Michael L. Wagman

Isotensor Axial Polarizability and Lattice QCD Input for Nuclear Double-β Decay Phenomenology

The potential importance of short-distance nuclear effects in double-β decay is assessed using a lattice QCD calculation of the nn→pp transition and effective field theory methods. At the unphysical quark masses used in the numerical computation, these effects, encoded in the isotensor axial polarizability, are found to be of similar magnitude to the nuclear modification of the single axial current, which phenomenologically is the quenching of the axial charge used in nuclear many-body calculations. This finding suggests that nuclear models for neutrinoful and neutrinoless double-β decays should incorporate this previously neglected contribution if they are to provide reliable guidance for next-generation neutrinoless double-β decay searches. The prospects of constraining the isotensor axial polarizabilities of nuclei using lattice QCD input into nuclear many-body calculations are discussed.

Double- β decay matrix elements from lattice quantum chromodynamics

A lattice quantum chromodynamics (LQCD) calculation of the nuclear matrix element relevant to the

Perturbative renormalization of neutron-antineutron operators

nn\to ppee\overline{\nu}_e\overline{\nu}_e

Exponential reduction of finite volume effects with twisted boundary conditions

transition is described in detail, expanding on the results presented in Ref. [1]. This matrix element, which involves two insertions of the weak axial current, is an important input for phenomenological determinations of double-

Life Outside the Golden Window: Statistical Angles on the Signal-to-Noise Problem

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Axial-Current Matrix Elements in Light Nuclei from Lattice QCD

decay rates of nuclei. From this exploratory study, performed using unphysical values of the quark masses, the long-distance deuteron-pole contribution to the matrix element is separated from shorter-distance hadronic contributions. This polarizability, which is only accessible in double-weak processes, cannot be constrained from single-

Neutron-Antineutron Operator Renormalization

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Proton-Proton Fusion and Tritium β Decay from Lattice Quantum Chromodynamics

decay of nuclei, and is found to be smaller than the long-distance contributions in this calculation, but non-negligible. In this work, technical aspects of the LQCD calculations, and of the relevant formalism in the pionless effective field theory, are described. Further calculations of the isotensor axial polarizability, in particular near and at the physical values of the light-quark masses, are required for precise determinations of both two-neutrino and neutrinoless double-

Nuclear modification of scalar, axial and tensor charges from lattice QCD.

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Statistics of baryon correlation functions in lattice QCD

decay rates in heavy nuclei.