Search for lepton-flavor-violating τ decay into a lepton and an f0(980)f0(980) meson

We search for lepton-flavor-violating τ   decays into a lepton (electron or muon) and an f0(980)f0(980) meson using 671 fb−1 of data collected with the Belle detector at the KEKB asymmetric-energy e+e−e+e− collider. No events are observed and we set the following 90% C.L. upper limits on the branching fraction products: B(τ−→e−f0(980))×B(f0(980)→π+π−)<3.2×10−8B(τ−→e−f0(980))×B(f0(980)→π+π−)<3.2×10−8 and B(τ−→μ−f0(980))×B(f0(980)→π+π−)<3.4×10−8B(τ−→μ−f0(980))×B(f0(980)→π+π−)<3.4×10−8. This is the first search performed for these modes.