Nonplanar 4-jets in quarkonium decays as a probe for 3-gluon coupling

We calculate the acoplanarity (a la Fox-Wolfram) distribution of 4 jets generated by orthoquarkonium decays: 3S1(Q anti Q) yields GGGG. GGq anti q. The result shows that the deviation from planar event due to 4 jets is significantly large showing the importance of the effect of 3-gluon couplings in quantum chromodynamics. The average acoplanarity lt D gt is calculated to be lt D gt = (4.45 + 0.153Nsub(f)) alpha sub(s)/ pi with Nsub(f) the number of flavors of produced quarks and alpha sub(s) the QCD coupling strength. As a by-product we calculated the decay rate of the parapositronium into 4 photons which results in GAMMA sub(4 gamma ) = (0.0139 +- 0.0001) alpha7msub(e) with msub(e) the electron mass. (author)