Parameter Inference from Final-State Entanglement in Higgs Decays

TL;DR

This paper investigates how entanglement in Higgs decay final states can serve as a quantum-information probe to infer fundamental Standard Model parameters, revealing extremal entanglement correlates with known particle masses.

Contribution

It introduces a novel entanglement-entropy criterion applied to Higgs decays, linking quantum entanglement measures to fundamental SM parameters and constraining coupling ratios.

Findings

Entanglement entropy peaks near observed Higgs and W masses.

The entanglement criterion constrains the ratio of vector to fermion couplings.

Results suggest entanglement extremality as a new parameter inference tool.

Abstract

The decay out-states of unstable Standard Model (SM) particles provide a unique, well-defined intrinsic quantum-information probe of the SM parameter space. We use Higgs decays as a test case: after tracing out kinematics, we compute entanglement among final-state spins and colors across all decay channels and impose a near-maximal entanglement-entropy criterion. This criterion yields quantitative indications for fundamental parameters. Within the SM, the entanglement entropy exhibits a global maximum close to the observed Higgs mass and the measured $W$ mass, the latter being equivalent to the $SU(2)_L$ gauge coupling. In a two-parameter kappa framework, applying the same criterion points to an SM-like balance between vector and fermion couplings, constraining the ratio of the sector-wide rescalings. These results suggest that entanglement extremality can serve as a complementary handle on fundamental parameters.