Notiziario Scientifico

Notiziario dei seminari di carattere matematico
a cura del Dipartimento di Matematica G. Castelnuovo, Sapienza Università di Roma

Settimana dal 01-02-2021 al 07-02-2021

Mercoledì 03 febbraio 2021
Ore 14:00, Seminario telematico via Google Meet all'URL http://meet.google.com/jjt-toji-skw, Dipartimento di Matematica, Sapienza Università di Roma
Seminario di Algebra e Geometria
Vikraman Balaji (Chennai Mathematical Institute)
On a "wonderful" Bruhat-Tits group scheme
We make a universal construction of Bruhat-Tits group scheme on wonderful embeddings of adjoint groups in the absolute and relative settings of adjoint Kac-Moody groups. These group schemes have natural classifying properties reflecting the orbit structure on the wonderful embeddings. A theme which is reflected in the work is that the various wonderful embeddings give algebra-geometric realizations of the different kinds of buildings. This shows an intimate relationship between the wonderful embeddings and Bruhat-Tits theory.
Per informazioni, rivolgersi a: pezzini@mat.uniroma1.it

Mercoledì 03 febbraio 2021
Ore 14:30, teleconferenza, https://meet.google.com/pip-kvzt-fkz
Seminario delle Meccaniche
Vieri Mastropietro (Università di Milano)
Localization in interacting fermions with quasiperiodic disorder
Disorder in condensed matter can be represented by a random or a quasi-periodic potential, the second choice appearing naturally in cold atoms experiments. We consider a system of fermions on a lattice in d-dimensions with a many body interaction and a quasi-periodic disorder. We prove that localization at strong disorder persists in the ground state in presence of a many body interaction. The proof relies on a combination of Renormalization Group methods with number theoretical properties (Diophantine conditions) similar to the ones assumed in KAM theory.

Mercoledì 03 febbraio 2021
Ore 16:00, piattaforma Meet, https://meet.google.com/ucr-qati-aib
Seminario di Fisica Matematica
Luca Oddis (Università di Roma La Sapienza)
Two-Anyon Schrödinger Operators
Anyons are quantum particles with statistics intermediate between bosons and fermions, arising in less than 3 dimensions.There are two possible approaches: one uses multi-valued wave functions, which means topologically non trivial configuration spaces, the other one allows to work in a flat, topologically trivial space, but the non interacting Hamiltonian in this case contains a singular Aharonov-Bohm - type potential. Our analysis lies in the latter approach. The Aharonov-Bohm potential has a singular behaviour at the overlapping configurations. Thus, it is not obvious how to rigorously realize the corresponding Schrödinger operator(s). We mainly focuses on the case of two anyons, which reduces to a one-body problem. The self-adjointness question is investigated and solved via quadratic form techniques. The Dirichlet forms are defined both on the magnetic Gauge and on an appropriate weighted Sobolev space. We also derive the extensions as suitable limits of scaled regular potentials. We present some perspectives for the many-body problem.

Giovedì 04 febbraio 2021
Ore 10:00, On-line Seminar, Web site for information: https://www.dinamici.org/dai-seminar/
DinAmicI: Another Internet Seminar (DAI Seminar)
Gary Froyland (University of New South Wales (Australia))
The dynamic ocean
The circulation of our oceans strongly influences climate, weather and biology. Our ocean currents are dynamic, and fluctuate to varying extents. I will introduce data-driven numerical tools that can tease apart dynamic components of the ocean, with information sourced from ocean drifters, satellite imagery, and ocean models. These components, their lifecycles, and their response to external forcing, help us to build a dynamic picture of our ocean. Note: The zoom link to the seminar will be posted on https://www.dinamici.org/dai-seminar/ and on https://mathseminars.org/seminar/DinAmicI. Moreover, it will be streamed live on youtube via the DinAmicI channel: https://www.youtube.com/channel/UCyNNg155G3iLS7l-qZjboyg
Per informazioni, rivolgersi a: sorrentino@mat.uniroma2.it

