The low-temperature behavior of spin systems with a continuous symmetry is expected to be governed by Gaussian fluctuations around the ground state, known as spin waves. For classical models this picture has been rigorously established by Bricmont-Fontaine-Lebowitz-Lieb-Spencer (1982) for the O(2) model and, more recently, by Giuliani-Ott (2025) for general O(N) systems. In the quantum setting, however, the situation is more subtle: the low-energy
behavior arises from a nontrivial interplay ...
This dissertation contributes to the empirical literature on job quality. The first chapter introduces the broader debate and presents the overall structure of the thesis. The second chapter examines the implications of agglomeration for job quality using an urban–rural comparative approach across multiple indicators. The results show that rural workers are better off in terms of work intensity and job satisfaction, while urban workers benefit from stronger job-match opportunities. Overall, t...
The Lorentz gas is an important model in kinetic theory where one seeks to under- stand the behavior of a single particle interacting with a fixed environment. In certain scaling regimes, the complicated microscopic behavior of the particle can be well-approximated by an effective equation or stochastic process. A description of the effective behavior usually does not rely on all details of the microscopic dynamics. When the interactions are quantum mechanical, the model is referred to as the...
Ecological communities are high-dimensional interacting systems whose stability emerges from the structure of their interaction networks. This thesis applies tools from the statistical mechanics of disordered systems to study the equilibrium properties of large ecosystems modeled by generalized Lotka–Volterra (gLV) equations with sparse and symmetric interactions. Moving beyond the traditional fully-connected (mean-field) setting, we analyze systems on locally tree-like random graphs using th...
In today's world, the frequency and impact of disruptive events, such as extreme natural disasters, the enduring effects of the Covid-19 pandemic, wars, and societal polarisation, have highlighted the necessity for communities to be better prepared for these challenges. Attention has increasingly turned to social processes, including social cohesion and capital, as vital tools for enhancing community resilience. Concurrently, research and policy-making recognise the importance of culture and ...
This thesis explores the multi-faceted and promising science of gravitational waves (GWs) from compact binary coalescences (CBCs), focusing on the information they provide and how we can extract it. Central to our work is the question: What is the data content of the GW signals from CBCs, and how can we effectively analyze it to enhance our understanding of the Universe? This study addresses current detector networks and next-generation (XG) instruments, linking data analysis with multi-messe...
We are increasingly surrounded by systems connecting us with the digital world and facilitating our lives by supporting our work, leisure, activities at home, health, etc. These systems are pressed by two forces. On the one side, they operate in environments that are increasingly challenging due to uncertainty and uncontrollability. On the other side, they need to evolve, often in a continuous fashion, to meet changing needs, to offer new functionalities, or also to fix emerging failures. To ...
Observational evidence gathered from astrophysical and cosmological sources strongly
suggests the existence of dark matter. Constituting approximately 27% of the total
mass-energy of the Universe, dark matter plays a critical role in the evolution of the
Universe. Weakly interacting massive particles (WIMPs) are an important class of
potential dark matter candidates. One of the leading technology in WIMP detection is
the use of liquefied noble gases as the sensitive medium.
DarkSide-20k...
In numerical linear algebra, the problem of computing the distance of a given matrix A from a given set P arises in different fields of matrix and control theory, where it is used to characterize the robustness of considered systems. Some examples include, but
are not limited to, distance to singularity, matrix stability, measures in control theory,
etc. (see e.g. [28, 33, 44, 45, 46, 53]). The problem consists in computing an element
B ∈ P such that the distance between B and A is the sma...
The urgency of coping with the uneasiness of tackling race in Europe motivates this dissertation to explore how the racial and the urban connect. Scholars warn that a new era of conflicts played on racial lines is opening up hitting mainly the cities. As a result, race and the city are of increasing concern in public discourses. However, outside the US, the effects of race are often neglected or even denied. Although difficult to grasp, the race process has material and tangible effects that ...