Abstract
In this paper, we explore Bell inequality violation for 2 → 2 scattering in Effective Field Theories (EFTs) of photons, gluons, and gravitons. Using the CGLMP Bell parameter (I2), we show that, starting from an appropriate initial non-product state, the Bell inequality can always be violated in the final state (i.e.,I2 > 2) at least for some scattering angle. For an initial product state, we demonstrate that abelian gauge theories behave qualitatively differently than non-abelian gauge theories (or Gravity) from the point of view of Bell violation in the final state: in the non-abelian case, Bell violation (I2 > 2) is never possible within the validity of EFTs for weakly coupled UV completions. Interestingly, we also find that, for a maximally entangled initial state, scattering can reduce the degree of entanglement only for CP-violating theories. Thus Bell violation in 2 → 2 scattering can, in principle, be used to classify CP conserving vs violating theories.
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Acknowledgments
DG acknowledges support through the Ramanujan Fellowship and MATRICS Grant of the Department of Science and Technology, Government of India. The authors thank Farman Ullah for discussions, and Arijit Chatterjee for discussions and comments on the draft.
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Ghosh, D., Sharma, R. Bell violation in 2 → 2 scattering in photon, gluon and graviton EFTs. J. High Energ. Phys. 2023, 146 (2023). https://doi.org/10.1007/JHEP08(2023)146
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DOI: https://doi.org/10.1007/JHEP08(2023)146