scholarly journals Effective action of type II superstring theories at order α′3: NS-NS couplings

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Mohammad R. Garousi
Keyword(s):  
Matrix Element ◽  
Effective Action ◽  
Sigma Model ◽  
Linear Sigma Model ◽  
Type Ii ◽  
Gauge Invariant ◽  
Duality Transformations ◽  
S Matrix ◽  
Minimum Number ◽  
Superstring Theories

Abstract Recently, it has been shown that the minimum number of gauge invariant couplings for B-field, metric and dilaton at order α′3 is 872. These couplings, in a particular scheme, appear in 55 different structures. In this paper, up to an overall factor, we fix all parameters in type II supertirng theories by requiring the reduction of the couplings on a circle to be invariant under T-duality transformations. We find that there are 445 non-zero couplings which appear in 15 different structures. The couplings are fully consistent with the partial couplings that have been found in the literature by the four-point S-matrix element and by the non-linear Sigma model methods.

scholarly journals Effective action of bosonic string theory at order $$\alpha '^2$$

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Mohammad R. Garousi
Keyword(s):  
String Theory ◽  
Effective Action ◽  
Gauge Invariance ◽  
Bosonic String ◽  
Duality Transformations ◽  
S Matrix ◽  
Minimum Number ◽  
Bosonic String Theory

Abstract Recently, it has been shown that the gauge invariance requires the minimum number of independent couplings for B-field, metric and dilaton at order $$\alpha '^2$$α′2 to be 60. In this paper we fix the corresponding 60 parameters in string theory by requiring the couplings to be invariant under the global T-duality transformations. The Riemann cubed terms are exactly the same as the couplings that have been found by the S-matrix calculations.

scholarly journals Surface terms in effective action of O-plane at order $$\alpha '^2$$

2021 ◽  
Vol 81 (3) ◽  
Author(s):  
Yasser Akou ◽  
Mohammad R. Garousi
Keyword(s):  
String Theory ◽  
Effective Action ◽  
Type Ii ◽  
Leading Order ◽  
Open Manifold ◽  
Gauge Transformations ◽  
Duality Transformations ◽  
Boundary Terms ◽  
String Dualities ◽  
Superstring Theories

AbstractThe effective action of string theory has both bulk and boundary terms if the spacetime is an open manifold. Recently, the known classical effective action of string theory at the leading order of $$\alpha '$$ α ′ and its corresponding boundary action have been reproduced by constraining the effective actions to be invariant under gauge transformations and under string duality transformations. In this paper, we use this idea to find the classical effective action of the O-plane and its corresponding boundary terms in type II superstring theories at order $$\alpha '^2$$ α ′ 2 and for NS–NS couplings. We find that these constraints fix the bulk action and its corresponding boundary terms up to one overall factor. They also produce three multiplets in the boundary action that their coefficients are independent of the bulk couplings under the string dualities.

STRING THEORY EFFECTIVE ACTION: STRING LOOP CORRECTIONS

1988 ◽  
Vol 03 (02) ◽  
pp. 365-395 ◽  
Author(s):  
A.A. TSEYTLIN
Keyword(s):  
String Theory ◽  
Effective Action ◽  
Sigma Model ◽  
Closed String ◽  
Vertex Operators ◽  
S Matrix ◽  
String Loop ◽  
String Amplitudes ◽  
Loop Amplitudes

We discuss the general ideology of the computation of string loop corrections to the effective action for the massless modes of the string. Both the S-matrix and the sigma-model approaches are presented. It is emphasized that the effective action is a more general and better defined object than the S-matrix. In particular, it is finite in spite of modular infinities that may be present in loop amplitudes computed near a “wrong” vacuum. The case of the disc topology in the open-closed string theory is treated in some detail. Some issues concerning the soft dilaton vertex operators related to the infinities of the string amplitudes are disucssed.

scholarly journals Minimal gauge invariant couplings at order $$\alpha '^3$$: NS–NS fields

