The Large Hadron Collider (LHC) is the world’s largest and most powerful particle accelerator. Situated at CERN, the European Organization for Nuclear Research, it collides protons at the highest currently possible energies. With the large datasets from previous Run 2 and the ongoing Run 3, the precision of LHC measurements will significantly improve over the next years. Colour-free processes (for which the final state of the hard interaction is colour neutral) are of central importance to several high-priority areas of the LHC precision physics programme, e.g. measurements of the W-boson mass, of the couplings of the Higgs boson, and searches for the elusive dark matter particles.
The EU-funded COLORFREE project obtains precise theoretical predictions and combines different colour-free processes in order to unlock the full potential of existing and future precision measurements. The key innovation of COLORFREE is to combine many different colour-free processes into a new type of global analysis in which the dominant theory uncertainties are either eliminated or constrained by the experimental data itself, thereby improving the theoretical precision up to an order of magnitude to the 1-2% level and below.
This is achieved
1) by developing a ground-breaking new method to reliably quantify perturbative theory uncertainties leading to precision theory predictions with built-in uncertainties and correlations, and
2) by developing innovative new effective-field theory methods to account for all effects that are relevant at this precision but have been neglected before.
Important outcomes of COLORFREE are:
1) Determinations of fundamental parameters at the highest possible precision, and stringent tests for possible effects beyond the Standard Model.
2) A new type of precision theory predictions with built-in uncertainties and correlations, which solve a long-standing problem at the interface of theory and experiment. In particular, precision measurements often avoid theory limitations by relying on theory uncertainties to cancel between different control and signal regions, but until now have had no means to reliably quantify the remaining theory uncertainties.
