Dear colleagues and friends,
An esteemed colleague shared with us this article written by Ana Lopes, published on April 12, 2024 in the newsletter of the European Organization for Nuclear Research (CERN) and translated by us for this space. Let's see what it's all about...
Once we have a particle of matter, it will always be a particle of matter. Or not. Thanks to a peculiarity of quantum physics, four known particles formed by two different quarks (such as the electrically neutral D meson, composed of an enchantment quark (charm) and an antiquark up (up) can spontaneously oscillate in their antimatter companions and vice versa.
At a seminar held on March 26 at CERN, the collaboration LHCb (Large Hadron Collider beauty), an experiment that specializes in investigating the subtle differences between matter and antimatter, presented the results of its latest search for matter-antimatter asymmetry, in the oscillation of the neutral D meson, which, if found, could help shed light on the mysterious matter-antimatter imbalance in the universe.
The weak force of the standard model of particle physics induces an asymmetry between matter and antimatter, known as CP violation, in particles containing quarks. However, these sources of CP violation are difficult to study and are insufficient to explain the matter-antimatter imbalance in the universe, leading physicists to search for new sources and to study the known ones better than ever.
In their latest effort, LHCb researchers have “picked up their sleeves” to measure with unprecedented precision a set of parameters that determine the matter-antimatter oscillation of the neutral D meson and allow the search for the CP violation in the oscillation, hitherto not observed but predicted.
The research team had previously measured the same set of parameters, which are related to the decay of the neutral D meson into a positively charged kaon and a negatively charged pion, using their complete data set from the first LHC experiment (Run-1) and a partial data set from the second experiment (Run-2).
This time, the team analyzed the complete dataset from the second experiment (Run-2) and, by combining the result with that of their previous analysis, excluding the partial dataset from the second experiment, obtained the most accurate measurements of the parameters to date. The total measurement uncertainty is 1.6 times lower than the smallest uncertainty previously achieved by LHCb.
The results are consistent with previous studies, confirm the matter-antimatter oscillation of the neutral D meson, and show no evidence of CP violation in the oscillation. The findings call for future analyses of this and other decompositions of the neutral D meson using data from a third LHC experiment and its planned upgrade, the high-luminosity LHC.
Other interesting decompositions of the neutral D meson include its decay into a pair of two kaons or two pions, in which LHCb researchers observed for the first time a CP violation in particles containing enchantment quarks, and the decay into a neutral kaon and a pair of pions with which LHCb recorded the speed of the matter-antimatter oscillation of the particle. No path should be left unexplored in the search for clues to the matter-antimatter imbalance in the universe and other cosmic mysteries.
