Correlating uncertainties in global analyses within SMEFT matters

Understand

We investigate the impact of correlations between (theoretical and experimental) uncertainties on multi-experiment, multi-observable analyses within the Standard Model Effective Field Theory (SMEFT).

• To do so, we perform a model-independent analysis of $t$-channel single top-quark production and top-quark decay data from ATLAS, CMS, CDF and D0.
• We show quantitatively how the fit changes when different experimental or theoretical correlations are assumed.
• Scaling down statistical uncertainties according to the luminosities of future colliders with $300 \, {\rm fb}^{-1}$ and higher, we find that this effect becomes a matter of life and death: assuming no correlations returns a fit in agreement with the Standard Model while a 'best guess'-ansatz taking into account correlations would observe new physics.