Hamiltonian formulations of degenerate Lagrangian theories

Filiz Çağatay Uçgun
Maltepe Üniversitesi, İstanbul
Özet: In this talk, we present the Hamiltonian formulations of the dynamical systems generated by the second-order Pais-Uhlenbeck, Sarıoglu-Tekin and Clement Lagrangians. Pais-Uhlenbeck Lagrangian is non-degenerate in the sense of Ostrogradski whereas Sarıoglu-Tekin and Clement Lagrangians are degenerate. For the degenerate or/and constraint systems, the Legendre transformation is not possible in a straight forward way. For the degenerate systems, one additionally needs to employ, for example, the Dirac-Bergmann algorithm in order to arrive at the Hamiltonian picture. We shall follow several alternative methods while arriving at the Hamiltonian representations of Pais-Uhlenbeck, Sarıoglu-Tekin and Clement dynamics.
 
Yer: MSGSÜ Bomonti Binası, Fizik Bölümü
Tarih: 21 Mart 2019 Perşembe, 15.00

Topological phase transitions understood via the polarization amplitude

Balasz Hetenyi
Bilkent University, Ankara
Özet: Topological systems are one of the most active research areas in condensed matter physics.  The topological characterization of a condensed matter system relies on mathematical constructs such as the Berry phase, the winding number, or the Chern number.  In the first part of the talk, I will explain how the Berry phase can be understood as the first cumulant of a series. The cumulants themselves are derived from the polarization amplitude, a quantity introduced decades ago in the context of the Berry phase theory of polarization, and one which has received attention recently.   We calculate higher order cumulants and reconstruct the underlying distribution of the polarization for the Rice-Mele model.  Our approach allows the visualization of a topological transition, how a system goes between phases with different quantization. In the second part of the talk, I will go through constructing one-dimensional analogs of the Haldane and Kane-Mele models.  In the end, I will discuss the application of our cumulant method to an interacting model.
 
Yer: MSGSÜ Bomonti Binası, Fizik Bölümü
Tarih: 14 Mart 2019 Perşembe, 15.00

The massive IIA origin of 2d CFTs

Nicolo Petri
Bogazici University, Istanbul, Turkey
Abstract. Even if AdS3/CFT2 holography has been intensively studied in literature, the construction of 2d CFTs in string theory is still rather obscure. In this talk I will discuss some insights in this direction coming from a new class of exact AdS3 solutions in massive IIA supergravity. Within this class, some of these 10d backgrounds are derived by uplifting particular warped AdS3 solutions in 7d and 6d gauged supergravities featuring respectively AdS7 and AdS6 asymptotics. In these cases the corresponding dual 2d SCFTs are realized as conformal defects within the higher-dimensional SCFTs dual to the asymptotics. I will discuss about the brane intersections underlying these solutions and, in particular, on how the emergence of AdS3 in massive IIA is deeply related to D2 branes. To support this statement I will present a very simple brane solution involving only D2 and D8 branes with near-horizon given by a warped product of AdS3 with a squashed 7-sphere as internal space. In spite of the simplicity of this supergravity solution, the construction of the dual SCFT 2d is quite problematic, therefore I will conclude discussing these issues and the possible strategies to get rid of them.
Yer: MSGSÜ Bomonti Binası, Fizik Bölümü
Tarih: 07 Mart 2019 Perşembe, 15.00

TÜBİTAK 2221 Bilim İnsanı Destekleme Programı Hakkında

Mimar Sinan Güzel Sanatlar Üniversitesi, Fizik Bölümü öğretim üyesi Dr. Öğr. Üyesi İlmar Gahramanov’un, TÜBİTAK BİDEB tarafından yürütülen “2221 Konuk veya Akademik İzinli (Sabbatical) Bilim İnsanı Destekleme Programı” başvurusu kabul edilmiştir.

Program kapsamında Hesam Soltanpanahi (IPM, Tehran, Iran), Mimar Sinan Güzel Sanatlar Üniversitesi Fizik bölümünde 7 ay süreyle  misafir öğretim üyesi olarak, “Applications of AdS/CFT to strongly interacted systems” üzerine çalışmalar yapacatır.

Hesam Soltanpanahi‘nin yayınları için lütfen tıklayınız.