KMPB 2025/26 Winter Semester Kick-Off Meeting

The KMPB 2025/26 Winter Semester Kick-Off Meeting will take place on Friday, 5 December, from 9:00 to 12:00 in room 2.049 at the CSMB building.

Schedule:

9:00-9:45         Talk by Jan Plefka
9:45-10:30       Talk by Thilbault Langlais
10:30-11:00:    Get Together (coffee break)
11:00-12:00:    KMPB member’s meeting
(12:00 lunch at the nearby Om Mani restaurant, for those of us who have the time)

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Jan Plefka
Emergence of Calabi-Yau Manifolds in High-precision Black Hole Scattering

Abstract: The gravitational two-body problem has been fundamental to physics since Newton’s time. With the advent of gravitational wave astronomy and the anticipated third generation of gravitational wave detectors in the 2030s, there is an increasing need for high-precision predictions from Einstein’s theory of gravity regarding the encounters of black holes or neutron stars in our universe. Fascinatingly, perturbative quantum field theory methods—developed for high-precision predictions of elementary particle scattering at the LHC—have proven remarkably efficient for this classical physics problem. This unexpected connection has led to inspiring synergies between collider and gravitational wave physics.

In my talk, I will present our approach using a worldline quantum field theory, building on inspirations by string theory, which has emerged as the most efficient tool for quantifying the scattering of spinning black holes. We have achieved highest-precision perturbative results for the scattering angle, radiated energy, and momentum recoil of such black hole encounters at the fifth order in Newton’s gravitational coupling G, or NNNNLO, assuming a mass hierarchy between the two bodies. This four-loop calculation has moreover revealed the contribution of a new class of mathematical functions related to Calabi-Yau three-manifolds,  so far studied only in mathematics and string theory compactifications, that here contribute for the first time in a physical observable.

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Thibault Langlais
Moduli spaces of manifolds with special holonomy and the Swampland programme

Abstract: Since the development of string theory, manifolds with special holonomy (particularly SU(3) and G2) have played a central role in the development of quantum gravity theories. The huge number of known special holonomy manifolds has allowed physicists to engineer an equally huge number of effective field theories that could be obtained as the low-energy limit of string theory (or another quantum gravity theory) by choosing the right internal space. This raised an important question, as to whether any effective field theory could arise in this way.

This question was formalised by Vafa in the mid-2000s, who initiated the so-called Swampland programme, whose aim is to find criteria in order to distinguish between those field theories which admit a quantum gravity completion at high energies (termed the Landscape) and those which do not (the Swampland). This programme has attracted a lot of attention in the physics community over the past two decades, but in contrast with other conjectures coming from string theory, relatively little work has been done from a purely mathematical perspective.

The goal of this talk is to relate a specific conjecture from the Swampland programme – the Swampland Distance Conjecture – to the properties of the moduli spaces of manifolds with special holonomy, and to break it down into geometrical terms. I will also present some evidence for the conjecture and point out a number of interesting open questions for future study.