Isospin 1/2 Nucleon Resonance Production by a V,A Weak Neutral Current
Jun, 1975
50 pages
Published in:
- Phys.Rev.D 13 (1976) 1216
Report number:
- FERMILAB-PUB-75-052-THY,
- COO-2220-052,
- FERMILAB-PUB-75-052-T
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Abstract: (APS)
We define a set of ratios characterizing the production of the isospin-½ resonances D13(1514) and S11(1505), as well as the isospin-32 resonance P33(1232), by electromagnetic and weak (charged and neutral) currents. Assuming the most general weak neutral current with V, A spatial structure, we calculate the matrix elements needed to extract the production ratios in three dynamical models for resonance production: the Born-approximation model, the nonrelativistic quark model, and the quark-bag model. For the special case of the Weinberg-Salam theory neutral current, the three models suggest that for 0≤sin2θW≤0.5 the ratios D13P33 and S11P33 observed in neutral-current π0 or η production on a free nucleon target should be substantially smaller (by a factor of 2 to 4) than the corresponding ratios observed in charged-current π0 or η production. We also attempt to predict the ratios D13P33 and S11P33 to be expected in charged-current production from the corresponding ratios observed in electroproduction, but here the three models do not agree, and so we can only state a wide possible range in which the values of the ratios may lie. We briefly discuss the chargeexchange corrections needed for comparison with experiments on complex nuclear targets; we find for an aluminum target that the reduction factors quoted above are halved, so that in neutral-current-induced reactions the ratios D13P33 and S11P33 are smaller by a factor of 1 to 2 than the corresponding ratios observed in charged-current-induced reactions.- NUCLEON RESONANCE: PRODUCTION
- PRODUCTION: NUCLEON RESONANCE
- MODEL: PRODUCTION
- PRODUCTION: MODEL
- PRODUCTION: RATIO
- NEUTRAL CURRENT
- DELTA(1236)
- N'(1520)
- N'(1535)
- CHARGED CURRENT
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