnetic moment and the σ-term acquire substantial O (N 0 c ) contributions from virtual s s pairs. Those arise from matrix elements which are off-diagonal in Fock space, i.e., they do not have a simple interpretation in terms of the quark distributions. It is shown that, under certain circumstances, a similar behavior in QCD3+1 is conceivable.