Many-body dynamics and gap opening in interacting periodically driven systems

We study the transient dynamics in a two-dimensional system of interacting Dirac fermions subject to a quenched drive with circularly polarized light. In the absence of interactions, the drive opens a gap at the Dirac point in the quasienergy spectrum, inducing nontrivial band topology. Here we investigate the dynamics of this gap opening process in the presence of interactions, as captured by the generalized spectral function and correlators probed by photoemission experiments. Through a mechanism akin to that known for equilibrium systems, interactions renormalize and enhance the induced gap over its value for the non-interacting system. We additionally study the heating that naturally accompanies driving in the interacting system, and discuss the regimes where dynamical gap emergence and enhancement can be probed before heating becomes significant

Black Sea Geopolitics after the Russia-Ukraine War: View from Georgia

This article explores the impact of the Russian invasion of Ukraine on Georgia's foreign and domestic policies and the country's place and role in the Black Sea region. It draws on interviews and expert surveys to examine how Georgia's foreign policy community views recent dramatic developments in the Black Sea area and the impact of the latter on Georgia's security, stability, and evelopment. The article further critically assesses Georgia's response to the Russia-Ukraine war and how it fits with the country's main foreign policy trends, including the much criticized Finlandization policy towards Russia. The article concludes that while the Black Sea area remains of paramount importance to Georgia, the Russia-Ukraine war made Georgia's security more vulnerable to risks and threats emanating from the region. Furthermore, the war deepened the political and societal polarization in Georgia and, as our data suggest, exacerbated the schism between Georgia's mostly pro-Western foreign policy expert community and the government's balanced foreign policy

Political Radicalization in Georgia: The Role of the Orthodox Church

In this article, radicalization and illiberal tendencies in Georgia are analysed by focusing on the role of one of the most powerful actors involved, the Georgian Orthodox Church (GOC). The GOC is revealed to be an indirect source of political and societal polarization regarding LGBT rights, religious sentiments, family values and other issues that may be seen by church representatives as threats to Christian values and traditions. This perspective often coincides with the narratives propagated by the Kremlin in Georgia. Religious sentiments are broadly used by far-right groups to spread homophobic narratives in Georgian society for political purposes. Despite its softer rhetoric, the GOC is quite radical in its action, which intentionally or unintentionally endorses the agendas of far-right groups and the Kremlin. A new potential pattern in the Church’s actions were revealed by events surrounding the Tbilisi Pride Festival on July 5, 2021: a demonstration organized by the Church and far-right groups turned violent when some protesters attacked representatives of the media. The actions of some representatives of the GOC indicate an increasingly direct use of violence and radicalization in dealing with critics and opponents

Morita homotopy theory of C*-categories

In this article we establish the foundations of the Morita homotopy theory of C*-categories. Concretely, we construct a cofibrantly generated simplicial symmetric monoidal Quillen model structure M_Mor on the category C*cat1 of small unital C*-categories. The weak equivalences are the Morita equivalences and the cofibrations are the *-functors which are injective on objects. As an application, we obtain an elegant description of the Brown-Green-Rieffel Picard group in the associated Morita homotopy category Ho(M_Mor). We then prove that the Morita homotopy category is semi-additive. By group completing the induced abelian monoid structure at each Hom-set we obtain an additive category Ho(M_Mor)^{-1} and a canonical functor C*cat1 {\to} Ho(M_Mor)^{-1} which is characterized by two simple properties: inversion of Morita equivalences and preservation of all finite products. Finally, we prove that the classical Grothendieck group functor becomes co-represented in Ho(M_Mor)^{-1} by the tensor unit object.Comment: 35 page