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Constraining interactions mediated by axion-like particles with ultracold neutrons

Abstract : We report a new limit on a possible short range spin-dependent interaction from the precise measurement of the ratio of Larmor precession frequencies of stored ultracold neutrons and Hg-199 atoms confined in the same volume. The measurement was performed in a similar to 1 mu T vertical magnetic holding field with the apparatus searching for a permanent electric dipole moment of the neutron at the Paul Scherrer Institute. A possible coupling between freely precessing polarized neutron spins and unpolarized nucleons of the wall material can be investigated by searching for a tiny change of the precession frequencies of neutron and mercury spins. Such a frequency change can be interpreted as a consequence of a short range spin-dependent interaction that could possibly be mediated by axions or axion-like particles. The interaction strength is proportional to the CP violating product of scalar and pseudoscalar coupling constants g(S)g(P). Our result confirms limits from complementary experiments with spin-polarized nuclei in a model-independent way. Limits from other neutron experiments are improved by up to two orders of magnitude in the interaction range of 10(-6) < lambda < 10(-4) m. (C) 2015 The Authors. Published by Elsevier B.V.
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Submitted on : Friday, June 12, 2015 - 11:49:54 AM
Last modification on : Wednesday, September 16, 2020 - 5:43:41 PM
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S. Afach, G. Ban, G. Bison, K. Bodek, M. Burghoff, et al.. Constraining interactions mediated by axion-like particles with ultracold neutrons. Physics Letters B, Elsevier, 2015, 745, pp.58-63. ⟨10.1016/j.physletb.2015.04.024⟩. ⟨in2p3-01158512⟩



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