Charge symmetry breaking in rvec n - rvec p scattering at 183 MeV

Journal Article · Sat Aug 01 04:00:00 EDT 1992 · Physical Review, C (Nuclear Physics); (United States)

DOI:https://doi.org/10.1103/PhysRevC.46.410· OSTI ID:7105834

Vigdor, S E; Jacobs, W W; Knutson, L D; Sowinski, J; Bloch, C; Jolivette, P L; Wissink, S W; Byrd, R C; Whiddon, C ^[1]

---

1. Indiana University Cyclotron Facility and Department of Physics, Bloomington, Indiana 47405 (United States) Laboratoire National Saturne, 91191 Gif-sur-Yvette (France) Department of Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States) Department of Physics, Hope College, Holland, Michigan 49423 (United States) P-2 Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

We report the results of a precise test of charge symmetry in the scattering of polarized neutrons from polarized protons at a laboratory bombarding energy of 183 MeV. The observable sensitive to charge symmetry is the difference between the analyzing powers associated with the neutron spin ({ital A}{sub {ital n}}({theta})) and with the proton spin ({ital A}{sub {ital p}}({theta})). Systematic errors and experimental ambiguities in the measurement of this difference are extensively discussed. Our result for {Delta}{ital A}{equivalent to}{ital A}{sub {ital n}}{minus}{ital A}{sub {ital p}}, averaged over the angular range 82.2{degree}{le}{theta}{sub c.m.}{le}116.1{degree}, is (33.1{plus minus}5.9{plus minus}4.3){times}10{sup {minus}4}. With the statistical and systematic errors added in quadrature, this value is 3.4 standard deviations larger than the effect expected from pure photon exchange (the electromagnetic spin-orbit interaction) between the neutron and proton, and thus represents clear evidence of charge symmetry breaking in the strong interaction. We also extract information about the angular dependence of {Delta}{ital A}({theta}), within limitations imposed by uncertainties in the measured beam and target polarizations. Both the angle-averaged value and the angular dependence measured for {Delta}{ital A} are in excellent agreement with predictions from meson-exchange theory, when these include both the effect of the {ital n}-{ital p} mass difference on one-pion exchange and the isospin mixing of {rho}{sup 0} and {omega}{sup 0} mesons. In particular, the Bonn nucleon-nucleon ({ital NN}) potential model accounts for the present results utilizing {rho}{ital NN} and {omega}{ital NN} coupling constant values deduced previously for this potential from fits to more conventional {ital NN} scattering data.

• OSTI ID: 7105834
• Journal Information: Physical Review, C (Nuclear Physics); (United States), Journal Name: Physical Review, C (Nuclear Physics); (United States) Vol. 46:2; ISSN 0556-2813; ISSN PRVCA
• Country of Publication: United States
• Language: English

Related Subjects

663430* -- Nucleon-Induced Reactions & Scattering-- (1992-)
663510 -- Nuclear Mass Ranges-- A=1-5-- (1992-)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ANALYZING POWER
BARYON REACTIONS
BARYON-BARYON INTERACTIONS
BEAMS
C INVARIANCE
COMPOSITE MODELS
ENERGY RANGE
FLAVOR MODEL
HADRON REACTIONS
HADRON-HADRON INTERACTIONS
HYDROGEN 1 TARGET
INTERACTIONS
INVARIANCE PRINCIPLES
MATHEMATICAL MODELS
MEV RANGE
MEV RANGE 100-1000
NEUTRON REACTIONS
NUCLEAR REACTIONS
NUCLEON REACTIONS
NUCLEON-NUCLEON INTERACTIONS
PARTICLE INTERACTIONS
PARTICLE MODELS
POLARIZED BEAMS
POLARIZED TARGETS
PROTON-NEUTRON INTERACTIONS
PROTON-NUCLEON INTERACTIONS
QUARK MODEL
SCATTERING
SYMMETRY
TARGETS