QCD sum rules and neutron-proton mass difference

Journal Article · Thu Apr 01 04:00:00 EST 1993 · Physical Review, D (Particles Fields); (United States)

DOI:https://doi.org/10.1103/PhysRevD.47.3001· OSTI ID:6655702

Yang, K; Hwang, W P ^[1]; Henley, E M ^[2]; Kisslinger, L S ^[3]

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1. Department of Physics, National Taiwan University, Taipei, Taiwan 10764 (Taiwan, Province of China)
2. Department of Physics FM-15, University of Washington, Seattle, Washington 98195 (United States)
3. Department of Physics, Carnegie-Mellon University, Pittsburgh, Pennsylvania 15213 (United States)

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 [ital up] and [ital down] current-quark masses ([ital m][sub [ital u]][ne][ital m][sub [ital d]]), and distinguish between [l angle]0[vert bar]:[ital [bar u]u]:[vert bar]0[r angle] and [l angle]0[vert bar]:[ital [bar d]d]:[vert bar]0[r angle], the condensates of the [ital up] and [ital down] quarks. Using the typical current-quark masses [ital m][sub [ital u]]=5.1 MeV and [ital m][sub [ital d]]=8.9 MeV and the standard condensate values for average current-quark masses, we perform numerical analyses of the resultant QCD [ital p] and unity sum rules. In particular, numerical analyses of the difference equation from the [ital p] sum rules yield [ital M][sub [ital n]][minus][ital M][sub [ital p]]=(1.35[plus minus]0.24) MeV or (1.42[plus minus]0.19) MeV, depending on the method of the analysis. Analogously, the difference equation from the unity sum rules yields [ital M][sub [ital n]][minus][ital M][sub [ital p]]=(1.35[plus minus]0.35) MeV or (0.95[plus minus]0.25) MeV. These predictions are consistent among themselves and all are in reasonable agreement with the experimental value of 1.29 MeV.

• OSTI ID: 6655702
• Journal Information: Physical Review, D (Particles Fields); (United States), Journal Name: Physical Review, D (Particles Fields); (United States) Vol. 47:7; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

662230* -- Quantum Chromodynamics-- (1992-)
662410 -- Properties of Baryons & Baryon Resonances-- (1992-)
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BARYONS
COMPOSITE MODELS
ELEMENTARY PARTICLES
EQUATIONS
FERMIONS
FIELD THEORIES
HADRONS
MASS DIFFERENCE
MATHEMATICAL MODELS
MATHEMATICS
NEUTRONS
NUCLEONS
NUMERICAL ANALYSIS
PARTICLE MODELS
PARTICLE PROPERTIES
PERTURBATION THEORY
PROPAGATOR
PROTONS
QUANTUM CHROMODYNAMICS
QUANTUM FIELD THEORY
QUARK MODEL
SUM RULES