Seminarios – Grupo de Pequisa – Física-Matemática

Seminars

1
Date: 27/02, Time: at 14:00, Location: Room S-302-3, Campus Santo André.
Title: Invitation to Higher Spin Gravity
Speaker: Alexey Sharapov
Abstract: The talk is intended as a gentle introduction to the subject of Higher Spin Gravity with emphasis on general ideas and methods. I am going to discuss the following topics:
1) $L_\infty$ – algebras como uma abordagem universal da teoria do campo clássico.
2. The origin of Higher Spin Algebras.
3) Interações como deformações de $L_\infty$ – algebras.
4. Higher Spin Gravity in four dimensions and its integrability.
5. Chiral models of higher spin gravity. (If I have time.)
Presentation
2
Date: 27/02, Time: at 14:00, Location: Room S-302-3, Campus Santo André.
Title: Poisson gauge theory
Speaker: Vladislav Kupriyanov (UFABC)
Abstract: The semiclassical limit of full noncommutative gauge theory is known as Poisson gauge theory. In this talk I will describe the construction of Poisson gauge theory paying attention to the geometric meaning of the structures involved and advance in the direction of a further development of the proposed formalism, including the consistent interaction with matter. The proposed model is designed to investigate the semi-classical features of the full noncommutative gauge theory with coordinate dependent noncommutativity $\theta^{ab}(x)$ , especially whose with a non-constant rank.
Presentation
3
Date: 27/02, Time: at 14:00, Location: Room S-302-3, Campus Santo André.
Title: Braided quantum field theory
Speaker: Richard Szabo, Heriot-Watt University, UK
Abstract: Braided field theories are new classes of noncommutative field theories that are equivariant under a triangular Hopf algebra symmetry. They are constructed through a new mathematical notion of braided homotopy algebras. After describing the construction and novel features of these theories, we develop a braided generalization of the purely algebraic Batalin-Vilkovisky quantization techniques to explore the properties of braided quantum field theory. The techniques are illustrated by computing perturbative correlation functions for braided scalar field theories. The results of these calculations suggest that UV/IR mixing may be less severe or even absent in this class of noncommutative field theories.
Presentation
4
Date: 27/02, Time: at 14:00, Location: Room S-302-3, Campus Santo André.
Title: Kugo-Ojima-Nakanishi (KON) Quantization Formalism for QED_4 $QED_4$
Speaker: Gabriel Brandão de Gracia, UFABC
Abstarct: Formalism (Kon) is based on an indefinite metric formalism in Heisenberg's description. It is possible to prove that the quantization of the vector field without mass requires this structure. This is suitable for the QED_4 case described here. However, a subsidiary condition is really necessary to characterize physical sub-spaço. Extra auxiliary fields are added to reach a second -class nature system in which the correspondence principle can be constantly established. From the quantum equations of the movement, switches in unequal times are derived. Considering the expansion of the first order, radiative corrections are obtained. We display the methods to get them. By spectral representation and through the positive energy condition for Wightman's functions. $QED_4$ .
Presentation
5
Date: 27/02, Time: at 14:00, Location: Room S-302-3, Campus Santo André.
Title: Effects of wave propagation in canonical Poissongauge theory under an external magnetic field.
Speaker: Mario Junior Neves, UFRRJ
Abstract: Results of the noncommutative (NC) electrodynamics based on the canonical Poisson gauge theory is presented in this seminar. We investigate the effects of the plane wave solutions in the NC field equations, when the theory is submitted to an external and uniform magnetic field. The energy-momentum tensor, symmetric and gauge invariant, is obtained from the NC field equations. The plane wave solutions for the gauge potential yield the wave equations in the momentum space, in which we use the linear approximation on the noncommutative parameter. Thereby, we obtain the dispersion relations of the gauge theory in the presence of an external and uniform magnetic field. We show that the birefringence phenomenon depends on the noncommutative parameter, and using the bound of the PVLAS experiment for the vacuum magnetic birefringence, we estimate a theoretical value for the NC parameter
Presentation
6
Date: 27/02, Time: at 14:00, Location: Room S-302-3, Campus Santo André.
Title: Traversable wormholes in General Relativity
Speaker: Alexander Zhidenko, UFABC
Abstract: I will present spherically symmetric wormhole solutions of the Einstein equations and Standard Model fields. The wormholes do not require any exotic matter or an additional membrane at the throat. The obtained family of solutions is smooth everywhere, allowing for freefalling stationary observers, which are redshifted. In particular, there can be a small redshift between the asymptotic observers from different sides of the throat.
Presentation
7
Date: 27/02, Time: at 14:00, Location: Room S-302-3, Campus Santo André.
Title: Poisson electrodynamics and symplectic groupoids.
