Characteristics of Strong Interaction

Characteristics of Strong Interaction

strong interaction and strong force


In strong interactions the quarks exchange gluons, the carriers of the strong force. Gluons carry the color charge of the strong nuclear force. Color charge is analogous to electromagnetic charge, but quarks carry three types of color charge (red, green, blue) and antiquarks carry three types of anticolor (antired, antigreen, antiblue). Gluons may be thought of as carrying both color and anticolor.

Most of the mass of a common proton or neutron is the result of the strong force field energy. The individual quarks provide only about 1% of the mass of a proton. Noteworthy, because most of your mass is due to the protons and neutrons in your body, your mass (and therefore your weight on a bathroom scale) comes primarily from the gluons that bind the constituent quarks together, rather than from the quarks themselves. Mass is primarily a measure of the energies of the quark motion and the quark-binding fields.

Range of Strong Force

As was written, the strong interaction is very complicated interaction, because it significantly varies with distance. At distances comparable to the diameter of a proton, the strong force is approximately 100 times as strong as electromagnetic force. At smaller distances, however, the strong force between quarks becomes weaker, and the quarks begin to behave like independent particles. In particle physics, this effect is known as asymptotic freedom.

As a result, the strong force can leaks out of individual nucleons (as the residual strong force) to influence the adjacent particle. On the other hand, the strong force cannot reach outside the nucleus. This is due to color confinement, which implies that the strong force acts only between pairs of quarks. Simply, color charged particles (such as quarks and gluons) cannot be isolated (below Hagedorn temperature) and therefore in collections of bound quarks (i.e., hadrons), the net color-charge of the quarks essentially cancels out, resulting in a limit of the action of the forces.

Strength of Strong Force

It is the strongest of the four fundamental forces, but as was written, it significantly varies with distance. At the scale of quarks, the strong force is approximately 100 times as strong as electromagnetic force, a million times as strong as the weak interaction, and 1043 times as strong as gravitation.

Particles in Strong Interaction

hadrons-baryons-mesonsIn general, particles that do participate in strong interactions are called hadrons: protons and neutrons are hadrons. The hadrons are further sub-divided into baryons and mesons, according to the number of quarks they contain. Protons and neutrons each contain three quarks; they belong to the family of particles called the baryons. Other baryons are the lambda, sigma, xi, and omega particles. On the other hand mesons bosons and they are composed of two quarks: a quark and an antiquark. Besides charge and spin (1/2 for the baryons), two other quantum numbers are assigned to these particles: baryon number (B) and strangeness (S). Baryons have a baryon number, B, of 1, while their antiparticles, called antibaryons, have a baryon number of −1. A nucleus of deuterium (deuteron), for example, contains one proton and one neutron (each with a baryon number of 1) and has a baryon number of 2. Since baryons make up most of the mass of ordinary atoms, the everyday matter is often referred to as baryonic matter.

The conservation of baryon number is an important rule for interactions and decays of baryons. No known interactions violate conservation of baryon number.

Nuclear and Reactor Physics:

Advanced Reactor Physics:


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Strong Interactions