NON-ABELIAN TOPOLOGICAL SOLUTIONS IN STRINGY GRAVITY

1994 ◽  
Vol 03 (04) ◽  
pp. 755-771 ◽  
Author(s):  
D.V. GAL’TSOV ◽  
E.E. DONETS
Keyword(s):  
Black Holes ◽  
Effective Action ◽  
Low Energy ◽  
Heterotic String ◽  
Charged Black Holes ◽  
Extremal Limit

Non-Abelian solutions of the low-energy heterotic string effective action are discussed. Three types of solutions are shown to exist: regular uncharged shaleron-like solutions, uncharged non-Abelian black holes and charged black holes with non-Abelian hair. In the extremal limit charged non-Abelian black holes generate regular throat structure in the string frame similar to that of the Gibbons-Maeda-Horowitz-Strominger solution.

scholarly journals S-DUALITY AND THE ENTROPY OF BLACK HOLES IN HETEROTIC STRING THEORY

1996 ◽  
Vol 11 (39n40) ◽  
pp. 3103-3111 ◽  
Author(s):  
AMIT GHOSH ◽  
JNANADEVA MAHARANA
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Partition Function ◽  
Heterotic String ◽  
Heterotic String Theory ◽  
Charged Black Holes ◽  
Duality Transformations ◽  
Extremal Limit ◽  
Electrically Charged ◽  
Black Hole Solutions

Four-dimensional heterotic string effective action is known to admit non-rotating electrically and magnetically charged black hole solutions. The partition function and entropy is computed for electrically charged black holes and is vanishing in some extremal limit. For the magnetically charged black holes the entropy is also argued to be vanishing in the same extremal limit when these black hole solutions are related by S-duality transformations.

scholarly journals Shadows of charged rotating black holes: Kerr–Newman versus Kerr–Sen

2020 ◽  
Vol 29 (11) ◽  
pp. 2041005
Author(s):  
Sérgio Vinicius Monteiro C. B. Xavier ◽  
Pedro V. P. Cunha ◽  
Luís C. B. Crispino ◽  
Carlos A. R. Herdeiro
Keyword(s):  
Black Holes ◽  
String Theory ◽  
Gravitational Lensing ◽  
New Physics ◽  
Effective Field ◽  
Low Energy ◽  
Heterotic String ◽  
Physical Parameters ◽  
Heterotic String Theory ◽  
Gravitational Fields

Celebrating the centennial of its first experimental test, the theory of General Relativity (GR) has successfully and consistently passed all subsequent tests with flying colors. It is expected, however, that at certain scales new physics, in particular, in the form of quantum corrections, will emerge, changing some of the predictions of GR, which is a classical theory. In this respect, black holes (BHs) are natural configurations to explore the quantum effects on strong gravitational fields. BH solutions in the low-energy effective field theory description of the heterotic string theory, which is one of the leading candidates to describe quantum gravity, have been the focus of many studies in the last three decades. The recent interest in strong gravitational lensing by BHs, in the wake of the Event Horizon Telescope (EHT) observations, suggests comparing the BH lensing in both GR and heterotic string theory, in order to assess the phenomenological differences between these models. In this work, we investigate the differences in the shadows of two charged BH solutions with rotation: one arising in the context of GR, namely the Kerr–Newman (KN) solution, and the other within the context of low-energy heterotic string theory, the Kerr–Sen (KS) solution. We show and interpret, in particular, that the stringy BH always has a larger shadow, for the same physical parameters and observation conditions.

scholarly journals CHARGING INTERACTING ROTATING BLACK HOLES IN HETEROTIC STRING THEORY

2004 ◽  
Vol 19 (30) ◽  
pp. 2299-2315 ◽  
Author(s):  
ALFREDO HERRERA-AGUILAR
Keyword(s):  
Field Theory ◽  
Black Holes ◽  
String Theory ◽  
Effective Field Theory ◽  
Effective Field ◽  
Low Energy ◽  
Heterotic String ◽  
Target Space ◽  
Heterotic String Theory ◽  
Rotating Black Holes

We present a formulation of the stationary bosonic string sector of the whole toroidally compactified effective field theory of the heterotic string as a double Ernst system which, in the framework of general relativity describes, in particular, a pair of interacting spinning black holes; however, in the framework of low-energy string theory the double Ernst system can in particular be interpreted as the rotating field configuration of two interacting sources of black hole type coupled to dilaton and Kalb–Ramond fields. We clarify the rotating character of the Btφ-component of the antisymmetric tensor field of Kalb–Ramond and discuss on its possible torsion nature. We also recall the fact that the double Ernst system possesses a discrete symmetry which is used to relate physically different string vacua. Therefore we apply the normalized Harrison transformation (a charging symmetry which acts on the target space of the low-energy heterotic string theory preserving the asymptotics of the transformed fields and endowing them with multiple electromagnetic charges) on a generic solution of the double Ernst system and compute the generated field configurations for the 4-D effective field theory of the heterotic string. This transformation generates the U (1)n vector field content of the whole low-energy heterotic string spectrum and gives rise to a pair of interacting rotating black holes endowed with dilaton, Kalb–Ramond and multiple electromagnetic fields where the charge vectors are orthogonal to each other.

THE BACKGROUND FIELD METHOD AND THE ANOMALIES OF THE HETEROTIC σ-MODEL IN A CURVED (1, 0) SUPERSPACE

1991 ◽  
Vol 06 (17) ◽  
pp. 2971-2998 ◽  
Author(s):  
S.V. KETOV ◽  
O.A. SOLOVIEV
Keyword(s):  
Effective Action ◽  
Background Field ◽  
Field Method ◽  
Low Energy ◽  
Heterotic String ◽  
Explicit Calculation ◽  
Two Dimensional ◽  
Gauge Bosons ◽  
Background Field Method ◽  
Background Fields

The covariant (in the σ-model sense) background field method for calculating the anomalies of the heterotic string propagating on the background of its massless modes is developed in a curved superspace of the two-dimensional (1, 0) supergravity. As the massless background fields, we use a metric, an antisymmetric tensor, a dilaton and gauge bosons. Explicit calculation of the anomalies up to five loops is performed and the results are found to be in agreement with the known facts about the heterotic string low-energy effective action. The dilaton-dependent corrections to the anomalies at the two- and three-loop levels are shown to be absent.

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