Search for ultralight axion dark matter in a side-band analysis of a ${}^{199}$Hg free-spin precession signal
C. Abel, N. J. Ayres, G. Ban, G. Bison, K. Bodek, V. Bondar, E. Chanel, Christopher Crawford, M. Daum, B. Dechenaux, S. Emmenegger, P. Flaux, W. C. Griffith, Philip Harris, Y. Kermaidic, K. Kirch, S. Komposch, P. Koss, J. Krempel, B. Lauss, T. Lefort, P. Mohanmurthy, O. Naviliat Cuncic, D. Pais, F. M. Piegsa, Guillaume Pignol, M. Rawlik, D. Ries, Stéphanie Roccia, D. Rozpedzik, P. Schmidt-Wellenburg, N. Severijns, Yevgeny V Stadnik, Jacob Thorne, A. Weis, E. Wursten, J. Zejma, G. Zsigmond
Abstract
Ultra-low-mass axions are a viable dark matter candidate and may form a coherently oscillating classical field. Nuclear spins in experiments on Earth might couple to this oscillating axion dark-matter field, when propagating on Earth’s trajectory through our Galaxy. This spin coupling resembles an oscillating pseudo-magnetic field which modulates the spin precession of nuclear spins. Here we report on the null result of a demonstration experiment searching for a frequency modulation of the free spin-precession signal of 199Hg in a magnetic field. Our search covers the axion mass range 10^{-16} \textrm{eV} \lesssim m_a \lesssim 10^{-13} \textrm{eV} <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>16</mml:mn> </mml:mrow> </mml:msup> <mml:mspace width="0.222em"/> <mml:mtext mathvariant="normal">eV</mml:mtext> <mml:mo>≲</mml:mo> <mml:msub> <mml:mi>m</mml:mi> <mml:mi>a</mml:mi> </mml:msub> <mml:mo>≲</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>13</mml:mn> </mml:mrow> </mml:msup> <mml:mspace width="0.222em"/> <mml:mtext mathvariant="normal">eV</mml:mtext> </mml:mrow> </mml:math> and achieves a peak sensitivity to the axion-nucleon coupling of g_{aNN} \approx 3.5 \times 10^{-6} \textrm{GeV}^{-1} <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:msub> <mml:mi>g</mml:mi> <mml:mrow> <mml:mi>a</mml:mi> <mml:mi>N</mml:mi> <mml:mi>N</mml:mi> </mml:mrow> </mml:msub> <mml:mo>≈</mml:mo> <mml:mn>3.5</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>6</mml:mn> </mml:mrow> </mml:msup> <mml:mspace width="0.222em"/> <mml:msup> <mml:mtext mathvariant="normal">GeV</mml:mtext> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> .