2 JUL 2020
11:00 - 12:00

Abstract: In this talk, I would like to review the concept of contraction, deformation, and stabilization of finite and infinite-dimensional Lie algebras. Then, I will consider the deformation of infinite-dimensional Lie algebras which are obtained as asymptotic/near horizon symmetry algebras in gravitational physics. Finally, I will present the physical realization of obtained algebras through deformation procedure.


https://www.skyroom.online/ch/ipm-particles/theory-weekly-seminar

2 JUL 2020
15:00 - 17:00

(Webinar)
Helicity and spin as conserved quantities have been considered vastly in recent years, especially in the fields of optics and fluid dynamics. In contrast to what is usually thought, helicity and spin of the electromagnetic fields are definable and useful at the classical level as well as the quantum level. The classical quantities have the expected relation with their quantum counterparts. Besides, it has been clarified to a certain extent that the separation of the total angular momentum of light into orbital and intrinsic (spin) parts leads to meaningful and consistent definitions of these independently conserved quantities. The importance of this fact In applied optics is that it has opened the possibility of preparing laser beams in eigenstates of orbital angular momentum in order to carry huge amounts of information for communication purposes. On the other hand, helicity is considered to be tightly related with the chirality of electromagnetic waves and has been successfully used to explain the interaction of light with chiral molecules. These results have also inspired similar investigations in fluid dynamics for spinning acoustic waves. From the theoretical point of view, the symmetries of the action (and the equations of motion) underlying the conservation of helicity and spin according to the Noether theorem and the major role of the duality symmetry have been studied. The inter-relation of helicity and spin at classical level as well as their non-local nature have also been investigated. In this talk, I will try to touch on different aspects and current status of this research and review some of the most important, old and new discussions under this topic as much as I can and at the end say a few words about this subject in the context of gravity.

2 JUL 2020
08:30 - 09:30

Abstract: We study the torus partition functions of free compatic bosonic CFTs in two dimensions. Integrating over Narain moduli defines an ensemble-averaged free CFT. We calculate the averaged partition function and show that it can be reinterpreted as a sum over topologies in three dimensions. This result leads us to conjecture that an averaged free CFT in two dimensions is holographically dual to an exotic theory of three-dimensional gravity.

1 JUL 2020
11:00 - 12:00

Based on :https://doi.org/10.1016/j.nima.2020.163401


Abstract: A digital data acquisition system together with MATLAB software for data analysis were utilised to measure the pulse specification of the scintillation detector assembly. Besides, the sensitivity of a photomultiplier tube (PMT) window to gamma-rays was studied to discriminate the signals produced as a result of gamma-ray
interactions inside the glass window from those originating from the scintillator cell. The result showed that an algorithm based on the time features was capable to evaluate the contributions of these two different signals.


https://www.skyroom.online/ch/ipm-particles/school-of-particles-and-accelerators-weekly-meeting


Indico: https://indico.particles.ipm.ir/indico/event/362/?view=standard

1 JUL 2020
15:30 - 17:30

Abstract: Dynamic (topological) systems are mathematical models of change or movement in space which have applications in various branches of mathematics and the physical sciences. Formally, they consist of pairs (X,S), where X is a topological space and S: X->X is continuous. From a modal logic perspective this natually leads to a combination of spatial and temporal modal logics called Dynamic Topological Logic (DTL).
In this two-day course we will cover the main results and techniques leading up to the state of the art in the field of Dynamic Topological Logic. The proposed schecule is as follows.
DAY 1 (24/06/2020)
We begin with a brief introduction to topological dynamics, then introduce the logic S4C and summarize its main results. We then introduce the full DTL with "henceforth" and sketch the proof of undecidability for this full logic. Finally we discuss Kripke-incompleteness and how it can be, in a sense, avoided with the use of non-deterministic quasimodels.
DAY 2 (01/07/2020)
We intrdouce the logic DTL*, which extends the logic DTL with the "tangled closure" operator, a generalization of the standard topological closure to a polyadic version defined via a greatest fixed point. With this we give an axiomatization for DTL* and sketch its completeness proof. We then introduce Intuitionistic Temporal Logic (ITL), a variant of DTL which omits the interior modality and instead interprets implication in the Heyting algebra of open sets. We conclude by detailing how the techniques developed for DTL can be modified to obtain a decidability proof in this setting.
Please send an email to: r.zoghi@gmail.com to join this lecture.

1 JUL 2020
14:00 - 15:00

Abstract:

Colloids in nematic liquid crystals (NLCs) locally distort the uniform nematic order because of the boundary conditions on their surfaces so-called *surface anchoring*. This behavior naturally increases the free energy amount. Under some conditions, adjacent colloids can reduce the free energy by sharing a part of their accompanying distortions and make elastic bonds, just like atoms share their electrons in covalent bonds. The colloids in NLCs even make the specific number of bonds in specific directions depending on their shape and surface anchorings. This effect allows the colloids to form various crystalline and semi-crystalline colloidal structures in nematic environments. Such structures are known as *colloidal crystals* made by *colloidal atoms*, or photonic crystals due to their fabulous photonic properties. During this session, I will talk about the elastic properties of NLCs, the colloid surface anchorings in NLCs, interactions between the colloids and possible crystalline structures they form.

Organized by: School of Nano Science (IPM)