A twisted tale of the transverse-mass tail

TL;DR

This paper suggests that misinterpreted missing momentum in collider experiments, caused by a new physics particle, could explain discrepancies in measured W-boson mass, highlighting a potential source of systematic error.

Contribution

It introduces a model where a new particle affects missing momentum measurements, providing a novel explanation for W-mass measurement discrepancies in collider experiments.

Findings

Exotic events can pass current selection criteria at high rates.

Misinterpretation of missing momentum can bias W-mass measurements.

The proposed model aligns with existing experimental constraints.

Abstract

We propose a tantalizing possibility that misinterpretation of the reconstructed missing momentum may have yielded the observed discrepancies among measurements of the $W$-mass in different collider experiments. We introduce a proof-of-principle scenario characterized by a new physics particle, which can be produced associated with the $W$-boson in hadron collisions and contributes to the net missing momentum observed in a detector. We show that these exotic events pass the selection criteria imposed by various collaborations at reasonably high rates. Consequently, in the presence of even a handful of these events, a fit based on the ansatz that the missing momentum is primarily due to neutrinos (as it happens in the Standard Model), yields a $W$-boson mass that differs from its true value. Moreover, the best fit mass depends on the nature of the collider and the center-of-mass energy of collisions. We construct a barebones model that demonstrates this possibility quantitatively while satisfying current constraints. Interestingly, we find that the nature of the new physics particle and its interactions appear as a variation of the physics of Axion-like particles after a field redefinition.