TRANSVERSE CHARGE AND MAGNETIZATION DENSITIES IN THE NUCLEON'S CHIRAL PERIPHERY

In the light–front description of nucleon structure the electromagnetic form factors are expressed in terms of frame–independent transverse densities of charge and magnetization. Recent work has studied the transverse densities at peripheral distances [Formula: see text], where they are governed by universal chiral dynamics and can be computed in a model–independent manner. Of particular interest is the comparison of the peripheral charge and magnetization densities. We summarize (a) their interpretation as spin–independent and –dependent current matrix elements; (b) the leading–order chiral effective field theory results; (c) their mechanical interpretation in the light–front formulation; (d) the large–Nc limit of QCD and the role of Δ intermediate states; (e) the connection with generalized parton distributions and peripheral high–energy scattering processes.

Download Full-text

Accurate nucleon electromagnetic form factors from dispersively improved chiral effective field theory

Physics Letters B ◽

10.1016/j.physletb.2018.07.060 ◽

2018 ◽

Vol 784 ◽

pp. 373-377 ◽

Cited By ~ 12

Author(s):

J.M. Alarcón ◽

C. Weiss

Keyword(s):

Field Theory ◽

Effective Field Theory ◽

Form Factors ◽

Effective Field ◽

Electromagnetic Form Factors ◽

Chiral Effective Field Theory

Download Full-text

Isovector axial form factors of the nucleon in two-flavor lattice QCD

International Journal of Modern Physics A ◽

10.1142/s0217751x1950009x ◽

2019 ◽

Vol 34 (02) ◽

pp. 1950009 ◽

Cited By ~ 23

Author(s):

S. Capitani ◽

M. Della Morte ◽

D. Djukanovic ◽

G. M. von Hippel ◽

J. Hua ◽

...

Keyword(s):

Excited State ◽

Axial Vector ◽

Form Factors ◽

Heavy Baryon ◽

Axial Current ◽

Effective Field ◽

Chiral Effective Field Theory ◽

Axial Charge ◽

Systematic Uncertainties ◽

Axial Form

We present a lattice calculation of the nucleon isovector axial and induced pseudoscalar form factors on the CLS ensembles using [Formula: see text] dynamical flavors of nonperturbatively [Formula: see text]-improved Wilson fermions and an [Formula: see text]-improved axial current together with the pseudoscalar density. Excited-state effects in the extraction of the form factors are treated using a variety of methods, with a detailed discussion of their respective merits. The chiral and continuum extrapolation of the results is performed both using formulae inspired by Heavy Baryon Chiral Perturbation Theory (HBChPT) and a global approach to the form factors based on a chiral effective field theory (EFT) including axial vector mesons. Our results indicate that careful treatment of excited-state effects is important in order to obtain reliable results for the axial form factors of the nucleon, and that the main remaining error stems from the systematic uncertainties of the chiral extrapolation. As final results, we quote [Formula: see text], [Formula: see text], and [Formula: see text] for the axial charge, axial charge radius and induced pseudoscalar charge, respectively, where the first error is statistical and the second is systematic.

Download Full-text