Particle Physics

Far-infrared spectroscopy can reveal secrets of galaxy evolution and heavy-element enrichment throughout cosmic time, and astronomers worldwide are designing cryogenic space telescopes for far-IR spectroscopy. The most challenging aspect is a far-IR detector which is both exquisitely sensitive (limited by the zodiacal-light noise in a narrow band (lambda/delta lambda ~1000)) and array able to tens of thousands of pixels. The quantum capacitance detector (QCD) being developed at MDL, is a 50mK device adapted from quantum computing applications in which photon-produced free electrons in a superconductor tunnel into a small capacitive island embedded in a resonant circuit. The QCD has optically-measured noise equivalent power (NEP) of 2x10-20 W Hz-1/2 at 1.5THz under 10-19W of optical loading, making it the most sensitive far-IR detector ever demonstrated. The QCD has further demonstrated individual far-IR photon counting, confirming the exquisite sensitivity and suitability for cryogenic space astrophysics. In this lecture, the development of the Quantum Capacitance detector will be highlighted, from inception through proof of concept devices, culminating with the demonstration of single photon detection. Current development efforts will be discussed.

In this talk I will discuss the application of the so-called “consistency relations” for large scale structures to the study of primordial non-Gaussianities of the local f_NL type. I will first introduce the consistency relations themselves, commenting on some important aspects and underlying assumptions. I will then verify them (and their violation) using N-body simulations for the matter density in the Universe. This proves consistency relations to be a promising tool to apply in the forthcoming large scale structures surveys. I will conclude describing some work in progress aimed at finding a practical recipe to constrain f_NL from these relations.

It has been proposed that microscopic black holes can catalyze decay of metastable false vacuum. The calculations of the decay rate existing in the literature make use of the Euclidean time formalism developed for equilibrium configurations. This is not the case, however, for a realistic black hole formed by gravitational collapse and emitting Hawking radiation. I will review the motivations to study black hole catalysis of vacuum decay, propose a general method to calculate the decay rate, and illustrate it on a two-dimensional toy model.

Following the recommendation of the Update of the European Strategy for Particle Physics and in view of rising interest shown in the US Snowmass process, a new International Muon Collider Collaboration is forming, hosted at CERN. The presentation will introduce the muon collider concept, the reason for the renewed interest and the main challenges and opportunities.

From dark matter to the strong CP problem to the dynamics behind the weak scale, a variety of observations make for a compelling case that the Standard Model is an incomplete description of subatomic physics. Yet none of these puzzles provides unambiguous guidance on how we should proceed to find what comes next.

I will argue that this state of affairs calls for a multi-directional strategy in our quest for physics Beyond-the-Standard-Model. Only a combination of new theoretical developments and original ideas, confronted with the vast array of experiments at our disposal, will provide us with the big picture we need to move beyond.

Models of Dark Matter (DM) can leave unique imprints on the Universe's small scale structure by boosting density perturbations on small scales. We study the capability of Pulsar Timing Arrays to search for, and constrain, subhalos from such models. The models of DM we consider are ordinary adiabatic perturbations in ΛCDM, QCD axion miniclusters, models with early matter domination, and vector DM produced during inflation.