Forward doubly-virtual Compton scattering off the nucleon in chiral perturbation theory: The subtraction function and moments of unpolarized structure functions

Alarcón, Jose Manuel; Hagelstein, Franziska; Lensky, Vadim; Pascalutsa, Vladimir (2020). Forward doubly-virtual Compton scattering off the nucleon in chiral perturbation theory: The subtraction function and moments of unpolarized structure functions. Physical review. D - particles, fields, gravitation, and cosmology, 102(1), 014006. American Physical Society 10.1103/PhysRevD.102.014006

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The forward doubly-virtual Compton scattering (VVCS) off the nucleon contains a wealth of information on nucleon structure, relevant to the calculation of the two-photon-exchange effects in atomic spectroscopy and electron scattering. We report on a complete next-to-leading-order (NLO) calculation of low-energy VVCS in chiral perturbation theory (χPT). Here we focus on the unpolarized VVCS amplitudes T1ðν;Q2Þ and T2ðν;Q2Þ, and the corresponding structure functions F1ðx;Q2Þ and F2ðx;Q2Þ. Our results are confronted, where possible, with “data-driven” dispersive evaluations of low- energy structure quantities, such as nucleon polarizabilities. We find significant disagreements with dispersive evaluations at very low momentum-transfer Q; for example, in the slope of polarizabilities at zero momentum transfer. By expanding the results in powers of the inverse nucleon mass, we reproduce the known “heavy-baryon” expressions. This serves as a check of our calculation, as well as demonstrates the differences between the manifestly Lorentz-invariant (BχPT) and heavy-baryon (HBχPT) frameworks.

Item Type:

Journal Article (Original Article)

Division/Institute:

10 Strategic Research Centers > Albert Einstein Center for Fundamental Physics (AEC)
08 Faculty of Science > Institute of Theoretical Physics

UniBE Contributor:

Hagelstein, Franziska Elfriede

Subjects:

500 Science > 530 Physics

ISSN:

1550-7998

Publisher:

American Physical Society

Language:

English

Submitter:

Esther Fiechter

Date Deposited:

05 Aug 2020 15:49

Last Modified:

05 Aug 2020 15:49

Publisher DOI:

10.1103/PhysRevD.102.014006

ArXiv ID:

2005.09518

BORIS DOI:

10.7892/boris.145597

URI:

https://boris.unibe.ch/id/eprint/145597

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