ABSTRACT |
Flavor symmetries are useful to realize fermion flavor structures in the standard model (SM). In particular, the discrete A(4) symmetry is used to realize lepton flavor structures, and some scalars-called flavons-are introduced to break this symmetry. In many models, flavons are assumed to be much heavier than the electroweak scale. However, our previous work showed that a flavon mass around 100 GeV is allowed by experimental constraints in the A(4) symmetric model with a residual Z(3) symmetry. In this paper, we discuss collider searches for such a light flavon phi(T). We find that electron-photon collisions at the International Linear Collider have advantages for searching for these signals. In electron-photon collisions, flavons are produced as e(-)gamma -> l(phi T)(-) and decay into two charged leptons. Then, we analyze signals of the flavor-conserving final state tau(+)tau(-)e(-) and the flavor-violating final states tau(+)mu(-)mu(-) and mu(+)tau(-)tau(-) by carrying out numerical simulations. For the former final state, SM background can be strongly suppressed by imposing cuts on the invariant masses of final-state leptons. For the latter final states, SM background is extremely small, because in the SM there are no such flavor-violating final states. We then find that sufficient discovery significance can be obtained, even if flavons are heavier than the lower limits from flavor physics. |