PrecisOnium

Quarkonium production is central to many aspects of the Standard Model of particle physics. The discovery of the J/Psi, the first of these composite particles made of a heavy (charm or bottom) quark and an antiquark, was the ultimate proof of the existence of quarks as physical particles in spite of being confined. The quarkonia are the quark analogues of positronia, the e+e- bound states, and share some of their properties. Quarkonia are now used to study the quark-gluon plasma at colliders, or to probe the dynamics of gluons in large nuclei and (un)polarised nucleons. Yet their production remains a challenge for theory at the interface between the short and long-distance domains of the strong interaction whose confinement property remains to be understood. Some state-of-the-art studies are still done at leading order (LO) in the strong coupling constant and not a single quarkonium production process is known at next-to-next-to leading order (NNLO), i.e. the standard precision in particle physics. PrecisOnium will push the precision frontiers for quarkonium production via 3 fronts: 1) the long distance at which the quarks bind, by systematising data-theory comparisons with a new automated tool at NLO allowing us to perform the first global fits of the non-perturbative parameters of the theory; 2) the short distance at which the quarks are created, by pioneering NNLO computations; 3) the phenomenology of quarkonium production, by enriching the EU virtual access NLOAccess with a dedicated NLO tool taking into account the parton spins and our NNLO codes. The maintenance of NLOAccess is funded by the EU and aims at an integrated ensemble of scientific codes open to any interested scholars. To do so we propose to set up a dynamic research team devoted to PrecisOnium, gathering different expertises such as tool automation for high-energy physics, TMD factorisation, loop computations and quarkonium phenomenology. It involves 2 French groups from IJCLab Orsay and LPTHE Paris and 3 groups from CERN, UCLouvain and Groningen U. Such a focused team certainly will advance our knowledge of the field with a positive impact, not only on the LHC community, but also on many physicists working with facilities dedicated to heavy-ion and nucleon-spin studies at BNL, FNAL, JLab, FAIR, KEK, at fixed-target experiments at CERN and at the planning of projects such as the ILC, FCC and the EIC whose planning is moving fast in the US.