Colour reconnections have emerged as one of the main uncertain aspects of soft hadron-hadron collider physics, with significant implications for minimum-bias and underlying-event physics, as well as for precision measurements, most importantly the determination of the top quark mass in hadronic final states. We argue that a vital missing ingredient in current models is an understanding of the implications of QCD coherence on the process of hadronization, especially in the context of multiple parton interactions (MPI). We present a new model, implemented in PYTHIA 8, that combines the multiplet structure of full-colour SU(3) with the string area law to decide between which partons confining potentials (strings) should arise. The model includes the possibility to form ``baryonic'' colour topologies, such as when two quarks combine to form an overall antitriplet charge. We tune the model to a set of ee and pp reference data, and investigate the consequences of the remaining model uncertainties on the top-quark mass extraction.

Jesper Roy Christiansen
February, 2014 to June, 2014