Type I string theory

{{Short description|Aspect of theoretical physics}} {{String theory|cTopic=Theory}} In [[theoretical physics]], '''type I string theory''' is one of five consistent supersymmetric [[string theory|string theories]] in ten dimensions. It is the only one whose strings are unoriented<ref>Tzitzimpasis, P.https://webspace.science.uu.nl/~caval101/homepage/Students_files/TzitzimpasisMaster.pdf</ref> (both orientations of a string are equivalent) and the only one which perturbatively contains not only [[closed string]]s, but also [[Open string (physics)|open strings]]. The terminology of type I and [[type II string theory|type II]] was coined by [[John Henry Schwarz]] in 1982 to classify the three string theories known at the time.<ref>{{cite journal|last1=Schwarz|first1=J.H.|authorlink1=John Henry Schwarz|date=1982|title=Superstring theory|url=https://dx.doi.org/10.1016/0370-1573%2882%2990087-4|journal=Physics Reports|volume=89|issue=3|pages=223–322|doi=10.1016/0370-1573(82)90087-4|pmid=|arxiv=|bibcode=1982PhR....89..223S |s2cid=|access-date=|url-access=subscription}}</ref>

==Overview== The classic 1976 work of [[Ferdinando Gliozzi]], [[Joël Scherk]] and [[David Olive]]<ref>F. Gliozzi, J. Scherk and D. I. Olive, "Supersymmetry, Supergravity Theories and the Dual Spinor Model", ''Nucl. Phys. B'' '''122''' (1977), 253.</ref> paved the way to a systematic understanding of the rules behind string spectra in cases where only [[closed string]]s are present via [[modular invariance]]. It did not lead to similar progress for models with open strings, despite the fact that the original discussion was based on the type I string theory.

As first proposed by [[Augusto Sagnotti]] in 1988,<ref> {{cite book |last1=Sagnotti |first1=A. |year=1988 |chapter=Open strings and their symmetry groups |editor1-last='t Hooft |editor1-first=G. |editor2-last=Jaffe |editor2-first=A. |editor3-last=Mack |editor3-first=G. |editor4-last=Mitter |editor4-first=P. K. |editor5-last=Stora |editor5-first=R. |title=Nonperturbative Quantum Field Theory |publisher=[[Plenum Publishing Corporation]] |pages=521–528 |arxiv=hep-th/0208020 |bibcode=2002hep.th....8020S}}</ref> the type I string theory can be obtained as an [[orientifold]] of [[type IIB string]] theory, with 32 half-[[D9-brane]]s added in the vacuum to cancel various [[anomaly (physics)|anomalies]] giving it a gauge group of SO(32) via [[Chan–Paton factor]]s.

At low energies, type I string theory is described by the [[type I supergravity]] in ten dimensions coupled to the SO(32) [[supersymmetric]] [[Yang–Mills theory]]. The discovery in 1984 by [[Michael Green (physicist)|Michael Green]] and John H. Schwarz that anomalies in type I string theory cancel sparked the [[first superstring revolution]]. However, a key property of these models, shown by A. Sagnotti in 1992, is that in general the Green–Schwarz mechanism takes a more general form, and involves several two forms in the cancellation mechanism.

The relation between the [[Type II string theory#Type IIB string theory|type IIB]] string theory and the type I string theory has a large number of surprising consequences, both in ten and in lower dimensions, that were first displayed by the String Theory Group at the [[University of Rome Tor Vergata]] in the early 1990s. It opened the way to the construction of entire new classes of string spectra with or without supersymmetry. [[Joseph Polchinski]]'s work on D-branes provided a geometrical interpretation for these results in terms of extended objects ([[D-brane]], [[orientifold]]).

In the 1990s it was first argued by [[Edward Witten]] that type I string theory with the string coupling constant <math>g</math> is equivalent to the SO(32) [[heterotic string]] with the coupling <math>1/g</math>. This equivalence is known as [[S-duality]].

== Notes == {{reflist}}

== References == * E. Witten, "String theory dynamics in various dimensions", ''Nucl. Phys. B'' '''443''' (1995) 85. [https://arxiv.org/abs/hep-th/9503124 arXiv:hep-th/9503124]. * J. Polchinski, S. Chaudhuri and C.V. Johnson, "Notes on D-Branes", [https://arxiv.org/abs/hep-th/9602052 arXiv:hep-th/9602052]. * C. Angelantonj and A. Sagnotti, "Open strings", ''Phys. Rep.'' '''1''' [(Erratum-ibid.) 339] [https://arxiv.org/abs/hep-th/0204089 arXiv:hep-th/0204089].

{{DEFAULTSORT:Type I String Theory}} [[Category:String theory]]