%0 Journal Article
%A Borsanyi, S.
%A Durr, S.
%A Fodor, Z.
%A Hoelbling, C.
%A Katz, S. D.
%A Krieg, S.
%A Lellouch, L.
%A Lippert, T.
%A Portelli, A.
%A Szabo, Kalman
%A Toth, B. C.
%T Ab initio calculation of the neutron-proton mass difference
%J Science
%V 347
%N 6229
%@ 1095-9203
%C Washington, DC [u.a.]
%I American Association for the Advancement of Science64196
%M FZJ-2015-02252
%P 1452 - 1455
%D 2015
%Z Preprint: http://arxiv.org/abs/arXiv:1406.4088
%X The existence and stability of atoms rely on the fact that neutrons are more massive than protons. The measured mass difference is only 0.14% of the average of the two masses. A slightly smaller or larger value would have led to a dramatically different universe. Here, we show that this difference results from the competition between electromagnetic and mass isospin breaking effects. We performed lattice quantum-chromodynamics and quantum-electrodynamics computations with four nondegenerate Wilson fermion flavors and computed the neutron-proton mass-splitting with an accuracy of 300 kilo–electron volts, which is greater than 0 by 5 standard deviations. We also determine the splittings in the Σ, Ξ, D, and Ξcc isospin multiplets, exceeding in some cases the precision of experimental measurements.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000352136400034
%$ pmid:25814578
%R 10.1126/science.1257050
%U https://juser.fz-juelich.de/record/188968