Indexed on: 01 Jun '16Published on: 31 May '16Published in: Nuclear and Particle Physics Proceedings
Some models of physics beyond the Standard Model have predicted the existence of a light neutral vector particle, called the U boson, which would mediate a new dark gauge interaction. KLOE has searched for the production of U bosons in five analyses comprising four types of production processes with various final states. We've used Dalitz decays of the ϕ meson, ϕ→ηUϕ→ηU with U→e+e−U→e+e− and the two final states η→π+π−π0η→π+π−π0 and η→π0π0π0η→π0π0π0, to provide limits on the mixing strength between the dark sector and the Standard Model in the range 50<mU<520 MeV/c250<mU<520 MeV/c2. We've set a limit using e+e−→Uγe+e−→Uγ, U→μ+μ−U→μ+μ− in the range 520<mU<980 MeV/c2520<mU<980 MeV/c2 and provided a preliminary limit using e+e−→Uγe+e−→Uγ, U→e+e−U→e+e− in the range ∼5<mU<520 MeV/c2∼5<mU<520 MeV/c2. We've also searched for a U boson in the dark Higgsstrahlung process, e+e−→Uh′e+e−→Uh′, U→μ+μ−U→μ+μ−, placing a preliminary limit on the product of the kinetic mixing parameter and the dark coupling constant in the parameter space 2mμ<mU<900 MeV/c22mμ<mU<900 MeV/c2 and 10<mh′<500 MeV/c210<mh′<500 MeV/c2.