Pagina 7

Date | Type | Start | End | Room | Speaker | From | Title |
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21/03/18 | Seminario | 16:00 | 17:00 | 1201 Dal Passo | Wojciech Dybalski | TUM Munich | Infravacuum representations and velocity superselection in non-relativistic QED It is well established that in QED plane-wave configurations of the electron corresponding to different velocities induce inequivalent representations of the algebra of the electromagnetic field. This phenomenon of velocity superselection is one of the standard features of the infraparticle picture of the electron, which
relies on mild fluctuations of the electromagnetic field at spacelike infinity. As these fluctuations are large in the complementary infravacuum description of the electron, it has long been conjectured that velocity superselection, and other aspects of the infraparticle problem, can be cured in this approach. We consider two implementations of the infravacuum picture in a Pauli-Fierz model of QED. In the first one, which relies on a
decomposition of the electron into the bare electron and a cloud of soft photons, we prove the absence of velocity superselection. In the second one, which does not rely on such a decomposition, we show that velocity superselection persists, but can be eliminated by suitably inverting the representations. In the language of superselection theory,
we exhibit an unusual situation, where a family of distinct sectors has one and the same conjugate sector. (Joint work with Daniela Cadamuro). |

20/03/18 | Seminario | 14:30 | 15:30 | 1201 Dal Passo | Mikaela Iacobelli | Durham University | Recent results on quasineutral limit for Vlasov-Poisson via Wasserstein stability estimates The Vlasov-Poisson system is a kinetic equation that models collisionless plasma. A plasma has a characteristic scale called the Debye length, which is typically much shorter than the scale of observation. In this case the plasma is called 'quasineutral'. This motivates studying the limit in which the ratio between the Debye length and the observation scale tends to zero. Under this scaling, the formal limit of the Vlasov-Poisson system is the Kinetic Isothermal Euler system.
The Vlasov-Poisson system itself can formally be derived as the limit of a system of ODEs describing the dynamics of a system of N interacting particles, as the number of particles approaches infinity. The rigorous justification of this mean field limit remains a fundamental open problem.
In this talk we present the rigorous justification of the quasineutral limit for very small but rough perturbations of analytic initial data for the Vlasov-Poisson equation in dimensions 1, 2, and 3. Also, we discuss a recent result in which we derive the Kinetic Isothermal Euler system from a regularised particle model. Our approach uses a combined mean field and quasineutral limit. |

06/02/18 | Seminario | 14:00 | 16:00 | 1201 Dal Passo | Edoardo Sernesi | Roma Tre | Curves on K3 surfaces III (Lecture series, in the framework of Research Project "Families of curves: their moduli and their related varieties" -
Mission Suistanability Tor Vergata, CUP: E81|18000100005, Principal Investigator Flaminio Flamini)
Course Abstract: (1) Generalities on Brill-Noether theory. Lazarsfeld's proof of Petri's conjecture. (2) Gaussian maps, ribbons and extendability. Results of Wahl and Beauville-Merindol.
(3) The problem of characterizing K3 curves: some results.
Link:http://www.mat.uniroma2.it/~flamini/workshops/LectSernesi.html
[Lecture series, in the framework of Research Project "Families of curves: their moduli and their related varieties" - Mission Suistanability Tor Vergata, CUP: E81|18000100005, Principal Investigator Flaminio Flamini] |

30/01/18 | Seminario | 14:00 | 16:00 | 1201 Dal Passo | Edoardo Sernesi | Roma Tre | Curves on K3 surfaces II (Lecture series, in the framework of Research Project "Families of curves: their moduli and their related varieties" -
Mission Suistanability Tor Vergata, CUP: E81|18000100005, Principal Investigator Flaminio Flamini)
Course Abstract: (1) Generalities on Brill-Noether theory. Lazarsfeld's proof of Petri's conjecture. (2) Gaussian maps, ribbons and extendability. Results of Wahl and Beauville-Merindol.
(3) The problem of characterizing K3 curves: some results.
Link:http://www.mat.uniroma2.it/~flamini/workshops/LectSernesi.html
[Lecture series, in the framework of Research Project "Families of curves: their moduli and their related varieties" - Mission Suistanability Tor Vergata, CUP: E81|18000100005, Principal Investigator Flaminio Flamini] |

23/01/18 | Seminario | 14:00 | 16:00 | 1201 Dal Passo | Edoardo Sernesi | Roma Tre | Curves on K3 surfaces I (Lecture series, in the framework of Research Project "Families of curves: their moduli and their related varieties" - Mission Suistanability Tor Vergata, CUP: E81|18000100005, Principal Investigator Flaminio Flamini)
Course Abstract: (1) Generalities on Brill-Noether theory. Lazarsfeld's proof of Petri's conjecture. (2) Gaussian maps, ribbons and extendability. Results of Wahl and Beauville-Merindol. (3) The problem of characterizing K3 curves: some results.
Link:http://www.mat.uniroma2.it/~flamini/workshops/LectSernesi.html
[Lecture series, in the framework of Research Project "Families of curves: their moduli and their related varieties" - Mission Suistanability Tor Vergata, CUP: E81|18000100005, Principal Investigator Flaminio Flamini] |