Ab initio calculation of the neutron-proton mass difference

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...

Full description

Saved in:
Bibliographic Details
Published in:arXiv.org 2015-04
Main Authors: 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
Format: Article
Language:English
Subjects:
Atomic properties
Electrodynamics
Fermions
Flavor (particle physics)
Quantum chromodynamics
Universe
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary: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 \(\Xi_{cc}\) isospin multiplets, exceeding in some cases the precision of experimental measurements.
ISSN:2331-8422
DOI:10.48550/arxiv.1406.4088