У оквиру семинара Групе за гравитацију, честице и поља Института за физику у Београду, у четвртак, 18. маја 2023. године у 15 часова, на Физичком факултету у Београду, у сали 665, др Игор Прлина (Институт за физику у Београду) одржаће предавање:

Amplitugicians: Using (non-magic) Tricks to Find Scattering Amplitudes

САЖЕТАК:

This talk will introduce the audience to the goals and methods of the so-called Amplitudes project, where alternatives to the Feynman diagram approach are used to calculate scattering amplitudes in different theories. Some common themes in the Amplitudes approach are symmetry adapted variables, recursive relations and geometric interpretation. These themes will be illustrated by introducing spinor helicity formalism, BCFW recursion, momentum twistors, and the Amplituhedron. Finally, some of the lecturer’s own results on the connection of the boundaries of the Amplituhedron with amplitude singularities will be presented.

У оквиру семинара Центра за изучавање комплексних система Института за физику у Београду, у четвртак, 18. маја 2023. године у 14 часова путем Zoom платформе, др Андреј Парначев (Математичка школа и Математички институт Хамилтон, Тринити колеџ, Даблин, Ирска), одржаће предавање:

Holographic correlators at finite temperature

САЖЕТАК:

In this talk we will consider finite temperature two-point functions in strongly coupled quantum field theories described by holographically dual gravities and will discuss their applications. After reviewing the basics of gravitational holography at finite temperature, we will introduce some recent results, which hint at a universal behavior of the correlators in certain kinematical regimes.

Приступите предавању
Meeting ID: 818 0946 2344
Passcode: 851078

У оквиру семинара Центра за изучавање комплексних система Института за физику у Београду, у четвртак, 11. маја 2023. године у 14 часова путем Zoom платформе, др Милан Радоњић (Центар за изучавање комплексних система, Институт за физику у Београду; Институт за теоријску физику, Универзитет у Хамбургу, Немачка), одржаће предавање:

Out of equilibrium dynamical properties of Bose-Einstein condensates in ramped up weak disorder

САЖЕТАК:

In this talk we will discuss, from the theoretical point of view, how the superfluid and the condensate deformation of a weakly interacting ultracold Bose gas evolve during the ramping up of an external weak disorder potential. Both resulting deformations turn out to consist of two distinct contributions, i.e., a reversible equilibrium one [1,2], as well as a non-equilibrium dynamical one, whose magnitude depends on the details of the ramping protocol [3]. For the specific case of the exponential ramping up protocol, we will derive analytic time-dependent expressions for the aforementioned quantities. After sufficiently long time, the steady state emerges that is generically out of equilibrium. We will discuss how to examine properties of such a state by studying the relaxation dynamics into it. Also, we will consider the two-time correlation function and elucidate its relation to the equilibrium and the dynamical part of the condensate deformation.

[1] K. Huang and H.-F. Meng, Phys. Rev. Lett. 69, 644 (1992).
[2] B. Nagler, M. Radonjić et al., New J. Phys. 22, 033021 (2020).
[3] M. Radonjić and A. Pelster, SciPost Phys. 10, 008 (2021).

Приступите предавању
Meeting ID: 831 9906 2589
Passcode: 402537

У оквиру семинара Центра за изучавање комплексних система Института за физику у Београду, у четвртак, 04. маја 2023. године у 14 часова путем Zoom платформе, др Јелена Весић (Департман за физику ниских и средњих енергија, Институт Јожеф Стефан, Љубљана, Словенија), одржаће предавање:

FAIR – The Universe in the laboratory

САЖЕТАК:

The Facility for Antiproton and Ion Research (FAIR) is one of the largest projects for fundamental research in the world. The accelerator complex is currently being built on the premises of one of the leading laboratories for nuclear physics, GSI (GSI Helmholtzzentrum for Heavy Ion Research), Germany. Its existing accelerator facilities will become part of FAIR and will serve as the first acceleration stage. Including Slovenia, nine partners and one associated partner are currently member states of FAIR. Unlike many such large projects with highly specific science goals FAIR is planned to serve the interests of four major research communities: high-energy nuclear physics, nuclear structure, nuclear reactions and astrophysics, atomic and plasma physics, and hadron physics using antiprotons.

NUSTAR, standing for Nuclear Structure, Astrophysics and Reactions, is the largest nuclear physics collaboration in the world. It has been initiated as one of the four research pillars of FAIR. Construction of the FAIR buildings and production of the machine and experiment components are proceeding well. Until the FAIR facility will become operational for first experiments, a Phase-0 experimental program is being pursued at GSI employing already available experimental set-ups.

This talk will provide an overview of current research opportunities, as well as Slovenian involvement in the NUSTAR physics programme.

У оквиру семинара Групе за гравитацију, честице и поља Института за физику у Београду, у петак, 28. априла 2023. године у 11 часова на Физичком факултету у Београду, у сали 665, др Џејмс Фулвуд (Школа математичких наука, Шангајски универзитет Јиао Тонг) одржаће предавање:

On Quantum States Over Time

САЖЕТАК:

While in relativity theory space evolves over time into a single entity known as spacetime, quantum theory lacks a standard notion of how to encapsulate the dynamical evolution of a quantum state into a single „state over time“. Recently there is an emerging interest in the formulation of such dynamical quantum states, resulting in various approaches to their construction. In our work with Arthur Parzygnat, we have developed a general approach which we have recently shown is equivalent to the pseudo density matrix formalism of Fitzsimons, Jones and Vedral, which was initially introduced to treat temporal and spatial correlations in quantum theory on equal footing. In this talk, we review the general theory of such states over time, and go over some recent applications, such as a dynamical quantum Bayes’ rule, time-reversal for quantum systems, and quantum mechanical world lines. We then conclude with some ideas on how quantum states over time may yield „spacetime states“ associated with a causal set.