Shift in the LHC Higgs diphoton mass peak from interference with background

TL;DR

This paper studies how quantum interference between Higgs signal and background processes at the LHC causes a measurable shift in the observed diphoton mass peak, impacting precise Higgs mass measurements.

Contribution

It quantifies the shift in the Higgs diphoton mass peak due to interference effects, highlighting its dependence on data analysis methods.

Findings

Interference shifts the mass peak by about 150 MeV or more.

The shift's magnitude depends on analysis and fitting techniques.

This effect must be considered for accurate Higgs mass determination.

Abstract

The Higgs diphoton amplitude from gluon fusion at the LHC interferes with the continuum background induced by quark loops. I investigate the effect of this interference on the position of the diphoton invariant mass peak used to help determine the Higgs mass. At leading order, the interference shifts the peak towards lower mass by an amount of order 150 MeV or more, with the precise value dependent on the methods used to analyze and fit the data.