QCD sum rules and neutron proton mass difference
Journal
Phys. Rev.
Journal Volume
D47
Pages
3001-3012
Date Issued
1993
Author(s)
Abstract
We use the method of QCD sum rules to investigate the neutron-proton mass difference. We include diagrams consistently up to dimension 9, assuming different up and down current-quark masses (mu md), and distinguish between 0|:uu:|0 and 0|:dd:|0, the condensates of the up and down quarks. Using the typical current-quark masses mu=5.1 MeV and md=8.9 MeV and the standard condensate values for average current-quark masses, we perform numerical analyses of the resultant QCD p and unity sum rules. In particular, numerical analyses of the difference equation from the p sum rules yield Mn-Mp=(1.350.24) MeV or (1.420.19) MeV, depending on the method of the analysis. Analogously, the difference equation from the unity sum rules yields Mn-Mp=(1.350.35) MeV or (0.950.25) MeV. These predictions are consistent among themselves and all are in reasonable agreement with the experimental value of 1.29 MeV. © 1993 The American Physical Society.
Type
journal article