Year: 2015
Type: article
Abstract: 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.
Source: Science
Authors: Sz. Borsanyi, S. Durr, Z. Fodor, C. Hoelbling, S. D. Katz, S. Krieg, L. Lellouch, T. Lippert, A. Portelli, K. K. Szabo, B. C. Toth
Institutions: University of Wuppertal, Forschungszentrum Jülich, Jülich Supercomputing Centre, Eötvös Loránd University, Hungarian Academy of Sciences, Centre National de la Recherche Scientifique, Université de Toulon, Aix-Marseille Université, Centre de Physique Théorique, University of Southampton
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: Deutsche Forschungsgemeinschaft, Agence Nationale de la Recherche, Partnership for Advanced Computing in Europe AISBL, Forschungszentrum Jülich, Magyar Tudományos Akadémia, Labex, Grand Équipement National De Calcul Intensif, Gauss Centre for Supercomputing, Leibniz-Gemeinschaft, Leibniz-Rechenzentrum, H2020 European Research Council
OpenAlex ID: W2071360735