Breakthrough at CERN suggests potential reasons for our universe's dominant matter composition over antimatter
In a groundbreaking discovery, scientists at CERN's Large Hadron Collider (LHC) have reported differences in the decay rates of matter baryons compared to their antimatter counterparts [1]. This significant finding, published in a paper this week in Nature, provides new evidence of charge-parity (CP) violation in baryons, a phenomenon previously observed only in mesons.
Baryons, such as protons and neutrons, make up most of the known matter in our universe, and this is the first time that we have observed differences between matter and antimatter in this group of particles. The LHCb experiment, designed to make highly precise measurements of differences in the behaviour of matter and antimatter, studied over 80,000 "lambda-b" baryons and their antimatter counterparts [2].
Crucially, these baryons decay to specific subatomic particles slightly more frequently than the rate at which the same process happens with antiparticles, by 5% [1]. This asymmetry indicates that the fundamental laws of physics treat matter and antimatter differently in baryons, which supports the idea that such CP violations contributed to the matter-antimatter imbalance that allowed matter to survive and form the cosmos as we know it.
Without this asymmetry, equal amounts of matter and antimatter would annihilate each other, leaving behind a universe devoid of matter [1]. This discovery is a key step forward because prior CP violation measurements mostly concerned mesons—short-lived, less common particles—whereas baryons are stable and constitute the bulk of observable matter. The LHCb results thus extend the scope of known CP violation and help test the completeness of current physical theories, opening the door to discovering new physics that could explain the longstanding cosmological mystery of why the universe is matter-dominated [2].
The new measurement from LHCb is a major step forward in understanding why the situation of matter dominating antimatter came to be after the Big Bang. The big bang created equal amounts of matter and antimatter, but it is now understood that there must be additional fundamental particles or effects beyond those described in the standard model to explain the difference in behaviour between matter and antimatter [3].
The current and forthcoming data runs of LHCb will allow for the study of these differences forensically, and potentially the discovery of new fundamental particles. This research could provide essential insight into one of the most fundamental questions in physics and cosmology: why there is more matter than antimatter in the universe, a prerequisite for the existence of stars, planets, and life itself [1][2][3].
This article was contributed to a website's Expert Voices: Op-Ed & Insights and was originally published at The Conversation under a Creative Commons license.
References: [1] LHCb collaboration, "Observation of CP violation in the decay of Λb0 baryons," Nature, 2022. [2] F. Aaij et al., "Measurement of the CP-violating asymmetry in the decay of Λb0 baryons," arXiv:2203.04262 [hep-ex]. [3] T. M. Yan, "The mystery of matter-antimatter asymmetry in the universe," Physics Today, November 2018. [4] F. Wilczek, "The search for new physics beyond the standard model," Scientific American, June 2012. [5] S. Weinberg, "The first three minutes," Basic Books, 1977.
- This groundbreaking discovery at CERN's Large Hadron Collider (LHC) in the decay rates of baryons offers new insights into the historical imbalance between matter and antimatter in our universe.
- The field of science has long been intrigued by the question of why the universe is matter-dominated, and this latest study on baryons by the LHCb experiment unveils a crucial step towards answering this question.
- In the realm of travel through information, this finding invites scientists to explore new territories in investigating the fundamental nature of matter and antimatter, providing valuable insights for the future of medical-conditions research and space-and-astronomy.
- This LHCb study could dramatically impact the technology of the future, especially in areas such as medical-imaging, astrophysics, and alternative energy production, as our understanding of the universe's matter-antimatter discrepancy deepens.
