Interference Effect on Resonance Studies in Searches of Heavy Particles

TL;DR

This paper investigates how interference effects influence resonance line shapes in heavy particle searches, highlighting the potential to discern coupling signs through line shape analysis at future colliders.

Contribution

It demonstrates that interference effects cause asymmetric resonance distortions and explores how line shape measurements can reveal coupling signs in high-luminosity experiments.

Findings

Interference causes asymmetric resonance line shapes.

Line shape analysis can determine coupling signs.

High luminosity improves confidence in coupling sign determination.

Abstract

The interference between resonance signal and continuum background can be either constructive or destructive, depending on the relative sign of couplings between the signal and background amplitudes. Different interference schemes lead to asymmetric distortions of the resonance line shape, which could be distinguished in experiments, when the internal resonance width is larger than the detector resolution. Interpreting the ATLAS diboson excesses by means of a toy $W'$ model as an illustrative example (though it is disfavored by the 13 TeV data), we find that the signs of resonance couplings can only be revealed in the line shape measurements up to a high confidence level at a high luminosity, which could bring us further information on the underlying theory beyond resonance searches at future lepton and hadron colliders.