Improved limits on Fierz interference using asymmetry measurements from the Ultracold Neutron Asymmetry (UCNA) experiment
X. Sun, Evan Adamek, B. Allgeier, Yelena Bagdasarova, D. B. Berguno, M. Blatnik, T. J. Bowles, L. J. Broussard, Michael Brown, R. Carr, Steven Clayton, C. Cude-Woods, S. Currie, Eric Dees, Xuefeng Ding, B. W. Filippone, A. Garcı́a, P. Geltenbort, S. Hasan, K. P. Hickerson, J. Hoagland, R. Hong, A. T. Holley, T. M. Ito, A. Knecht, C.-Y. Liu, J. Liu, M. Makela, R. Mammei, Jean Martin, D. Melconian, M. P. Mendenhall, S. D. Moore, C. L. Morris, S. Nepal, Nima Nouri, R. W. Pattie, A. Pérez Galván, D. G. Phillips, R. Picker, M. L. Pitt, B. Plaster, D. J. Salvat, A. Saunders, E. I. Sharapov, Sky Sjue, S. Slutsky, W. E. Sondheim, Christopher Swank, E. Tatar, R. B. Vogelaar, B. VornDick, Z. Wang, W. Wei, J. Wexler, T. L. Womack, C. Wrede, A. R. Young, B. A. Zeck
Abstract
The UCNA Collaboration reanalyzed and combined results from previous experiments that measured the $\ensuremath{\beta}$-decay asymmetry for polarized ultracold neutrons confined in a trap in order to search for the so-called Fierz interference term. They demonstrate that systematic uncertainties from the asymmetry analysis related to the experimental efficiency and calibration can be reduced. This work suggests that a robust path forward to improved limits on the Fierz term in next-generation neutron-decay experiments exists and holds promise of providing an improved probe of whether physics beyond the Standard Model is at play.