What is a Baryon?

  • Author: ChemistryViews.org
  • Published Date: 01 August 2017
  • Copyright: Wiley-VCH Verlag GmbH & Co. KGaA
thumbnail image: What is a Baryon?

A baryon is a composite subatomic particle. It is made up of three quarks. The most stable baryons are protons and neutrons, so most building blocks of matter are baryons.


Baryon comes from the Greek word βαρύς (barys) for heavy. At the time of their naming, most known elementary particles had lower masses than the baryons.

 

Quarks and Hadrons

Quarks have many properties, including electric charge, mass, color charge, and spin. There are six types of quarks, known as flavors: up, down, strange, charm, top, and bottom quarks. Up and down quarks have the lowest masses of all quarks. Only up and down quarks are stable; all heavier quarks decay very quickly into these.

For every quark flavor, there is a corresponding type of antiparticle, known as an antiquark. So each baryon has a corresponding antiparticle, an antibaryon. Here, quarks are replaced by their corresponding antiquarks.


A composite particle made of quarks is called a hadron (Greek: ἁδρός, hadrós, "stout, thick"). Baryons belong to the hadron family of particles. Baryons (3 quarks) and mesons (2 quarks) as well as exotic conditions such as pentaquarks with 5 quarks, dibaryon with 6 quarks belong to the hydron family. For reasons of symmetry, particles of only 1 quark are not allowed.

 

Baryon with Two Heavy Quarks

In July 2017, physicists at CERN first demonstrated a baryon with two heavy quarks [1]. It consists of two heavy charm quarks and a light up quark and is double positively charged. It is the first proof of a baryon with two equally heavy quarks. The existence of such doubly charged baryon has been considered possible since the 1970s, but it has never been demonstrated so far.

The researchers discovered the baryon named Ξcc++ using the Large Hadron Collider beauty (LHCb) detector at the Large Hadron Collider (LHC) at CERN. The new particle has a mass of 3,621 megaelectron volt (MeV). This makes it about four times as heavy as a proton. The reason for this is the two heavy charm quarks, each weighing 1.275 MeV.



[1] Observation of the doubly charmed baryon Ξcc++, Phys. Rev. Lett. 2017. submitted (Link)

 

Also of interest

 

Article Views: 1233

Sign in Area

Please sign in below

Additional Sign In options

Please note that to comment on an article you must be registered and logged in.
Registration is for free, you may already be registered to receive, e.g., the newsletter. When you register on this website, please ensure you view our terms and conditions. All comments are subject to moderation.

Article Comments - To add a comment please sign in

Bookmark and Share

If you would like to reuse any content, in print or online, from ChemistryViews.org, please contact us first for permission. more


CONNECT:

ChemistryViews.org on Facebook

ChemistryViews.org on Twitter ChemistryViews.org on YouTube ChemistryViews.org on LinkedIn Sign up for our free newsletter


A product of ChemPubSoc Europe (16 European Chemical Societies)and Wiley-VCH