The Proton

<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 Proton<br></strong><br>With a mass of 938.27 MeV, the proton is the lowest energy configuration of a trio of <a href="https://pasayten.org/the-field-guide-to-particle-physics/up-and-down-quarks">quarks</a>. It has two up quarks and a down, but remember most of that mass is made up of subnuclear goo. You can find protons literally everywhere: from the nuclei of atoms on Earth to collisions at ultra high speeds from deep in outer space.</p><p>From our accounting of electric charge, the proton has two copies of the up charge, and one of the down, which means that electric the charge of the proton is</p><p>2/3e + 2/3e − 1/3e = e.</p><p>So far as we can tell, the proton is stable. It’s the only stable quark triplet or <strong>baryon</strong> because it has the lowest mass. Anything heavier would decay… to it. There are a host of experiments looking for evidence that protons decay, but so far all we can say is that it’s average lifetime longer than 10^34 =10000000000000000000000000000000000 years. That’s like expecting to find only a single proton decay out of all the atoms in one million people per year. </p><p>There are a lot of reasons to expect the proton to decay - at lot of really compelling, interesting ones. But they’re all hypothetical extensions to the standard model of particle physics. So again, as far as we know, the proton is stable. And all quark triplets - the baryons - eventually decay to th