Quantum Gravity from the QFT perspective

April 1-5, 2019

São Paulo, Brazil

ICTP-SAIFR/IFT-UNESP

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Lecturer: Ilya L. Shapiro (Universidade Federal de Juiz de Fora – UFJF, Brazil)

Place: Auditorium of IFT-UNESP

Times: There will be 5 lectures of 1h30~2h each, from Monday to Friday. Times to be announced.

Description:
A short introductory and review course on perturbative Quantum Gravity. The first part is about the semiclassical approach, and includes renormalization, trace anomaly and some applications to cosmology. In the second part we describe the Lagrangian quantization of gravity and sketch the standard demonstration of the invariant renormalizability of the theory. The analysis of power counting shows that there are possibilities for non-renormalizable, renormalizable and superrenormalizable models of Quantum Gravity, but in the last two cases there is a problem of unphysical massive ghosts, unitarity of quantum theory and instability. Possible solutions of the problem of ghosts are discussed, including those related to the effective approach to Quantum Field Theory (QFT). Alternative possibilities include various versions of induced gravity, including string theory and treating Quantum Gravity as effective QFT at low energies.

Contents:
1) GR and its limits of applicability. Why should we quantize gravity. Semiclassical approach and higher derivatives.
2) Trace anomaly and anomaly-induced action. Applications to inflation and implications for particle physics. Effect of masses of quantum fields and possible running of cosmological and Newton constants at low energy cosmic scales.
3) Gauge-invariant renormalization of gravity. Power counting. Quantum GR vs Higher derivative QG. How we can (if so) live with ghosts? More higher derivatives and more ghosts. Superrenormalizable QG.
4) Renormalization Group (RG). For which versions of QG can RG be used? Ambiguities related to gauge fixing and parametrization of quantum field.
5) Alternative approaches. Induced gravity paradigm: from Zeldovich and Sakharov to string theory. Does induced gravity idea solve the issue of ghosts? Effective approach to QG.

There is no registration fee.

Announcement

Click here for online application

Application deadline: February 24, 2019

Bibliography:
1. I.L. Buchbinder, S.D. Odintsov, I.Sh., Effective Action in Quantum Gravity. (1992 – IOPP).
2. I.Sh., Class. Q. Grav. 25 (2008) 103001 (Topical review); 0801.0216.
3. I.L. Buchbinder, I.Sh. Introduction to quantum field theory with applications to quantum gravity (Oxford University Press, book in preparation, 2020).