29 OCT 2020
11:00 - 12:00

Abstract: In this talk, we will study a particular deformation of the Jackiw-Teitelboim gravity recently considered by Witten and others. We will compute the partition function of this model as well as its higher order correlators to all orders in genus expansion in the low temperature limit for small perturbations. In this limit, the results match with those obtained from the Airy limit of a Hermitian random matrix ensemble. Using this result, we will also study the free energy of the model. One observes that although the annealed free energy has pathological behaviors, under certain assumptions, the quenched free energy evaluated by replica trick exhibits the desired properties at low temperatures.


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

28 OCT 2020
11:00 - 12:00

Abstract: We talk about the contribution of the chiral vortical effect, in addition to that of the chiral magnetic effect, to the evolution of the hypermagnetic field and the matter-antimatter asymmetry in the symmetric phase of the early Universe in the temperature range 100 GeV ≤ T ≤ 10 TeV. We show that the most pronounced effect of the chiral vorticity is the production and initial growth of the hypermagnetic field; while, further growth and saturation of the hypermagnetic field occurs due to the chiral magnetc effect. Moreover, damping of the vorticity due to the presence of viscosity which typically occurs extremely rapidly, does not significantly affect the evolution.


Phys.Rev. D100 (2019) no.11, 116022
Phys.Rev. D99 (2019) no.9, 096009
Phys.Rev. D95 (2017) no.5, 056001
Phys.Rev. D94 (2016) no.5, 056013


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


Indico: https://indico.particles.ipm.ir/indico/event/387

28 OCT 2020
14:00 - 15:00

Abstract:

Magnetization dynamics can be affected by lattice distortions and vice versa through magnetoelastic coupling, as demanded by reciprocity. The magnetoelastic coupling results in a hybridized state, i.e., a magnon-polaron. While the magnon and elastic modes repel each other via the magnetoelastic coupling in a ferromagnetic insulator, for the coupled magnon and acoustic modes in an antiferromagnetic insulator, a level attraction can occur upon varying the external magnetic field. I will discuss a nonlocal spin transport that can probe the anomalous features caused by magnon-polaron formation.


Date: Wednesday, October 28, 2020

Time: 14:00-15:00

To join the webinar, please follow this link:
https://www.skyroom.online/ch/schoolofphysics/condensed-matter-and-statistical-physics
and log in as guest.

Organized by: Condensed Matter and Statistical Physics Group, School of Physics (IPM)

Queries about this event should be addressed to Dr. A. Faridi at azadeh.faridi@ipm.ir

28 OCT 2020
13:30 - 15:00

One of the important questions in galaxy formation and evolution is to understand how the stellar mass has been assembled within galaxies. The formation of prominent central densities known as bulges is an example of this evolution and the true mechanisms behind this transformation are a matter of debate. In this talk, I will overview the importance of addressing this question and describe the observational methods that we used for tracing the assembly of stellar mass within galaxies. I will also explain how we can benefit from studying the scaling relations such as size-mass relation. In addition, possible connections of the structural evolutions with star-formation activities and environments will be discussed.

28 OCT 2020
15:30 - 17:30

This talk should be regarded as a continuation of the latest talk delivered at IPM logic webinar by Veličković. I will review briefly the Veličković' story, and then introduce certain combinatorial principles originating from large cardinals. Though I will be concentrating on their correlation with other well-known consequences of PFA, if time permits, I will also sketch the proof of a theorem obtained in collaboration with Veličković.
To join this webinar, please send an email to r.zoghi@gmail.com.

27 OCT 2020
16:30 - 18:00

We use the method of atomic decomposition to study the action of transfer operators associated to piecewise expanding maps. It turns out that these transfer operators are quasi-compact even when the associated potential, the dynamics and the underlying phase space have very low regularity. In particular it is often possible to obtain exponential decay of correlations, the Central Limit Theorem and almost sure invariance principle for fairly general observables, including unbounded ones. Indeed the class of observables for which we obtain such results often coincides with certain Besov spaces. Joint work with Alexander Arbieto (UFRJ-Brazil).

To get the access link, register at
https://forms.gle/3AbXZeCucKWCuumR7
by the day before the event.

[ICMC-IMPA-IPM Joint Mathematics Seminars]

27 OCT 2020
14:00 - 15:00

Abstract:

In the scattering amplitude program, one directly bootstraps the S-matrix by implementing analyticity, locality, and unitarity without resorting to the language of Lagrangians and introducing gauge redundancies. Recently much effort has been dedicated to developing similar methods in cosmology. The primary goal here is to discover a set of basic rules implied by locality, analyticity, and unitarity, that uniquely pinpoint consistent boundary correlation functions without invoking the time evolution in the bulk. In this work, we set forward new ideas in the arena of "cosmological bootstrap" by deriving the consequences of perturbative unitarity for the wavefunction of the universe. We state a cosmological optical theorem from which new consistency conditions on the coefficients of the wavefunction of the universe are inferred. We use similar methods to BCFW to showcase the restraining power of our optical theorem by bootstrapping a sample Trispectrum in the Effective Field Theory of inflation.


