4 new particles were found at CERN — and they could crack the secrets of nature’s laws
Charming new particles
The LHC has now discovered 59 new hadrons. These include the tetraquarks most recently discovered, but also new mesons and baryons. All these new particles contain heavy quarks such as “charm” and “bottom.”
These hadrons are interesting to study. They tell us what nature considers acceptable as a bound combination of quarks, even if only for very short times. They also tell us what nature does not like. For example, why do all tetra- and pentaquarks contain a charm-quark pair (with just one exception)? And why are there no corresponding particles with strange-quark pairs? There is currently no explanation.
Another mystery is how these particles are bound together by the strong force. One school of theorists considers them to be compact objects, like the proton or the neutron. Others claim they are akin to “molecules” formed by two loosely bound hadrons. Each newly found hadron allows experiments to measure its mass and other properties, which tell us something about how the strong force behaves. This helps bridge the gap between experiment and theory. The more hadrons we can find, the better we can tune the models to the experimental facts.
These models are crucial to achieving the ultimate goal of the LHC: to find physics beyond the standard model. Despite its successes, the standard model is certainly not the last word in the understanding of particles. It is for instanceinconsistent with cosmological modelsdescribing the formation of the universe.
The LHC is searching for new fundamental particles that could explain these discrepancies. These particles could be visible at the LHC, but hidden in the background of particle interactions. Or they could show up as small quantum mechanical effects in known processes. In either case, a better understanding of the strong force is needed to find them. With each new hadron, we improve our knowledge of nature’s laws, leading us to a better description of the most fundamental properties of matter.
This article byPatrick Koppenburg, Research Fellow in Particle Physics,Dutch National Institute for Subatomic PhysicsandHarry Cliff, Particle physicist,University of Cambridgeis republished fromThe Conversationunder a Creative Commons license. Read theoriginal article.
Story byThe Conversation
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