3 AUG 2022
11:00 - 12:00

Abstract:

Recently the island conjecture has gained a lot of attention in order to address the information paradox problem and a considerable amount of work has been done in numerous cases. We have studied two different setups in this context, flat space cosmologies and Kerr-de Sitter spacetime in three dimensions. It is argued that by coupling an auxiliary flat bath system at the timelike singularities of these spacetimes one can reconstruct the Page curve and namely solve the information paradox. Furthermore the relationship between the two island regions in these cases has been discussed.

Indico Link
https://indico.hep.ipm.ir/e/S.Azarnia

Meeting Link
https://meet.google.com/jmr-cpbg-rux

3 AUG 2022
18:00 - 19:00

High–mass stars are cosmic engines known to dominate the energetics in the Milky Way and other galaxies. However, they are very rare and their formation is still not well understood. High-mass, cold, dense clouds are the nurseries of high-mass stars. Mainly I will be discussing two projects that I am currently leading. One part of my talk will focus on a large systematic search for Cold Cores with ALMA (CoCoA). With a survey machine like ALMA, CoCoA aims to reveal the truly high-mass starless cores if they exist. SIMPLIFI is a SOFIA HAWC+ Legacy pilot program that is carrying out the first high resolution large-scale study of the magnetic polarization of filaments. Our understanding of star formation has been revolutionized by the insight that star-forming cores and hubs are embedded in complex filamentary networks that penetrate molecular clouds. Fragmentation as well as level of star formation within filaments differ greatly. Still, the exact role of filaments in star formation remains unclear. In particular, magnetic fields might play an important role, as indicated by well-ordered polarized dust emission that imply strong magnetic fields. The aim of SIMPLIFI is to clarify the role of magnetic fields in star-forming filaments, and provide a framework to “simplify” the diversity of filament properties. To join the seminar, please click on the following link


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


Then click on the guest button to participate

This seminar is open to the public

2 AUG 2022
14:00 - 15:00

Date and time
Tuesday, 2nd of August 2022 (11th of Mordad, 1401), 2:00 pm (Tehran zone)



Link
https://us02web.zoom.us/j/83538126663?pwd=VTNQWVpOdDZ1ajAvbVI1WklKODZGUT09


Meeting ID: 835 3812 6663
Passcode: 785277


Abstract
In this talk, I will first briefly review generalized volume-complexity $\mathcal{C}_{\rm gen}$ which was recently introduced in [arXiv:2111.02429]. This quantity is an extension of volume in the Complexity=Volume (CV) proposal, by adding higher curvature corrections with a coupling constant $\lambda$ to the volume functional. Next, I will talk about the calculation of $\mathcal{C}_{\rm gen}$ for two-sided Hyperscaling Violating (HV) black branes in $d+2$ dimensions for different values of the hyperscaling violation exponent $\theta$ and dynamical exponent $z$. It is observed that $\mathcal{C}_{\rm gen}$ always grows linearly at late times provided that we choose $\lambda$ properly. Moreover, it approaches its late time value from below. I will also discuss the dependence of the growth rate of $\mathcal{C}_{\rm gen}$ on $d$, $\theta$, $z$ and $\lambda$. In the end, I will report our results for the complexity of formation obtained from volume-complexity and show that it is not UV divergent. I will also discuss its dependence on the thermal entropy and temperature of the black brane.

1 AUG 2022
11:00 - 12:00

Abstract:

We present the radio frequency design of an S-band (2998 MHz) accelerating tube. The accelerator structure is a π/2 mode constant impedance traveling wave structure. This presentation details 3D and 2D electromagnetic design simulations using CST-MWS software and the SUPERFISH code. In a cavity, the beam is not the only energy absorber but It can behave exactly like an internal generator. When the beam current increases, the interaction between the beam and the cavity will be significant. The effect of beam in the excitation of accelerated modes is known as beam loading. These modes, in turn, can affect the energy increase of the beam passing through the cavity and its energy distribution. In this presentation, the beam loading effect for a constant impedance traveling wave accelerating tube in S band is simulated by CST software and the results are compared with the analytical relation of the beam loading voltage. The results show that by using these relations, it is possible to have a correct estimate of the loading value of the beam and to optimize the different parameters of the structure.

Meeting Link

https://meet.google.com/fme-mvgz-dhp