Bell inequalities in 2-2 scattering

Abstract

We consider Bell inequalities in 2-2 scattering of photons, gravitons, fermions and pions. We choose measurement settings that give maximum Bell violation for maximally entangled states and calculate the relevant Bell inequalities for these processes. For photon scattering at low energies, QED exhibits Bell violation for all scattering angles except for a small transverse region. This leads to a fine-tuning problem. Incorporating a light axion/axion-like particle (ALP) removes the fine-tuning problem and constrains the axion-coupling--axion-mass parameters. Allowing for graviton exchange and demanding Bell violation in photon scattering, we find that the Weak Gravity Conjecture is satisfied. Quantum gravity effect on axion coupling is discussed. For 2-2 graviton scattering, we find that CEMZ bounds allow for at most small Bell violations. Restriction on the Weinberg angle is found by demanding Bell violation in Bhabha scattering. We use recent S-matrix bootstrap data for pions and photons to study the Bell parameter in the space of allowed S-matrices. In the photon case, we study the Bell parameters as a function of energy and find support for the EFT observations. We discuss Bell parameter for pion S-matrices, which are qutrits. For pions, we find that there is a minimization of a suitable Bell parameter for S-matrices which exhibit Regge behaviour.

v3, 21 pages, 12 figures, version to appear in PRD

References in corpus (13)

• Causality, Analyticity and an IR Obstruction to UV Completion
• Revisiting the bound on axion-photon coupling from Globular Clusters
• Very-High-Energy Gamma Rays from a Distant Quasar: How Transparent Is the Universe?
• Infrared Consistency and the Weak Gravity Conjecture
• Causality constraints on corrections to Einstein gravity
• Bell violation in the Sky
• Crossing Symmetric Spinning S-matrix Bootstrap: EFT bounds
• Bootstrapping Pions at Large $N$
• Bounding Violations of the Weak Gravity Conjecture
• Cornering Large-$N_c$ QCD with Positivity Bounds
• Partial transpose as a direct link between concurrence and negativity
• Nonperturbative Bounds on Scattering of Massive Scalar Particles in $d\ge 2$
• Comment on "Spin correlations in elastic $e^{+}{e}^{-}$ scattering in QED"

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