Precise β-decay calculations for experiments searching for new physics

  Ayala Glick-Magid [1]  ,  Doron Gazit [1]  ,  Christian Forssen [2]  ,  Daniel Gazda [3]  ,  Peter Gysbers [4,5]  ,  Petr Navratil [4]  ,  Javier Menendez [6]  ,  Yonatan Mishnayot [1,7]  ,  Guy Ron [1]  
[1] Hebrew University of Jerusalem
[2] Chalmers University of Technology
[3] UJF Rez
[5] University of British Columbia
[6] University of Barcelona
[7] Soreq Nuclear Research Center

New β-decay precision experiments provide a robust test for the existence of exotic interactions beyond the Standard Model of Particle Physics. To do so, however, they must be compared with highly accurate predictions, requiring very precise calculations of high-order nuclear effects. Using many-body calculations of the nuclear structure, within a novel formalism we developed, we present the needed accurate predictions for the observables of nuclei being measured.

Following its role in several ongoing or soon-to-be initiated precision β-decay experiments, we compute the nuclear structure corrections for the 6He β-decay. They are obtained by calculating wave functions using an ab-initio no-core shell model, with potentials derived from chiral effective field theory interactions. Applied within the impulse approximation, and augmented with an analysis of relevant uncertainties, we show that these nuclear corrections produce significant deviations from the pure Gamow-Teller predictions – within the sensitivity of future experiments – making their accurate assessment essential in searches for BSM physics.

For 23Ne, using gold-standard shell model interactions in the sd-shell, and together with new branching ratio measurements of 23Ne in SARAF accelerator, Israel, we reanalyze experimental data and establish new bounds on the presence of exotic BSM tensor interactions, and pave the way for new, even higher precision, experiments.



  1. A. Glick-Magid, D. Gazit, A formalism to assess the accuracy of nuclear structure weak interaction effects in precision β-decay studies, arXiv:2107.10588 (2021)
  2. A. Glick-Magid, C. Forssén, D. Gazda, D. Gazit, P. Gysbers, P. Navrátil, Nuclear ab initio calculations of 6He β-decay for beyond the standard model studies, arXiv:2107.10212 (2021)
  3. Y. Mishnayot, A. Glick-Magid, H. Rahangdale, G. Ron, D. Gazit, J. T. Harke, M. Hass, B. Ohayon, A. Gallant, N. D. Scielzo, S. Vaintruab, R. O. Hughes, T. Hirsch, C. Forssén, D. Gazda, P. Gysbers, J. Menéndez, P. Navrátil, L. Weissman, A. Kreisel, B. Kaizer, H. Daphna, M. Buzaglo, Constraining new physics with a novel measurement of the 23Ne β-decay branching ratio, arXiv:2107.14355 (2021)