Collider Phenomenology

It is not too early to think about the next major accelerator after the LHC.  It can take decades to design and construct a new accelerator, but theorists can play an important role at an early stage by defining the physics case and the essential motivating experiments.  Today there is a strong motivation to build an electron-positron collider to make precision measurements of the properties of the Higgs boson.  Already for many years, Michael Peskin has been investigating what one can learn from such a collider, including the interpretation of the data in a unified way using Effective Field Theory.

Over a longer term, particle physicists are interested in accelerators to reach the multi-10-TeV scale in parton-parton collision energies.   Accelerator technologies to reach these energies are still being developed.  These include proton colliders in 100 km tunnels, muon colliders, and electron colliders using advanced acceleration methods such as plasma wakefield acceleration.  We can dream about such high energies, but it would be helpful to be more concrete:  What new physics do we expect there, and how does this expectation shape the requirements for a collider?  Michael Peskin has been thinking about these questions, most recently, about a photon-photon collider as the “ultimate” discovery machine.