The Charged Pion

<p><strong>The Field Guide to Particle Physics <br></strong><a href="https://pasayten.org/the-field-guide-to-particle-physics">https://pasayten.org/the-field-guide-to-particle-physics</a><br>©2021 The Pasayten Institute <a href="https://creativecommons.org/licenses/by-sa/4.0/">cc by-sa-4.0</a><br>The definitive resource for all data in particle physics is the Particle Data Group: <a href="https://pdg.lbl.gov/">https://pdg.lbl.gov</a>.</p><p>The Pasayten Institute is on a mission to build and share physics knowledge, without barriers! <a href="http://pasayten.org/heysean">Get in touch</a>.</p><p><strong>The Charged Pions<br></strong>Quarks make up more than big, triplet particles like <a href="https://pasayten.org/the-field-guide-to-particle-physics/proton">protons</a> and <a href="https://pasayten.org/the-field-guide-to-particle-physics/neutron">neutrons</a>. Sometimes they come in pairs. A pair of <a href="https://pasayten.org/the-field-guide-to-particle-physics/up-and-down-quarks">up and down down quarks</a> is called a <strong>pion</strong>.</p><p>There are three kinds of pions: pi plus, pi minus and pi zero. Compared to the proton, they’re quite small and a little quirky. They’re certainly unstable. Today we’ll talk about those charged pions, π±.</p><p><br>Like the proton, pions are mostly comprised of nuclear goo. Unlike the proton, that goo surrounds only two quarks. Or, really, a quark/antiquark pair. A π+ has an up quark together with an antidown quark. That gives is an electric charge of 2/3 + 1/3 = 1, That is to say, π+ has exactly the same charge as the proton. Being the antiparticle, π− is made up of a down quark, with an anti up quark. And of course all that nuclear goo. Its electric charge is precisely the opposite.</p><p>The charged pions have a mass of 139.6 MeV, making them just a tiny bit heavier than the <a href="https://pasayten.org/the-field-guide-to-particle-physics/muon">muon</a>. They are unstable particles, and given their mass typically decay into such muon, emitting a <a href="