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

(ProQuest: ... denotes formulae and/or non-USASCII text omitted)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 G sub(E)/G sub(M) in the region 1.0 < or =...

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Veröffentlicht in:Physical review. D, Particles, fields, gravitation, and cosmology Particles, fields, gravitation, and cosmology, 2014-03, Vol.89 (5), Article 054005
Hauptverfasser: Galynskii, M. V., Kuraev, E. A.
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Sprache:eng
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Zusammenfassung:(ProQuest: ... denotes formulae and/or non-USASCII text omitted)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 G sub(E)/G sub(M) in the region 1.0 < or = Q super(2) < or = 8.5 GeV super(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 ... for the full set of spin combinations corresponding to the number of the spin-flipped quarks, which contribute to the proton transition without spin-flip ... and with spin-flip ... 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 G sub(E), G sub(M) ~ 1/Q super(6), (ii) the dipole dependence (G sub(E), G sub(M) ~ 1/Q super(4)) is realized in the asymptotic regime of pQCD when [tau] " 1 ([tau] = Q super(2)/4M super(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 G sub(E)/G sub(M) at [tau] < 1 is due to additional contributions to ... by spin-flip transitions of two quarks and an additional contribution to ... by spin-flip transitions of three quarks.
ISSN:1550-7998
1550-2368
DOI:10.1103/PhysRevD.89.054005