= Bosonic string
A <bosonic string> is a relativistic one-dimensional object whose embedding coordinates are bosonic fields on a two-dimensional <worldsheet>. Its classical motion can be described by the <Nambu–Goto action>, proportional to the worldsheet area, or by the equivalent <Polyakov action> with an auxiliary worldsheet metric.
An open string has endpoints; a closed string forms a loop and has independent left- and right-moving oscillations. Quantization produces a tower of particle states. In the ordinary flat critical <bosonic string theory>, anomaly cancellation selects 26 spacetime dimensions, and the closed-string spectrum includes a massless <graviton>. The tachyonic ground state indicates instability of the chosen vacuum.<String Theory by David Tong>[Sections 1–2, actions, quantization and spectrum]{ref}
Back to article page