Speaker: Alexey Sharapov (Tomsk State University and UFABC)
Abstract: Poisson electrodynamics is a low-energy (or semi-classical) limit of noncommutative U(1) gauge theory. I will present a new approach to Poisson electrodynamics based on the geometry of symplectic groupoids integrating a given Poisson manifold. From the physical viewpoint, a symplectic groupoid is just the phase space of a point particle on noncommutative spacetime, and the gauge fields are identified with the group of bi-sections of the groupoid. The natural action of bi-sections on the symplectic groupoid allows us to define a minimal coupling of a charged particle to the electromagnetic field. Unlike usual classical mechanics, the particle’s momentum space appears to be curved (or even compact), which can have dramatic physical consequences.
8
Date: 27/02, Time: at 14:00, Location: Room S-302-3, Campus Santo André.
Title: Electrodynamics in wormhole space-time
Speaker: Nail Khusnutdinov, UFABC
Abstract: The different questions about electrodynamics in the Bronnokov-Ellis wormhole spacetime are considered, with special attention to the gravitational self-force.
Presentation
9
Date: 27/02, Time: at 14:00, Location: Room S-302-3, Campus Santo André.
Title: Anomalies, Boundaries, and Boundary States
Speaker: Dmitry Vassilevich, UFABC
Abstract: Quantum anomalies on manifolds with boundaries naturally have boundary contributions. In CFTs, these contributions are responsible for boundary central charges, while in the condensed matter applications they define anomalous Hall conductivity of the boundary, for example. In this talk, I will describe the main properties of boundary anomalies and the methods of computations. I will show, that in some cases the anomalies on manifolds with boundaries are totally defined by anomalies in effective boundary theories. (This phenomenon is called the anomaly inflow.) I will conclude with a discussion of the relations between anomalies and boundary states.
Presentation
10
Date: 27/02, Time: at 14:00, Location: Room S-302-3, Campus Santo André.
Title: Casimir Interactions: New Developments Inspired by Novel Materials
Speaker: Lilia M. Woods, Department of Physics, University of South Florida, Tampa, FL, USA
Abstract: The Casimir force is a universal interaction originating from electromagnetic fluctuations between objects, however, its magnitude, sign, and scaling laws are strongly affected by the materials response properties and boundary conditions of the objects. The expanding materials library continues presenting new opportunities to probe fundamental physics concepts through Casimir phenomena. In this presentation, I will review several types of systems and their effects on fluctuation induced interactions. For example, 2D topological materials may experience vastly different Casimir force behavior, in 3D materials, nontrivial topology has a secondary effect on the interaction. The reduced dimensionality and inherent anisotropy of quasi-one-dimensional metasurfaces composed of aligned single wall carbon nanotubes, on the other hand, is a key factor in separating thermal vs quantum contributions at submicron separations, such that the Casimir interaction is dominated by thermal fluctuations, while the Casimir torque is primarily determined by quantum mechanical effects. We argue that novel materials present an excellent platform for light-matter interactions, and, in particular, to show that the universal Casimir force has non-universal dependence upon distance, sign, magnitude, and various fundamental constants.
Presentation
11
Date: 27/02, Time: at 14:00, Location: Room S-302-3, Campus Santo André.
Title: High energy particle collisions near black holes
Speaker: O. B. Zaslavskii, Kharkov State University, Ukraine
Abstract: If two particles move towards a black hole and collide in the vicinity of the horizon, under certain conditions their energy Ec.m. in the center of mass frame can grow unbounded. This is the Banados-Silk-West (BSW) effect. Usually, this effect is considered for extremal horizons and geodesic (or electrogedesic) trajectories. Simple explanation of this effect from the geometric and kinematic viewpoints is considered. We review this effect for different types of horizon and take into account a force acting on a particle. We also give general classification of possible trajectories that include so-called usual, subcritical, critical and ultracritical ones depending on the near-horizon behavior of the radial component of the four-velocity.
Presentation
12
Date: 27/02, Time: at 14:00, Location: Room S-302-3, Campus Santo André.
Title: Compactification scenario in Gauss-Bonnet cosmology
Speaker: Alexey Toporensky, Sternberg Astronomical Institute, Moscow University, Russia
Abstract: I consider anisotropic cosmological dynamics in Einstein-Gauss-Bonnet gravity. It is shown that a natural outcome of such evolution is a splitting of initially totally anisotropic space into a product of two isotopic sub spaces. If the expanding sub space is 3-dimensional, this scenario could explain the appearance of our world within multidimensional Universe. Moreover, non-zero spatial curvature of “inner” sub space can stabilise it, leading to effective Friedmann dynamics for the expanding sub space.
Presentation