{pi}{ital N}{sigma} term, {ital {bar s}}{ital s} in the nucleon, and the scalar form factor: A lattice study
- Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506 (United States)
We report on a lattice QCD calculation of the {pi}{ital N}{sigma} term, the scalar form factor, and {l_angle}{ital N}{vert_bar}{ital {bar s}}{ital s}{vert_bar}{ital N}{r_angle}. The disconnected insertion part of {sigma}{sub {pi}{ital N}} is found to be 1.8{plus_minus}0.1 times larger than the connected insertion contribution. The {ital q}{sup 2} dependence of {sigma}{sub {pi}{ital N}}({ital q}{sup 2}) is about the same as {ital G}{sub {ital E}}({ital q}{sup 2}) of the proton so that {sigma}{sub {pi}{ital N}}(2{ital m}{sub {pi}}{sup 2}){minus}{sigma}{sub {pi}{ital N}}(0)=6.6{plus_minus}0.6 MeV. The ratio {ital y}={l_angle}{ital N}{vert_bar}{ital {bar s}}{ital s}{vert_bar}{ital N}{r_angle}/{l_angle}{ital N}{vert_bar}{ital {bar u}}{ital u}+{ital {bar d}}{ital d}{vert_bar}{ital N}{r_angle}=0.36{plus_minus}0.03. Both results favor a {sigma}{sub {pi}{ital N}}{approximately}53 MeV, slightly larger than our direct calculation of {sigma}{sub {pi}{ital N}}=49.7{plus_minus}2.6 MeV. We also compute {ital F}{sub {ital s}} and {ital D}{sub {ital s}} and find that the agreement with those from the octet baryon mass splittings crucially depends on the inclusion of the large disconnected insertion. Finally, we give our result for the {ital KN}{sigma} term. {copyright} {ital 1996 The American Physical Society.}
- DOE Contract Number:
- FG05-84ER40154
- OSTI ID:
- 388435
- Journal Information:
- Physical Review, D, Journal Name: Physical Review, D Journal Issue: 9 Vol. 54; ISSN PRVDAQ; ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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