Dip or nothingness of a Higgs resonance from the interference with a complex phase

TL;DR

This paper explores how interference effects with a complex phase can produce novel resonance shapes like dips or nothingness in heavy Higgs boson signals, impacting detection strategies at the LHC.

Contribution

It introduces a general framework for resonance interference with a phase, modifies the narrow width approximation, and applies these to Higgs boson searches in multiple channels.

Findings

New resonance shapes such as dips and nothingness are theoretically possible.

Heavy Higgs bosons can produce distinctive interference patterns in collider signals.

Current search techniques can potentially detect these interference-induced resonance shapes.

Abstract

We show that new resonance shapes -- a pure dip, nothingness and an enhanced pure peak -- can be produced from the interference between resonance and continuum with a relative phase. Production conditions of those new shapes are derived based on a general parameterization of the interference. The narrow width approximation is modified to work with the non-zero imaginary part of interference, and the correction factor can characterize the resonance shape. We demonstrate that the new resonance shapes of heavy Higgs bosons, $H^0$ and $A^0$ in the Type II aligned two Higgs doublet model, generally show up in $gg \to H^0/A^0 \to t\bar{t}$ as well as $b\bar{b}$ and $\gamma \gamma$ channels. The pure $A^0$ resonance dip in the $t\bar{t}$ channel is a particularly interesting signal as it can be probed well by the current search techniques that do not even take into account interferences; the high-luminosity LHC 14 TeV can perhaps probe a large part of its parameter space.