학술논문
Search for an interaction mediated by axion-like particles with ultracold neutrons at the PSI
Document Type
Working Paper
Author
Ayres, N. J.; Bison, G.; Bodek, K.; Bondar, V.; Bouillaud, T.; Chanel, E.; Chiu, P. -J.; Clement, B.; Crawford, C. B.; Daum, M.; Doorenbos, C. B.; Emmenegger, S.; Fertl, M.; Flaux, P.; Griffith, W. C.; Harris, P. G.; Hild, N.; Kasprzak, M.; Kirch, K.; Kletzl, V.; Koss, P. A.; Krempel, J.; Lauss, B.; Lefort, T.; Mohanmurthy, P.; Naviliat-Cuncic, O.; Pais, D.; Piegsa, F. M.; Pignol, G.; Rawlik, M.; Rienäcker, I.; Ries, D.; Roccia, S.; Rozpedzik, D.; Schmidt-Wellenburg, P.; Severijns, N.; Shen, B.; Svirina, K.; Dinani, R. Tavakoli; Thorne, J. A.; Touati, S.; Weis, A.; Wursten, E.; Yazdandoost, N.; Zejma, J.; Ziehl, N.; Zsigmond, G.
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Abstract
We report on a search for a new, short-range, spin-dependent interaction using a modified version of the experimental apparatus used to measure the permanent neutron electric dipole moment at the Paul Scherrer Institute. This interaction, which could be mediated by axion-like particles, concerned the unpolarized nucleons (protons and neutrons) near the material surfaces of the apparatus and polarized ultracold neutrons stored in vacuum. The dominant systematic uncertainty resulting from magnetic-field gradients was controlled to an unprecedented level of approximately 4 pT/cm using an array of optically-pumped cesium vapor magnetometers and magnetic-field maps independently recorded using a dedicated measurement device. No signature of a theoretically predicted new interaction was found, and we set a new limit on the product of the scalar and the pseudoscalar couplings $g_sg_p\lambda^2 < 8.3 \times 10^{-28}\,\text{m}^2$ (95% C.L.) in a range of $5\,\mu\text{m} < \lambda < 25\,\text{mm}$ for the monopole-dipole interaction. This new result confirms and improves our previous limit by a factor of 2.7 and provides the current tightest limit obtained with free neutrons.