Period 1 element lithium and fluorine (appearing twice), or left floating above the other elements and not assigned to any group in the periodic table. Helium is almost always placed above neon (which is in the p-block) in the periodic table as a noble gas, although it is occasionally placed above beryllium due to their similar electron configuration. Hydrogen (H) is the chemical element with atomic number 1. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly flammable diatomic gas with the molecular formula H. With an atomic mass of 1.00794 amu, hydrogen is the lightest element. Hydrogen is
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,