New Leading Contribution to Neutrinoless Double-β Decay

Area of Science:

• Nuclear Physics
• Particle Physics
• Quantum Field Theory

Background:

• Neutrinoless double-beta decay (0νββ) is a hypothetical process crucial for determining if neutrinos are Majorana particles.
• Current theoretical models of 0νββ decay often omit certain short-range contributions.
• Understanding the nature of neutrinos is a key goal in fundamental physics.

Purpose of the Study:

• To investigate the leading contributions to the neutrinoless double-beta decay transition operator induced by light Majorana neutrinos.
• To identify and incorporate a previously missing leading-order short-range operator in theoretical calculations.
• To explore methods for determining the parameters of this new operator and its impact on nuclear matrix elements.

Main Methods:

• Utilizing chiral effective field theory (ChEFT) as the theoretical framework.
• Applying renormalization arguments using dimensional regularization with minimal subtraction.
• Employing a coordinate-space cutoff scheme to analyze short-range contributions.
• Discussing matching to lattice quantum chromodynamics (QCD) and chiral symmetry relations.

Main Results:

• Demonstrated the necessity of a leading-order short-range operator in 0νββ decay calculations, which is absent in current models.
• Proposed strategies for determining the finite part of the short-range coupling constant.
• Identified potential connections to isospin-breaking observables in the two-nucleon sector.

Conclusions:

• The inclusion of the novel short-range operator is essential for accurate theoretical predictions of neutrinoless double-beta decay.
• Determining this operator's contribution will refine nuclear matrix element calculations.
• This work provides a pathway to more precise experimental interpretations and searches for new physics.