Abstract

The ability to distinguish quark-initiated jets from those seeded by gluons would greatly enhance the physics potential of the LHC , including searches for BSM physics and measurements of the Standard Model. This long-standing puzzle has had many techniques and methods applied to it and in this seminar the various approaches over the years at ATLAS and CMS are summarised.

Previous efforts used variables that aimed to exploit the observable differences between quark and gluon jets; including, but by no means limited to, the charged track multiplicity. Quantities with the most separation power are often combined to form two dimensional likelihoods which are more performant. However, in the modern age of machine learning techniques quark gluon-tagging is an ideal use case for these sophisticated methods.

How will the power of these discriminators increase into Run 3 of the LHC and beyond to the High Luminosity LHC ? Is the separation of these highly entangled theoretical abstractions even a reasonably achievable goal experimentally?