LHC sensitivity to lepton flavour violating Z boson decays

Abstract

Abstract We estimate that the LHC could set bounds BR(Z → μ ± e ∓) < 4.1 × 10−7 and BR(Z → τ ± μ ∓) < 3.5 × 10−6 (at 95% C.L.) with 20 fb−1 of data at 8 TeV. A similar sensitivity can be anticipated for Z → τ ± e ∓, because we consider leptonic τ decays such that Z → τ ± μ ∓ → e ± μ ∓ + invisible. These limits can be compared to the LEP1 bounds of order 10−5 → 10−6. Such collider searches are sensitive to a flavour-changing effective Z coupling which is energy dependent, so are complementary to bounds obtained from $ \tau \to \ell \overline \ell \ell $ and $ \mu \to e\overline e e $ .