Jul 6 – 13, 2022
Bologna, Italy
Europe/Rome timezone

Lund and Cambridge multiplicity for precision physics

Jul 8, 2022, 2:45 PM
Room 1 (Europa Auditorium)

Room 1 (Europa Auditorium)

Parallel Talk Strong interactions and Hadron Physics Strong interactions and Hadron Physics


Rok Medves (University of Oxford)


Multiplicity is one of the simplest experimental observables in collider events, whose importance stretches from calibration to advanced tagging techniques. We introduce a new (sub)jet multiplicity, the Lund multiplicity, for lepton and hadron collisions. It probes the full multiple branching structure of QCD and is calculable in perturbation theory. We introduce a formalism allowing us to calculate the average Lund and Cambridge multiplicities to all orders, reaching next-to-next-to double logarithmic (NNDL) accuracy in $e^+e^-$ collisions, an order higher than the existing state-of-the-art, and next-to-double logarithmic accuracy (NDL) in hadronic collisions. Matching our resummed calculation to the NLO result, we find a reduction of theoretical uncertainties by up to 50% compared to the previous state-of-the-art. Adding hadronisation corrections obtained through Monte Carlo simulations, we also show a good agreement with existing Cambridge multiplicity data.

In-person participation Yes

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