On December 13, 2023, 8 minutes reading
Introduction
It has a bold new plan to explore the quantum universe from the smallest particles to the farthest reaches. On December 7, the Particle Physics Project Prioritization Panel (P5) presented its draft report, outlining a path for particle physics in the United States over the next two decades. “What we really strive for is: ‘How does the universe work?’” says Hitoshi Murayama, chair of P5 and a theorist at the University of California, Berkeley.
Open Questions
Over the past century, physicists have used increasingly energetic and precise experiments to uncover how the universe operates at its smallest scales. Their efforts have led to the Standard Model of particle physics, which describes the fundamental components of matter (leptons and quarks) and the forces that govern them (electromagnetic, strong, and weak forces). Simultaneously, scientists have also developed a standard model of cosmology to explain cosmic evolution, from the beginning of time to today (and beyond): start with the Big Bang. Add one part dark matter, two parts dark energy, and just a bit of ordinary matter. Let it simmer for about 13.8 billion years.
Cosmic Options
The P5 report places high priority on the CMB-S4 project, an $800 million initiative to study the cosmic microwave background – the first light that can be seen after the Big Bang – using a number of radio telescopes on the ground. Jim Stehr, a physicist at Fermilab and director of CMB-S4, describes the support as a “vote of confidence” in the project’s significance and plan.
Collider Impact
Negative results have also impacted future particle collider plans. After decades of theoretical predictions confirmed by the discovery of the Higgs boson in 2012, which validated how other particles acquire their mass, CERN’s Large Hadron Collider (LHC) has failed to find any new fundamental particles.
High Hopes for Higher Energies
The lack of new particles at the LHC has also pushed physicists toward higher energies. Specifically, they want a device that collides particles to explore the energy range of 10 tera-electron volts (TeV), which is an order of magnitude increase over the current energy of the LHC and many researchers hope is the minimum at which new phenomena will emerge. (For comparison, 1 tera-electron volt is approximately the kinetic energy carried by a flying mosquito.)
Muon Collisions
Muons, the heavier twins of electrons, have recently entered the field of interest – particularly among American physicists – for two main reasons. First, new design studies have shown that building a muon collider is likely feasible even though muons have a very short lifetime of 2.2 microseconds, making them harder to work with than longer-lived protons and electrons. Second, a muon collider presents an opportunity to reach 10 tera-electron volts in the United States in a shorter timeframe compared to most potential international competitors. A 10 tera-electron volt muon collider with a circumference of only 16 kilometers – could fit within Fermilab’s boundaries.
Source: https://www.scientificamerican.com/article/road-map-for-u-s-particle-physics-wins-broad-approval/
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