Application of current-algebra techniques to soft-pion production by the weak neutral current: S , P , T case

• Published in: Physical review. D, Particles and fields Particles and fields, 1975-12, Vol.12 (11), p.3501-3521
• Main Authors: Adler, Stephen L., Colglazier, E. W., Healy, J. B., Karliner, Inga, Lieberman, Judy, Ng, Yee Jack, Tsao, Hung-Sheng
• Format: Article
• Language: English
• Subjects: 641103; CURRENT ALGEBRA; DEEP INELASTIC SCATTERING N; DELTA-1236 RESONANCES; N64230 -Physics (High Energy)-Particle Interactions & Properties (Theoretical)-Weak; N64320 -Physics (High Energy)-Particle Invariance Principles & Symmetry-Applications (Electromagnetic & Weak); NEUTRINO-NUCLEON INTERACTIONS- NEUTRINOS- NUCLEONS- PARTICLE PRODUCTION- PIONS; NEUTRINO-PROTON INTERACTIONS- WEAK NEUTRAL CURRENTS; PSEUDOSCALARS; QUARK MODEL; RENORMALIZATION; SCALARS; TENSORS ELASTIC SCATTERING
• ISSN: 0556-2821; 1089-4918
• DOI: 10.1103/PhysRevD.12.3501

We develop the cross-section formulas needed to correlate information on neutral currents obtained from deep-inelastic neutrino scattering, neutrino-- proton elastic scattering, and neutral-current--induced soft-pion production, in the case of neutral currents with S, P, T spatial structure. (The necessary S, P, T current renormalization constants were estimated by us in a previous paper.) The pion-emission amplitude is obtained by current-algebra soft-pion techniques, with the effects of (3, 3)-resonance--excitation taken into account to leading nonvanishing order in the static approximation. We analyze recently reported Brookhaven National Laboratory results for neutral-current--induced soft-pion production under the simplifying assumption of a purely isoscalar S, P, T neutral current, while simultaneously imposing existing bounds on neutrino--proton elastic scattering and fitting existing data on neutral-current--induced deep- inelastic scattering. If all S, P, T renormalization constants are given their central quark-model values, the elastic-scattering and deep-inelastic restrictions constrain the pion-production cross section to be too low compared with experiment; if apparently reasonable deviations of the parameters from the quark-model values are permitted, satisfactory fits to all data are obtained with S, T, with P, T or with S, P, T mixtures. An isovector tensor or pseudoscalar neutral current is found to lead to a strong (3,3) peak in $pi$N invariant-mass plots, but an isovector scalar neutral current can be present without producing a visible (3,3) peak, even when ratios of the various $pi$N charge states produced by the neutral current are appreciably changed from the values which they have in the isoscalar-current case. Constructive T interference with S (or S and P) in $nu$ + N $Yields$ $nu$ + N + $pi$ and observation of unequal neutrino- and antineutrino-induced neutral-current cross sections are also indicated. (AIP)