Signal-background interference for a singlet spin-0 digluon resonance at the LHC

TL;DR

This paper investigates how interference effects between a spin-0 digluon resonance and the QCD background alter dijet mass distributions at the LHC, affecting resonance searches especially for broader widths.

Contribution

It demonstrates the significant impact of signal-background interference on dijet resonance searches, highlighting the need to consider these effects for accurate interpretation.

Findings

Interference substantially modifies the dijet mass distribution.

Effects are more pronounced with increasing resonance width.

Implications for interpreting potential signals like the 750 GeV excess.

Abstract

Dijet mass distributions can be used to search for spin-0 resonances that couple to two gluons. I show that there is a substantial impact on such searches from the interference between the resonant signal and the continuum QCD background amplitudes. The signal dijet mass distribution is qualitatively modified by this interference, compared to the naive expectation from considering only the pure resonant contribution, even if the total width of the resonance is minimal and very small compared to the experimental dijet mass resolution. The impact becomes more drastic as the total width of the resonance increases. These considerations are illustrated using examples relevant to the 750 GeV diphoton excess recently observed at the LHC.