Physics Goals
Solving for X
A proposed new accelerator complex at Fermilab would open up the Intensity Frontier of particle physics.
What are the most basic building blocks of the universe? What are the forces that enable these elementary constituents to form all that we see around us? What unknown properties of these particles and forces drive the evolution of the universe from the Big Bang to its present state, with its complex structures that support life—including us? These are the questions that particle physics seeks to answer.
Particle physics has been very successful in creating a major synthesis, the Standard Model. At successive generations of particle accelerators in the US, Europe and Asia, physicists have used high-energy collisions to discover many new particles. By studying these particles they have uncovered both new principles of nature and many unsuspected features of the universe, resulting in a detailed and comprehensive picture of the workings of the universe.
Recently, however, revolutionary discoveries have shown that this Standard Model, while it represents a good approximation at the energies of existing accelerators, is incomplete. They strongly suggest that new physics discoveries beyond the Standard Model await us.
A set of interrelated questions defines the path ahead:
- How do particles acquire mass? Does the Higgs boson exist, or are new laws of physics required? Are there extra dimensions of space?
- What is the nature of new particles and new principles beyond the Standard Model?
- What is the dark matter that makes up about one quarter of the contents of the universe?
- What is the nature of the dark energy that makes up almost three quarters of the universe?
- Do all the forces of nature become one at high energies? How does gravity fit in? Is there a quantum theory of gravity?
- Why is the universe as we know it made of matter, with no antimatter present?
- What is the origin of this matter-antimatter asymmetry?
- What are the masses and properties of neutrinos and what role did they play in the evolution of the universe? How are they connected to matter-antimatter asymmetry?
- Is the building block of the stuff we are made of, the proton, unstable?
- How did the universe form?
The three frontiers of research in particle physics -- the energy frontier, the intensity frontier and the cosmic frontier -- form an interlocking framework that addresses fundamental questions about the laws of nature and the cosmos. These three approaches ask different questions and use different techniques, but they are ultimately aimed at the same transformational science. Discoveries on one frontier will have much greater impact taken together with discoveries on the other frontiers. For example, the discovery of new particles at the energy frontier, combined with discoveries from the intensity frontier about neutrinos and rare processes, may explain the dominance of matter over antimatter. Synthesizing discoveries from all three frontiers creates the opportunity to understand the most intimate workings and origins of the physical universe.
New accelerator and detector technologies bring within reach the discoveries that may transform our understanding of the physical nature of the universe. The Particle Physics Project Prioritization Panel (P5) has recommended an R&D program to design a multi-megawatt proton source at Fermilab. This proton source, known as Project X, would open a path to discovery in neutrino science and in precision experiments with charged leptons and quarks.