Fundamental physics and the absence of sub-millisecond pulsars B. Haskell, J. L. Zdunik, M. Fortin, M. Bejger, R. Wijnands and A. Patruno A&A, 620 (2018) A69 Published online: 04 December 2018 DOI: 10.1051/0004-6361/201833521