Giovedì 04 febbraio 2021
Ore 14:00, Streaming via MS Teams, Dipartimento di Matematica, Università degli Studi di Roma "Tor Vergata"
Seminario di Equazioni Differenziali
Lorenzo Valvo (Università degli Studi di Roma "Tor Vergata")
Hamiltonian Control of Magnetic Field Lines: Computer Assisted Results Proving the Existence of KAM Barriers
A control theory for Hamiltonian systems, based on KAM theory, was introduced in [Ciraolo, 2004] and applied to a model of magnetic field in [Chandre, 2006]. By a combination of Frequency Analysis and of a rigorous (Computer Assisted) KAM algorithm we show that in the phase space of the magnetic field, due to the control term, a set of invariant tori appears, and it acts as a transport barrier. Our analysis, which is common (but often also limited) to celestial mechanics, is very general and can be applied to quasi-integrable Hamiltonian systems satisfying a few additional mild assumptions. Note: This talk is part of the activity of the MIUR Excellence Department Project MATH@TOV CUP E83C18000100006 MS Teams Link for the streaming
Per informazioni, rivolgersi a: sorrentino@mat.uniroma2.it

Giovedì 04 febbraio 2021
Ore 14:30, Sala di Consiglio - https://meet.google.com/ads-dekx-bgm, Dipartimento di Matematica, Sapienza Università di Roma
Seminario P(n)
Italo Capuzzo Dolcetta (Sapienza Università di Roma)
Weak Maximum Principle for cooperative systems: the degenerate elliptic case
In this talk I will consider cooperative systems of nonlinear degenerate elliptic equations. Conditions for the validity of the weak Maximum Principle are obtained through a reduction to a single scalar equation. A suitable index related to the principal eigenvalues of the Dirichlet problems for the operators involved in the system is introduced. The positivity of this index enforces the validity of the weak Maximum Principle
Per informazioni, rivolgersi a: galise@mat.uniroma1.it

Giovedì 04 febbraio 2021
Ore 14:30, online al seguente link, Dipartimento di Matematica e Fisica, Università degli Studi RomaTre, Largo San Leonardo Murialdo 1
Seminario di Geometria
Gabriele Mondello (Università di Roma La Sapienza)
On spherical surfaces of genus 1 with 1 conical point
A spherical metric on a surface is a metric of constant curvature 1, which thus makes the surface locally isometric to \(S^2\). Such a metric has a conical point \(x\) of angle \(2\pi\theta\) if its area element vanishes of order \(2(\theta-1)\) at \(x\). If the conformal class is prescribed, a spherical metric can be viewed as a solution of a suitable singular Liouville equation. If the conformal class is not prescribed, isotopy classes of spherical metrics can be considered as flat \((SO(3,R),S^2)\)-structure, and so their deformation space has a natural finite-dimensional real-analytic structure. Additionally, the moduli space of spherical surfaces of genus g with n conical points comes endowed with a natural forgetful map to the moduli space of Riemann surfaces of genus \(g\) with \(n\) marked points. I will begin by giving an overview of what is known about the topology of the moduli space of spherical surfaces and the above mentioned forgetful map. I will then focus on the case of genus 1 with 1 conical point (joint works with Eremenko-Panov and with Eremenko-Gabrielov-Panov).

Giovedì 04 febbraio 2021
Ore 15:00, Il seminario sarà tenuto in modalità telematica, Link per partecipare: https://uniroma1.zoom.us/j/85943796292?pwd=dDliSTJBTFVmazRNYXZGV0lBVUJCZz09
Seminari di Ricerca in Didattica e Storia della Matematica
Nicoletta Lanciano (Sapienza Università di Roma)
Conoscere le concezioni iniziali e trattare gli errori nella didattica delle scienze

Le comunicazioni relative a seminari da includere in questo notiziario devono pervenire esclusivamente mediante apposita form da compilare online, entro le ore 24 del giovedì precedente la settimana interessata. Le comunicazioni pervenute in ritardo saranno ignorate. Per informazioni, rivolgersi all'indirizzo di posta elettronica seminari@mat.uniroma1.it.
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