Precision Jet Substructure of Boosted Boson Decays with Energy Correlators

TL;DR

The paper develops a precision framework for boosted jet substructure using energy correlators (EEC) to study hadronic Higgs decays. It introduces a boost kernel $\mathcal{K}_\gamma(z,z')$ that maps rest-frame EEC distributions to boosted observables and identifies a characteristic peak at $\theta_{\rm peak} \approx \arccos(1-2/\gamma^2)$ reflecting the two-prong boosted topology. The analysis shows how infrared scales such as $m_b$ and $\Lambda_{\rm QCD}$, dead-cone effects, and confinement leave imprints on the boosted angular distribution, with collinear and back-to-back regions treated via fixed-order and high-accuracy resummation (up to $\text{N}^4\text{LL}$). NNLO production inputs weight the boosted kinematics and enable applications to precision electroweak studies and new physics searches, potentially extending to other boosted resonances and polarization-sensitive observables.

Abstract

We initiate the precision study of boosted jet substructure using energy correlators, applying this framework to hadronic Higgs decays. We demonstrate that the two-body decay of the Higgs manifests as a distinct angular peak at $θ\sim \arccos(1-2/γ^2)$ for Lorentz boost factor $γ$. We show that infrared scales, such as the dead-cone effect and confinement transition, are also resolved within the boosted distribution. Precision analytic studies of boosted jet substructure may enable precision electroweak studies and open new avenues for new physics searches.

Figures (6)

• Figure 1: The angular distribution of the energy-energy correlators for hadronic Higgs decays at rest for $gg$ and $b\bar{b}$ decay channels. The angular variable $\theta$ scans across distinct physical regimes: the wide-angle region governed by hard fixed-order QCD ($\theta \sim 1$); the collinear limit ($\theta \ll 1$), characterized by classical $1/\theta$ scaling, DGLAP resummation, and modifications from infrared scales $m_b$ and $\Lambda_{\rm QCD}$; and the back-to-back region ($\theta \to \pi$) dominated by Sudakov double logarithms. The exclusive measurement of $B$-hadron correlations in the $H \to b\bar{b}$ channel is dominated by the back-to-back region.
• Figure 2: The angular distribution of the energy-energy correlators for a boosted Higgs boson with $m_H = 125$ GeV and $\gamma = 4$ for $gg$ and $b\bar{b}$ decay channels. We compare the inclusive $gg$ and $b\bar{b}$ decay channels, as well as the exclusive measurement of correlations between $B$-hadrons. All distributions exhibit a characteristic peak near $\theta_{\rm peak} \approx \arccos(1-2/\gamma^2)$. The vertical dashed line indicates this kinematic value, corresponding to the boosted topology of the back-to-back two-body decay in the rest frame.
• Figure 3: The evolution of the energy-energy correlator distribution for the $H \to b\bar{b}$ decay channel under varying Lorentz boosts $\gamma$. As the boost increases, the characteristic peak shifts to smaller angles, reflecting the increasing collimation of the decay products into a single jet-like topology.
• Figure 4: The energy-energy correlator distribution for $H \to b\bar{b}$ decays in the scalar rest frame for varying masses $m_H = 125, 200, 300$ GeV. While the qualitative features of the distribution remain consistent, the angular positions of the peaks shift systematically with the scalar mass. The collinear peak location scales as $m_H \theta/2 \sim m_b$, while the back-to-back peak location is governed by the onset of Sudakov saturation given in Eq. \ref{['eq:onset']}.
• Figure 5: The angular distribution of the EEC for boosted scalars with fixed energy $E_H = 500$ GeV and varying masses $m_H = 125, 200, 300$ GeV. The angular position of the peak depends on the resonance mass. The vertical dashed lines indicate $\arccos(1-2/\gamma^2)$ for different $\gamma = E_H/m_H$.