Particle physics at the Energy and Intensity Frontiers
André de Gouvêa, Northwestern University
The goal of particle physics is to identify the fundamental building blocks of Nature, un¬derstand their properties and interactions, and, hopefully, glimpse at the most fundamental Laws of Physics. Understanding the fundamental building blocks of Natural is also indis¬pensable for addressing a large variety of scientiﬁc issues, from the properties of nuclei to the history of the universe we live in. Almost all fundamental physics phenomena can be explained by a theoretical framework that was developed over the second half of the twen¬tieth century. Only one prediction of this so-called standard model is yet to be conﬁrmed – the existence of a new fundamental force associated to a yet-to-be-observed particle called the Higgs boson.
Observations that violate standard model expectations – like discovery of “dark matter,” a new form of matter with properties inconsistent with the ingredients of the standard model – are very, very few. The only concrete one relates to neutrinos, one of the building blocks of Nature. Neutrinos are ghost-like particles produced during radioactive decays and nuclear fusion. The standard model dictates that neutrinos are perfectly massless, but it was recently revealed that neutrinos have tiny, non-zero masses. Driven by the search for the Higgs force and the rare short-comings of the standard model, particle physicists are forced into extreme experimental physics. On the one hand, we want to observe the Higgs force. To accomplish that, we must study phenomena at distance scales around 10−18 m. This is the goal of the Large Hadron Collider, the most powerful particle accelerator ever, which aims at colliding protons moving at 99.999999% of the speed of light. On the other hand, we would like to understand the new mysterious properties of the neutrinos. To accomplish that, we need incredibly intense neutrino beams aimed at humongous amounts of stuﬀ (thousands of kilo-tons) located hundreds of kilometers away from the neutrino birthplace.