Behavior of tachyon in string cosmology based on gauged wzw model

Sunggeun Lee; Soonkeon Nam

doi:10.1142/S0217732309030059

Behavior of tachyon in string cosmology based on gauged wzw model

Sunggeun Lee
, Soonkeon Nam

Research output: Contribution to journal › Article › peer-review

Abstract

We investigate a string theoretic cosmological model in the context of the gauged Wess-Zumino-Witten model. Our model is based on a product of non-compact coset space and a spectator flat space; [SL(2, R)/U(1)]_k × ². We extend the formerly studied semiclassical consideration with infinite Kac-Moody level k to a finite one. In this case, the tachyon field appears in the effective action, and we solve the Einstein equation to determine the behavior of tachyon as a function of time. We find that tachyon field dominates over dilaton field in early times. In particular, we consider the energy conditions of the matter fields consisting of the dilaton and the tachyon which affect the initial singularity. We find that not only the strong energy but also the null energy condition is violated.

Original language	English
Pages (from-to)	277-289
Number of pages	13
Journal	Modern Physics Letters A
Volume	24
Issue number	4
DOIs	https://doi.org/10.1142/S0217732309030059
Publication status	Published - 10 Feb 2009

Bibliographical note

Funding Information:
This work was supported by the Science Research Center Program of the Korea Science and Engineering Foundation through the Center for Quantum Spacetime (CQUeST) of Sogang University with grant No. R11-2005-021. It was also supported by the Korea Research Foundation Grant funded by the Korean Government-(MOEHRD) (KRF-2007-314-C00056).

Keywords

Cosmological singularity
Gauged WZW
Tachyon

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title = "Behavior of tachyon in string cosmology based on gauged wzw model",

abstract = "We investigate a string theoretic cosmological model in the context of the gauged Wess-Zumino-Witten model. Our model is based on a product of non-compact coset space and a spectator flat space; [SL(2, R)/U(1)]k × 2. We extend the formerly studied semiclassical consideration with infinite Kac-Moody level k to a finite one. In this case, the tachyon field appears in the effective action, and we solve the Einstein equation to determine the behavior of tachyon as a function of time. We find that tachyon field dominates over dilaton field in early times. In particular, we consider the energy conditions of the matter fields consisting of the dilaton and the tachyon which affect the initial singularity. We find that not only the strong energy but also the null energy condition is violated.",

keywords = "Cosmological singularity, Gauged WZW, Tachyon",

author = "Sunggeun Lee and Soonkeon Nam",

note = "Funding Information: This work was supported by the Science Research Center Program of the Korea Science and Engineering Foundation through the Center for Quantum Spacetime (CQUeST) of Sogang University with grant No. R11-2005-021. It was also supported by the Korea Research Foundation Grant funded by the Korean Government-(MOEHRD) (KRF-2007-314-C00056).",

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doi = "10.1142/S0217732309030059",

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AU - Lee, Sunggeun

AU - Nam, Soonkeon

N1 - Funding Information: This work was supported by the Science Research Center Program of the Korea Science and Engineering Foundation through the Center for Quantum Spacetime (CQUeST) of Sogang University with grant No. R11-2005-021. It was also supported by the Korea Research Foundation Grant funded by the Korean Government-(MOEHRD) (KRF-2007-314-C00056).

PY - 2009/2/10

Y1 - 2009/2/10

N2 - We investigate a string theoretic cosmological model in the context of the gauged Wess-Zumino-Witten model. Our model is based on a product of non-compact coset space and a spectator flat space; [SL(2, R)/U(1)]k × 2. We extend the formerly studied semiclassical consideration with infinite Kac-Moody level k to a finite one. In this case, the tachyon field appears in the effective action, and we solve the Einstein equation to determine the behavior of tachyon as a function of time. We find that tachyon field dominates over dilaton field in early times. In particular, we consider the energy conditions of the matter fields consisting of the dilaton and the tachyon which affect the initial singularity. We find that not only the strong energy but also the null energy condition is violated.

AB - We investigate a string theoretic cosmological model in the context of the gauged Wess-Zumino-Witten model. Our model is based on a product of non-compact coset space and a spectator flat space; [SL(2, R)/U(1)]k × 2. We extend the formerly studied semiclassical consideration with infinite Kac-Moody level k to a finite one. In this case, the tachyon field appears in the effective action, and we solve the Einstein equation to determine the behavior of tachyon as a function of time. We find that tachyon field dominates over dilaton field in early times. In particular, we consider the energy conditions of the matter fields consisting of the dilaton and the tachyon which affect the initial singularity. We find that not only the strong energy but also the null energy condition is violated.

KW - Cosmological singularity

KW - Gauged WZW

KW - Tachyon

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DO - 10.1142/S0217732309030059

M3 - Article

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SN - 0217-7323

VL - 24

SP - 277

EP - 289

JO - Modern Physics Letters A

JF - Modern Physics Letters A

IS - 4

ER -

Behavior of tachyon in string cosmology based on gauged wzw model

Abstract

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Keywords

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