String Theory | ||
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All Roads Lead to String Theory (Polchinski) | ||
Prior to the First Superstring Revolution
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Early History | S-Matrix Theory Regge Trajectory | |
Bosonic String Theory | Worldsheet String Bosonic String Theory String Perturbation Theory Tachyon Condensation | |
Supersymmetric Revolution | Supersymmetry RNS Formalism GS Formalism BPS | |
Superstring Revolutions
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First Superstring Revolution | GSO Projection Type II String Theory Type IIB String Theory Type IIA String Theory Type I String Theory Type H String Theory Type HO String Theory Type HE String Theory |
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Second Superstring Revolution | T-Duality D-Brane S-Duality Horava-Witten String Theory M-Theory Holographic Principle N=4 Super-Yang-Mills Theory AdS CFT BFSS Matrix Theory Matrix String Theory (2,0) Theory Twistor String Theory F-Theory String Field Theory Pure Spinor Formalism |
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After the Revolutions
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Phenomenology | String Theory Landscape Minimal Supersymmetric Standard Model String Phenomenology | |
Like T-Duality, S-Duality is a duality, or equivalence, between theories. Unlike T-Duality, S-Duality is not a purely stringy concept as it also appears in Quantum Field Theorys. S-Duality is useful because equates a Strongly-Coupled theory with a Weakly-Coupled theory. I.e. it equates a theory with coupling constant with a theory with coupling constant .
S-Duality and the Dilaton[]
In String Theory, the coupling constant is related to the Dilaton Field:
Negating the Dilaton Field is equivalent to inverting the coupling constant:
Therefore, S-Duality negates the Dilaton Field, in a similar way as to how T-Duality negates the bosonic and fermionic fields, ; and /.
S-Duality in String Theory[]
In String Theory, analysing the massless fields and mass spectra of String Theoryies shows that Type I String Theory is S-Dual to Type HO String Theory and Type IIB String Theory is S-Dual to itself. More specifically, Type I String Theory with D-Branes instead of F1-Strings is S-Dual to Type HO String Theory and Type IIB String Theory with D-Branes instead of F1-Strings is S-Dual to itself (but with F1 Strings).