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Beyond the speculative hypothetized role of string theory as a physical theory of fundamental strings that constitute the observed fundamental particles in the standard model of particle physics, the theory has shed light on many aspects of quantum field theory as such, both on the conceptual structure of QFT as well as on concrete theories and their concrete properties such as of. This entry lists such instances of string theory results having lead to insights in non-stringy physics and in particular into experimentally confirmed physics, such as QCD in the standard model of particle physics.
Le plus court chemin entre deux vérités dans le domaine réel passe par le domaine complexe.
The two basic theories that underlie observed fundamental physics – and which string theory unifies at least qualitatively and in perturbation theory – are Yang-Mills theory and Einstein gravity/general relativity.
Many of the insights are based on the gauge/gravity duality in string theory:
AdS/CFT correspondence open/closed string duality
talks at
The worldline formalism for expressing QFT scattering amplitudes in an effective gauge invariant way (different from but equivalent to the Feynman rules) was originally found by taking the point-particle limit of the expressions for string scattering amplitudes. See at worldline formalism for more.
By embedding quantum field theories in string theory (typically as the worldvolume theories of various branes) the various dualities of string theory will relate different QFTs in ways that are typically far from obvious from just looking at these QFTs themselves.
The investigation specifically of N=1 D=4 super Yang-Mills theory and N=2 D=4 super Yang-Mills theory in this fashion has come to be known as geometric engineering of quantum field theory.
Montonen-Olive duality of (super) Yang-Mills theory derives from conformal invariance of the 6d (2,0)-supersymmetric QFT (see there) compactified on a torus.
gauge theory induced via AdS-CFT correspondence
M-theory perspective via AdS7-CFT6 | F-theory perspective |
---|---|
11d supergravity/M-theory | |
$\;\;\;\;\downarrow$ Kaluza-Klein compactification on $S^4$ | compactificationon elliptic fibration followed by T-duality |
7-dimensional supergravity | |
$\;\;\;\;\downarrow$ topological sector | |
7-dimensional Chern-Simons theory | |
$\;\;\;\;\downarrow$ AdS7-CFT6 holographic duality | |
6d (2,0)-superconformal QFT on the M5-brane with conformal invariance | M5-brane worldvolume theory |
$\;\;\;\; \downarrow$ KK-compactification on Riemann surface | double dimensional reduction on M-theory/F-theory elliptic fibration |
N=2 D=4 super Yang-Mills theory with Montonen-Olive S-duality invariance; AGT correspondence | D3-brane worldvolume theory with type IIB S-duality |
$\;\;\;\;\; \downarrow$ topological twist | |
topologically twisted N=2 D=4 super Yang-Mills theory | |
$\;\;\;\; \downarrow$ KK-compactification on Riemann surface | |
A-model on $Bun_G$, Donaldson theory |
$\,$
gauge theory induced via AdS5-CFT4 |
---|
type II string theory |
$\;\;\;\;\downarrow$ Kaluza-Klein compactification on $S^5$ |
$\;\;\;\; \downarrow$ topological sector |
5-dimensional Chern-Simons theory |
$\;\;\;\;\downarrow$ AdS5-CFT4 holographic duality |
N=4 D=4 super Yang-Mills theory |
$\;\;\;\;\; \downarrow$ topological twist |
topologically twisted N=4 D=4 super Yang-Mills theory |
$\;\;\;\; \downarrow$ KK-compactification on Riemann surface |
A-model on $Bun_G$ and B-model on $Loc_G$, geometric Langlands correspondence |
The realization of Yang-Mills theory that describes quarks and their interaction by the strong nuclear force carried by gluons is quantum chromodynamics (QCD).
The string scattering amplitudes exhibit certain relations due to the extended nature of the string which are retained in the point particle limit and hence explain and serve to discover subtle relations in QFT scattering amplitudes.
twistor string theory explains some (super) Yang-Mills theory scattering amplitudes
Precision scattering amplitudes in QCD use twistor string theory on-shell recursion methods,
This also goes by the term “on-shell methods”. See also at amplituhedron.
Reviews include
Matthew Strassler, From string theory to the large hadron collider (blog post)
Lance Dixon, Calculating Amplitudes, December 2013 (web)
Original articles include
Zvi Bern, Lance Dixon, David Kosower, On-Shell Methods in Perturbative QCD (arXiv:0704.2798)
Joseph Polchinski, Matthew Strassler, Hard Scattering and Gauge/String Duality, Phys.Rev.Lett.88:031601,2002, (arXiv:hep-th/0109174)
See also below Application to gravity – Scattering amplitudes.
Properties of quark-gluon plasma from AdS/CFT-dual type II string theory
Pavel Kovtun, Quark-Gluon Plasma and String Theory, RHIC news (2009) (blog entry)
Makoto Natsuume, String theory and quark-gluon plasma (arXiv:hep-ph/0701201)
Steven Gubser, Using string theory to study the quark-gluon plasma: progress and perils (arXiv:0907.4808)
Discussion of confinement in the context of the AdS-CFT correspondence is in
David Berman, Maulik K. Parikh, Confinement and the AdS/CFT Correspondence, Phys.Lett. B483 (2000) 271-276 (arXiv:hep-th/0002031)
Henrique Boschi Filho, AdS/QCD and confinement, Seminar at the Workshop on Strongly Coupled QCD: The confinement problem, November 2011 (pdf)
Seiberg duality in super Yang-Mills theory is conceptually explained by type II string theory on certain D-brane configurations (…)
open/closed string duality in string scattering amplitudes allows to compute gravity scattering amplitudes in terms of Yang-Mills theory scattering amplitudes: the KLT relations
more on this string-organizatioon of graviton scattering amplitudes is in
David C. Dunbar, Paul S. Norridge, Calculation of Graviton Scattering Amplitudes using String-Based Methods, Nucl.Phys. B433 (1995) 181-208 (arXiv:hep-th/9408014)
KLT relations used for instance to demonstrate:
Semi-classical QFT computations suggest that there should be entropy associated with black holes, the Bekenstein-Hawking entropy, without however providing microscopic degrees of freedom of which this would be an entropy in the ordinary sense.
Since the quantum dynamics of general black holes is outside the reach of perturbative methods in string theory, certain supersymmetric black hole? solutions in supergravity have properties independent of the coupling and are known to be the strong-coupling limit of what at weak coupling is a certain configuration of branes in flat space. Therefore the ordinary entropy of these brane configurations should match the Bekenstein-Hawking entropy of the corresponding black holes, and this has been confirmed to good precision.
While this argument does not give direct information about the origin of the BH-entropy of physically observed black holes, it does show conceptually, in the general context of black holes in theories of gravity, BH-entropy can be accounted for by microscopic degrees of freedom in a theory of quantum gravity.
Reviews include
chapter 5 of
(…)