Calendar

Mag
22
Mer
Black hole microstate geometries and their holographic duals (Dr. Sami Rawash, IIT Genova) @ 501
Mag 22@2:00 pm–3:00 pm

Seminario Fisica Teorica

Despite General Relativity’s experimental success, theoretical motivations suggest it may not offer the ultimate description of black hole physics. The entropy puzzle and the black hole information paradox are two challenges that any proposed theory of quantum gravity must confront. In this talk, I will introduce the “fuzzball proposal”, a conjecture arising from string theory’s construction of black holes in terms of strings and branes. According to this conjecture, strong quantum gravity effects that occur already at the horizon scale hold promise for providing a consistent microscopic description of black hole physics. I will then discuss various tools and techniques (including holography, shockwave perturbations and computational methods) which can be used to examine and corroborate this conjecture.

Mag
29
Mer
Cosmology with Euclid and the Dark Energy Spectroscopic Instrument (DESI) (Florian Beutler, Edinburgh) @ Aula 501
Mag 29@2:00 pm–3:00 pm

Galaxy redshift surveys provide a large number of observables to constrain fundamental parameters of our universe. I will provide a general introduction to the concept of spectroscopic galaxy surveys as well as an overview of Baryon Acoustic Oscillations. I will then discuss the first results of the year 1 analysis of DESI together with an outlook for the upcoming year 3 and year 5 analysis.

Giu
4
Mar
Update on Superconducting Magnets & Devices Development at CERN (Arnaud Devred (CERN)) @ Aula Magna
Giu 4@3:00 pm–4:00 pm

Physics Colloquia
Abstract: The High Luminosity LHC (HL-LHC) project at CERN has offered the opportunity to promote and develop various types of enabling accelerator technologies, such as MgB2 superconducting links for cold powering and Nb3Sn accelerators magnets for the interaction regions. The superconducting link is in an advanced prototyping phase and is expected to be fully validated in the coming months. The Nb3Sn magnet development has encountered serious difficulties characterized by performance limitation or degradation which have now been overcome. We report on the status and challenges of HL-LHC magnets and devices at CERN, with a primary focus on the root cause analysis and recovery actions implemented for the final focusing Nb3Sn quadrupole magnets, and a comparison with similar issues encountered over a decade ago on the Nb3Sn Cable-in-Conduit conductors for ITER magnets. We also present two ongoing spin-off projects which benefit from HL-LHC technology developments: a strongly curved, Nb-Ti, canted cosine theta (CCT) magnet and an energy-efficient, MgB2, superferric dipole magnet.

Lug
11
Gio
Laser spectroscopy and implantation of exotic radioisotopes at the RISIKO mass separator of Mainz University (Dr. Klaus Wendt for the LARISSA Collaboration, Institute of Physics, Johannes Gutenberg University Mainz) @ Aula 502
Lug 11@3:00 pm–5:00 pm

Seminario di gruppo II

The implementation of resonance ionization using powerful tunable laser systems at high transmission mass separators has led to numerous research activities on stable as well as radioactive isotopes. Aside of the application as highly selective and efficient ion source for rare species at radioactive ion beam (RIB) facilities like ISOLDE at CERN or ISAC at TRIUMF, direct in-source spectroscopy on atomic structure and nuclear ground state properties are carried out, e.g., in the range of the actinides and other radioisotopes. At the RISIKO off-line mass separator facility the laser systems are adapted and such investigations are prepared, complementing efficient implantation runs of ultrapure radioisotope samples for specific programs. These include collections of 6Li, 53Mn, 55Fe, 158Tb, 163Ho, and 226Ra in microscopic metallic calorimeters (MMCs) and on other targets. The technology will be presented with special emphasis on the laser systems and the required mass separator optimizations together with some recent applications of relevance.

Ott
2
Mer
Phenomenological aspects of Electroweak interactions – Dr Lorenzo Mai (Università di Genova e INFN) @ A500
Ott 2@2:30 pm–3:30 pm

Seminario di Fisica Teorica

This talk will cover key elements of the Electroweak (EW) sector of the Standard Model (SM). I will firstly review the underlying structure and general features of EW interactions, from the well known Spontaneous Symmetry Breaking (SSB) mechanism to the complex-mass scheme for the decay of weak gauge bosons. An overview of relevant related topics, such as the Goldstone Boson Equivalence Theorem (GBET), will also be discussed. Finally, I will briefly address the behavior of EW corrections at high energy. In this regime, one-loop EW corrections are logarithmically enhanced and in tail of kinematic distributions can yield correction factors of several tens of percent, reaching a similar size to the corresponding QCD ones. Thus, a very good control of these effects, and of remaining theoretical uncertainties, is crucial for the success of many physics endeavours at the LHC.

