Magnetic field dependence of muonium-antimuonium conversion
Abstract We study the magnetic field dependence of muonium-antimuonium conversion for all relevent operators, such as ( V − A ) ( V − A ), ( V − A ) ( V + A ), SS and PP . The traditional ( V − A ) ( V − A ) interaction suffers two stage quenching and becomes strongly suppressed by 10 3 Gauss fields or higher. In contrast, all other operator types (except ( S − P ) ( S − P )) have a weaker field dependence and in general are not strongly quenched by strong fields. Since ongoing experiments are done with sizable magnetic fields, our results are useful for the interpretation of experimental results as bounds on different effective interactions.
New search for the spontaneous conversion of muonium to antimuonium.
To search for spontaneous conversion of muonium to antimuonium with very low background, a new signature was implemented that required the coincident detection of the decay products of the antimuonium atom, the energetic e- and the atomic e+. No conversion events were seen, which sets an improved upper limit of 6.5 x 10(-7) (90% C.L.) on the conversion probability. The corresponding limit on the coupling constant, using a V - A form for the conversion Hamiltonian, is G(MMBAR) < 0.16G(F) (90% C.L.), where G(F) is the Fermi coupling constant.
Colour gluons and scaling in a unified gauge model
Deep inelastic weak and electromagnetic processes are considered within the parton framework taking the partons to be integrally charged quarks and coloured gluons. Despite the participation of the spin-one gluons in these processes, scaling is shown to be maintained by treating the problem in a unified gauge model based on the groupSU (3)colour⊗SUL (2)⊗U(1). This is a consequence of the vector-dominance type of couplings between the gluons and the weak or electromagnetic vector bosons which are induced by the spontaneous breakdown of gauge symmetry. As a further consequence it is found that in the asymptotic region far above the gluon masses the colour octet parts of the weak and electromagnetic currents of the quarks are damped so that, in particular, the integrally charged quarks behave as fractionally charged quarks in this region.