Measurement of the parity-violating asymmetry in inclusive electroproduction of π - Near the Δ0 resonance

D. Androić, D. S. Armstrong, J. Arvieux, S. L. Bailey, D. H. Beck, E. J. Beise, J. Benesch, F. Benmokhtar, L. Bimbot, J. Birchall, P. Bosted, H. Breuer, C. L. Capuano, Y. C. Chao, A. Coppens, C. A. Davis, C. Ellis, G. Flores, G. Franklin, C. FurgetD. Gaskell, M. T.W. Gericke, J. Grames, G. Guillard, J. Hansknecht, T. Horn, M. K. Jones, P. M. King, W. Korsch, S. Kox, L. Lee, J. Liu, A. Lung, J. Mammei, J. W. Martin, R. D. McKeown, A. Micherdzinska, M. Mihovilovic, H. Mkrtchyan, M. Muether, S. A. Page, V. Papavassiliou, S. F. Pate, S. K. Phillips, P. Pillot, M. L. Pitt, M. Poelker, B. Quinn, W. D. Ramsay, J. S. Real, J. Roche, P. Roos, J. Schaub, T. Seva, N. Simicevic, G. R. Smith, D. T. Spayde, M. Stutzman, R. Suleiman, V. Tadevosyan, W. T.H. Van Oers, M. Versteegen, E. Voutier, W. Vulcan, S. P. Wells, S. E. Williamson, S. A. Wood

Research output: Contribution to journalArticlepeer-review


The parity-violating (PV) asymmetry of inclusive π - production in electron scattering from a liquid deuterium target was measured at backward angles. The measurement was conducted as a part of the G0 experiment, at a beam energy of 360 MeV. The physics process dominating pion production for these kinematics is quasifree photoproduction off the neutron via the Δ0 resonance. In the context of heavy-baryon chiral perturbation theory, this asymmetry is related to a low-energy constant dΔ- that characterizes the parity-violating γNΔ coupling. Zhu et al. calculated dΔ- in a model benchmarked by the large asymmetries seen in hyperon weak radiative decays, and predicted potentially large asymmetries for this process, ranging from Aγ-=-5.2 to +5.2ppm. The measurement performed in this work leads to Aγ-=-0.36±1.06±0.37±0.03ppm (where sources of statistical, systematic and theoretical uncertainties are included), which would disfavor enchancements considered by Zhu et al. proportional to V ud/V us. The measurement is part of a program of inelastic scattering measurements that were conducted by the G0 experiment, seeking to determine the N-Δ axial transition form factors using PV electron scattering.

Original languageEnglish (US)
Article number122002
JournalPhysical review letters
Issue number12
StatePublished - Mar 20 2012

ASJC Scopus subject areas

  • General Physics and Astronomy


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