Abstract
We explore the collider phenomenology of spin- $$1/2$$ excited top quarks arising from QCD-invariant magnetic transition operators, motivated by scenarios in which Standard Model fermions are composite objects. Assuming the absence of electroweak and contact interactions, we consider a minimal effective field theory framework where the excited top decays exclusively via the strong channel $$t^{*}\to tg$$ . Both pair and single excited top production are studied at proton–proton colliders with center-of-mass energies $$\sqrt{s}=13$$ and $$14$$ TeV, corresponding to the LHC and HL-LHC regimes. We compute the total cross sections for both production modes, including all gauge and magnetic contributions, and examine their dependence on the compositeness scale $$\Lambda$$ and excited top mass $$m_{t^{*}}$$ . While pair production proceeds primarily through minimal QCD couplings and exhibits limited sensitivity to $$\Lambda$$ , single production is governed by the magnetic transition operator and provides a complementary probe with distinct kinematic features. Our results highlight the dominant role of single production across a wide region of parameter space, particularly in the natural scenario $$\Lambda=m_{t^{*}}$$ , underscoring its relevance for future searches targeting excited top signatures with boosted topologies.