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 0.51Vmm1. 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.
Amole, C.Ashkezari, M. D.Baquero-Ruiz, M.Bertsche, W.Butler, E.Capra, A.Cesar, C. L.Charlton, M.Eriksson, S.Fajans, J.Friesen, T.Fujiwara, M. C.Gill, D. R.Gutierrez, A.Hangst, J. S.Hardy, W. N.Hayden, M. E.Isaac, C. A.Jonsell, SvanteKurchaninov, L.Little, A.Madsen, N.McKenna, J. T. K.Menary, S.Napoli, S. C.Nolan, P.Olchanski, K.Olin, A.Povilus, A.Pusa, P.Rasmussen, C. O.Robicheaux, F.Sarid, E.Silveira, D. M.So, C.Tharp, T. D.Thompson, R. I.van der Werf, D. P.Vendeiro, Z.Wurtele, J. S.Zhmoginov, A. I.Charman, A. E.