Main-group element Main-group element In chemistry and atomic physics, the main group is the group of elements whose lightest members are represented by helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, and fluorine as arranged in the periodic table of the elements. The main group includes the elements (except hydrogen, which is sometimes not included) in groups 1 and 2 (s-block), and groups 13 to 18 (p-block). The s-block elements are primarily characterised by one main oxidation state, and the p-block elements, when they have multiple oxidation states, often have common oxidation states separated by two units. Main-group elements (with some of the
Lightest Supersymmetric Particle scatter light and thus not be "dark". They must also almost certainly be non-colored. With these constraints, the LSP could be the lightest neutralino, the gravitino, or the lightest sneutrino. In extra-dimensional theories, there are analogous particles called "LKP"s or "Lightest Kaluza-Klein Particle". These are the stable particles of extra-dimensional theories. Lightest Supersymmetric Particle In particle physics, the lightest supersymmetric particle (LSP) is the generic name given to the lightest of the additional hypothetical particles found in supersymmetric models. In models with R-parity conservation, the LSP is stable; in other words, the LSP cannot decay into any Standard Model particle,