A new insight on dark matter at the Large Hadron Collider

点击翻译按钮获取中文摘要

"What is dark matter made of?" is the big question of our times in particle physics. Five times more abundant than ordinary matter, the elusive dark matter has shaped the cosmological evolution of our universe.Many theoretical frameworks state that dark matter is made of new particles that interact only through electroweak interaction with ordinary matter. The Large Hadron Collider at CERN is the only existing machine that may be able to produce such particles in high-energy proton-proton collisions: this is a unique chance to discover, and possibly study, dark matter in controlled, reproducible conditions.A Higgs boson-like particle might play a crucial role as mediator of dark matter production. Their large Yukawa couplings make the study of candidate events where third generation quarks are produced in association with dark matter interesting. Scenarios where the associated bottom or top quarks are produced with low transverse momentum are theoretically compelling and not well studied yet.Low transverse momentum bottom quarks (possibly from top decay) are tricky to identify, as they do not necessarily yield a hadronic jet in the final state. However, they still feature the presence of a displaced decay vertex. I will select such events with a multivariate analysis exploiting innovative low transverse momentum bottom quark tagging techniques on top of information about the event kinematics. These events have never been investigated in the past: their study will bring valuable new information to the quest for dark matter search.