scholarly journals A TOY MODEL OF CLOSED STRING TACHYON EFFECTIVE ACTION

2005 ◽  
Vol 20 (07) ◽  
pp. 1481-1493
Author(s):  
J. KLUSOŇ
Keyword(s):  
Exact Solution ◽  
String Theory ◽  
Effective Action ◽  
Flat Space ◽  
Closed String ◽  
Space Time ◽  
Bosonic String ◽  
Two Dimensional ◽  
Linear Dilaton ◽  
Bosonic String Theory

In this paper we propose the toy model of the closed string tachyon effective action that has marginal tachyon profile as its exact solution in case of constant or linear dilaton background. Then we will apply this model for description of two-dimensional bosonic string theory. We will find that the background configuration with the spatial dependent linear dilaton, flat space–time metric and marginal tachyon profile is the exact solution of our model even if we take into account backreaction of tachyon on dilaton and on metric.

scholarly journals GRAVITY ON NONCOMMUTATIVE D-BRANES

2003 ◽  
Vol 18 (07) ◽  
pp. 1051-1066 ◽  
Author(s):  
F. ARDALAN ◽  
H. ARFAEI ◽  
M. R. GAROUSI ◽  
A. GHODSI
Keyword(s):  
String Theory ◽  
Effective Action ◽  
Low Energy ◽  
Bosonic String ◽  
First Order ◽  
Energy Scattering ◽  
Bosonic String Theory ◽  
Brane Action

The effective action for the low energy scattering of two gravitons with a D-brane in the presence of a constant antisymmetric B field in bosonic string theory is calculated and the modification to the standard D-brane action to first order in α′ is obtained.

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 STRING-LOOP CORRECTIONS TO EFFECTIVE ACTION AND BLACK HOLE INSTABILITIES

1995 ◽  
Vol 10 (07) ◽  
pp. 575-585
Author(s):  
V. V. BELOKUROV ◽  
M. Z. IOFA
Keyword(s):  
Black Hole ◽  
String Theory ◽  
Effective Action ◽  
Black Hole Solution ◽  
Bosonic String ◽  
Superstring Theory ◽  
Integration Measure ◽  
String Loop ◽  
Bosonic String Theory ◽  
Closed Bosonic String

Following the ideas of Ref. 3, to account for instability of 2-D black hole solution, we discuss possible imaginary string-loop corrections to the coefficient at the Einstein term in string effective action (EA). In closed bosonic string theory, such corrections appear because of the tachyon contribution to the integration measure over the moduli. In superstring theory, several possible sources of complex one-string-loop contributions to the EA are considered. It is argued that none of them can account for complex corrections to the Einstein term in the effective action.

scholarly journals O(25, 25) symmetry of bosonic string theory at order $$\alpha '^2$$

2021 ◽  
Vol 81 (8) ◽  
Author(s):  
Mohammad R. Garousi
Keyword(s):  
String Theory ◽  
Effective Action ◽  
Bosonic String ◽  
Invariant Form ◽  
Total Derivative ◽  
One Dimensional ◽  
Bosonic String Theory

AbstractIt has been recently observed that the imposition of the O(1, 1) symmetry on the circle reduction of the classical effective action of string theory, can fix the effective action of the bosonic string theory at order $$\alpha '^2$$ α ′ 2 , up to an overall factor. In this paper, we use the cosmological reduction on the action and show that, up to one-dimensional field redefinitions and total derivative terms, it can be written in the O(25, 25)-invariant form proposed by Hohm and Zwiebach.

scholarly journals Beta functions for the duality-invariant sigma model

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Roberto Bonezzi ◽  
Tomas Codina ◽  
Olaf Hohm
Keyword(s):  
String Theory ◽  
Sigma Models ◽  
Sigma Model ◽  
Equations Of Motion ◽  
Background Field ◽  
Field Method ◽  
Bosonic String ◽  
Two Dimensional ◽  
Background Field Method ◽  
Bosonic String Theory

Abstract The O(d, d) invariant worldsheet theory for bosonic string theory with d abelian isometries is employed to compute the beta functions and Weyl anomaly at one-loop. We show that vanishing of the Weyl anomaly coefficients implies the equations of motion of the Maharana-Schwarz action. We give a self-contained introduction into the required techniques, including beta functions, the Weyl anomaly for two-dimensional sigma models and the background field method. This sets the stage for a sequel to this paper on generalizations to higher loops and α′ corrections.

De la combinatoire du modèle de l'échiquier de Feynman et des fonctions spéciales

1984 ◽  
Vol 62 (7) ◽  
pp. 632-638
Author(s):  
J. G. Williams
Keyword(s):  
Exact Solution ◽  
Dirac Equation ◽  
Hypergeometric Series ◽  
Jacobi Polynomials ◽  
Dimensional Space ◽  
Space Time ◽  
Continuous Limit ◽  
Two Dimensional ◽  
Dimensional Space Time

The exact solution of the Feynman checkerboard model is given both in terms of the hypergeometric series and in terms of Jacobi polynomials. It is shown how this leads, in the continuous limit, to the Dirac equation in two-dimensional space-time.

scholarly journals Brane with transverse rotation and background fields: boundary state and tachyon condensation

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
Davoud Kamani
Keyword(s):  
String Theory ◽  
Tachyon Condensation ◽  
Internal Field ◽  
Open String ◽  
Bosonic String ◽  
Boundary State ◽  
Bosonic String Theory ◽  
Transverse Rotation ◽  
Background Fields

Abstract The boundary state corresponding to the Dp-brane with a transverse rotation in the presence of the Kalb–Ramond and tachyon background fields and a U(1) internal field will be constructed. We shall investigate effects of the open string tachyon condensation on this brane via its boundary state. We demonstrate that the background fields and transverse rotation cannot protect the brane against the collapse. Our calculations are in the context of the bosonic string theory.

QUANTUM CLOSED STRINGS FROM MINIMAL AREA

1990 ◽  
Vol 05 (32) ◽  
pp. 2753-2762 ◽  
Author(s):  
BARTON ZWIEBACH
Keyword(s):  
Exact Solution ◽  
Quantum Theory ◽  
String Theory ◽  
Master Equation ◽  
Closed String ◽  
Feynman Rules ◽  
Higher Genus ◽  
Quantum Action ◽  
Full Quantum ◽  
Minimal Area

Canonical and factorizable off-shell amplitudes for covariant closed string theory can be obtained from string diagrams of minimal area. Evidence is given that all higher genus minimal area string diagrams can be built using vertices and propagators, implying that the off-shell amplitudes arise from the Feynman rules of a full quantum theory of closed strings. The quantum action gives an exact solution of the full master equation of Batalin and Vilkoviski.

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