String Theory: Bosonic String

We continue the discussion of our previous paper on writing down gauge-invariant interacting equations for a bosonic string using the loop variable approach. In the earlier paper the equations were written down in one higher dimension where the fields are massless. In this paper we describe a procedure for dimensional reduction that gives interacting equations for fields with the same spectrum as in bosonic string theory. We also argue that the on-shell scattering amplitudes implied by these equations for the physical modes are the same as for the bosonic string. We check this explicitly for some of the simpler equations. The gauge transformation of space–time fields induced by gauge transformations of the loop variables are discussed in some detail. The unintegrated (i.e. before the Koba–Nielsen integration), regularized version of the equations, are gauge invariant off-shell (i.e. off the free mass shell).

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GRAVITY ON NONCOMMUTATIVE D-BRANES

International Journal of Modern Physics A ◽

10.1142/s0217751x03010991 ◽

2003 ◽

Vol 18 (07) ◽

pp. 1051-1066 ◽

Cited By ~ 20

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.

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

The European Physical Journal C ◽

10.1140/epjc/s10052-020-8212-3 ◽

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.

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

The European Physical Journal C ◽

10.1140/epjc/s10052-019-7357-4 ◽

2019 ◽

Vol 79 (10) ◽

Cited By ~ 4

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.

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STRING-LOOP CORRECTIONS TO EFFECTIVE ACTION AND BLACK HOLE INSTABILITIES

Modern Physics Letters A ◽

10.1142/s0217732395000612 ◽

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.

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