The baryon number is a term used in physics to describe the number of baryons in a system. The word "baryon" is pronounced /ˈbɛərɪɒn/. This is represented using the International Phonetic Alphabet (IPA) where the "b" is pronounced as a voiced bilabial stop, followed by the "a" pronounced as a short open-mid vowel, "r" is pronounced as an alveolar trill, "y" as an open front unrounded vowel and "n" as a nasal consonant. Together, these sounds make up the word "baryon."
Baryon number refers to a fundamental concept in physics used to describe the presence or absence of baryons, which are subatomic particles made up of three quarks. It is a numerical value assigned to every particle or system of particles, representing the specific combination of baryons present in the system.
The baryon number of a particle is determined by counting the number of baryons present and including a positive (+1) value for each baryon and a zero (0) value for all non-baryonic particles, such as leptons or mesons. In a similar manner, the baryon number of a system is calculated by summing up the baryon numbers of each constituent particle.
Baryon number is a conserved quantity in most fundamental interactions, including strong, weak, and electromagnetic interactions, as guided by the laws of conservation of energy and charge. This means that the total baryon number before and after a particle interaction or decay remains constant. For instance, in a nuclear reaction or decay process, the total baryon number of the reactants will be equal to the total baryon number of the products.
The conservation of baryon number plays a crucial role in the understanding of particle physics and cosmology, as any violation or change in the total baryon number would have significant implications for the laws of physics and the structure of the universe.
The word "baryon" originates from the Greek word "barys", meaning "heavy". The term was introduced in 1953 by the American physicist Murray Gell-Mann, who was working on classifying the numerous subatomic particles that had been discovered at the time. Gell-Mann used the term baryon to refer to a class of particles that exhibit a specific set of characteristics.
The term "number" refers to the numerical value associated with the count or amount of baryons. In physics, baryon number is a conserved quantum number, meaning it remains the same before and after any particle interactions. It provides information about the total number of baryons present in a given system. Thus, "baryon number" refers to the numerical quantity assigned to the count of baryons.