Putting m$_{2}$ ∼ m$_{Z}$ and examining Table I, we obtain Since the heavy leptons are SU (2)-doublets, the main production mechanism at the LHC will be qq ′ → χχ via electroweak interactions. The production rate is model independent. It is suppressed by the electroweak gauge couplings, but not by any flavor factors. The most significant process involves an intermediate W $^{+}$-boson, producing a heavy charged lepton along with a heavy neutral lepton, u ¯ d → χ $^{+}$χ$^{0}$. The second most important process is Drell- Yan production involving an intermediate photon or Z $^{0}$-boson, q ¯ q → χ $^{+}$χ $^{−}$. The production cross sections for a single generation of vector-like heavy leptons are shown in Fig. 1. The simulation was done using MadGraph v4 [24] with default cut values at E$_{cm}$ = 14 TeV and using CTEQ6L1 parton distribution functions [25]. There are two points that we need to emphasize: 2. Since the coupling of heavy and light leptons is suppressed by O ( v/M$_{2}$ ), single heavy lepton production is negligible. 1. Within the MLFV framework, the production is always of a same flavor pair, i.e. χ$_{i}$χ$_{i}$ (and not χ$_{i}$ ¯ χ$_{j}$ with i = j ). 7 A. Production III. LHC PHENOMENOLOGY Δ T ( χ$_{i}$ ) ∼ ( m$_{2}$/M$_{2}$ ) 2 ×     i LE y 4 i LL 1 EE . (2.8) Δ T ( χ ) ∼     τ ∼ 10 − 16 LE 10 − $^{2}$y4 τ ∼ 10 − 10 LL 10 − 2 EE . (2.9) Since m$_{2}$/M$_{2}$ ∼ 10 − 6 (10 − $^{1}$) for model LE (LL,EE), we have $^{10}$$^{−}$$^{12}$$^{y}$$^{2}$ Exact calculations confirm these rough estimates. We made similar calculations for Δ S ( χ ) and Δ U ( χ ). We find that for m$_{2}$/m (lightest χ ) ∼ < 0 . 1, our models satisfy the constraints from electroweak precision measurements.