Cirigliano, Vincenzo; Dekens, Wouter; de Vries, Jordy; Hoferichter, Martin; Mereghetti, Emanuele (2021). Determining the leading-order contact term in neutrinoless double β decay. Journal of High Energy Physics, 2021(5) Springer 10.1007/JHEP05(2021)289
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Cirigliano2021_Article_DeterminingTheLeading-orderCon.pdf - Published Version Available under License Creative Commons: Attribution (CC-BY). Download (2MB) | Preview |
We present a method to determine the leading-order (LO) contact term con- tributing to the nn → ppe−e− amplitude through the exchange of light Majorana neutrinos. Our approach is based on the representation of the amplitude as the momentum integral of a known kernel (proportional to the neutrino propagator) times the generalized forward Compton scattering amplitude n(p1)n(p2)W+(k) → p(p′1)p(p′2)W−(k), in analogy to the Cottingham formula for the electromagnetic contribution to hadron masses. We construct model-independent representations of the integrand in the low- and high-momentum regions, through chiral EFT and the operator product expansion, respectively. We then construct a model for the full amplitude by interpolating between these two regions, using appropriate nucleon factors for the weak currents and information on nucleon-nucleon (NN) scattering in the 1S0 channel away from threshold. By matching the amplitude ob- tained in this way to the LO chiral EFT amplitude we obtain the relevant LO contact term and discuss various sources of uncertainty. We validate the approach by computing the analog I = 2 NN contact term and by reproducing, within uncertainties, the charge- independence-breaking contribution to the 1S0 NN scattering lengths. While our analysis is performed in the MS scheme, we express our final result in terms of the scheme-independent renormalized amplitude Aν(|p|,|p′|) at a set of kinematic points near threshold. We illustrate for two cutoff schemes how, using our synthetic data for Aν, one can determine the contact-term contribution in any regularization scheme, in particular the ones employed in nuclear-structure calculations for isotopes of experimental interest.
Item Type: |
Journal Article (Original Article) |
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Division/Institute: |
10 Strategic Research Centers > Albert Einstein Center for Fundamental Physics (AEC) 08 Faculty of Science > Institute of Theoretical Physics |
UniBE Contributor: |
Hoferichter, Martin |
Subjects: |
500 Science > 530 Physics |
ISSN: |
1029-8479 |
Publisher: |
Springer |
Language: |
English |
Submitter: |
Esther Fiechter |
Date Deposited: |
21 Jun 2021 14:51 |
Last Modified: |
05 Dec 2022 15:51 |
Publisher DOI: |
10.1007/JHEP05(2021)289 |
ArXiv ID: |
2102.03371 |
BORIS DOI: |
10.48350/156981 |
URI: |
https://boris.unibe.ch/id/eprint/156981 |
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