string in nLab

> This entry is about the notion in [[particle physics]]/[[quantum gravity]]. For the notion in [[computer science]] see at *[[string (computer science)]]*.

+-- {: .rightHandSide}
+-- {: .toc .clickDown tabindex="0"}
###Context###
#### String theory
+-- {: .hide}
[[!include string theory - contents]]
=--
#### Physics
+--{: .hide}
[[!include physicscontents]]
=--
=--
=--



#Contents#
* table of contents
{:toc}

## Idea

A _string_ or *1-brane* is a [[brane]] of dimension one higher than an ordinary [[particle]]:

where a 1-[[dimension|dimensional]] [[sigma-model]] may be thought of a describing the dynamics of [[particle]]s propagating of a [[target space]] $X$, a 2-dimensional [[sigma-model]] is said to described the dynamics of a string on some target space.

Much of traditional [[quantum field theory]] on $X$ may be understood in terms of [[second quantization]] of 1-dimensional [[sigma-models]] with [[target space]] $X$. What is called _[[string theory]]_ is the corresponding study of what happens to this situation as the 1-dimensional $\sigma$-model is replaced by a 2-dimensional one (for more on this see at *[[worldline formalism]]*).

A key motivation/application for strings is their identification with [[flux tubes]] in [[confinement|confined]] [[Yang-Mills theory]]/[[QCD]] &lbrack;[Polyakov (1998)](#Polyakov98), [Polyakov (1999)](#Polyakov98)&rbrack;, for more on this see at *[[AdS-CFT correspondence]]* and *[[AdS-QCD correspondence]]*.

There is 

* the [[bosonic string]] of [[bosonic string theory]]

* the [[superstring]] of [[superstring theory]]

(also called the _[[F1-brane]]_)

* there is also the [[D1-brane]].

## Related entries

* [[noncommutative open string theory]]

* [[relativistic particle]]

* [[relativistic string]]

* [[relativistic membrane]]

* [[vortex string]]

* [[string theory]]

  * [[string scattering amplitudes]]

  * [[string field theory]]

  * [[string theory FAQ]]

$\,$

[[!include table of branes]]


## References

### General

See references at *[[string theory]]*, *[[bosonic string]]* and *[[superstring]]*.



[[!include Polyakov gauge-string duality -- references]]





[[!redirects strings]]

[[!redirects fundamental string]]
[[!redirects fundamental strings]]


[[!redirects open string]]
[[!redirects open strings]]
[[!redirects closed string]]
[[!redirects closed strings]]

[[!redirects relativistic string]]
[[!redirects relativistic strings]]


[[!redirects 1-brane]]
[[!redirects 1-branes]]