Hidden strangeness in the proton Determination of the real part of the isospin-even forward-scattering amplitude of pion-nucleon scattering at 54. 3 MeV

Journal Article · Fri Dec 01 04:00:00 EST 1989 · Physical Review (Section) D: Particles and Fields; (USA)

DOI:https://doi.org/10.1103/PhysRevD.40.3568· OSTI ID:7273735

Wiedner, U; Goring, K; Jaki, J; Klein, U; Kluge, W; Matthay, H; Metzler, M ^[1]; Pedroni, E ^[2]; Fetscher, W; Gerber, H J ^[3]

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1. Kernforschungszentrum Karlsruhe, Institut fuer Kernphysik, and Institut fuer Experimentelle Kernphysik, Universitaet Karlsruhe, Postfach 3640, D-7500 Karlsruhe 1, (Germany, F.R.)
2. Schweizerisches Institut fuer Nuklearforschung, CH-5234 Villigen, (Switzerland)
3. Institut fuer Mittelenergiephysik, Eidgenossische Technische Hochschule, CH-5234 Villigen, (Switzerland)

The contradiction of the {sigma} term of pion-nucleon scattering as deduced from the Karlsruhe-Helsinki phase shifts with the smaller value calculated by the chiral perturbation theory of QCD is well known. In an effort to clarify the discrepancy we have determined the real part of the isospin-even forward-scattering amplitude of pion-nucleon scattering at a pion energy {ital T}{sub {pi}}=54.3 MeV by measurement of the elastic scattering of positive and negative pions on protons in the Coulomb-nuclear interference region. The deduced value is in agreement with the prediction of the Karlsruhe-Helsinki phase-shift analysis for that energy. The resulting large value of the {sigma} term may be interpreted as being due to the influence of {ital {bar s}s} sea pairs even at large distances (small {ital Q}{sup 2}) as previously suggested by the European Muon Collaboration measurement of deep-inelastic scattering of polarized muons on polarized protons.

• OSTI ID: 7273735
• Journal Information: Physical Review (Section) D: Particles and Fields; (USA), Journal Name: Physical Review (Section) D: Particles and Fields; (USA) Vol. 40:11; ISSN PRVDA; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

645204* -- High Energy Physics-- Particle Interactions & Properties-Theoretical-- Strong Interactions & Properties
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
AMPLITUDES
ANGULAR DISTRIBUTION
BARYONS
BEAMS
CHIRAL SYMMETRY
DEEP INELASTIC SCATTERING
DISTRIBUTION
ELASTIC SCATTERING
ELEMENTARY PARTICLES
EMC EFFECT
ENERGY RANGE
FERMIONS
FIELD THEORIES
HADRON-HADRON INTERACTIONS
HADRONS
INELASTIC SCATTERING
INTERACTIONS
ISOSPIN
LEPTON-BARYON INTERACTIONS
LEPTON-HADRON INTERACTIONS
LEPTON-NUCLEON INTERACTIONS
MESON-BARYON INTERACTIONS
MESON-NUCLEON INTERACTIONS
MEV RANGE
MEV RANGE 10-100
NUCLEONS
PARTICLE INTERACTIONS
PARTICLE PROPERTIES
PHASE SHIFT
PION-NUCLEON INTERACTIONS
POLARIZED BEAMS
POSTULATED PARTICLES
PROTONS
QUANTUM CHROMODYNAMICS
QUANTUM FIELD THEORY
QUARKS
SCATTERING
SCATTERING AMPLITUDES
STRANGENESS
SYMMETRY