Neutrino researches in Kamioka -past, present and future-

More than 30 years ago, Kamiokande experiment began in Kamioka, Japan. It observed Supernova neutrinos, atmospheric neutrino deficit, and solar neutrinos. Because of the importance of these studies, Super-Kamiokande was then constructed. It began the experiment in 1996. In 1998, neutrino oscillation was discovered with the studies of atmospheric neutrinos. In Kamioka, a new large neutrino project is under planning. In this lecture, I will discuss the past, present and future of the researches in Kamioka.

Monday, 2 July 2018, ore 14:30 — Aula Magna "Tullio Regge"

Philosophy of science meets statistical inference: reviving the concept of corroboration

The most common way of testing statistical hypotheses is to conduct null hypothesis significance tests (NHST) and to use a p-value to describe evidence against the null hypothesis. In this talk, I would like to highlight a fundamental conceptual problem with this approach: the impossibility to express support for the null hypothesis. Since null hypotheses are often simple and precise idealizations of complex models with substantial theoretical importance, a good method for scientific hypothesis tests has to be able to express support for them. Also, the one-sided nature replication of crisis p-values in various arguably scientific aggravates the disciplines. My approach is twofold: first I explain why classical NHST and classical Bayesian inference fail to evaluate a null hypothesis in an appropriate way; then I develop a measure of corroboration, taking inspiration from both Bayesian and frequentist procedures. I argue that degrees of corroboration achieve a more nuanced judgment on the evidence in favor of a null hypothesis and that they can be used in a variety of cases in statistical inference.

Friday, 22 June 2018, ore 14:30 — Sala Wataghin

The holographic universe

String theory is the evolution of theoretical constructions developed during the past century, embracing and extending general relativity and quantum mechanics. One of the lessons of string theory has been the discovery of relationships between seemingly different theories, called dualities. In particular, the gauge/gravity duality postulates that a theory of gravity is equivalent to a quantum field theory in one lower dimension. In this seminar I will explain why imagining the universe as a holographic projection of a lower dimensional space-time has radically changed the way we think about fundamental questions in theoretical physics.

Friday, 1 June 2018, ore 14:30 — Aula Magna "Tullio Regge"

From the Motion of Planets to Elementary Particles

Planetary orbits, energy levels of atoms, and elementary particle interactions are all governed by the same hidden symmetry principles. I will describe these symmetries and how they help simplify calculations. In particular, I will focus on recent progress for scattering amplitudes in quantum field theory.

Friday, 4 May 2018, ore 14:30 — Sala Wataghin

From Navier Stokes Equation to Earthquake Dynamics

Many materials around us respond elastically to small applied stresses, but flow once a threshold stress (the yield stress) is exceeded. This is the case for food products, powders, cosmetics, foams, etc? It turns out that understanding the yield stress transition in these materials, often called soft glasses, is a challenging question. Similar to structural glasses, soft glasses exhibit aging and complex dynamics. Also, the size of the elementary building block of a soft glass is usually ranging from 1 micron to 1mm, ruling out the possibility to investigate the problem by molecular dynamics. Recently, a new approach has been proposed: using a mesoscopic formulation of the system, the dynamics of relative simple soft glasses, like foams or micro emulsions, has been investigated. Numerical simulations allow the computation of several important properties of the systems, such as the yield stress transition. In this talk, I will review the new approach and explain how the complexity of soft glass dynamics may be disentangled in a systematic way. Last but not least, I will show that if the material is slimulated below yield stress, plastic events occur, which have strong similarities to seismic events. Based on a suitable definition of displacement in the continuum, I show that the plastic events obey a Gutenberg-Richter law with exponents similar to those for real earthquakes.

