The Charged Kaons

<p><strong>The Field Guide to Particle Physics : Season 2<br></strong><a href="https://pasayten.org/the-field-guide-to-particle-physics">https://pasayten.org/the-field-guide-to-particle-physics</a><br>©2022 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>Charge Kaons<br></strong><br>Strangeness - as a property of particles - was an attempt to explain why some particles took a really long time to decay. By that measure, the charged Kaons are definitely strange.</p><p>Weighing in at 493 MeV, the charged kaons are heavy. Three times as heavy as the <a href="https://pasayten.org/the-field-guide-to-particle-physics/charged-pion">pions</a>. And yet, given their mass, it’s surprising that they’re lifetime is also measured in nanoseconds. About 12 nano seconds, actually. Quite long for such heavy particles.</p><p>The charged kaons are composed of a <a href="https://pasayten.org/the-field-guide-to-particle-physics/strange-quark">strange quark</a> and an <a href="https://pasayten.org/the-field-guide-to-particle-physics/up-and-down-quarks">antiup quark</a>. Or an <a href="https://pasayten.org/the-field-guide-to-particle-physics/up-and-down-quarks">up quark</a> and an anti-strange quark. Kind of like pions. Only STRANGE.</p><p>Kaons are strange in more than the technical sense. Their decays <a href="https://inspirehep.net/literature/369605">confused everyone</a> for quite some time.</p><p>In the late 1940s, particle physicists discovered a few strange particles that all seemed to have about half the mass of the proton, but decayed very differently.</p><p>Something physicists originally called the tau+ (a historical name, which should not to be confused with