Coherent Quantum Evaluation of Collider Amplitudes for Effective Field Theory Constraints

TL;DR

This paper introduces a hybrid quantum-classical method to compute collider scattering amplitudes, enabling direct comparison with experimental data and constraining Standard Model and effective field theory parameters.

Contribution

It presents a novel quantum computing framework for calculating helicity amplitudes in collider physics, bridging quantum algorithms with phenomenological analysis.

Findings

Quantum amplitudes match Standard Model expectations.

Method successfully constrains effective field theory operators.

Demonstrates feasibility of quantum computing in collider data analysis.

Abstract

Precision measurements at electron-positron colliders provide stringent tests of the Standard Model and powerful probes of possible higher-dimensional interactions. We present a hybrid quantum-classical framework for computing leading-order helicity amplitudes for $e^+e^-\to \ell^+\ell^-$ scattering on gate-based quantum hardware and using the resulting cross sections to constrain both Standard Model couplings and effective field theory operators. In our approach, external kinematics are encoded into single-qubit Weyl spinors, and full helicity amplitudes are reconstructed by coherently combining diagrammatic contributions within a single quantum circuit. Classical post-processing yields physical amplitudes and differential cross sections that can be directly compared with collider data. As a proof of concept, we compute unpolarised angular distributions and perform binned likelihood fits to precision electron-positron measurements. The extracted bounds are statistically consistent with Standard Model expectations, demonstrating that quantum-assisted amplitude evaluation can interface directly with phenomenological analyses and experimental data. This work establishes a concrete pathway toward applying quantum computing to precision collider physics and effective field theory studies.