Unambiguously Testing Positivity at Lepton Colliders.

Area of Science:

• High Energy Physics
• Quantum Field Theory
• Collider Physics

Background:

• The diphoton (γγ) production at lepton colliders (e^{+}e^{-}(μ^{+}μ^{-})→γγ) is sensitive to dimension-eight operators in new physics scenarios.
• These dimension-eight operators are constrained by positivity bounds derived from fundamental quantum field theory principles like unitarity and Lorentz invariance.

Purpose of the Study:

• To investigate the capability of future lepton colliders in probing dimension-eight operators via the diphoton channel.
• To assess the effectiveness of positivity bounds as a direct and unambiguous test of fundamental quantum field theory principles.

Main Methods:

• Analysis of the diphoton cross section as a direct observable sensitive to dimension-eight operators.
• Estimation of the sensitivity of various future lepton colliders to these operators and their associated positivity bounds.
• Exploration of the impact of positivity bounds on global effective field theory analyses.

Main Results:

• Positivity bounds provide a robust and unambiguous test of quantum field theory principles in the diphoton channel.
• Future lepton colliders show significant potential for probing dimension-eight operators and testing these bounds.
• Positivity bounds can resolve degeneracies in effective operator parameter spaces, refining global analyses.

Conclusions:

• The diphoton channel at lepton colliders offers a unique window into new physics and fundamental principles.
• Positivity bounds are a powerful tool for constraining new physics and validating quantum field theory.
• Future collider experiments will play a crucial role in testing these bounds and advancing our understanding of fundamental physics.