Physics Letters B 797 (2019) 134888
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Physics Letters B
www.elsevier.com/locate/physletb
Quantum corrected black holes from string T-duality
Piero Nicolini
a,b,∗
, Euro Spallucci
c,d
, Michael F. Wondrak
a,b
a
Frankfurt Institute for Advanced Studies (FIAS), Ruth-Moufang-Straße 1, 60438 Frankfurt am Main, Germany
b
Institut für Theoretische Physik, Johann Wolfgang Goethe-Universität Frankfurt am Main, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
c
Dipartimento di Fisica, Università degli Studi di Trieste, Strada Costiera 11, 34151 Trieste, Italy
d
Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Trieste, Strada Costiera 11, 34151 Trieste, Italy
a r t i c l e i n f o a b s t r a c t
Article history:
Received
22 May 2019
Received
in revised form 21 August 2019
Accepted
21 August 2019
Available
online 30 August 2019
Editor: A.
Ringwald
Keywords:
Quantum
corrected black hole
String
T-duality
Zero-point
length
Path
integral duality
In this letter we present some stringy corrections to black hole spacetimes emerging from string T-
duality.
As a first step, we derive the static Newtonian potential by exploiting the relation between the
T-duality and the path integral duality. We show that the intrinsic non-perturbative nature of stringy
corrections introduces an ultraviolet cutoff known as zero-point length in the path integral duality
literature. As a result, the static potential is found to be regular. We use this result to derive a consistent
black hole metric for the spherically symmetric, electrically neutral case. It turns out that the new
spacetime is regular and is formally equivalent to the Bardeen metric, apart from a different ultraviolet
regulator. On the thermodynamics side, the Hawking temperature admits a maximum before a cooling
down phase towards a thermodynamically stable end of the black hole evaporation process. The findings
support the idea of universality of quantum black holes.
© 2019 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP
3
.
1. Introduction
General relativity (GR) is in excellent agreement with astronom-
ical
observations and experimental findings and has passed several
high-precision tests [1]. There is, however, a fundamental prob-
lem:
the classical description of the gravitational field breaks down
at short scales. Curvature singularities plague GR and attempts to
amend it by the formulation of a quantum theory of gravity have
not been completely satisfactory so far. In particular it is still miss-
ing
a derivation of a singularity free black hole or a cosmological
spacetime from the first principles of a theory of quantum gravity.
Given
this background, there have been attempts to amend the
bad short distance behavior of black hole solutions by assuming,
as a guiding principle, the boundedness of spacetime curvature.
Being the gravitational coupling G
N
=l
P
2
in natural units, the cur-
vature
cannot exceed l
P
−2
, where l
P
is the Planck length. Probably
the first example of regular black hole is the Bardeen spacetime
[2]. By assuming a non-linear electrodynamics Lagrangian, the ul-
traviolet
cut off is obtained in terms of the magnetic charge of
the black hole itself [3]. This work has been followed by further
singularity free models based on non-linear electrodynamics [4,5].
*
Corresponding author.
E-mail
addresses: nicolini@fias.uni-frankfurt.de (P. Nicolini), spallucci@ts.infn.it
(E. Spallucci),
wondrak@fias.uni-frankfurt.de (M.F. Wondrak).
Magnetic monopoles are, however, not yet observed in nature. Fur-
thermore,
the electric charge is quickly shed via Hawking emission
and Schwinger pair production mechanism [6–8].
To
overcome such a limitation, neutral black hole models with
a regular central core have been proposed in the literature, by a
process of “black hole engineering”, i.e. by assuming a limiting cur-
vature
without a derivation from first principles of a given theory
[9–14](for a review see [15] and the references therein).
A
major breakthrough has been achieved with a family of regu-
lar
black holes that have been derived in a string-inspired way by
averaging noncommutative coordinates on suitable coherent states
[16–18]. Apart from the singularity freedom, such black holes offer
an intriguing scenario for the end stage of the evaporation. Rather
than a divergent Hawking emission, one finds a SCRAM phase,
namely a cooling down towards a zero temperature extremal con-
figuration,
even in the absence of charge and angular momentum
[19]. Interestingly, noncommutative effects have later been found
to be equivalent to a non-local deformation of the Einstein-Hilbert
action [20,21]. This fact has propelled the recent interest about
black hole solutions in non-local gravity [22–26]. Further string-
based
solutions can be found for instance in [27–29].
In
this letter we aim to do a further step forward. We propose
to exploit the ultraviolet finiteness of string theory to tame the sin-
gularity
of classical black holes. To reach the goal, we consider, as a
key ingredient, the concept of T-duality. The latter identifies string
theories on higher-dimensional spacetimes with mutually inverse
https://doi.org/10.1016/j.physletb.2019.134888
0370-2693/
© 2019 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by
SCOAP
3
.