Measurement of the Correlation between Nuclear Alignment and Electron Direction inB12Decay as a Direct Search for the Second-Class Axial-Vector Current

The decay of theT=1 isospin triplet inA=12 systems. III. Higher order effects in the evaluation of the asymmetry parameters ?? for the electron emission from aligned12B and12N

“…For the sake of completeness we evaluated the asymmetry parameters using the ratios x =0.91 (obtained from Morita's value 0.98) and y=3.6 reported by Morita et al [12] in conjunction with our Equation (11) Table 1. It is interesting to mention that a (W0/2)=0.0355 %/MeV is in agreement with data from [10,11], however a (Wo) =0.0178 %/MeV agrees with the datum obtained at Louvain [9] only within two standard deviations.…”

“…In Figure 1 we desplay the experimental values for a together with the theoretical prediction as a function the energy. The datum a(Wo) reported by the Louvain group [9] is correctly reproduced by our calculation. Since the data of the Ztirich [10] and Osaka [11] groups have been obtained averaging over electron energies it is not striking that they rather agree well with evaluations performed at intermediate en-…”

“…Meanwhile new measurements of the asymmetry parameters ~+ for the decay of aligned I2B and 12N have been carried out at few laboratories. Quite recently, new experimental results have been reported for 12B by the Louvain [9] and Ztirich [10] groups and for t2B and 12N by the Osaka group [11]. All these data are listed in Table 1.…”

“…Since the value of c~ reported in [9] correspond to a well defined Let us continue our analysis going back to (10). Instead of Yo and x o other parameters y and x are currently used in the literature.…”

The decay of theT=1 isospin triplet inA=12 systems: IV. The energy dependence of the asymmetry coefficients $$\alpha _{\beta ^ \mp } $$ of the beta-ray angular distribution in aligned12B and12N and the induced pseudotensor interaction

“…These features have encouraged new measurements of the asymmetry parameters. At the present all new experimental results [8][9][10][11] are in very good overall agreement and it is currently accepted that the data of c~p~ provide a strong evidence against an axial SCC [8][9][10][11][12][13][14][15][16]. Hitherto all the publications [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] which tackled this matter have been mainly focused to the question if the asymmetry parameters c~ can be interpreted without invoking the existence of the IPT interaction.…”