THE ORTHOPOSITRONIUM DECAY PUZZLE AND PRIMORDIAL NUCLEOSYNTHESIS

The discrepancy between the experimental decay rate of orthopositroniu m (o-Ps) and the QED theoretical prediction can be solved by invoking decays of o-Ps into exotic particles with branching ratios similar to 10(-3). We show that considerations based on primordial nucleosynthesi s and effective Lagrangians place a very stringent upper bound: B = Ga mma(o-Ps --> ''exotic'' +...)/Gamma(o-Ps) less than or equal to 2 x 10 (-15), ruling out the exotic decay solution to the puzzle.