Ott
9
Mer
Spindles, Toric Orbifolds and Holography – Alessio Fontanarossa (Università di Torino) @ Aula 500
Ott 9@2:30 pm–3:30 pm

Seminario di fisica teorica

Since the proposal of the AdS/CFT correspondence, several examples of this conjecture involving branes wrapped on smooth Riemann surfaces $Sigma$ have appeared in the literature. In all these constructions, the $D=10,11$ supergravity solutions exhibit a boundary of the schematic form $AdS_{d+1}times M_{D-(d+1)}$ and a near-horizon geometry of the type $AdS_{d+1-n}times Sigma_ntimes M_{D-(d+1)}$, where $M$ is a compact manifold. After reducing the higher-dimensional theory on $M$, these solutions are interpreted as black branes in $AdS_{d+1}$ wrapped on $Sigma$. In this setup, supersymmetry is preserved via the so-called topological twist, which ensures that the supersymmetry spinor is independent of the coordinates on $Sigma$. A pivotal shift occurred with the work arXiv:2011.10579, which showed that branes could also be wrapped on orbifolds (specifically, the spindle). This breakthrough revealed that supersymmetry can be preserved in a completely novel way through the anti-twist, an orbifold generalization of the no-twist. Following this, significant efforts have been devoted to constructing similar and even more intricate solutions. Of particular interest is the case $d=1$, as the resulting metric is expected to correspond to the near-horizon limit of supersymmetric black holes in string theory. In the first part of this seminar, I will introduce the main characters of this game, with a focus on why black holes play a central role in the study of quantum gravity. I will then discuss my current research on spindles, with reference to arXiv:2210.16128, arXiv:2402.08724 and arXiv:2409.xxxxx.

Ott
16
Mer
da definire @ aula 500
Ott 16@2:30 pm–3:30 pm

seminario di fisica teorica

Ott
23
Mer
NATURAL SWARMS IN 3.99 DIMENSIONS: LOOKING FOR UNIVERSAL LAWS IN THE COLLECTIVE BEHAVIOUR OF LIVING SYSTEMS – Dr Andrea Cavagna (ICS-CNR e INFN) @ Aula Magna
Ott 23@2:30 pm–3:30 pm

seminario Colloquium

From the standpoint of physics, life is a mess. Biological phenomena cross spatial and temporal scales in a startling way, involving organisms that are greatly diverse at the structural and functional level. Amid this jumble, though, some connections with the physical and mathematical sciences often emerge, stirring hopes to partially extend to biology the predictive power of theoretical physics. To pursue this idea, though, the great diversity of biology needs to be drastically simplified. Physics is optimally suited for this task, rooted as it is on the idea that not all microscopic details are important, as only a couple of relevant variables are needed to describe a system. The tool physics uses to cut irrelevant details is the renormalization group. In 1972, Kenneth Wilson and Michael Fisher wrote a seminal paper titled “Critical Exponents in 3.99 Dimensions”, where they gave mathematical flesh to the idea that when we coarse-grain short-scale fluctuations the parameters of different models may flow towards the same fixed point ruling their large-scale behaviour, thus organizing into a handful of universality classes both statistical and quantum field theory. Can we use the renormalization group to describe the phenomena of life? Can we employ the same fundamental language to understand both the Higgs boson and a flock of starlings? In the field of collective behaviour the answer to this question seems to be positive. A unifying ingredient of collective biological systems is the presence of strong correlations: experiments in bird flocks, fish schools, mammal herds, insect swarms, and bacterial clusters find that the correlation length is significantly larger than the microscopic scales, a natural stepping stone to an RG analysis. In this talk I will provide a very simplified explanation of the renormalizationgroup (mostly using Google Maps) and then show how it can be applied to the study of natural swarms of insects, which are strongly correlated systems obeying dynamic scaling with an experimental dynamical exponent z=1.37 +/- 0.11. A one-loop RG calculation that takes into account both off-equilibrium activity and inertial dynamics gives z=1.35, a value remarkably close to the experimental exponent. This is the first positive test within biophysics of an RG prediction, hence strengthening our hopes that the renormalization group and its most fruitful consequence – universality – may have an incisive impact also in biology.

Ott
30
Mer
da definire @ aula 500
Ott 30@5:00 pm–5:30 pm

seminario di fisica teorica

Nov
6
Mer
da definire @ Aula 500
Nov 6@2:30 pm–3:30 pm

Seminario di fisica teorica