Ponente
Dr.
Anthony Palladino
(Laboratori Nazionali di Frascati dell'INFN)
Descripción
In some models of physics beyond the Standard Model it is
predicted the existence of light neutral vector particles
(U bosons) mediator of new gauge interactions under
which ordinary matter is uncharged. Motivated by astrophysical
considerations, their mass, M_U, is expected to be of order
1 GeV or ligther.
These new particles can be observed as sharp resonances at M_U
in the invariant mass distribution of charged lepton or pion pairs
in reactions of the type e+e- --> l(pi)+l(pi)- gamma, or in meson
Dalitz decays.
KLOE has formerly searched for U boson production using
phi daitz decay events, setting limits in the
mass region 50 < M_U < 520 MeV. We have now completed our
analysis of e+e- --> mu+mu- gamma, which has
allowed us setting the best limits to date in the region
between 500 and 1000 MeV.
Preliminary results for the electron-positron final state
are also available.
Autor primario
Dr.
Fabio Bossi
(INFN-LNF)
