1branes
1branes, or 1-branes, are one-dimensional extended objects in theories that describe fundamental building blocks of matter and spacetime, such as string theory. A p-brane is an object with p spatial dimensions; therefore a 1-brane has one spatial dimension, i.e., it is a string. In string theory, 1-branes appear in two broad forms: fundamental strings, which are the basic excitations of the theory, and D1-branes, which are D-branes carrying Ramond-Ramond charge and on which open strings can end. Closed 1-branes form loops, while open 1-branes typically have endpoints constrained to lie on higher-dimensional branes.
The dynamics of a 1-brane are described by a two-dimensional worldsheet swept out in spacetime. The classical
1branes play a central role in non-perturbative aspects of string theory and in brane-based constructions of