The CERN particle-physics lab in Switzerland is famous for the Large Hadron Collider (LHC), but that is not the only game in town when it comes to looking for new physics beyond the Standard Model. For example, the lab has an “Antimatter Factory” that looks for new physics by trying to measure tiny differences in the properties of hydrogen and antihydrogen.
“Physics beyond colliders at CERN: beyond the Standard Model working group report” is a comprehensive 115-page document that focuses on new experiments and facilities that could be built at CERN and are complementary to the LHC.
It is written by the “PBC BSM study group”, which is an international team of 33 physicists. They considered 18 different proposals that could be built at CERN to “exploit” the lab’s accelerator complex and scientific infrastructure to look for new physics.
They say that the search for new physics beyond the Standard Model is motivated by four unexplained phenomena that are readily observed in the universe. These are neutrino oscillations; the abundance of matter and dearth of antimatter; dark matter; and cosmological inflation and dark energy.
Electric dipole moments
One avenue that has long intrigued me is looking for new physics by making precision measurements. One of my favourites is the idea of trying to detect the electric dipole moments (EDMs) of particles such as the electron or proton. Standard-Model symmetry rules prevent these particles from having EDMs, so measuring even the tiniest value would provide a glimpse of new physics.
Other ideas that are scrutinized in the report focus on detecting axions and axion-like particles (ALPS). Axions are hypothetical particles that were first proposed to resolve an inconsistency in quantum chromodynamics – the theory of how quarks and gluons interact to form particles such as neutrons. ALPs have yet to be discovered but they are expected couple very weakly to matter – thus making them candidates for dark matter. As a result, discovering axions could open windows into several mysteries beyond the Standard Model.
For a wide-ranging discussion of new experiments that could soon be searching for ALPs, EDMs and more, have a good read of the report. My favourite experiment name is KLEVER, which looks at the decay of long-lived neutral kaons (ΚL). The first two letters represent ΚL, but I am not sure about the “EVER”.
