In 1958, Sidney Bludman suggested that there might be another arm of the weak force, the so-called "weak neutral current," mediated by an uncharged partner of the W bosons, which later became known as the Z boson.
The property of interaction with each other is very different from the other exchange particles, and raises the possibility of gluon collections referred to as "glueballs". Feynman diagrams for: The gluon exchange picture there converts a blue quark to a green one and vice versa.
That short-range nucleon-nucleon interaction can be considered to be a residual color force extending outside the boundary of the proton or neutron. Other electromagnetic processes can be represented, as in the examples below. Since gravity is an inverse square force of apparently infinite range , it can be implied that the rest mass of the graviton is zero.
That strong interaction was modeled by Yukawa as involving an exchange of pions , and indeed the pion range calculation was helpful in developing our understanding of the strong force. These results culminated in the need to search for the final piece of the Standard Model — the Higgs boson.
Each vertex must conserve charge, baryon number and lepton number. Neutrinos are particles that interact only via the weak interaction, and when the physicists shot neutrinos through the bubble chamber they were able to detect evidence of the weak neutral current, and hence indirect evidence for the Z boson. Enrico Fermi was the first to put forth a theory of the weak force in 1933, but it was not until the 1960s that Sheldon Glashow, Abdus Salam and Steven Weinberg developed the theory in its present form, when they proposed that the weak and electromagnetic forces are actually different manifestations of one electroweak force.
Lamb shift. Within their range of about a fermi , the gluons can interact with each other, and can produce virtual quark-antiquark pairs.
They can be drawn for protons, neutrons, etc. Properties of W and Z The W and Z particles are called intermediate vector bosons and are the exchange particles for the weak interaction.
The photon is the exchange particle responsible for the electromagnetic force. Index Particle concepts References Griffiths Ch 2. Like its electrically charged cousin, the W , the Z boson carries the weak force. The time axis points upward and the space axis to the right. Theoretical calculations show that at a fundamental level the weak and electromagnetic forces have the same strength if the W and Z particles have masses of 80 and 90 GeV respectively.
Particles are represented by lines with arrows to denote the direction of their travel, with antiparticles having their arrows reversed. Here two electrons enter, exchange a photon, and then exit.
The prediction included a prediction of the masses of these particles as a part of the unified theory of the electromagnetic and weak forces, the electroweak unification. A backward arrow represents the antiparticle, in these cases a positron.