Abstract
We present an exploratory lattice QCD calculation of the neutrinoless double beta decay ππ→ee. Under the mechanism of light-neutrino exchange, the decay amplitude involves significant long-distance contributions. The calculation reported here, with pion masses m_{π}=420 and 140MeV, demonstrates that the decay amplitude can be computed from first principles using lattice methods. At unphysical and physical pion masses, we obtain that amplitudes are 24% and 9% smaller than the predication from leading order chiral perturbation theory. Our findings provide the lattice QCD inputs and constraints for effective field theory. A follow-on calculation with fully controlled systematic errors will be possible with adequate computational resources.
Highlights
Introduction.—It is a fundamental question whether the neutrinos are Dirac or Majorana-type fermions
According to the lightneutrino exchange mechanism, the observation of 0ν2β decay would give us information about the absolute neutrino mass, which oscillation experiments cannot predict
We find that the decay amplitude receives dominant long-distance contributions from the eνπ intermediate state
Summary
2 ud d4xHμνðxÞLμνðxÞ; ð3Þ where the hadronic factor HμνðxÞ 1⁄4 T1⁄2JμLðxÞJνLð0Þ with JμLðxÞ 1⁄4 u LγμdLðxÞ. While the condition of jp⃗ 1 − p⃗ 2j=kF ≪ 1 is no more valid, we target on the determination of the amplitude given in Eq (9), which is more relevant for chiral effective field theory inputs to ab initio many-body calculation [18]. We use the discrete lattice momenta ð2π=LÞm⃗ for the intermediate hadronic particles and the momenta p⃗ ν;i 1⁄4 −p⃗ i − ð2π=LÞm⃗ for the intermediate neutrino, where p⃗ i is the momentum carried by the electron. P≠ N0⃗ r) r1⁄41 of the propagator can be conφrðxÞφÃrðyÞ using the stochastic method, with φrðxÞ pffi1ffiffiffiffiffi VT q⃗ ≠0⃗ ;qt qffiqffiffitffi2ffiffiξffiþffirffiffiðffiffiqPffiffiÞffiffieffiiffiffiqiffiqffiiffixd ffiffiþffiffiffiffikffiffiffiiffi2ffi
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
