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An experimental limit on the charge of antihydrogen

  • Author(s): Amole, C
  • Ashkezari, MD
  • Baquero-Ruiz, M
  • Bertsche, W
  • Butler, E
  • Capra, A
  • Cesar, CL
  • Charlton, M
  • Eriksson, S
  • Fajans, J
  • Friesen, T
  • Fujiwara, MC
  • Gill, DR
  • Gutierrez, A
  • Hangst, JS
  • Hardy, WN
  • Hayden, ME
  • Isaac, CA
  • Jonsell, S
  • Kurchaninov, L
  • Little, A
  • Madsen, N
  • McKenna, JTK
  • Menary, S
  • Napoli, SC
  • Nolan, P
  • Olchanski, K
  • Olin, A
  • Povilus, A
  • Pusa, P
  • Rasmussen, C
  • Robicheaux, F
  • Sarid, E
  • Silveira, DM
  • So, C
  • Tharp, TD
  • Thompson, RI
  • Van Der Werf, DP
  • Vendeiro, Z
  • Wurtele, JS
  • Zhmoginov, AI
  • Charman, AE
  • et al.
Abstract

The properties of antihydrogen are expected to be identical to those of hydrogen, and any differences would constitute a profound challenge to the fundamental theories of physics. The most commonly discussed antiatom-based tests of these theories are searches for antihydrogen-hydrogen spectral differences (tests of CPT (charge-parity-time) invariance) or gravitational differences (tests of the weak equivalence principle). Here we, the ALPHA Collaboration, report a different and somewhat unusual test of CPT and of quantum anomaly cancellation. A retrospective analysis of the influence of electric fields on antihydrogen atoms released from the ALPHA trap finds a mean axial deflection of 4.1±3.4mm for an average axial electric field of 0.51Vmm-1. Combined with extensive numerical modelling, this measurement leads to a bound on the charge Qe of antihydrogen of Q=(-1.3±1.1±0.4) × 10-8. Here, e is the unit charge, and the errors are from statistics and systematic effects. © 2014 Macmillan Publishers Limited. All rights reserved.

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