Bounds on ortho-positronium and J/ψ–Υ quarkonia invisible decays and constraints on hidden braneworlds in a SO(3,1)-broken 5D bulk

Abstract

While our visible Universe could be a 3-brane, some cosmological scenarios consider that other 3-branes could be hidden in the extra-dimensional bulk. Matter disappearance toward a hidden brane is mainly discussed for neutron — both theoretically and experimentally — but other particles are poorly studied. Recent experimental results offer new constraints on positronium or quarkonium invisible decays. In the present work, we show how a two-brane Universe allows for such invisible decays. We put this result in the context of the recent experimental data to constrain the brane energy scale [Formula: see text] (or effective brane thickness [Formula: see text]) and the interbrane distance [Formula: see text] for a relevant two-brane Universe in a [Formula: see text]-broken 5D bulk. Quarkonia present poor bounds compared to the results deduced from previous passing-through-walls-neutron experiments for which scenarios with [Formula: see text] GeV and [Formula: see text] fm are excluded. By contrast, positronium experiments can compete with neutron experiments depending on the matter content of each brane. To constrain scenarios up to the Planck scale, positronium experiments in vacuum cavity should be able to reach [Formula: see text].