Physics

The third observing run of advanced LIGO, Virgo and KAGRA brought unprecedented sensitivity towards a variety of quasi-monochromatic, persistent gravitational-wave signals. These signals, called continuous waves, allow us to probe not just the canonical asymmetrically rotating neutron stars, but also different forms of dark matter, thus showing the wide-ranging astrophysical implications of using a relatively simple signal model. In this colloquium, I will first describe the framework within which we try to detect continuous gravitational waves from asymmetrically rotating neutron stars, as well as how we can use these signals to constrain the millisecond pulsar hypothesis for the galactic-center GeV excess. I will then generalize continuous-wave methodologies to include the different forms of dark matter that we could detect using gravitational-wave detectors, specifically: (1) the direct interaction of dark matter with the gravitational-wave detectors themselves; (2) gravitational waves from planetary- or asteroid-mass primordial black hole inspirals and so-called "mini" extreme mass ratio inspirals, and (3) gravitational waves from annihilating boson clouds around spinning black holes.

Hawking evaporation offers a unique mechanism for particle production, unlike any other process involving fundamental interactions. Moreover, a black hole will emit all existing degrees of freedom in nature, including those which might not interact with the Standard Model sector. Thus, even a small primordial black hole population could have altered different processes in the Early Universe, such as the generation of dark matter, dark radiation, baryon asymmetry or a stochastic gravitational wave background. We will analyse the production of these cosmological observables assuming monochromatic and extended black hole mass and spin distributions, and give prospects on how future observables could test the existence of primordial black holes.

In this talk, I will give a brief introduction to the basis of mathematical modeling in biology, mainly in ecology and epidemiology.  I will then focus on recent works and challenges in the modeling of the dynamics of epidemics, discussing the difference between modeling past epidemics and ongoing outbreaks.  In the end, I will discuss the place of theoretical developments in this area.

While it is relatively widely accepted that cosmic inflation took place, the actual physics behind it are still elusive. One of the main open questions concerns the number of degrees of freedom active during inflation, which can be answered through searches for primordial non-Gaussianity and isocurvature perturbations. Analyses of cosmic microwave background (CMB) data could not provide definite answers, but future large-scale structure (LSS) surveys are expected to do so by piercing into the theoretically interesting parameter space regions. In this lecture I will describe how galaxy clustering data can be used to very efficiently probe primordial non-Gaussianity and isocurvature. I will focus in particular on the special role played by the phenomenon of "galaxy bias", which has been overlooked in the past, but which must be understood significantly better to let us both (i) robustly constrain inflation models and (ii) optimize our galaxy observations for tests of inflation.

I will describe a construction that allows to understand spinors in an arbitrary number of dimensions, with arbitrary signature. I will describe what pure spinors are, and how in low dimensions all spinors are pure. The first impure spinors arise in 8 dimensions, and "purest" impure spinors are octonions. I will describe how a spinor in an arbitrary dimension defines a set of geometric structures. The easiest example of this is how a pure spinor defines a complex structure. As one increases the dimension, the types of geometric structures that are described by spinors become more and more exotic. If time permits, I will describe some examples in 14 and 16 dimensions. Almost nothing is known about spinors in dimension beyond 16.

Zoom link:  https://pitp.zoom.us/j/94776499052?pwd=RGVURlRnaEx6REJwVE10VXhqa1Q5Zz09

Nils Siemonsen, Perimeter Institute & University of Waterloo

Dark Photon Superradiance

Gravitational and electromagnetic signatures of black hole superradiance are a unique probe of ultralight particles that are weakly-coupled to ordinary matter. Considering the lowest-order interactions one can write down for spin-1 dark photons, the kinetic mixing, a dark photon superradiance cloud sources a rotating visible electromagnetic field. A pair production cascade ensues in the superradiance cloud, resulting a turbulent plasma with strong electromagnetic emissions. The emission is expected to have a significant X-ray component and to potentially be periodic, with period set by the dark photon mass. The luminosity is comparable to the brightest X-ray sources in the Universe, allowing for searches at distances of up to hundreds of Mpc with existing telescopes. Therefore, multi-messenger search campaigns are sensitive to large parts of unexplored beyond the Standard Model parameter space.

