LHCb Finds 4-Sigma B-Meson Decay Anomaly in 650 Billion Events
Updated
Updated · Scientific American · May 31
LHCb Finds 4-Sigma B-Meson Decay Anomaly in 650 Billion Events
2 articles · Updated · Scientific American · May 31
A new LHCb analysis found that angles in rare B-meson decays to a kaon and two muons deviate from standard-model predictions with about 4-sigma significance.
The result comes from roughly 650 billion decays collected in 2011-2018, and the channel is especially sensitive to new physics because the bottom-to-strange transition runs through a quantum loop.
The anomaly has been building since 2015 and gets tentative support from CMS, but theorists caution that hard-to-model charm-quark effects could mimic part of the signal.
Possible explanations include a heavier Z-prime boson tied to a new force or a leptoquark, both of which could alter the decay through virtual-particle effects.
With other major standard-model anomalies largely fading, this is one of the strongest remaining hints of new physics; more LHCb results are expected no earlier than 2027.
With conflicting results from CERN, is our fundamental theory of physics finally breaking or being confirmed?
Could one new force explain a particle anomaly and the universe's entire dark matter mystery?
The 4-Sigma B-Meson Anomaly: A Potential Crack in the Standard Model and the Search for New Physics
Overview
The 4-sigma anomaly is a striking deviation from the Standard Model, seen in rare B-meson decays studied by the LHCb experiment since 1994. This result, published in Physical Review Letters, shows a four standard deviation tension—meaning there’s only a one in 16,000 chance it’s a random fluctuation if the Standard Model is correct. These B-meson 'penguin' decay processes are especially sensitive to the effects of very heavy, hypothetical new particles that cannot be directly produced at the LHC. While this finding is compelling, it still falls short of the five-sigma threshold needed for a scientific discovery.