Physicists from the CMS Collaboration at CERN’s Large Hadron Collider (LHC) have significantly advanced a decades-old test of the delicate imbalance that enables the universe’s existence. This breakthrough utilized the largest sample ever of particles known as beauty mesons.
Beautiful neutral mesons can transform into their antimatter counterparts. Image credit: Ansar Iqbal/CMS.
One of the greatest enigmas in physics is why the universe is predominantly comprised of ordinary matter, like that which forms us and our environment.
Each matter particle is paired with an antiparticle that shares the same mass but has an opposite charge. Our leading theories suggest that the Big Bang should have generated approximately equal amounts of matter and antimatter, yet very little antimatter remains today.
Among these investigations, a new research paper by CMS physicists examined a potential factor explaining this disparity: a subtle difference in the behavior between matter and antimatter known as charge parity (CP) violation.
“Studying the neutral beauty meson, which consists of a beauty antiquark paired with a down-type quark, is one of the most effective ways to explore CP violation,” the researchers stated.
“This is due to the unexpected ability of neutral mesons to transform spontaneously into their own antiparticles and back.”
By analyzing the minute differences in the decay rates of matter and antimatter variants of these particles over time, scientists can test the Standard Model with immense precision.
The research team evaluated proton-proton collision data collected between 2022 and 2025, reconstructing the distinct decays of around 1.4 million B0 mesons containing down quarks and 16,000 B0s mesons with strange quarks.
A major challenge was identifying the type of each meson at the time of its creation, before it decayed into a J/ψ meson and a neutral kaon.
To overcome this, scientists utilized cutting-edge artificial intelligence algorithms.
This system integrates data from muons, electrons, jets, and, for B0s mesons, surrounding particles produced during the collision event.
This approach significantly enhanced the experiment’s ability to ascertain the initial state of the meson compared to earlier analyses.
“The observed CP violations align with Standard Model predictions and comprise the most precise measurements to date of CP violations in the decay of B0 particles into J/ψ mesons and neutral kaons,” the researchers stated.
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CMS Collaboration. 2026. Time-dependent CP violation in B0(s) → J/ψK0S decay measured using the CMS detector. CMS-PAS-BPH-26-005
Source: www.sci.news
