Friday 22 April, 11.00h, at Nikhef/CWI in Z011.
Speaker: Juan Rojo (VU)
Title: “Intrinsic Charm in the Proton”
The theory of the strong force, Quantum Chromodynamics, describes the proton in terms of quarks and gluons. While the proton is a bound state of two up and one down quark, quantum theory predicts that in addition there is an infinite number of quark-antiquark pairs. Both light and heavy quarks, whose mass is respectively smaller or bigger than the proton’s, are revealed inside the proton in high-energy collisions. However, it is unclear whether heavy quarks also exist as a part of the static nucleon wave-function: so-called intrinsic heavy quarks. It has been argued for more than 40 years that the proton could have a sizable intrinsic component of the lightest heavy quark, the charm quark, yet innumerable efforts to establish intrinsic charm in the proton have remained inconclusive. I this talk I provide first unambiguous evidence for intrinsic charm in the proton by exploiting a high-precision determination of the quark-gluon content of the nucleon based on machine learning and the largest experimental dataset ever. We establish the existence of intrinsic charm at the 3-sigma level, with a momentum distribution in remarkable agreement with model predictions and we confirm these findings by comparing to very recent data on Z production with charm jets from the LHCb experiment.
This colloquium will be hybrid: