That's odd: Unruly penguins hint where all the antimatter went

 作者:仲孙榔     |      日期:2019-03-15 09:08:00
Ciara Phelan By Michael Brooks Why does matter exist? We wouldn’t be around to ask the question if it didn’t, but our best theory of material reality implies that the existence of stable matter is an anomaly. So how did everything around us come to be? We don’t have an answer. But in our efforts to make sense of this, the anomaly to begin all anomalies, we are uncovering other hints that our understanding of the stuff contained in the universe is far from complete. That understanding is rooted in the standard model of particle physics, the quantum-theory-based melange that bundles up our knowledge of all the forces of nature besides gravity (see diagram). One of its revelations is that every fundamental matter particle has an antimatter twin – a particle identical in every way apart from having the opposite electric charge. For the familiar negatively charged electron there is a positively charged “positron”, and so on. The big bang should have made equal amounts of matter and antimatter. But here’s the thing: when matter and antimatter meet, they annihilate in a puff of energy. So neither should have survived the early days of the universe. Yet one of them did. Various experiments have tried to find some mismatch between processes involving matter and antimatter to explain this. The latest is LHCb at the CERN particle physics lab, which is looking for an imbalance in decays of particles known as mesons, made up of a quark and an antiquark. In 2011, one result looked promising: