Calendar

Feb
27
Mar
Physics in Wonderland: esplorando i segreti dell’universo (Anna Marini e Bianca Bottino) @ Aula Magna DIFI
Feb 27 @ 5:00 pm – 6:30 pm

Si tratta di un evento all’interno dell’iniziativa “Un Mare di Scienza”, serie di conferenze di divulgazione scientifica organizzate dalla Scuola di Scienze Matematiche, Fisiche e Naturali.

Relatrici: Anna Marini (INFN) e Bianca Bottino (UNIGE)

I raggi cosmici sono messaggeri preziosi che ci aiutano a decifrare il nostro Universo. Attraverso la loro rivelazione possiamo captare segnali dallo spazio profondo. In questo incontro vedremo e utilizzeremo un rivelatore di raggi cosmici, partendo dai processi microscopici innescati dal passaggio dei raggi cosmici nella materia, per arrivare all’acquisizione di veri e propri segnali.

Feb
28
Mer
A History of Neutrino and its mass (Dr. Francesco Vissani LNGS Istituto Nazionale di Fisica Nucleare) @ Aula Magna
Feb 28 @ 3:00 pm – 4:00 pm

nell’ambito del workshop NuMass 2024

In this seminar, the history of the neutrino and its mass is recounted in six short chapters, with a bit of emphasis on the theoretical aspects:
1. Pauli’s proposal is presented, clarifying its significance and the context in which it arose, that of the earliest theories of the atomic nucleus.
2. The first beta-ray theory, due to Enrico Fermi, is described, clarifying its potential but also its formal and conceptual limitations.
3. Majorana’s ideas, from which the modern treatment of neutrinos and fermions in general originated, are illustrated.
4. Major advances in the next 30 years concern the existence of fermion families and the chiral structure of weak interactions, directly related to the hypothesis of neutrinos with zero mass.
5. Conceptions on the mass of neutrinos and the main ways to probe them are then summarised.
6. Prospects for development are briefly discussed in the last chapter of the story, which is the one yet to be written.

Feb
29
Gio
Odd Viscoelasticity (Prof.Piotr Surowka, Wrokaw U. of Science and Technology @ A601 e online
Feb 29 @ 2:00 pm – 3:00 pm

Seminario di Fisica Teorica

Active matter encompasses systems that are not in equilibrium, consisting of elements that either consume energy or exert work. Consequently, their macroscopic characteristics diverge significantly from those predicted by continuum field theories based on equilibrium statistical mechanics. Recent advancements in active matter research have prompted a reevaluation of the fundamental principles of materials science. This has led to the development of a novel theoretical framework known as odd(visco)elasticity. Traditional elasticity treats solids as continuous media that change shape in response to external forces. On a microscopic scale, applying force to a crystalline structure displaces its atoms, which then exert a counterforce to regain the crystal’s original configuration. However, this dynamics is fundamentally altered in active odd materials, where the response to applied forces includes not only compression or deformation but also deflection. In this presentation, I will provide an overview of the recent advancements in this field.

Per connettersi a zoom:

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Mar
6
Mer
COSMOLOGY OF THE QCD AXION: FROM THERMAL TO INFLATIONARY PRODUCTION (Alessio Notari, Universitat de Barcelona) @ Aula 501
Mar 6 @ 2:00 pm – 3:30 pm

Seminario Fisica Teorica

The axion is a hypothetical particle that could explain the absence of CP violation in QCD and has a very rich cosmological phenomenology.
In particular a population of thermally produced axions is expected to exist, in addition to a cold dark matter population. I discuss a new conservative bound on the axion mass, from production in the early universe from scattering with pions. In addition I will show that to exploit the reach of upcoming cosmological surveys, non-perturbative calculations above the QCD crossover are needed. Moreover I will also review production from other Standard Model particles (quarks, leptons).
Then, I will discuss the axion cold dark matter population, showing that its abundance depends on non-trivial evolution during primordial inflation.
Finally I will discuss the non-standard case of a heavy QCD axion, which could give rise to a detectable gravitational wave signal at Pulsar Timing Arrays or at interferometers.

Per connettersi a zoom:

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Mar
7
Gio
Inflationary scenario and de Sitter conjecture ( Dr Kunihito Uzawa, Kwansei Gakuin Univ. and Keio Univ.) @ Aula 605
Mar 7 @ 2:00 pm – 3:00 pm

Seminario Fisica Teorica

Several simple criteria were proposed to assess if vacua emerging from an effective scalar field theory are part of the string “landscape” or “swampland”. However, there has been little attempt to examine the swampland criterion against explicit context of kinetic terms made up of scalar fields. In this presentation, we discuss the universal behavior that in the region wherein the moduli are expected to be stable, the theory of gravity may be part of the landscape. By contrast, in the region where they may be faithful runaway potential, in the sense they possess a finite kinetic term for scalar field, the theory should thus be part of the swampland. We also consider the inflationary scenario interpolating between the cosmological landscape and the swampland and establish the part of the domain of existence where the swampland criteria are violated.

Per connettersi a zoom:

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Mar
13
Mer
Holographic match of subleading corrections to the BPS entropy of AdS5 black holes (Dr. Alejandro Ruiperez, INFN Roma 2) @ Aula 501
Mar 13 @ 2:00 pm – 3:00 pm

Seminario di Fisica Teorica

The Bekenstein-Hawking entropy of supersymmetric AdS5 black holes is matched holographically via the Legendre transform of the superconformal index on the second sheet. In this talk I shall show how this approach can be extended to account for subleading corrections to the Bekenstein-Hawking entropy, which are computed in the gravity side by adding suitable higher-derivative corrections. After reviewing the universal case studied in 2208.01007 (and 2304.06101), I will focus on ongoing work aimed to understand the case in which the black hole is charged under additional flavor symmetries.

Per connettersi a zoom:

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Mar
20
Mer
Thermal spectra in QFTs and their reconstructions (Saso Grozdanov, Edimburgh) @ Aula 501
Mar 20 @ 2:00 pm – 3:30 pm

Seminario Fisica Teorica

The holographic duality provides an explicit reduction of quantum field theory (QFT) calculations in the semiclassical large-N limit to sets of “gravitational” differential equations whose analysis can reveal all details of the spectra of thermal QFT correlators. In the first part of my talk, I will discuss the state of affairs in our understanding of thermal spectra from the point of view of hydrodynamics, kinetic theory as well as perturbative QFTs and, finally, holographic QFTs. Then, I will discuss how, in spectra with analytic properties that appear in holography, a complete reconstruction of the spectrum and of the corresponding correlator is possible from only the knowledge of an infinite, discrete set of pole-skipping points (a “0/0” in the associated correlation function) traversed by a single (hydrodynamic) mode. The main step that will enable a unique reconstruction will be a series expansion of the problem in an inverse number of spacetime dimensions, expanded around infinity. Conceptually, this reduces the computation of a QFT correlator spectrum to performing a set of purely algebraic manipulations.

Per connettersi a zoom:

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Mar
27
Mer
SMEFT vs HEFT for new physics searches at the LHC (Ilaria Brivio, Università di Bologna) @ Aula 501
Mar 27 @ 2:00 pm – 3:00 pm

Semina di Fenomenologia delle Particelle Elementari

Over a decade after the Higgs discovery, the hunt for physics beyond the Standard Model is incorporating more and more searches for small, non-resonant traces of new physics, that can be described by an Effective Field Theory (EFT).
The so-called Standard Model EFT (SMEFT) is now the standard framework used for these searches. The Higgs EFT (HEFT) is an alternative extension of the SM, which differs from SMEFT in the representation chosen for the scalar fields, a feature that results in a higher complexity and that, so far, has made HEFT less attractive for phenomenological studies.
Nevertheless, it is well-established that HEFT is more general than SMEFT, implying the existence of BSM scenarios which would be captured by the former but not by the latter. HEFT could also represent a useful candle to test the validity of the dimension-6 SMEFT approximation, an issue that has been raising significant concerns for LHC measurements.
After an introduction to the two frameworks, the first half of the talk will give an overview of the phenomenological characterization of HEFT and SMEFT. The second part will explore more formal aspects of the HEFT-SMEFT interplay, that build on a geometric description of the scalar sector.

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Apr
3
Mer
Precise QCD for associated top production ( Dr Simone Devoto, U. Ghent) @ Aula 501
Apr 3 @ 2:00 pm – 3:00 pm

Seminario di Fenomenologia delle Particelle Elementari

The production of a top quark pair in association with a heavy boson is a class of processes of high importance at LHC, both for precision Standard Model studies and new physics searches: top-pair production in association with a Higgs boson allows for a direct measurement of the top-quark Yukawa coupling, while the cross section of top-pair production in association with a W boson has been observed consistently higher than the Standard Model value by different experimental collaborations.
In this talk we present our recent computation of the NNLO QCD corrections to both these processes, with an emphasis on their phenomenological applications.

Per connettersi a zoom:

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Apr
10
Mer
Constraining dark matter properties with cosmological structure formation (Prof Matteo Viel (SISSA)) @ Aula 501
Apr 10 @ 2:00 pm – 3:00 pm

Physics Colloquia

I will review constraints on dark matter nature like, i.e. the dark matter free streaming, in the context of structure formation by using hydrodynamical simulations and observational data sets. In particular, I will focus on ordinary matter that does not shine in between galaxies: the intergalactic medium.
I will show that the most competitive constraints on warm dark matter (with a non-negligible free streaming) can be obtained from the main manifestation of the intergalactic medium, the so-called Lyman-alpha forest produced by neutral hydrogen in the filamentary cosmic web.
Moreover, I will show quantitative constraints on neutrino masses, comment on other dark matter scenarios (scalar dark matter, dark matter interacting with baryons or radiation) and assess the prospects of 21cm intensity mapping in addressing dark matter nature.