Nucleon Anomalous Moments via Pion-Pion Attraction

Abstract

The importance of a pion-pion attraction for calculating nucleon anomalous moments is emphasized. It is found that reasonably strong pion-pion attraction is capable of giving large enough moments, even if the mirror condition of Sachs is imposed. It is pointed out that many effects, such as core recoil, interaction currents, and excited cores offer no relief in calculating large enough moments.

Electromagnetic pion and kaon form factors in light-cone resummed perturbative QCD

“…For large Q 2 , the asymptotic scaling behavior F M ðQ 2 Þ $ 1=Q 2 follows from the well-known dimensional ''quark counting,'' while for small Q 2 , the behavior is well described by the vector meson dominance (VMD) model [43][44][45] and is given by…”

Mesonic form factors

“…We can also see from Z (1) S that the smeared pseudoscalar operator has a strong overlap with the zero momentum pion but that the overlap diminishes rapidly with increasing momenta. From Z S we see that the smeared axial-vector operator has good overlap over a wide range of non-zero momenta, with maximal overlap around ap ∼ 0.5.…”

The Pion Form Factor at Large Momentum Transfer

“…There are several reasons: First, the asymptotic forms of the pion form factor at both large and small Q 2 are known. At large Q 2 it scales as [1,2,3,4,5,6,7,8,9] F π (Q 2 ) = 8πα s (Q 2 ) f 2 π Q 2 as Q 2 → ∞ (1.1) while at small Q 2 , the pion form factor can be well described by the Vector Meson Dominance (VMD) Model [10,11,12] F π (Q 2 ) ≈ 1 1 + Q 2 m 2 VMD for Q 2 m 2 VMD (1.2) Therefore at some Q 2 there must be a transition from the VMD behavior to the large Q 2 scaling predicted by pQCD. Since the pion is the lightest hadron, the transition is expected to occur at lower Q 2 than heavier hadrons, which makes it relatively easier to probe by both experiments and Lattice QCD (LQCD).…”

“…while at small Q 2 , the pion form factor can be well described by the Vector Meson Dominance (VMD) Model [10,11,12]…”