Astroparticle Physics

334 16 Glossarytime-reversal invarianceTopological defects like magnetic monopoles, cosmic strings, do-main walls, or cosmic textures might have been created in the earlyuniverse.topological defectt; the sixth quark flavour (if quarks are arranged according to in-creasing mass). The top quark carries the electric charge + 2 3 e.Themass of the top quarks is comparable to the mass of a gold nucleus(≈ 175 GeV/c 2 ).top quarktriple-alpha processtritiumUuncertainty relationUnified Theoryup quarkVvacuum energy densityVan Allen beltsVela pulsarT invariance or simply time reversal. The operation of replacingtime t by time −t. As with CP violation, T violation occurs inweak interactions of kaon decays. The CPT operation which is asuccession of charge conjugation, parity transformation, and timereversal is regarded as a conserved quantity.Reaction in which three α particles are fused to carbon. Such aprocess requires high α-particle densities and a large resonancelikecross section.Hydrogen isotope with two additional neutrons in the nucleus.The quantum principle first formulated by Heisenberg which statesthat it is not possible to know exactly both the position x and themomentum p of an object at the same time. The same is true forthe complementary quantities energy and time.Any theory that describes all four forces and all of matter within asingle all-encompassing framework (see also Grand Unified Theory,GUT).u; the lightest quark flavour with electric charge + 2 3 e.Quantum fields in the lowest energy state describing the vacuummust not necessarily have the energy zero.Low-energy particles of the solar wind are trapped in certain regionsof the Earth’s magnetic field and stored.Vela X1, supernova remnant in the constellation Vela at a distanceof about 1500 light-years; the Vela supernova explosion was observedby the Sumerians 6000 years ago.