Fundamental properties and time-scan of QCD matter at high densities and temperature exposed by jet substructure in heavy ion collisions with CMS experiment at the LHC

Quantum Chromodynamics (QCD) is the theory of the strong force.

Its high-temperature phase can be accessed experimentally via high energy heavy-ion collisions, allowing us to investigate how the macroscopic properties of nuclear matter arise from QCD interactions between quarks and gluons.

With this proposal I aim to solve several fundamental and long-standing questions concerning the strong force and the evolution of the high density phase of QCD, the Quark Gluon plasma (QGP), that are related to the evolution of the early universe: a) Characterize the transport coefficient, qhat, of the Quark Gluon Plasma, which is related to its density b) Perform the equivalent of the Rutherford experiment in the QGP, to resolve the point-like quark and gluon scatterers within the QGP. c) Provide first experimental evidence of two important interference mechanisms that are expected to play a main role in the evolution of jets in a QGP, such as the Landau Pomeranchuk Migdal effect in QCD and the color coherence effect d) Study the phenomenology of the Lund plane, in particular selections on the branching time obtained from the splitting kinematics.

Can it be used to draw a time-dependent picture of the jet shower? e)Perform the first attempt to time-scan the QGP with a yoctosecond chronometer using hadronic decays of W and Z bosons.As a world leader in the field of jet physics, also with a strong phenomenological background, I am in a unique position to to solve some of the most interesting problems concerning QCD at high densities by applying new ideas and techniques and exploring the jet substructure.

The CMS detector capabilities for jet and electroweak boson reconstruction and the synergy between the pp and heavy ion communities within, make of CMS the ideal experimental detector to capitalize on my ideas and existing expertise.

This grant will also provide the opportunity to reinforce the european contribution to the CMS heavy ion program and lead it.