
Ab initio calculation of the neutron-proton mass difference - chopin
http://www.sciencemag.org/content/347/6229/1452
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bwood
Paywalls are frustrating, especially when the content is available elsewhere
for free. Here's the paper on arXiv.org:
[http://arxiv.org/abs/1406.4088v1](http://arxiv.org/abs/1406.4088v1)