2020 ◽  
Vol 80 (11) ◽  
Author(s):  
Mohammad R. Garousi
Keyword(s):  
Type Ii ◽  
Total Derivative ◽  
Gauge Invariant ◽  
Bianchi Identities ◽  
Minimum Number ◽  
Alpha Beta

AbstractRemoving the field redefinitions, the Bianchi identities and the total derivative freedoms from the general form of gauge invariant NS–NS couplings at order $$\alpha '^3$$ α ′ 3 , we have found that the minimum number of independent couplings is 872. We find that there are schemes in which there is no term with structures $$R,\,R_{\mu \nu },\,\nabla _\mu H^{\mu \alpha \beta }$$ R , R μ ν , ∇ μ H μ α β , $$ \nabla _\mu \nabla ^\mu \Phi $$ ∇ μ ∇ μ Φ . In these schemes, there are sub-schemes in which, except one term, the couplings can have no term with more than two derivatives. In the sub-scheme that we have chosen, the 872 couplings appear in 55 different structures. We fix some of the parameters in type II supersting theory by its corresponding four-point functions. The coupling which has term with more than two derivatives is constraint to be zero by the four-point functions.

CONSISTENCY BETWEEN THE S-MATRIX AND THE SIGMA- MODEL APPROACHES TO THE CLOSED STRING EFFECTIVE ACTION ON THE DISC

1988 ◽  
Vol 03 (06) ◽  
pp. 561-569 ◽  
Author(s):  
L.V. ROZHANSKY ◽  
A.A. TSEYTLIN
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Effective Action ◽  
Sigma Model ◽  
Closed String ◽  
Effective Field ◽  
Cosmological Term ◽  
S Matrix ◽  
String Amplitudes ◽  
Closed Bosonic String

We show that a part of logarithmic divergences in the closed bosonic string amplitudes on the disc was over-looked in the previous studies. The sum of all logarithmic divergences is found to be in agreement with the “tadpole” divergences in the effective field theory with the “cosmological term” representing the disc correction. This resolves the problem raised recently by Fischler, Klebanov and Susskind.

FACTORIZABLE S-MATRIX FOR $\frac{{\rm SO} (D)}{{\rm SO} (2) \otimes {\rm SO} (D -2)}$ NON-LINEAR σ MODELS WITH FERMIONS

1988 ◽  
Vol 03 (03) ◽  
pp. 311-317 ◽  
Author(s):  
E. ABDALLA ◽  
A. LIMA-SANTOS
Keyword(s):  
String Theory ◽  
Sigma Model ◽  
Linear Sigma Model ◽  
S Matrix ◽  
Non Linear ◽  
External Curvature

We compute the exact S matrix for the non-linear sigma model with symmetry SO(D)/SO(2)⊗SO(D−2) coupled to fermions in a minimal or supersymmetric way. The model has some relevance in string theory with non-zero external curvature.

scholarly journals Extended DBI and its generalizations from graded soft theorems

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Karol Kampf ◽  
Jiří Novotný ◽  
Petr Vaško
Keyword(s):  
Sigma Model ◽  
Power Counting ◽  
Linear Sigma Model ◽  
Tree Level ◽  
Bottom Up ◽  
Slight Generalization ◽  
S Matrix ◽  
New Type ◽  
Mixed Power ◽  
Special Case

Abstract We analyze a theory known as extended DBI, which interpolates between DBI and the U(N) × U(N)/U(N) non-linear sigma model and represents a nontrivial example of theories with mixed power counting. We discuss symmetries of the action and their geometrical origin; the special case of SU(2) extended DBI theory is treated in great detail. The revealed symmetries lead to a new type of graded soft theorem that allows us to prove on-shell constructibility of the tree-level S-matrix. It turns out that the on-shell constructibility of the full extended DBI remains valid, even if its DBI sub-theory is modified in such a way to preserve its own on-shell constructibility. We thus propose a slight generalization of the DBI sub-theory, which we call 2-scale DBI theory. Gluing it back to the rest of the extended DBI theory gives a new set of on-shell reconstructible theories — the 2-scale extended DBI theory and its descendants. The uniqueness of the parent theory is confirmed by the bottom-up approach that uses on-shell amplitude methods exclusively.

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