One of the universe’s fundamental forces appears to be stronger than we thought, a finding that could lead to the discovery of new particles. The electroweak force unifies the electromagnetic and the weak nuclear forces. Under ordinary conditions, the two forces are distinct and play a role in different processes, such as the weak force being part of radioactive decay and the electromagnetic force affecting charged objects.
But at very high energies and temperatures, like as seen in some stages of the early universe and in particle colliders, the two forces combine. Alessandro Conigli at Johannes Gutenberg University Mainz in Germany and his colleagues have now calculated several properties that capture the strength of the electroweak force with unprecedented precision and found a discrepancy with past calculations. Calculating details of nuclear forces is notoriously difficult.
For decades, researchers could only do so with “phenomenological methods” where they could not solve equations exactly but had to include inputs from experiments. This made it more difficult to say whether the best theoretical predictions agreed with experimental findings or not, as the two approaches were mixed. Lost quantum traces could reveal dark matter at the Large Hadron Collider In 2024, the phenomenological method was called into question when an experiment involving particles called muons appeared not to match theoretical calculations.
However, when researchers refined these calculations using a new technique called lattice quantum chromodynamics (QCD), everything worked again. Conigli and his colleagues used this same technique to calculate two numbers that capture how quantum pairs of virtual particles and their antimatter “antiparticles” affect the strength of the electroweak force at different energy levels. Across two studies, the team found that the lattice QCD results differed from the phenomenological calculations by around 1 per cent.
While small, this discrepancy is significant because the researchers managed to halve the errors in their calculation. This level of precision is crucial for unravelling several mysteries that currently plague our understanding of particles. Specifically, it will help in the search for phenomena not contained in the standard model of particle physics, which tabulates all known forces and particles, including the electroweak force.
It is a remarkably well-tested theory of the world, yet it currently doesn’t explain important phenomena such as dark matter, which is very abundant in our universe. The mystery of nuclear ‘magic numbers’ has finally been resolved The properties that the team calculated are badly needed to aid experimental searchers of new particles, says Colin Morningstar at Carnegie Mellon University in Pennsylvania. Krishna Kumar at the University of Massachusetts Amherst says the biggest implications of the work will be for particle colliders that are yet to be built, such as the proposed Future Circular Collider, which will surpass the precision of existing experiments.
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