Could a new interaction exist in nature ? Beyond weak, electromagnetic and strong interactions, it is natural to enquire about an additional one, associated with an extra-U(1) gauge group. The corresponding boson, called U forty years ago, may be (very) light, and (very) weakly coupled, its properties depending on m_U, the size of its coupling, and corresponding current (which depends on the BE-Higgs symmetry-breaking sector). Its vector part is a combination of electromagnetic with B and L (or B-L) currents. Axial couplings may also be present, which may make the spin-1 U boson interact much like a spin-0 axionlike particle.
We discuss some of the effects of such a new boson, including its production in e+e- annihilations and beam dump experiments, ψ, Υ and K decays, parity-violation effects in atomic physics, anomalous magnetic moments of charged leptons, non-standard neutrino interactions, a possible "protophobic" behaviour suppressing π° -> γ U decays (related with a tentative interpretation of the Atomki anomaly). The U may also serve as a mediator to a new dark sector, allowing for thermally-produced light dark matter particles.
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Meeting ID: 860 3496 9060