Induced second-class-current effects in hyperon beta decay

Journal Article · Thu Nov 01 00:00:00 EST 1973 · Phys. Rev., D, v. 8, no. 9, pp. 2963-2986

DOI:https://doi.org/10.1103/PhysRevD.8.2963· OSTI ID:4340340

Pritchett, P L; Deshpande, N G

Within the framework of the Cabibbo theory we investigate the role played by SU(3) -symmetry breaking in generating a pseudotensor form factor g/sub 2/(q/sup 2/) in the hadronic matrix element for hyperon beta decay. Such an estimate is necessary before one can infer the existence of second-class currents from the experimental observation of this term. g/sub 2/(q/sup 2/) is assumed to obey an unsubtracted dispersion relation, amd t he contributions to the dispersion integral from the lowest-mass two-body intennediate states (the vector- pseudoscalar-meson states) are studied. The imaginary part of the fonn factor is computed from the triangle graph in which single-baryon exchange is retained as the scattering mechanism. The violation of unitarity by this mechanism above the BB annihilation threshold provides a natural cutoff in the dispersion integral. Known-max breakings and estimates of SU(3) -coupling breakings are used to determine values of g/sub 2/(0) for all the DELTA S = 1 beta decays of the J/sup p/ = (1/2)+ hyperons and for the SIGMA /sup plus or minus / yields DELTA beta d ecays. The corrections to this calculation arising from higher-mass states (tensor-pseudosealer-meson and baryon-antibaryon) are found to be quite small. The effects of axial-vector-meson resonances on the vector-pseudoscalar calculation are also examined. The computed value of g/sup 2/(0) for DELTA yields p beta decay is more than an order of magnitude smaUer than the value suggested by some experiments. The implications of this result for the existence of second-class currents are discussed. The DELTA /sup plus or minus / yields DELTA decays are predicted to have the largest induced value of g/sup 2/(0). The utility of these decays in distingishing between real second-class effects and those induced by SU(3) breaking is stressed. (auth)

• Research Organization: Department of Physics, Northwestern University, Evanston, Illinois 60201
• Sponsoring Organization: USDOE
• NSA Number: NSA-29-022556
• OSTI ID: 4340340
• Journal Information: Phys. Rev., D, v. 8, no. 9, pp. 2963-2986, Other Information: Orig. Receipt Date: 30-JUN-74
• Country of Publication: United States
• Language: English

Related Subjects

N64230* -Physics (High Energy)-Particle Interactions & Properties (Theoretical)-Weak
N64320 -Physics (High Energy)-Particle Invariance Principles & Symmetry-Applications (Electromagnetic & Weak)
*HYPERONS- BETA DECAY
CABIBBO ANGLE
DISPERSION RELATIONS
FORM FACTORS
LAMBDA PARTICLES
MATRIX ELEMENTS
SU-3 GROUPS
SYMMETRY BREAKING