# Dr. Teresa Bautista

Postdoc in the Quantum Gravity and Unified Theories department

## What is your current position at our institute?

I am a postdoc in the Quantum Gravity and Unified Theories department

## What is your academic education?

- Llicenciatura in Physics at University of Barcelona, including Erasmus exchange to University of Amsterdam
- MSc in Theoretical Physics at the University of Amsterdam
- PhD in Theoretical Physics from the University Pierre et Marie Curie- Sorbonne in Paris, half of the time spent at the International Centre for Theoretical Physics in Trieste, Italy

## What were your previous academic positions?

- Tata Institute for Fundamental Research in Mumbai, India, as a postdoc visitor with an Indo-French grant
- postdoc at AEI

## Please describe your research in general language.

I currently work on two slightly different topics. One has to do with two-dimensional quantum gravity. In two dimensions, if we have matter that exhibits a particular symmetry, the so-called conformal symmetry (such as free fermions or massless scalars), then the gravitational interaction of the system also exhibits this symmetry, even if a cosmological constant is present. I work in building a quantum theory of this matter with a gravity system that is fully consistent with the constraints that this conformal symmetry imposes. The hope is that resolving the issues of this two-dimensional toy model sheds light into how to do proceed with those of quantum gravity in four dimensions.

The second topic has to do with exploring the implications of causality in general quantum field theories. Causality is a property that physical systems should respect, and which has already been shown to put constraints on the quantum theories that describe them, such as limiting the range or the sign of parameters characterising interactions. It has also been shown to constrain how a theory at high energies is related to the same theory at low energies, but the full implications of these constraints have yet to be uncovered. My work deals with understanding better the relation between causality and the change of theories under continuous changes of energy scale, and in particular its possible implications for gravity.

## Do you have a favorite figure from a paper you (co-)authored?

Yes, it's from *Lorentzian CFT 3-point functions in momentum space*. Three-point correlators are certain mathematical objects that represent measurements of three different physical variables, at three different points in spacetime or equivalently at three different momenta. In our world, the three-dimensional flat space (x, y, z coordinates of the volume) is described by a Euclidean geometry. However, time is slightly different, and the four-dimensional spacetime requires instead a Lorentzian geometry. While we are interested in constructing quantum field theories in a four-dimensional Lorentzian spacetime to properly describe the implications of causality, the calculations have mostly been done by treating time as if it were Euclidean. My last work consisted of calculating three-point correlators of a particular type of quantum field theories in Lorentzian geometry, by doing a rotation of the ones known in Euclidean geometry.

The figure corresponds to this ‘Wick’ rotation, from Euclidean to Lorentzian, of the momentum-space conformal three-point correlator. The horizontal axis corresponds to Euclidean momentum, and the vertical axis to Lorentzian momentum. The black closed contour is what relates the Euclidean momentum along the horizontal line with the Lorentzian one, which runs vertically along the zig-zag lines. The blue zig-zag contours depict singular mathematical behaviors of the correlators, and are the ones precisely encoding the implications of causality.

## Please let us know why you chose the Max Planck Institute for Gravitational Physics for your research.

Because it is a very good place with some top leading researchers, and with a wide variety of research topics on gravity being covered. Also I liked the resources provided to travel and attend conferences. It also mattered to me that it is not too far from my family and friends.