12 MAY 2021
13:30 - 15:00

Abstract
In the standard scenario of cosmology, EB and TB cross correlation power spectra as well as Cosmic Birefringence in CMB radiation vanish due to the parity invariant. So, one can use the cross-correlation power spectra to check new physics such as some parity-violating interactions. We have shown that in the context of the standard model of particles, the weak interaction of cosmic microwave background (CMB) and cosmic neutrino background (CnB), in order of one loop forward scattering, can generate non-vanishing TB and EB power spectra in the presence of scalar perturbation which is in contrast with the standard scenario of cosmology. By comparing our results with current experimental data, significant information can be extracted about the nature of CnB. It is shown that the contribution of CMB-CnB forward scattering for TB, TE, and EB power spectra in the case of CnB as Majorana particles is twice larger than in the case of CnB as Dirac one. In following, it is shown that the mean opacity due to cosmic neutrino background can behave as a birefringent medium. Finally, we discuss the evidence of cosmic neutrino background in the Planck 2018 polarization data which is reported on a new measurement of the Cosmic Birefringence (CB) angle β.

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11 MAY 2021
17:30 - 19:30

We give several new moduli interpretations of the special fibers of several Shimura varieties over certain prime numbers. As a corollary we obtain that for every prescribed odd characteristic p every bounded symmetric domain possesses quotients by arithmetic subgroups, whose models have good reduction at a prime divisor of p.




Zoom Meeting link:


https://zoom.us/j/9299700405?pwd=VTM5OW53dWFkbjcxQXBBalhiNWc2dz09




Meeting ID: 929 970 0405


Passcode: 210406

11 MAY 2021
14:00 - 15:00

Abstract:
In standard effective field theories, the notion of causality is intrinsically linked with that of subluminality and with a set of positivity constraints to be imposed on the low-energy scattering amplitudes. I will highlight how the presence of gravity leads to a more subtle relation between causality, (sub)luminality and positivity bounds. These considerations are relevant for putting constraints on cosmological and gravitational effective field theories and I will provide explicit criteria to be satisfied so as to ensure causality and a standard high energy completion in gravitational effective field theories.


Date: Tuesday, May 11th
2 p.m. - 3 p.m. (Tehran time)

Zoom. (click)
Meeting ID: 884 3079 2016
Passcode: 395721

6 MAY 2021
18:00 - 20:00

Lifting theory for modules was studied intensively by Auslander, Ding, and Solberg. This notion is tightly connected to the deformation theory of modules and has important applications in the theory of maximal Cohen-Macaulay approximations. Later, Yoshino generalized the lifting results for modules to the case of complexes. Further generalization was given by Nasseh and Sather-Wagstaff for DG modules (a notion from rational homotopy theory) in order to obtain a clearer insight on a conjecture of Vasconcelos (which is not a conjecture anymore) in commutative algebra. In this talk, I will survey recent developments on lifting theory for DG modules and describe the relationship between this notion and another conjecture in commutative algebra, namely, the Auslander-Reiten conjecture.

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Meeting ID: 929 970 0405
Passcode: 210406

5 MAY 2021
13:30 - 15:00

Abstract
As we know, we need celestial observations for cosmic studies. These observations are made by telescopes. Our effort has been to increase the bandwidth of balloon telescopes. Previously, the useful bandwidth extracted from this type of detectors was about 10%, but we managed to increase the bandwidth in new designs. Here we are going to talk about increasing the bandwidth of cold electron bolometers.

