Ab initio calculation of the neutron-proton mass difference

2014/06/30 by Sz. Borsanyi, S. Durr, Z. Fodor +8 · 1 citation
Physics and Astronomy · #hep-lat #hep-ph #nucl-th

paper · pdf · doi:10.1126/science.1257050

published as Science 347:1452-1455,2015 · 57 pages, 15 figures, 6 tables, revised version

arxiv created 2015/04/07 · arxiv updated 2015/04/08

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 Ξ_cc isospin multiplets, exceeding in some cases the precision of experimental measurements.

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• Neural-Accelerated Bayesian Calibration of Chiral Mean-Field Models to Nuclear Saturation and Vacuum Properties

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