A factorization framework and two-qubit description allow photon pairs at lepton colliders to be treated as qubits for measuring Bell inequality violation, quantum discord, and nonstabilizerness using Belle data.
Entanglement and Bell Nonlocality in $\tau^+ \tau^-$ at the LHC using Machine Learning for Neutrino Reconstruction
9 Pith papers cite this work. Polarity classification is still indexing.
abstract
Experiments at the CERN Large Hadron Collider (LHC) have accumulated an unprecedented amount of data corresponding to a large variety of quantum states. Although searching for new particles beyond the Standard Model of particle physics remains a high priority for the LHC program, precision measurements of the physical processes predicted in the Standard Model continue to lead us to a deeper understanding of nature at high energies. We carry out detailed simulations for the process $pp \to \tau^+\tau^- X$ to perform quantum tomography and to measure the quantum entanglement and the Bell nonlocality of the $\tau^+\tau^-$ two qubit state, including both statistical and systematic uncertainties. By using advanced machine learning techniques for neutrino momentum reconstruction, we achieve precise measurements of the full spin density matrix, a critical advantage over previous studies limited by reconstruction challenges for missing momenta. Our analysis reveals a clear observation of Bell nonlocality with high statistical significance, surpassing 5$\sigma$, establishing $\tau^+ \tau^-$ as an ideal system for quantum information studies in high-energy collisions. Given its experimental feasibility and the high expected sensitivity for Bell nonlocality, we propose that $\tau^+ \tau^-$ should be regarded as the new benchmark system for quantum information studies at the LHC, complementing and extending the insights gained from the $t\bar{t}$ system.
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representative citing papers
An automated framework in MadGraph5_aMC@NLO computes tree-level production spin-density matrices and quantum observables for generic collider processes, with validation on ttbar and VV and new applications to multi-top final states.
Concurrence minima in neutrino oscillations identify low-entanglement energy regions that, when aligned with NOνA and T2K data, yield tighter joint constraints on sin²θ₂₃, δ_CP, and Δm²₃₁.
Computes entanglement negativities for the tripartite spin system in e+e- -> ttZ and projects that collective entanglement is accessible but genuine multipartite entanglement has limited sensitivity at a polarized ILC with expected luminosity.
Transverse polarization in e+e- collisions generates maximally entangled fermion pairs in QED processes and boosts entanglement in electroweak and Bhabha scattering.
Under mild assumptions, local hidden variable theories become testable at colliders and can be disproved via Bell-like inequalities for muon and tau pairs.
Including soft gluons in Monte Carlo generators for DIS aligns parton distributions with inclusive PDFs and makes entropy grow with decreasing x, indicating initial-state origin of the bulk entropy.
Monte Carlo feasibility study at STCF finds reconstructed concurrence of 0.279 ± 0.007 for τ⁺τ⁻ pairs in the ππ channel using quantum tomography.
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