Breakthrough at CERN: Scientists Measure Elusive Tau Particle’s Magnetic Moment

Groundbreaking Method Unveils New Insights into the Fundamental Nature of the Universe

In a groundbreaking achievement at CERN, scientists have successfully measured the magnetic moment of the elusive tau particle using a novel method. By analyzing near-miss particle interactions in the Large Hadron Collider, researchers have made significant advancements in the field of particle physics. This breakthrough has the potential to unveil previously unknown aspects of the universe’s fundamental nature, shedding light on the mysteries that lie beyond our current understanding.

A Novel Approach to Measuring Particle Wobble:

In a recent paper published in Physical Review Letters, a team of international nuclear and particle physicists introduced a new method for measuring the wobble of the tau particle. Instead of focusing on head-on collisions, the researchers analyzed the times when incoming particles in the accelerator narrowly missed each other. Surprisingly, this approach enabled far more accurate measurements of the tau particle’s wobble, known as the tau magnetic moment. This marks the first time in nearly two decades that scientists have successfully measured this wobble, and it holds the potential to provide crucial insights into the known laws of physics.

Why Measure a Wobble?

Electrons, muons, and taus are the three cousins in the family of particles that make up the building blocks of atoms. When placed in a magnetic field, these particles exhibit a wobbling motion, similar to a spinning top. This wobble is known as a particle’s magnetic moment and can be predicted using the Standard Model of particle physics, which outlines how particles interact.

Physicists have long been interested in measuring magnetic moments as they offer a glimpse into the quantum world. According to quantum physics, particles and antiparticles constantly appear and disappear, causing slight alterations in the wobble of electrons, muons, and taus. By precisely measuring this wobble, scientists can explore the possibility of undiscovered particles.

Testing Electrons, Muons, and Taus:

Since the 1940s, physicists have been measuring the wobble of electrons to uncover intriguing effects in the quantum realm. The electron’s wobble has been measured to an extraordinary 13 decimal places. However, due to their light mass, electrons are less sensitive to new particles.

Muons and taus, on the other hand, are heavier particles that wobble at different speeds due to the presence of undiscovered particles in their quantum clouds. In 2021, scientists at Fermilab measured the muon’s magnetic moment to 10 decimal places and discovered that it wobbled noticeably faster than predicted by the Standard Model. This discrepancy suggests the existence of unknown particles.

Taus, being the heaviest particle in the family, are 17 times more massive than muons and 3,500 times heavier than electrons. This makes them highly sensitive to potential undiscovered particles. However, due to their incredibly short lifespan, measuring the tau’s magnetic moment has been challenging.

Lead Ions for Near-Miss Physics:

To address the difficulty of measuring the tau’s wobble, researchers turned to lead ion experiments conducted at CERN from 2015 to 2018. These experiments involved colliding lead ions, which produce strong electromagnetic fields. When these ions narrowly missed each other, their accompanying photons collided, creating a variety of particles, including taus.

Surprisingly, the data from these near-miss events revealed the creation of tau particles, presenting an opportunity to measure the tau’s magnetic moment. This discovery, made in 2019 by scientists Jesse Liu and Lydia Beresford, was a total surprise and marked a hidden experiment within the existing data.

A Landmark Discovery and Future Prospects:

In April 2022, the CERN team announced the direct evidence of tau particles created during lead ion near misses. Using this data, the team successfully measured the tau magnetic moment, matching the precision of the previous best measurement achieved over several years. This landmark result represents a significant advancement after nearly two decades of limited progress.

The Large Hadron Collider has recently resumed lead ion data collection, and the team plans to quadruple the sample size of near-miss data by 2025. This increased data will double the accuracy of the tau magnetic moment measurement, potentially surpassing the required precision to test the predictions of the Standard Model. The future holds exciting prospects for uncovering surprises and deepening our understanding of the fundamental nature of the universe through the study of tau particles.


The measurement of the tau particle’s magnetic moment using near-miss particle interactions in the Large Hadron Collider represents a breakthrough in particle physics. This innovative method has provided scientists with a more accurate understanding of the tau’s wobble, opening up new avenues for exploring the mysteries of the universe. With ongoing research and future advancements, the study of tau particles holds the promise of revealing unknown aspects of the fundamental nature of our reality.






Leave a Reply

Your email address will not be published. Required fields are marked *