Publikationsdatum:
2015-03-31
Beschreibung:
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 Sigma, Xi, D, and Xicc isospin multiplets, exceeding in some cases the precision of experimental measurements.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Borsanyi, Sz -- Durr, S -- Fodor, Z -- Hoelbling, C -- Katz, S D -- Krieg, S -- Lellouch, L -- Lippert, T -- Portelli, A -- Szabo, K K -- Toth, B C -- New York, N.Y. -- Science. 2015 Mar 27;347(6229):1452-5. doi: 10.1126/science.1257050.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics, University of Wuppertal, D-42119 Wuppertal, Germany. ; Department of Physics, University of Wuppertal, D-42119 Wuppertal, Germany. Julich Supercomputing Centre, Forschungszentrum Julich, D-52428 Julich, Germany. ; Department of Physics, University of Wuppertal, D-42119 Wuppertal, Germany. Julich Supercomputing Centre, Forschungszentrum Julich, D-52428 Julich, Germany. Institute for Theoretical Physics, Eotvos University, H-1117 Budapest, Hungary. fodor@bodri.elte.hu. ; Institute for Theoretical Physics, Eotvos University, H-1117 Budapest, Hungary. Lendulet Lattice Gauge Theory Research Group, Magyar Tudomanyos Akademia-Eotvos Lorand University, H-1117 Budapest, Hungary. ; CNRS, Aix-Marseille Universite, Universite de Toulon, CPT UMR 7332, F-13288, Marseille, France. ; CNRS, Aix-Marseille Universite, Universite de Toulon, CPT UMR 7332, F-13288, Marseille, France. School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25814578" target="_blank"〉PubMed〈/a〉
Print ISSN:
0036-8075
Digitale ISSN:
1095-9203
Thema:
Biologie
,
Chemie und Pharmazie
,
Informatik
,
Medizin
,
Allgemeine Naturwissenschaft
,
Physik
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