Sommerfeld Theory Colloquium (ASC)

Latest Episodes:

Searching for New Forces Using Torsion Pendula Jun 10, 2026

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Equivalence principle violation, deviations from the inverse-square law of gravity, and long-range interactions between particle spins o�er powerful tests of beyond-the-standard-model physics. Using a torsion pendulum, a technique that dates to the 18th century, is still the most sensitive way to search for these signatures of new physics. I will talk about how the experiments are done and give an update on the current and future status of such torsion balance experiments in the Eot-Wash group.

Quantum Mechanics and Geometry of Spacetime Jun 10, 2026

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Quantum mechanics is important for determining the geometry of spacetime. We will review the role of quantum fluctuations that determine the large scale structure of the universe. In some model universes we can give an alternative description of the physics in terms of a theory of particles that lives on its boundary. This implies that the geometry is an emergent property. Furthermore, entanglement plays a crucial role in the emergence of geometry. Large amounts of entanglement are conjectured to give rise to geometric connections, or wormholes, between distant and non-interacting systems.

The Black Hole Information Paradox Revisited Jun 10, 2026

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I describe the physics of black holes and show how the traditional approach leads to the information paradox. I will then discuss some of the proposed resolutions and the difficulties they need to overcome. I then discuss soft black hole hair and describe how it may help to resolve the information paradox. Finally, I will review the problems that still need to be overcome.

Effects of Dark Matter linear in Interaction Strength Jun 10, 2026

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Low-mass boson dark matter particles produced after the Big Bang form a classical field and/or topological defects. Effects produced by the interaction of ordinary matter with dark matter may be first power in the underlying interaction strength rather than the second power. This may give a big advantage, since the dark matter interaction constant is extremely small. Limits on certain types of dark matter have been improved up to 15 orders of magnitude. New experiments are proposed.

Quantum Critical Points in Metals: Non-Fermi Liquids and their Field Theoretical Description Jun 10, 2026

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Metals are found frequently in nature and their properties are usually very well described within Landaus Fermi liquid theory. Various strongly correlated materials exhibit strange metallic phases which do not fit into the Fermi-liquid framework, however. The theoretical description of such non-Fermi liquids remains one of the main unsolved problems in condensed matter physics. In this talk I will give an introduction to the problem and show how interesting strongly coupled field theories arise in the low energy description of such states, which are still very poorly understood. I will focus on the paradigmatic problem of a metal coupled to fluctuations of a critical Ising order parameter and discuss unexpected scaling properties at finite temperature.

Gone with the wind: The demise of protoplanetary discs and the birth of planets Jun 10, 2026

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Protoplanetary discs are natural consequence of star formation. These discs hold the left-over material from star formation, which constitutes the reservoir from which new planetary systems may form. The fate of a new planetary is then intimately linked to the evolution and ﬁnal dispersal of the disk from which is born, which determines also the striking diversity observed in extra-solar planetary systems. I will brieﬂy review our understanding of disc dispersal via a photoevaporative wind in the context of planet formation, and show how both processes are ﬁnally dominated by the irradiation from their central star.

From materials science to basic physics Jun 10, 2026

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Condensed matter provides us deep insights into quantum physics. Giving just two examples, wave-corpuscle duality manifests itself in spectroscopy of strongly correlated systems as coexistence of itinerant and atomic-like features, and graphene and other Dirac materials provide a natural playground to study vacuum reconstruction, Klein tunneling and other fundamental quantum relativistic phenomena. Electron-photon interaction is the key tool to understand this rich and nontrivial physics.

Revisiting the S-matrix bootstrap Jun 10, 2026

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Sommerfeld Theory Colloquium

The Search for New Interactions at the LHC: The top quark Window Jun 10, 2026

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New Physics searches at the LHC are mostly being performed with the aim of detecting new states. A complementary strategy is to look for new interactions, something that typically involves precise measurements. In this talk I argue how many of the current SM (and BSM) measurements in the top sector could be used to efficiently and consistently determine of the couplings of an effective field theory and in particular that of the SM at dimension 6.

Status of the Electroweak Standard Model Jun 10, 2026

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With the discovery of the Higgs boson and the determination of its mass, the Standard Model is complete and its parameters are now known and over-constrained. I will review the status and future directions in precision electroweak physics both at high and low en- ergies. There is strong evidence that the Standard Model is correct at the level of quantum corrections, and that in the absence of major conspiracies, any new physics beyond it is either significantly heavier than the electroweak scale or very weakly coupled.