Bruno Torres, Perimeter Institute & University of Waterloo

Optimal coupling for local entanglement extraction from a quantum field

The entanglement structure of quantum fields is of central importance in various aspects of the connection between spacetime geometry and quantum field theory. However, it is challenging to quantify entanglement between complementary regions of a quantum field theory due to the formally infinite amount of entanglement present at short distances. We present an operationally-motivated way of analyzing entanglement in a QFT by considering the entanglement which can be transferred to a set of local probes coupled to the field. In particular, using a lattice approximation to the field theory, we show how to optimize the coupling of the local probes with the field in a given region to most accurately capture the original entanglement present between that region and its complement. This coupling prescription establishes a bound on the entanglement between complementary regions that can be extracted to probes with finitely many degrees of freedom.

Neutrinos, proposed last century, have revolutionized particle physics by providing a unique window into the subatomic world. Initially proposed to preserve energy conservation in beta decays, it was later discovered that they come in three flavors and have a non-zero mass, fundamentally changing our understanding of the Standard Model.In this talk, we take an "epic poem" approach to review the historical development of neutrino physics. We start by presenting the current status of neutrino physics, then delve into the fascinating journey of how scientists discovered the properties of these elusive particles, with a particular focus on the groundbreaking discovery of neutrino oscillations. Finally, we explore exciting possibilities for future research, such as studying atmospheric, supernovae, and diffuse supernova neutrinos and neutrino scatterings, in order to deepen our understanding of the unique properties of these particles and their connections to broader topics in particle physics.

The large-scale distribution of mass and energy in the Universe, called the large-scale structure (LSS), contains a wealth of information about fundamental physics and cosmology (dark energy, dark matter, gravity, inflation and particle physics). In this talk I will discuss both (i) the opportunities for fundamental discoveries from upcoming LSS observational surveys, as well as (ii) the two main challenges that need to be overcome. These challenges relate to the "invisibility" and the "non-Gaussianity" of the LSS: I will describe these and report on recent progress that has been made to address them

The session is addressed to educating startups, SMEs, and researchers to acquire fundamental knowledge on IP within the quantum computing domain. This introductory session includes real-world examples to explain the patent process with a view to commercialization of quantum computing projects. Other forms of IP are also covered. The session is facilitated by Benjamin Mak and Marco Clementoni of Ridout & Maybee LLP. 

Zoom Link: TBD

The aim of the presentation is to review the beautiful geometry underlying the standard model of particle physics, as captured by the framework of "SO(10) grand unification." Some new observations related to how the Standard Model (SM) gauge group sits inside SO(10) will also be described. 

I will start by reviewing the SM fermion content, organising the description in terms of 2-component spinors, which give the cleanest picture. 

I will then explain a simple and concrete way to understand how spinors work in 2n dimensions, based on the algebra of differential forms in n dimensions.

This will be followed by an explanation of how a single generation of standard model fermions (including the right-handed neutrino) is perfectly described by a spinor in a 10 ("internal") dimensions. 

I will review how the two other most famous "unification" groups -- the SU(5) of Georgi-Glashow and the SO(6)xSO(4) of Pati-Salam -- sit inside SO(10), and how the SM symmetry group arises as the intersection of these two groups, when they are suitably aligned.

I will end by explaining the more recent observation that the choice of this alignment, and thus the choice of the SM symmetry group inside SO(10), is basically the choice of two Georgi-Glashow SU(5) such that the associated complex structures in R^{10} commute. This means that the SM gauge group arises from SO(10) once a "bihermitian" geometry in R^{10} is chosen. I will end with speculations as to what this geometric picture may be pointing to. 

Zoom link:  https://pitp.zoom.us/j/95984379422?pwd=SE1ybktzQzcreWREblhEUkZWWElMUT09

ChatGPT has spread like wildfire, and is now the face of the Artificial Intelligence revolution. However, this revolution, albeit in a quiter way, has been ongoing for some time. In the case of materials science and condensed matter physics, it has led to a paradigm change in the way we design and study novel materials. In this talk I will discuss some of the important advances in the field, and some of the issues that are yet to be tackled.