Ditau-Jet Tagging and Boosted Higgses from a Multi-TeV Resonance

TL;DR

The paper introduces ditau-jet tagging to identify boosted Higgs jets from multi-TeV resonances via the subdominant h→ττ decay. By extending hadronic tau tagging with mutual isolation, it achieves around 50% ditau-tag efficiency with very low QCD mistag rates at TeV-scale pT, even under pileup. It demonstrates Higgs mass reconstruction using MET-based techniques and assesses the discovery reach for Z′→Zh in both leptonic and hadronic Z channels, showing that the hadronic Z channel can be competitive or superior in certain mass ranges. The approach offers a new, robust handle for boosted Higgs searches, with potential applicability to other heavy resonances and beyond-Higgs contexts.

Abstract

New TeV-scale physics processes at the LHC can produce Higgs bosons with substantive transverse Lorentz boost, such that the Higgs's decay products are nominally contained in a single jet. In the case of a light Higgs decaying predominantly to bb, previous studies have shown that these Higgs-jets can be identified by capitalizing on jet substructure techniques. In this work, we explore the possibility of also utilizing the subdominant but very distinctive decay h -> tau tau. To this end, we introduce the concept of a ``ditau-jet,'' or a jet consisting of two semi-collinear taus where one or both decay hadronically. We perform simple modifications to ordinary tau tagging methods to account for this configuration, and estimate tag rates of order 50% and QCD mistag rates of order 0.1%-0.01% for p_T TeV, even in the presence of pileup. We further demonstrate the feasibility of reconstructing the ditau invariant mass by using traditional MET projection techniques. Given these tools, we estimate the sensitivity of the LHC for discovery of a multi-TeV Z' decaying to Zh, utilizing both leptonic and hadronic Z decay channels. The leptonic Z channel is limited due to low statistics, but the hadronic Z channel is potentially competitive with other searches.

Figures (7)

• Figure 1: Illustration of tracker-seeded hadronic tau tag.
• Figure 2: Illustration of mutual isolation cones and inner activity cone for a semileptonic ditau.
• Figure 3: Illustration of mutual isolation cones and inner activity cones for an all-hadronic ditau.
• Figure 4: Reconstructed Higgs invariant mass from 2 TeV (left) and 3 TeV (right) $Z'$ decays. The solid red line shows Higgs reconstruction using our default modeling of the ${\not}E_T$ measurement, and the dashed blue line shows Higgs reconstruction if perfect ${\not}E_T$ is used.
• Figure 5: Reconstructed $Z'$ invariant mass for 2 TeV (left) and 3 TeV (right), with the Higgs mass window cut applied. Plots are normalized to the signal rate before the Higgs mass window cut. The solid red line uses our nominal ${\not}E_T$ reconstruction, and the dashed blue line uses perfect ${\not}E_T$.