Sommerfeld Theory Colloquium (ASC)

The life of a protein, from birth till death, is complex and challenging. At times, because of stresses or bad luck, it might take the wrong conformation and start aggregating. This process is intrinsic to the physics of proteins, and life has had to cope with it since its early days. The solution devised by evolution comes in the form of chaperone protein, a broad class of machines, present in all organisms on Earth, that repair conformationally damaged proteins, making them functional again, at an energy cost. In this talk I will provide a view of our present understanding of the molecular mechanism of function of Hsp70, possibly the most central of all chaperones, and of its consequences on proteins.

Understanding how fluctuations propagate across spatial scales is central to our understanding of inanimate matter from turbulence to critical phenomena. In contrast to these systems, many non-equilibrium systems are organised into a spatial hierarchy of nested processes on different spatial scales, including biological and robotic systems. In this talk, I will discuss physical principles underlying the propagation of fluctuations in these multi-scale systems. I will also show how manipulating probability fluxes across spatial scales is used to perform biological signal processing.

Localization of the eigenfunctions of quantum particles in a random potential was discovered by P.W. Anderson more than 50 years ago. In spite of its respectable maturity and rather intensive theoretical and experimental studies this field is by far not exhausted. Anderson localization was originally discovered in connection with spin relaxation and charge transport in disordered conductors. Later this phenomenon was observed for light, microwaves, sound, and more recently for cold atoms. Moreover, it became clear that the domain of applicability of the concept of localization is much broader. For example, it provides an adequate framework for discussing the transition between integrable and chaotic behavior in quantum systems. We will discuss current understanding of the Anderson localization and its manifestation in different physical situations.

Interesting erasure phenomena arise from interactions between lower-dimensional and higher-dimensional objects and impact cosmology and fundamental physics. In the first part of the colloquium, I will examine the case for topological defects, revealing insights into the interactions of magnetic monopoles, cosmic strings, and domain walls.

For objects like cosmic or QCD flux strings, encounters with domain walls or D-branes result in erasure through coherence loss during collisions, introducing a new string break-up mechanism. The collisions between magnetic monopoles and domain walls in an SU(2) gauge theory lead to monopole erasure, which is pivotal in post-inflationary phase transitions and potentially solves the cosmological monopole problem. Simulations show that strings or monopoles cannot penetrate domain walls. Entropy-based arguments highlight the significance of the erasure phenomena that can produce correlated gravitational waves and electromagnetic radiation, impacting cosmology and astrophysics.

The second part of the colloquium focuses on the saturation of unitarity and the emergence of Saturons. These self-sustained objects, which reach the maximal entropy allowed by unitarity, resemble black holes.

I discuss a "black hole-saturon" correspondence in a renormalizable SU(N) invariant theory. Despite lacking gravity, saturons show features like an information horizon, Bekenstein-Hawking entropy, thermal evaporation, and a characteristic information retrieval time. This correspondence has significant implications for black hole physics and saturated systems. We will examine recent results on saturon mergers, vortices in black holes, and primordial black holes, offering new perspectives on fundamental theory and observations.

It has long been expected that the symmetry structure of quantum gravity is highly constrained. In particular it has been conjectured that global symmetries do not exist, and also that there must exist objects carrying all possible gauge charges. Until recently however there has been no systematic way of deriving such statements. In this talk I'll explain how these two conjectures can be derived in the special case of quantum gravity with negative cosmological constant, and also argue they are true more generally in any theory of quantum gravity where the evaporation of black holes is a unitary process. Along the way I'll clarify what is really meant by ``global'' and ``gauge'' symmetries, consider possible implications of these conjectures for particle physics, and present a new formula counting how many microstates of a black hole transform in each representation of a finite gauge group.

We study universal traits which emerge both in real-world complex datasets, as well as in artificially generated ones. Our approach is to analogize data to a physical system and employ tools from statistical physics and Random Matrix Theory (RMT) to reveal their underlying structure. We focus on the feature-feature covariance matrix, analyzing both its local and global eigenvalue statistics. Our main observations are: (i) The power-law scalings that the bulk of its eigenvalues exhibit are vastly different for uncorrelated random data compared to real-world data, (ii) this scaling behavior can be completely recovered by introducing long range correlations in a simple way to the synthetic data, (iii) both generated and real-world datasets lie in the same universality class from the RMT perspective, as chaotic rather than integrable systems, (iv) the expected RMT statistical behavior already manifests for empirical covariance matrices at dataset sizes significantly smaller than those conventionally used for real-world training, and can be related to the number of samples required to approximate the population power-law scaling behavior, (v) the Shannon entropy is correlated with local RMT structure and eigenvalues scaling, and substantially smaller in strongly correlated datasets compared to uncorrelated synthetic data, and requires fewer samples to reach the distribution entropy. These findings can have numerous implications to the characterization of the complexity of data sets, including differentiating synthetically generated from natural data, quantifying noise, developing better data pruning methods and classifying effective learning models utilizing these scaling laws.

Many particle physics theories beyond the Standard Model (BSM) admit topologically stable cosmic string solutions. If Nature is described by such a theory, a network of strings will form in the early universe and persist to the present time. The strings carry energy and hence lead to characteristic signatures in many observational windows. Searching for signals of strings in the sky can lead to new constraints on BSM models. Conversely, cosmic strings may also help solve some current mysteries in astrophysics, e.g. the origin of super-massive black holes.

The upshot of extensive studies of �uctuations in condensed matter systems is that

their qualitative importance is typically con#ned to isolated critical points of

continuous transitions between phases of matter. This conventional wisdom also

predicts the number of low energy Goldstone modes based on the so-called “G/H”

pattern of symmetry breaking. I will discuss a class of systems, some quite wellknown,

that violate this standard paradigm. Namely, they exhibit a fewer than “G/H”

number of low-energy modes due to an emergent Higgs mechanism. Even more

spectacularly, such systems exhibit “critical” ordered phases, with universal power-law

properties reminiscent of a critical point, but requiring no #ne-tuning and extending

throughout the ordered phase. One exciting recently discovered state is the heliconical

nematic that in addition to above phenomena also exhibits spontaneous chiral

symmetry breaking.

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.

The study of black holes has revealed a deep connection between

quantum information and spacetime geometry. Its origin must lie

in the quantum theory of gravity, which offers a valuable hint in

our search for a unified theory. Precise formulations of this relation

recently led to new insights in Quantum Field Theory, some of which

have been rigorously proven. An important example is our discovery

of the first universal lower bound on the local energy density. The

energy near a point can be negative but it is bounded below by a

quantity related to the information flowing past the point.