# Anomalous $H\to ZZ \to 4\ell$ decay and its interference effects at the LHC

## TL;DR

This paper calculates anomalous Higgs decay amplitudes to four leptons, incorporates them into simulation tools, and analyzes interference effects and constraints on new physics couplings using LHC data.

## Contribution

It provides analytic formulas for anomalous $H o ZZ o 4 ext{l}$ decay amplitudes and studies their interference with Standard Model processes at the LHC.

## Key findings

- Interference effects significantly impact off-shell Higgs measurements.
- Constraints on anomalous couplings are derived from LHC data.
- Analytic amplitude formulas are implemented in the MCFM package.

## Abstract

We calculate the spinor helicity amplitudes of anomalous $H\to ZZ \to 4\ell$ decay. After embedding these analytic formulas into the $\texttt{MCFM}$ package, we study the interference effects between the anomalous $gg\to H\to ZZ \to 4\ell$ process and the SM processes, which are indispensable in the Higgs off-shell region. Subsequently, the constraints on the anomalous couplings are estimated using LHC experimental data.