Hola! I'm Alexa Guido, a young and curious woman passionate about science. Join me on an exciting journey to explore the wonders of the universe through the lens of physics.
Atoms, the fundamental building blocks of matter, are composed of neutrons and protons, but what about electrons? We know that neutrons and protons are made up of quarks, but electrons are way different. The electron is the most significant lepton in high school physics classes, even if we have never heard of the term “lepton” then.
In exploring the different particles that form the Standard Model of particle physics, we encounter various families, including the Lepton family. As we have described in “Have you heard about the Standard Model?”, this category comprises six distinct leptons, organized into three generations: the “electron” and the “electron neutrino,” the “muon” and the “muon neutrino,” and lastly the “tau” and the “tau neutrino.”
To clarify, leptons are the electron, the muon, and the tau, each accompanied by its respective neutrino. The term “lepton” is derived from the Greek leptos, meaning “small, delicate”. Notably, the electron, muon, and tau are characterized by an electric charge and a sizeable mass, whereas the neutrinos are electrically neutral and have minimal mass.
For a deeper understanding of neutrinos, visit “Have you heard about neutrinos?”.
In a more technical sense, a Lepton is a subatomic and fundamental particle that responds to the electromagnetic force, the weak force, and the gravitational force yet remains unaffected by the strong force.
You may be familiar with these fundamental forces, but what are these about? Firstly, the electromagnetic force is the interaction between charged particles. The weak force plays a crucial role in some forms of radioactivity, the decay of unstable particles, and initiates nuclear fusion. On the other hand, the strong force binds quarks together to make protons and neutrons and holds together atomic nuclei. Lastly, the famous gravitational force is the universal force of attraction between matter.
Returning to Leptons, they are classified as Fermions of spin ½, which means these particles are limited by Pauli's Exclusion Principle. This stipulates that 2 electrons cannot share the same quantum numbers; in simpler terms, no more than two electrons can reside in the same orbital, and if they do, they must have opposite spins. Basically, this property is what allows the construction of the periodic table of elements, eradicating the chance of finding 2 electrons in the same place.
Is the term “positron” familiar to you? Have you ever encountered the concept of antiparticles? The positron was the very first antiparticle discovered by Paul Dirac but theorized by Carl Anderson nearly a century ago. This new particle was immensely significant as it sparked the search for other antiparticles.
A positron is a fundamental particle that keeps the same mass and spin as the electron, but it has the opposite electric charge. Every antiparticle has the same properties as the original one, which mirrors the properties differing solely in charge. For instance, while a proton carries a positive charge, what charge an antiproton would have? A negative one!
This phenomenon illustrates one of the craziest aspects of quantum physics. Like we have a complete zoom of particles, we have to deal with their interactions and try to find a way to understand them. And surprise! The work is doubled because of the existence of antiparticles, and an additional layer of complexity is added.
Surely, every part of the Standard Model presents its unique challenges; the mysteries around leptons like neutrinos, electrons, taus, and muons are especially captivating. Thanks to CERN and especially the work of teams as CMS, we have the opportunity to research more about these particles and discover more astonishing truths!
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