Quantum detection of CP violation in the $t\bar{t}$ system: tomography

• URL: http://arxiv.org/abs/2607.25034v1
• Date: Mon, 27 Jul 2026 19:45:42 GMT
• Title: Quantum detection of CP violation in the $t\bar{t}$ system: tomography
• Abstract summary: We develop a quantum-tomographic framework for determining whether possible CP-odd effects in $tbar t$ events originate in production, in decay, or in both.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: We develop a quantum-tomographic framework for determining whether possible CP-odd effects in $t\bar t$ events originate in production, in decay, or in both. In the narrow-width approximation, the process $I\to t\bar t\to b\ell^+ν\,\bar b\ell^-\barν$ factorises into a production density matrix and top and antitop decay density matrices. We extend the standard tomography procedure to a general anomalous $Wtb$ vertex and derive the corresponding angular distributions. Polar-angle distributions retain their usual tomographic form, up to modifications of the spin-analysing powers, and can therefore be used to reconstruct the production density matrix and test its CP properties. By contrast, dedicated azimuthal observables involving the $b$--lepton decay planes contain characteristic sine modulations that provide linear probes of possible new CP-violating interactions in the decay vertex. Combining the two classes of observables gives a systematic strategy for separating sources of CP violation in production and in decay. We illustrate the resulting angular signatures for representative $t\bar t$ production scenarios at hadron and lepton colliders.

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