Studies of Exotic Physics with Antiprotons and Protons

<!--HTML--><p class="western"><span><span><span><u><strong>S. Ulmer</strong></u> $^1$&nbsp;<strong>, F. Abbass</strong> $^2$<strong>&nbsp;</strong><strong>, </strong><strong>K. Blaum</strong> $^3$<strong>&nbsp;</strong><strong>, M. Bohman </strong>$^{1,3}$<strong>&nbsp;</strong><strong>, M. Borchert </strong>$^{1,4}$<strong>&nbsp;</strong><strong>, J. A. Devlin </strong>$^{1,5}$<strong>&nbsp;</strong><strong>, S. R. Erlewein&nbsp;</strong>$^{1,3,5}$,<strong> M. Fleck </strong>$^{1,6}$<strong>, J. I. Jaeger&nbsp;</strong>$^{1,3}$,<strong> B. M. Latacz </strong>$^{1}$<strong>, D. Popper </strong>$^2$<strong>, </strong><strong>C. Smorra </strong>$^{1,2}$<strong>, G. Umbrazunas </strong>$^{1,7}$<strong>, M. Wiesinger </strong>$^{1,3}$,<strong> C. Will </strong>$^{3}$<strong>, </strong><strong>E. J. Wursten </strong>$^{1,3}$<strong>,</strong><strong> </strong><strong>Y. Matsuda </strong>$^{6}$,<strong> C. Ospelkaus </strong>$^{4}$<strong>, W. Quint </strong>$^{7}$<strong>,</strong><strong>&nbsp;A. Soter </strong>$^{8}$&nbsp;<strong>, J. Walz </strong>$^{2}$&nbsp;<strong>, Y. Yamazaki </strong>$^{1}$</span></span></span></p> <p>$^{1}$<span><span><span><span>&nbsp;RIKEN, Ulmer Fundamental Symmetries Laboratory, Saitama, Japan; </span></span></span></span>$^{2}$&nbsp;<span><span><span><span>Johannes Gutenberg-Universität, Mainz, Germany; </span></span></span></span>$^{3}$<span><span><span><span>&nbsp;Max-Planck-Institut für Kernphysik, Heidelberg, Germany; $^{4}$&nbsp;PTB, Braunschweig, Germany; $^{5}$&nbsp;CERN, Geneva, Switzerland; $^{6}$&nbsp;The University of Tokyo, Tokyo, Japan; $^{7}$&nbsp;GSI - Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany; $^{8}$&nbsp;ETH, Zuerich, Switzerland;</span></span></span></span></p> <p>&nbsp;</p> <p><span><span>The Standard Model of particle physics is both incredibly successful and glaringly incomplete. Among the questions left open is the striking imbalance of matter and antimatter in our universe, which inspires experiments to compare the fundamental properties of matter/antimatter conjugates with high precision. The BASE collaboration at the antiproton decelerator of CERN is performing such high-precision comparisons with protons and antiprotons. Using advanced cryogenic Penning traps, we have performed the most precise measurement of the proton-to-antiproton charge-to-mass ratio with a fractional uncertainty of 69 parts per trillion (p.p.t.) [1], which was recently improved by a factor of four to 16 p.p.t.[2]. In another measurement, we have invented a novel spectroscopy method, that allowed for the first direct measurement of the antiproton magnetic moment with a fractional precision of 1.5 parts in a billion [3]. Together with our last measurement of the proton magnetic moment [4] this improves the precision of previous magnetic moment based tests of the fundamental CPT invariance [5] by more than a factor of 3000. A time series analysis of the sampled magnetic moment resonance furthermore enabled us to set first direct constraints on the interaction of antiprotons with axion-like particles (ALPs) [6], and most recently, we have used our ultra-sensitive single particle detection systems to derive narrow-band constraints on the conversion of ALPs into photons [7]. In my talk I will review the results produced by BASE since approval, with particular focus on the recent 16 p.p.t. comparison of the antiproton-to-proton charge-to-mass ratio. I will also outline strategies to further improve our high-precision studies of matter-antimatter symmetry. This outlook will include the implementation of sympathetic cooling of antiprotons using quantum logic methods, and the development of the transportable antiproton trap BASE-STEP. </span></span></p> <p><span><span>[1] S. Ulmer et al., Nature 524, 196 (2015).</span></span></p> <p><span><span>[2] M. J. Borchert et al., Nature 601, 35 (2022). </span></span></p> <p><span><span>[3] C. Smorra et al., Nature 550, 371 (2017). </span></span></p> <p><span><span>[4] G. Schneider et al., Science 358, 1081 (2017).</span></span></p> <p><span><span>[5] J. DiSciacca et al., Phys. Rev. Lett. 110, 130801 (2013).</span></span></p> <p><span><span>[6] C. Smorra et al., Nature 575, 310 (2019). </span></span></p> <p><span><span>[7] J. A. Devlin et al., Phys. Rev. Lett., accepted (2021). </span></span></p>