Friday, 20 April 2018, ore 14:30 — Sala Wataghin

Elettroni, fotoni e altre particelle: un viaggio nel mondo delle particelle elementari e delle onde gravitazionali

La ricerca dei costituenti ultimi della materia, le ?Particelle Elementari?, ha affascinato l?uomo fin dai primi passi del pensiero scientifico. Partendo dalla scoperta del fotone e dalle leggi intriganti che regolano il mondo dell?atomo, progressi straordinari della seconda metà del Novecento hanno individuato un nuovo livello di realtà, oltre l?atomo e il nucleo atomico: i quark, entrati ormai nel linguaggio di ogni giorno e nell?immaginario collettivo, i leptoni e i mediatori delle forze fondamentali. La scoperta del ?bosone di Higgs? ha sancito il successo di una descrizione della realtà fisica basata su elementi di semplicità impensabili solo cinquant?anni fa. Lungo questo percorso, si scoprono affascinanti relazioni tra la fisica del Microcosmo e le strutture su grande scala che si sono formate, nell'Universo, a partire dal Big Bang iniziale. Un nuovo strumento per esplorare l?Universo si è reso disponibile negli ultimi anni, i rivelatori di onde gravitazionali, con cui speriamo di comprendere eventi cosmici catastrofici, come la coalescenza di due stelle di neutroni, o, nel futuro, di esplorare l?Universo immediatamente prima del Big Bang. Ci sono ancora importanti misteri. Tra questi, a bassa energia ancora non dominiamo le possibili nuove forme di materia costituite dai quark, che intravediamo in nuovi tipi di adroni scoperti recentemente (adroni ?esotici?). Inoltre, ad alta energia, la possibile esistenza di nuove particelle che potrebbero essere la chiave della materia non luminosa che gravita intorno alle Galassie e rende conto di pi del 90% della materia esistente nell?Universo. Per chiarire i misteri, sono allo studio nuove macchine con energie e luminosità superiori di un ordine di grandezza all?energia del Large Hadron Collider del CERN.

Thursday, 12 April 2018, ore 14:30 — Aula Magna "Tullio Regge"

Thermalization and hydrodynamics of the quark-gluon plasma

There is experimental evidence that the quark-gluon plasma produced in ultra-relativistic heavy ion collisions is well described by viscous hydrodynamics, with a low value of the viscosity (relative to the entropy density). This observation, added to the recent discovery that the same description works well also for high energy proton-nucleus or high multiplicity proton-proton collisions, is raising a number of interesting theoretical questions: How does the system of gluons freed in the early stage of a collision evolve towards local thermal equilibrium? How does hydrodynamical behavior emerge in systems whose natural description is in terms of quantum field theory? Can we observe hydrodynamical behavior in the absence of local equilibrium? Such questions, among others, will be discussed during the talk, following a brief presentation of the experimental evidence.

Friday, 6 April 2018, ore 14:30 — Sala Wataghin

Higgs Compositeness: Why and How

The Higgs being a bound state of a new TeV-scale confining dynamics is arguably the simplest and sharpest solution to the Naturalness Problem. I will review the theoretical foundations of potentially viable Composite Higgs scenarios, their phenomenological signatures and the status of ongoing experimental searches at the LHC. I will also discuss the strong impact that present-day negative findings of Composite Higgs, and of other solutions to the Naturalness problems, are having on Fundamental Physics.

Friday, 23 March 2018, ore 14:30 — Sala Wataghin

PT-symmetric quantum mechanics - Physics in the complex domain

Complex-variable theory provides insight into the nature of physical theories. For example, it provides a simple and beautiful picture of quantization and it explains the underlying reason for the divergence of perturbation theory. By using complex-variable methods one can generalize conventional Hermitian quantum theories into the complex domain. The result is an exciting new class of parity-time-symmetric (PT-symmetric) theories whose remarkable physical properties are currently under intense study by theorists and experimentalists. Many theoretical predictions have been verified in recent laboratory experiments.

Friday, 9 March 2018, ore 14:30 — Sala Wataghin

Spectral Properties of Matter under Extreme Conditions

The question matter under extreme conditions relates to cosmological settings in the early universe and the physics of neutron stars. Of particular interest is the generation of mass through the strong interaction and the quark-hadron transition. This transition can be explored in collisions of relativistic heavy ions. In this talk I present a non-perturbative framework for dealing with the equilibrium properties of strong-interaction matter and its spectral properties. Special emphasis will be put on the role spontaneously broken chiral symmetry and its restoration at high temperatures and large baryon densities. Observable consequences in heavy-ion collisions will be discussed.

Friday, 23 February 2018, ore 14:30 — Aula Magna "Tullio Regge"