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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 nonstringy 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 YangMills theory and Einstein gravity/general relativity.
Many of the insights are based on the gauge/gravity duality in string theory:
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 pointparticle limit of the expressions for string scattering amplitudes. See at worldline formalism for more.
Example:
The first calculuation along these lines was actually done earlier in (MetsaevTseytlin 88), where the 1loop beta function for pure YangMills theory was obtained as the pointparticle limit of the partition function of a bosonic open string in a YangMills background field. This provided a theoretical explanation for the observation, made earlier in (Nepomechie 83) that when computed via dimensional regularization then this beta function coefficient of YangMills theory vanishes in spacetime dimension 26. This of course is the critical dimension of the bosonic string.
R.I. Nepomechie, Remarks on quantized YangMills theory in 26 dimensions, Physics Letters B Volume 128, Issues 3–4, 25 August 1983, Pages 177178 Phys. Lett. B128 (1983) 177 (doi:10.1016/03702693(83)903854)
Ruslan Metsaev, Arkady Tseytlin, On loop corrections to string theory effective actions, Nuclear Physics B Volume 298, Issue 1, 29 February 1988, Pages 109132 (doi:10.1016/05503213(88)903069)
AdS/CFT correspondenceopen/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 pointparticle limit of the expressions for string scattering amplitudes. See at worldline formalism for more.
Example:
The first calculuation along these lines was actually done earlier in (MetsaevTseytlin 88), where the 1loop beta function for pure YangMills theory from the partition function of a bosonic open string in a YangMills background field. This provided a theoretical explanation for the observation, made earlier in (Nepomechie 83) that when computed in via dimensional regularization then this beta function coefficient of YangMills theory vanishes in spacetime dimension 26. This of course is the critical dimension of the bosonic string.
R.I. Nepomechie, Phys. Lett. B128 (1983) 177
{MetsaevTseytlin88} Ruslan Metsaev, Arkady Tseytlin, On loop corrections to string theory effective actions, Nuclear Physics B Volume 298, Issue 1, 29 February 1988, Pages 109132 (doi:10.1016/05503213(88)903069903069))
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 YangMills theory and N=2 D=4 super YangMills theory in this fashion has come to be known as geometric engineering of quantum field theory.
MontonenOlive duality of (super) YangMills theory derives from conformal invariance of the 6d (2,0)supersymmetric QFT (see there) compactified on a torus.
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See also
The realization of YangMills 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) YangMills theory scattering amplitudes
Precision scattering amplitudes in QCD use twistor string theory onshell recursion methods,
This also goes by the term “onshell 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)
Rutger Boels, Onshell recursion for string theory amplitudes on the disk and the sphere (pdf)
Original articles include
Zvi Bern, Lance Dixon, David Kosower, OnShell Methods in Perturbative QCD (arXiv:0704.2798)
Joseph Polchinski, Matthew Strassler, Hard Scattering and Gauge/String Duality, Phys.Rev.Lett.88:031601,2002, (arXiv:hepth/0109174)
See also below Application to gravity – Scattering amplitudes.
Properties of quarkgluon plasma from AdS/CFTdual type II string theory
Pavel Kovtun, QuarkGluon Plasma and String Theory, RHIC news (2009) (blog entry)
Makoto Natsuume, String theory and quarkgluon plasma (arXiv:hepph/0701201)
Steven Gubser, Using string theory to study the quarkgluon plasma: progress and perils (arXiv:0907.4808)
Discussion of confinement in the context of the AdSCFT correspondence is in
David Berman, Maulik K. Parikh, Confinement and the AdS/CFT Correspondence, Phys.Lett. B483 (2000) 271276 (arXiv:hepth/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 YangMills theory is conceptually explained by type II string theory on certain Dbrane configurations (…)
open/closed string duality in string scattering amplitudes allows to compute gravity scattering amplitudes in terms of YangMills theory scattering amplitudes: the KLT relations
Zvi Bern, Perturbative Quantum Gravity and its Relation to Gauge Theory, Living Rev Relativ. 2002; 5(1): 5. (arXiv:grqc/0206071, doi:10.12942/lrr20025)
more on this stringorganizatioon of graviton scattering amplitudes is in
David C. Dunbar, Paul S. Norridge, Calculation of Graviton Scattering Amplitudes using StringBased Methods, Nucl.Phys. B433 (1995) 181208 (arXiv:hepth/9408014)
KLT relations used for instance to demonstrate:
Semiclassical QFT computations suggest that there should be entropy associated with black holes, the BekensteinHawking 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 strongcoupling 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 BekensteinHawking 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 BHentropy of physically observed black holes, it does show conceptually, in the general context of black holes in theories of gravity, BHentropy can be accounted for by microscopic degrees of freedom in a theory of quantum gravity.
Reviews include
chapter 5 of
(…)
Last revised on February 10, 2018 at 08:54:49. See the history of this page for a list of all contributions to it.