A class of models of dark sectors consider new very weak interaction between the ordinary and dark matter transmitted by U(1) gauge bosons A (dark photons) mixing with our photons. If such As exist, they could be searched for in a light-shining-throu
gh-a-wall experiment with a high energy electron beam from the CERN SPS. The proposed search scheme suggests detection of the e+e- pairs produced in the A -> e+e- decay with a very small opening angle. Coordinate chambers based on the thin-wall drift tubes with a minimal material budget and a two-hit resolution for e+ and e- tracks separated by more than 0.5 mm are considered as an option for detecting such pairs.
The 3.6 sigma discrepancy between the predicted and measured values of the anomalous magnetic moment of positive muons can be explained by the existence of a new dark boson Z_mu with a mass in the sub-GeV range, which is coupled predominantly to the
second and third lepton generations through the L_mu - L_tau current . After a discussion of the present phenomenological bounds on the Z_mu coupling, we show that if the Z_mu exists, it could be observed in the reaction mu+Z to mu+Z+Z_mu of a muon scattering off nuclei by looking for an excess of events with large missing muon beam energy in a detector due to the prompt bremsstrahlung Z_mu decay Z_mu to u u into a couple of neutrinos. We describe the experimental technique and the preliminary study of the feasibility for the proposed search. We show that this specific signal allows for a the search for the Z_mu with a sensitivity in the coupling constant alpha_mu > 10^{-11}, which is 3 orders of magnitude higher than the value required to explain the discrepancy. We point out that the availability of high-energy and -intensity muon beams at CERN SPS provides a unique opportunity to either discover or rule out the Z_mu in the proposed search in the near future. The experiment is based on the missing-energy approach developed for the searches for invisible decays of dark photons and (pseudo)scalar mesons at CERN and is complementary to these experiments.
The question if the Bose statistics is broken at the TeV scale is discussed. The decay of a new heavy spin 1 gauge boson Z into two photons, Z-> 2 gamma, is forbidden by the Bose statistics among other general principles of quantum field theory (Land
au-Yang theorem). We point out that the search for this decay can be effectively used to probe the Bose symmetry violation at the CERN LHC.
