Boosted Higgs Shapes

TL;DR

The paper addresses how boosted Higgs production in gluon fusion can reveal natural new physics even when the inclusive rate is SM-like. It combines an EFT framework with concrete models (MCHM and MSSM) to show how high-$p_T$ Higgs observables distinguish non-SM couplings, and analyzes H+jet events with $H\to WW^*$ and $H\to \tau\tau$ decays using reweighting to include finite top-mass effects. The study demonstrates that reconstructed boosted observables such as $M_{\rm col}$ and $m_{T,\ell\ell}$ can achieve meaningful signal significance and data-driven background control, with HL-LHC providing substantial constraints on $\kappa_g$ (e.g., excluding $\kappa_g<-0.4$ or $\kappa_g>0.3$ along $c_t+\kappa_g=1$ at 95% CL). Overall, boosted-Higgs shape measurements offer a valuable, complementary route to probing the top-Yukawa and heavy-partner dynamics that underlie natural EWSB, alongside direct $t\bar t H$ studies.

Abstract

The inclusive Higgs production rate through gluon fusion has been measured to be in agreement with the Standard Model (SM). We show that even if the inclusive Higgs production rate is very SM-like, a precise determination of the boosted Higgs transverse momentum shape offers the opportunity to see effects of natural new physics. These measurements are generically motivated by effective field theory arguments and specifically in extensions of the SM with a natural weak scale, like composite Higgs models and natural supersymmetry. We show in detail how a measurement at high transverse momentum of $H\to 2\ell+\mathbf{p}\!\!/_T$ via $H\to ττ$ and $H\to WW^*$ could be performed and demonstrate that it offers a compelling alternative to the $t\bar t H$ channel. We discuss the sensitivity to new physics in the most challenging scenario of an exactly SM-like inclusive Higgs cross-section.

Figures (7)

• Figure 1: Left panel: model points generated for this analysis in $(c_t, \kappa_g)$ plane. The shaded area shows parameter space which gives the inclusive cross-section consistent to the SM prediction within 20%. Right panel: parton level $p_{T,H}$ distributions for the SM, and $(c_t,\kappa_g)=(1 -\kappa_g, \kappa_g)$ with $\kappa_g =\pm 0.1,\pm 0.3,\pm 0.5$.
• Figure 2: Left panel: the invariant mass of the two leptons, $m_{\ell \ell}$, after cut 6. Central panel: The collinear mass $M_{\rm col}$ after cut 7, stacking the different processes. Histograms are normalized to the respective cross-sections. Right panel: stacked distributions of the 'Higgs' transverse momentum $p_{T,H}$ (defined in Eq. \ref{['eq:ptH']}) after selection cut 8, with a logarithmic scale.
• Figure 3: Distributions of the transverse mass $m_{T, \ell\ell}$ after all selection cuts up to $6'$ imposed (left panel) and the dilepton separation $\Delta R_{\ell\ell}$ after all selection cuts up to $7'$ imposed (central panel). Right: stacked distribution of the 'Higgs' transverse momentum $p^{\rm rec}_{T,H}$ (defined in Eq. \ref{['eq:ptH']}) after all selection cuts for $H \to W_\ell W_\ell^*$ optimization, with a logarithmic scale.
• Figure 4: Signal distributions for the SM and six model points, normalized to the respective cross-sections. Left panel: the collinear mass $M_{\rm col}$ after cut 7. $p_{T,H}^{\rm rec}$ is shown for $H\to \tau\tau$ ($H \to W_\ell W_\ell$) in the central (right) panel after all optimized selection cuts.
• Figure 5: CL$_s$ vs. the integrated luminosity for the model points $\kappa_g= 0$ (SM, left) and $\kappa_g=0.5$ (central) against a background-only hypothesis using the $\tau\tau$ mode. Right panel: CL$_s$ plot for the model point of $\kappa_g=0.5$ against a background-only hypothesis using the $WW$ mode.