Meson-meson nonresonant reactions governed by the quark-interchange mechanism are studied in a potential that is derived from QCD. S-wave elastic phase shifts for I = 2 ππ and I = 3/2 Kπ scattering are obtained with wave functions determined by the central spin-independent term of the potential. The reactions include inelastic scatterings of two mesons in the ground-state pseudoscalar octet and the ground-state vector nonet. Cross sections for reactions involving π, ρ, K and K * indicate that mesonic interactions in matter consisting of only K and K * can be stronger than mesonic interactions in matter consisting of only π and ρ and the reaction of I = 3/2 πK * → ρK is most important among the endothermic nonresonant reactions. By the quark-interchange mechanism we can offer √ s-dependences of φ absorption cross sections in collisions with π and ρ and relevant average cross sections what are very small for the reaction of I = 1 πφ → K * K * and remarkably large for the reaction of I = 1 ρφ → K * K * . It is found from the √ s-dependences of cross sections that ρ and K * creation cross sections can be larger than their absorption cross sections, respectively.

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We investigate the observability of the top anomalous tqZ couplings via the trilepton signatures at the Large Hadron Collider (LHC) with the center-of-mass energy of 14 TeV. We focus on signals of the tZ associated production with the decay mode t → W + b → bℓ + ν ℓ , Z → ℓ + ℓ − , and tt production with the decay modet → Z(→ ℓ + ℓ − )q and t → bℓ + ν ℓ , where ℓ = e, µ and q reflects up and charm quarks. It is shown that at 3σ level, the FCNC top quark decay branching ratios can be probed at, respectively, about Br(t → uZ) ≤ 1.3 × 10 −4 and Br(t → cZ) ≤ 4.2 × 10 −4 with the integrated luminosity of 100 fb −1 , and probed down to Br(t → uZ) ≤ 2.2 × 10 −5 and Br(t → cZ) ≤ 8 × 10 −5 for the high-luminosity LHC with 3000 fb −