Contribution to a conference proceedings/Contribution to a book

PUBDB-2022-03189

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Investigating the Compton amplitude subtraction function in lattice QCD

Hannaford-Gunn, A. (Corresponding author) ; Sankey, E. ; Can, K. U. ; Horsley, R. ; Perlt, H. ; Rakow, P. E. L. ; Schierholz, G.DESY* ; Stüben, H. ; Young, R. D. ; Zanotti, J. M. ; Sankey, E. ; Somfleth, K. ; CSSM/QCDSF/UKQCD Collaboration (Collaboration Author)

2022
Sissa Medialab Trieste, Italy

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Please use a persistent id in citations: doi:10.22323/1.396.0028  doi:10.3204/PUBDB-2022-03189

Report No.: ADP-22-24/T1195; DESY-22-108; LTH 1308; arXiv:2207.03040

Abstract: Theoretical predictions of the proton--neutron mass difference and measurements of the proton's charge radius require inputs from the Compton amplitude subtraction function. Model-dependent and non-relativistic calculations of this subtraction function vary significantly, and hence it contributes significant uncertainties to the aforementioned physical quantities. We report on the use of Feynman-Hellmann methods in lattice QCD to calculate the subtraction function from first principles. In particular, our initial results show anomalous high-energy behaviour that is at odds with the prediction from the operator product expansion (OPE). Therefore, we investigate the possibility that this unexpected behaviour is due to lattice artifacts, by varying the lattice spacing and volume, and comparing different discretisations of the vector current. Finally, we explore a Feynman-Hellmann implementation that is less sensitive to short-distance contributions and show that the subtraction function's anomalous behaviour can be attributed to these short-distance contributions. As such, this work represents the first steps in achieving a complete understanding of the Compton amplitude subtraction function.

Keyword(s): current, vector ; operator product expansion ; lattice field theory ; lattice ; high energy behavior ; nonrelativistic ; mass difference ; charge radius

Note: 13 pages, 6 figures. Contribution to the 38th International Symposium on Lattice Field Theory, LATTICE2021 26th-30th July, 2021 Zoom/Gather@Massachusetts Institute of Technology

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Contributing Institute(s):

1. Theorie-Gruppe (T)

Research Program(s):

1. 611 - Fundamental Particles and Forces (POF4-611) (POF4-611)

Experiment(s):

1. No specific instrument

Appears in the scientific report 2022

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