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THE SCIENTIFIC FOUNDATIONS OF JAINISM
uncharged particles, that is, electrically neutral. The simplest example of the atomic structure of a chemical element is provided by hydrogen, which has one electron and one proton; however, its ‘isotopes' can have either one or two neutrons without disturbing its chemical properties. For chemical stability, the number of electrons is always equal to the number of protons.
In the early 1970's, the picture changed completely (see Fig. 10.1). There are now three groups of elementary particles:
Quarks, Leptons and Gauge Bosons. The bosons form a glue between the other two. Quarks differ from leptons in that quarks have fractional charges, namely 2/3, 1/3, -1/3, and -2/3, whereas leptons have charge O or -1. Further, bosons differ from the other two because quarks and leptons have 1/2-spin, whereas bosons have 1-spin. The electron is an example of a lepton with charge -1. The neutrino is an example of a lepton with no charge.
Quarks can exist in clusters of two or three. One can have three quarks as in the proton. The groups containing three quarks are called "baryons”, and the groups containing only two quarks under certain compatability conditions are called “mesons". In the latter case, there can be one quark with one anti-quark. The simplest example of a meson is the “positive pion" which consists of one quark with one anti-quark. Note that like electrons, quarks are assessed to be perfect points without any structure.
The following are the properties which distinguish various elementary particles.
(1) Charge or no charge (colour). (2) Mass. (3) Spin (intrinsic angular momentum). (4) Lifespan.
(5) Force (four types, see § 10.3). Note that baryons have the greatest mass and leptons have the smallest mass, with bosons having an intermediate mass. Quarks have six flavours and three colours. Note that the use of these flavours and colours is only symbolic. Amongst the so called six flavours, the most important are "up" and "down" (for the lightest pair of quarks). If “u” denotes up-quark and “d” denotes downquark, then the corresponding notations for an anti-particle are “ū" and "d" respectively. A positive pion is then either ud or ūd. The three colours are red, green and blue: these are the three "electrical" colours.
