The Charged Sigma Baryons

<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><a href="https://pasayten.org/the-field-guide-to-particle-physics/charged-sigma-baryons"><strong>The Charged Sigma Baryons</strong></a></p><p><strong>Introduction</strong><br>The Sigma Baryons - that’s a capital Sigma - are a trio of slightly heavy cousins to everyday particles like the proton and the neutron. </p><p>With masses of almost 1200 MeV each, it may surprise you that the physics of Sigma baryons feels much closer to a comparatively puny trio of familiar particles: the pions.</p><p>The pions form a triplet of mesons: pi plus, pi zero and pi minus. So too, do the Sigmas: Sigma Plus, Sigma Zero and Sigma Minus. The similarities are helpful for building an intuition, but the differences are stark. While the charged pions are antiparticle partners, the charged Sigmas are anything but.</p><p>Today we’ll focus on that fact as we explore the pair of particles Sigma Plus and Sigma Minus. </p><p><strong>Charged Sigmas</strong></p><p>The charged Sigma baryons are your typical strange particle. They live much longer than they should, given their mass. Their lifetime is a sizable fraction of a nanosecond. Like the Lambda Zero, the charged Sigma baryons live so long because they have to wait for their constituent strange quark to decay.</p><p>The strange quark can only decay to an up quark, and while possible, it takes a while. It’s a quantum bottleneck that in particle decays that has come to be known as t