Date: Tuesday, 27 October- ۶ آبان

2 p.m. - 3 p.m.


Zoom Link. (click)

Meeting ID: 864 7408 3912

Passcode: 058816

26 OCT 2020
16:00 - 18:00

Social Emotions in Cognitive Neuroscience

26 OCT 2020
11:00 - 12:00

Based on
https://iopscience.iop.org/article/10.1088/1748-0221/14/07/P07001/meta
Abstract: By changing the resonant frequency of the cavity due to the power dissipation in its wall, the impedance matching will impair and the power will reflect. The acceptable frequency shift range which is based on the cooling system in the cavity design depends on the ability of the automatic frequency controller system and the bandwidth of the RF amplifier output frequency. This paper describes how to couple electromagnetic, thermal and mechanical analysis and calculates the cavity frequency shift during operation. Multiphysics analysis investigations had been done for an S-band side-coupled cavity. By using the Superfish code, the power loss ratio at different surfaces of the cavity could be accurately calculated and Steady-State Thermal (SST) analysis could be performed correctly. In this paper, the report on the simultaneous use of multiphysics analysis with the modules of the Ansys software is presented and the results of both simulations are compared. The temperature distribution of the cavity was obtained by using the Fluent software and its results were compared with the temperature distribution gained from applying the convection coefficient to the SST. Three cooling systems were investigated for different powers with different cross-sections. In this section of the investigation, after thermal analysis, deformed geometry was obtained due to thermal stresses. By electromagnetic analyzing of deformed geometry, its frequency shift was obtained for all different cases. In order to evaluate the simulations, after the construction of a single-cavity, frequency variations are measured in terms of temperature variation and the results are compared with each other. After constructing a single-cavity, frequency shifts based on temperature variations are measured and the results are compared with each other.


https://www.skyroom.online/ch/ipm-particles/journal-club-ep

22 OCT 2020
11:00 - 13:00

Let k be a field, S = k[x1,..., xm, y1, ..., yn] a standard bigraded polynomial ring, and M a finitely generated bigraded S-module. We set P = (x1,..., xm) and Q = (y1,...,yn). In this talk, we will discuss several algebraic properties of M/PM, namely:

(a) If M is Cohen-Macaulay with respect to Q, then M/PM is Cohen-Macaulay.

(b) If M is sequentially Cohen-Macaulay with respect to Q, then M/PM is sequentially Cohen-Macaulay.

(c) If M is generalized Cohen-Macaulay with respect to Q, then M/PM is generalized Cohen-Macaulay.

Finally, if M has Maximal depth with respect to Q, then M/PM has no maximal depth in general.



To join the meeting, go to the following link:
https://vmeeting.ipm.ir/b/mat-9px-g3c

21 OCT 2020
13:30 - 15:00

Abstract:
From the observational point of view, blackholes (BHs) appear in a wide variety of astrophysical environments, and there is wealth of direct or indirect evidence pointing towards the existence of supermassive black holes (SMBHs). In fact, it is believed that SMBHs reside in the center of most sufficiently massive galaxies, including ours. It is also believed that the result of gravitational collapse is a Kerr BH. However, I’ll explain the concept of the generalized blackholes and explain their two most important observational imprints, namely quasinormal oscillations and shadows. For the quasinormal oscillations we study the effect of the quadrupole and for shadows we consider the magnetic charge and scalar hair. We constrain the magnetic charge and scalar hair with bounds given by the event horizon telescope.
To join the seminar, please click on the following link

https://www.skyroom.online/ch/soa/weekly-seminar

21 OCT 2020
16:00 - 17:30

Organized by: School of Cognitive Sciences
to receive the link to join online, please send email to theoretical.neurosci.ipm@gmail.com

Abstract:


Locus Coeruleus (LC) noradrenergic system has widespread projections throughout the brain and affects sensory processing in various modalities. Inhibition of both spontaneous and sensory-driven cortical activity is well documented in early experiments by either LC electrical micro-stimulation or local application of norepinephrine (NE). However, the temporal profile of the LC modulation of sensory response is not well-established. Here, we recorded neuronal activity from the rat barrel cortex under urethane anesthesia and coupled LC micro-stimulation with brief mechanical deflection of whiskers at 10 different time lags (50-500 ms). LC micro-stimulation exhibited a biphasic effect on BC spontaneous activity: a period of suppression followed by a period of excitation. This profile was highly consistent across BC units. We observed a similar effect on the sensory-evoked response. In summary, we found that the LC modulation of sensory response crucially depends on the temporal lag between LC micro-stimulation and sensory input.

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