FIAS Scientific Report 2011 - Frankfurt Institute for Advanced Studies ...

Black holes in short scale modified theories
Collaborators: P. Nicolini 1 , M. Bleicher 1,2 , L. Modesto 3 , J. W. Moffat 3 , J.R. Mureika 4 , M. Sprenger 1,2 , E.
Winstanley 5
1 Frankfurt Institute for Advanced Studies, 2 Institut für Theoretische Physik, Johann Wolfgang Goethe-Universität,
3 Perimeter Institute for Theoretical Physics, Canada, 4 Loyola Marymount University, Los Angeles, USA, 5 University
of Sheffield, UK.
A curvature singularity in general relativity represents the breakdown of the description of the gravitational
field in classical terms. However, contrary to the other interactions, gravity escapes a direct quantization for the
appearance of an uncontrolled number of divergences in the perturbation theory at all orders. This fact prevents
to consistently apply any regularization scheme to gravity. To circumvent the problem we have followed another
route, namely the formulation of an ultraviolet finite quantum gravity by considering nonlocal terms in the
graviton Lagrangian.
As a test for the new theory, we studied nonlocal gravity as a static interaction emerging from the virtual
graviton exchange. We found relevant short scale modifications which provide an asymptotic safe character
of the gravitational field: the classical black hole curvature singularity is replaced by a regular deSitter core
accounting for the quantum vacuum energy of virtual gravitons. On the thermodynamics side the Hawking
emission is characterized by a maximum black hole temperature and a phase transition towards a positive heat
capacity cooling down even for the neutral non-rotating case. At the end of the evaporation a black hole remnant
forms corresponding to the extremal, zero temperature configuration.
Given this background we studied the repercussions of the new metric on the phenomenology of microscopic
black holes in particle detectors. By considering the case of additional spatial dimensions we showed that a
maximum temperature determines an emission of soft particles mostly on the brane. This result is in marked
contrast to previous findings based on inadequate classical metrics and opens the route to potentially distinctive
signatures for the black hole production in particle detectors.
The Hawking radiation as a quantum vacuum effect in the presence of an event horizon.
Related publications in 2011:
1) L. Modesto, J. W. Moffat and P. Nicolini, Black holes in an ultraviolet complete quantum gravity, Physics
Letters B 695 (2011) 290.
2) J. R. Mureika and P. Nicolini, Aspects of noncommutative (1+1)-dimensional black holes, Physical Review
D 84 (2011) 044020.
3) P. Nicolini and E. Winstanley, Hawking emission from quantum gravity black holes, JHEP 1111 (2011) 075.
4) M. Bleicher, P. Nicolini, M. Sprenger and E. Winstanley, Micro black holes in the laboratory, International
Journal of Modern Physics E 20S2 (2011) 7.
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