Quantum tomography program reconstructs the full spin density matrix of top-quark pairs from dilepton angular correlations at both electron-positron and hadron colliders. We use symmetry arguments to identify tomographic observables sensitive to CP violation in top quark couplings. As a concrete example, we study the sensitivity of these observables to (chromo-)electric dipole moment operators at the LHC and the FCC-ee. We also construct the optimal observable, which combines tomographic and kinematic information to achieve statistically optimal sensitivity for each operator and production process. The analysis is based on fast detector simulation of top pair production and decay in the dilepton channel. We project a $95\%$ CL sensitivity to new-physics scales (the inverse dipole couplings) of $10-15$ TeV for the electroweak electric dipoles at the FCC-ee ($365$ GeV, $3~{\rm ab}^{-1}$) and of 40 (200) TeV for the top chromo-electric dipole moment at the LHC Run 2 (HL-LHC). This sensitivities exceed those of the traditional observables currently used by experiments to use for these operators, indicating the power of the tomographic approach to search for CP violation.
We investigate how possible new CP-violating top-quark interactions are encoded in the quantum state of a produced $t\bar t$ pair. We derive analytic expressions for the production density matrix in several benchmark channels relevant to hadron, lepton and photon colliders. In a common spin basis, we identify two chara...
P. Lamba, F. Maltoni, Olimpia Miniati et al.· 1 citation
LHC measurements now reconstruct all fifteen parameters of the $t\bar t$ two-qubit spin density matrix, which amounts to a full quantum tomography of the pair. We show that this data constrains CP violation in the top-Yukawa coupling. The coupling enters the density matrix at one loop and produces spin correlations tha...
We study the sensitivity of top-quark pair production at the FCC-ee to heavy new physics, parametrised in the Standard Model effective field theory, using discriminants based on matrix elements. The analysis includes detector reconstruction effects, obtained with a fast simulation of the IDEA detector concept, and jet...
Jacopo De Piccoli, G. Durieux, Sergio Sánchez Cruz et al.· 0 citations
The naive-$T$-odd angular coefficients $A_5$--$A_7$ in Drell--Yan production are highly suppressed in the Standard Model (SM), making them sensitive probes of CP-violating interactions beyond the SM. We study these observables within the Standard Model Effective Field Theory (SMEFT), focusing on dimension-six electrowe...
We study how virtual next-to-leading-order electroweak corrections affect the quantum observables of entanglement and magic in lepton--lepton collisions. Treating the outgoing particles as multi-qudit systems, $\textit{i.e.}$, qubits for spin-$\tfrac{1}{2}$ fermions and qutrits for massive vector bosons, we compute ent...
Spencer Chang, T. Driscoll, S. Trifinopoulos· 1 citation
Momentum transfer distributions $d\sigma/dt$ in diffractive electroproduction of heavy quarkonia on nuclear targets are studied within a rigorous quantum-mechanical approach based on the light-front Green's function formalism. Such a formalism allows to include naturally the higher-twist and leading-twist shadowing cor...
J. Obertova, Jan Nemcik· Proceedings of the Internati...· 0 citations
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