Jet Vetoes Interfering with H->WW

TL;DR

The paper tackles how exclusive jet pT vetoes reshape far off-shell Higgs production, including signal-background interference, by deriving a SCET-based factorization that resums logs of √ŝ/pT^veto and expresses results in a differential, leptonic phase space.It demonstrates that the veto-induced Sudakov suppression depends strongly on the partonic initial state (gluon vs quark) and on √ ŝ, leading to nontrivial reweighting of off-shell and interference contributions across a wide energy range.A detailed gg→H→WW case study shows that jet vetoes can either suppress or enhance interference relative to the on-shell signal, and that the suppression shifts the shape of observables such as M_T, with important implications for width bounds derived from off-shell regions.The work emphasizes the necessity of incorporating jet veto effects, especially in 13 TeV analyses, and provides a framework (NLL with prospects for NNLL) to interpret off-shell measurements in Higgs width and coupling studies with controlled theoretical uncertainties.

Abstract

Far off-shell Higgs production in $H \rightarrow WW,ZZ$, is a particularly powerful probe of Higgs properties, allowing one to disentangle Higgs width and coupling information unavailable in on-shell rate measurements. These measurements require an understanding of the cross section in the far off-shell region in the presence of realistic experimental cuts. We analytically study the effect of a $p_T$ jet veto on far off-shell cross sections, including signal-background interference, by utilizing hard functions in the soft collinear effective theory that are differential in the decay products of the $W/Z$. Summing large logarithms of $\sqrt{\hat s}/p_T^{veto}$, we find that the jet veto induces a strong dependence on the partonic centre of mass energy, $\sqrt{\hat s}$, and modifies distributions in $\sqrt{\hat s}$ or $M_T$. The example of $gg\rightarrow H \rightarrow WW$ is used to demonstrate these effects at next to leading log order. We also discuss the importance of jet vetoes and jet binning for the recent program to extract Higgs couplings and widths from far off-shell cross sections.

Figures (8)

• Figure 1: The ratio $E_0(\hat{s})/E_0(m^2_H)$, for both a gluon-gluon initiated process in (a), and a quark-antiquark initiated process in (b). In both cases we consider $p_{T}^{veto}=20,30$ GeV. The jet veto causes an $\hat{s}$ dependent suppression, which is significantly stronger for initial state gluons than initial state quarks, due to the larger colour factor appearing in the Sudakov.
• Figure 2: The ratios $E_0(\hat{s})$, $E_{\geq 1}(\hat{s})$ for a gluon-gluon initial state, and $p_{T}^{veto}=30$ GeV. There is a large migration from the exclusive 0-jet bin to the inclusive 1-jet bin as a function of $\hat{s}$. This phenomenon is important for understanding the impact of jet binning on off-shell cross sections.
• Figure 3: A comparison of the effect of the jet veto at $E_\text{cm}=8,13,100$ TeV for a gluon-gluon initial state, and $p_{T}^{veto}=30$ GeV. At higher $E_\text{cm}$ a larger suppression in the exclusive zero jet bin is observed, due to the larger range of Bjorken $x$ probed.
• Figure 4: LO Higgs mediated, (a), and continuum, (b), diagrams contributing to the process $gg\rightarrow l\nu l\nu$. These are matched onto the helicity basis of SCET operators given in Eq. (\ref{['eq:operators']}).
• Figure 5: The off-shell Higgs cross section in the exclusive zero jet bin for $p_{T}^{veto}=30$ GeV in (a), and $p_{T}^{veto}=20$ GeV in (b), with $R=0.5$ in both cases. Results are normalized by the jet veto suppression at the Higgs mass, such that the on-shell cross section is the same in all cases, allowing one to focus on the modification to the shape of the distribution. NLL and NNLL results are similar, with a small modification due to the finite jet radius, which is not present in the NLL calculation.