Alternative way to understand the unexpected results of the JLab polarization experiments to measure the Sachs form factors ratio

Abstract

Alternative way to understand the unexpected results of the JLab polarization experiments to measure the Sachs form factors ratio In the one-photon exchange approximation we discuss questions related to the interpretation of unexpected results of the JLab polarization experiments to measure the Sachs form factors ratio GE/GM in the region 1.0 ≤ Q 2 ≤ 8.5 GeV 2 . For this purpose, we developed an approach which essentially is a generalization of the constituent-counting rules of the perturbative QCD (pQCD) for the case of massive quarks. We assume that at the lower boundary of the considered region the hard-scattering mechanism of pQCD is realized. Within the framework of the developed approach we calculated the hard kernel of the proton current matrix elements J ). This allows us to state that (i) around the lower boundary of the considered region, the leading scaling behavior of the Sachs form factors has the form GE, GM ∼ 1/Q 6 , (ii) the dipole dependence (GE, GM ∼ 1/Q 4 ) is realized in the asymptotic regime of pQCD when τ ≫ 1 (τ = Q 2 /4M 2 ) in the case when the quark transitions with spin-flip dominate, (iii) the asymptotic regime of pQCD in the JLab experiments has not yet been achieved, and (iv) the linear decrease of the ratio GE/GM at τ < 1 is due to additional contributions to J δ,δ p by spin-flip transitions of two quarks and an additional contribution to J −δ,δ p by spin-flip transitions of three quarks.

High energy hadron spin flip amplitude

“…In our HEGS model , which describes the maximum experimental data in a wide energy region from √ s = 9 GeV √ s = 8 TeV with minimum fitting parameters, the odderon has the same intercept as the standard soft Pomeron. Taking into account the form of the spin-flip amplitude, proposed in the works of Galynskii-Kuraev [38,39], the energy independence of the differential cross sections at large momentum transfer is explained by the contribution of the energy independent part of the spin-flip amplitude. The obtained size and momentum transfer dependence of the spin-flip amplitude allow one to describe the differential cross sections in the region of the diffraction minimum and at large momentum transfer.…”

“…In [38,39] on the basis of generalization of the constituent-counting rules of the perturbative QCD the proton current matrix elements J ±δδ p for the full set of spin combinations corresponding to the number of the spin-flipped quarks was calculated. It leads to part of the spin-flip amplitude…”

Possible Studies at the First Stage of the NICA Collider Operation with Polarized and Unpolarized Proton and Deuteron Beams

“…At large t our model calculations are extended up to −t = 15 GeV 2 . We added a small contribution of the energy independent part of the spin flip amplitude in the form similar to the proposed in [78] and analyzed in [14].…”

Froissaron and Maximal Odderon with spin-flip in $pp$ and $\bar pp$ high energy elastic scattering

“…Secondly, these measurements were made at low and middle energies. Nevertheless, the available data stimulate permanently the theoretical and phenomenological studies of spin phenomena in the regions of soft and hard kinematic were different approaches (nonperturbative approches from early [11] to relatively later and recent [6,[12][13][14][15], and perturbative QCD) are exploring [16].…”