Measurement of strange-quark contributions to the nucleon's form factors at Q2=0.230 (GeV/c)2
Creators
- 1. Institut fuer Kernphysik, Johannes Gutenberg Universitaet Mainz, J.J. Becherweg 45, D-55099 Mainz (Germany)
- 2. St. Petersburg Institute of Nuclear Physics, Gatchina (Russian Federation)
Description
We report on a measurement of the parity-violating asymmetry in the scattering of longitudinally polarized electrons on unpolarized protons at a Q2 of 0.230 (GeV/c)2 and a scattering angle of θe=30 deg. -40 deg. Using a large acceptance fast PbF2 calorimeter with a solid angle of ΔΩ=0.62 sr, the A4 experiment is the first parity violation experiment to count individual scattering events. The measured asymmetry is Aphys=(-5.44±0.54stat±0.26sys)x10-6. The standard model expectation assuming no strangeness contributions to the vector form factors is A0=(-6.30±0.43)x10-6. The difference is a direct measurement of the strangeness contribution to the vector form factors of the proton. The extracted value is GEs+0.225GMs=0.039±0.034 or F1s+0.130F2s=0.032±0.028
Additional details
Identifiers
- DOI
- 10.1103/PhysRevLett.93.022002;
- arXiv
- arXiv:nucl-ex/0401019v1;
Publishing Information
- Journal Title
- Physical Review Letters
- Journal Volume
- 93
- Journal Issue
- 2
- Journal Page Range
- p. 022002-022002.4
- ISSN
- 0031-9007
- CODEN
- PRLTAO
INIS
- Country of Publication
- United States
- Country of Input or Organization
- International Atomic Energy Agency (IAEA)
- INIS RN
- 36020731
- Subject category
- S72: PHYSICS OF ELEMENTARY PARTICLES AND FIELDS;
- Descriptors DEI
- ASYMMETRY; CALORIMETERS; ELECTRONS; FORM FACTORS; LEAD FLUORIDES; P INVARIANCE; PARITY; PROTONS; S QUARKS; SCATTERING; STANDARD MODEL; STRANGENESS
- Descriptors DEC
- BARYONS; ELEMENTARY PARTICLES; FERMIONS; FIELD THEORIES; FLUORIDES; FLUORINE COMPOUNDS; GRAND UNIFIED THEORY; HADRONS; HALIDES; HALOGEN COMPOUNDS; INVARIANCE PRINCIPLES; LEAD COMPOUNDS; LEAD HALIDES; LEPTONS; MATHEMATICAL MODELS; MEASURING INSTRUMENTS; NUCLEONS; PARTICLE MODELS; PARTICLE PROPERTIES; QUANTUM FIELD THEORY; QUARKS; STRANGE PARTICLES; UNIFIED GAUGE MODELS
Optional Information
- Notes
- (c) 2004 The American Physical Society