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29 APR 2021
18:00 - 20:00

Let $A, B$ be polynomial rings over a field $k$, and $Isubseteq A, Jsubseteq B$ proper homogeneous ideals. We analyze the associated primes of powers of $I+Jsubseteq Aotimes_k B$ given the data on the summands. The associated primes of large enough powers of $I+J$ are determined. We then answer positively a question due to I. Swanson and R. Walker about the persistence property of $I+J$ in many new cases. This is a joint work with Quang Hoa Tran.
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Meeting ID: 929 970 0405
Passcode: 210406

29 APR 2021
11:00 - 12:05

Abstract: The boundary degrees of freedom are gauge transformations that become physical in presence of a boundary. They are characterized by surface charges and are called asymptotic symmetries. In asymptotically flat spacetimes, these surface charges describe inequivalent vacua of the theory. The soft photons and gravitons are Goldstones bosons of the spontaneous breaking of such symmetries. I briefly review some aspects of recent development in the study of asymptotic symmetries in asymptotically flat and asymptotically Anti-de Sitter spacetimes. Then I explain the existence of infinitely many surface charges for the special example of Maxwell’s theory and p-form theories. I discuss the asymptotic behavior of the fields, specific boundary conditions, and how the holographic renormalization leads to the renormalization of the symplectic form.



http://meet.google.com/iys-ixfq-gwm

29 APR 2021
11:00 - 12:30

Abstract
The material presented in this Seminar is divided into two categories: the wavefront sensors for optical surface testing and the hyperspectral imaging. The Hartmann on-chip wavefront Sensor is introduced and its application on primary mirror surface quality validation test of Iranian national observatory telescope (INO340) is presented. In this regard, the process of fabrication and testing of two convex and concave spherical surfaces with a large F# is presented for validation test. The hyperspectral imaging is introduced as a remote sensing tool. While the Color Camera has only three color receptors in the blue, green and red, hyperspectral imaging measures at several hundred band of the spectrum for each point of the scene. Its sensitivity is not only in the visible but also in the near-infrared. Some of the application of hyperspectral imaging in the fields of medical, biotechnology, camouflage, detecting fraudulent documents and food analysis are introduced.

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27 APR 2021
14:00 - 15:00

Abstract:

We study surface charges on a generic null boundary in three dimensional topological massive gravity (TMG). We construct the solution phase space which involves four independent functions over the two dimensional null boundary. One of these functions corresponds to the massive chiral propagating graviton mode of TMG. The other three correspond to three surface charges of the theory, two of which can always be made integrable, while the last one can become integrable only in the absence of the chiral massive graviton flux through the null boundary. As the null boundary symmetry algebra we obtain Heisenberg ⊕ Virasoro algebra with a central charge proportional to the gravitational Chern-Simons term of TMG. We also discuss that the flux of the chiral massive gravitons appears as the (Bondi) news through the null surface.


Date: Tuesday, April 27th

2 p.m. - 3 p.m. (Tehran time)





Zoom. (click)

Meeting ID: 884 3079 2016

Passcode: 395721

27 APR 2021
17:30 - 19:30

Click here to see the abstract.



This is the first joint webinar organized by FGC-Istanbul and IPM-Tehran.


Zoom Meeting Link:

https://zoom.us/j/9299700405?pwd=VTM5OW53dWFkbjcxQXBBalhiNWc2dz09

Meeting ID: 929 970 0405

Passcode: 210406

22 APR 2021
11:00 - 12:00

We have around 170 million registered small molecules in the world. These small molecules potentially can interact with around 20,000 protein targets available in human body to modify their biological function and hopefully cure diseases. However, due to large search space, discover the right compound that bind to the right protein target is a daunting task. In recent years, using artificial intelligence (AI) has been successfully applied in almost every stage of the drug discovery project to speed up the process of research and reduce the cost and risk of failure. In this talk we will discuss potential applications of AI in different stages of the drug design pipeline from identify protein targets associated with a disease to evaluate a compound in clinical trial.

22 APR 2021
11:00 - 13:00

For a graded ideal $I$ of a polynomial ring $S=K[x_1,ldots,x_n]$ over a field $K$, the Cohen-Macaulayness of the ring $S/I$ may depend on the characteristic of the base field $K$ in general. Even when $I$ is the edge ideal of a graph, this is the case. Nevertheless, for some families of graphs like chordal graphs and K"onig graphs, the Cohen--Macaulay property of the edge ideal $I(G)$ has combinatorial descriptions which means that it is independent of the base field. In this talk, inspired by the notion of K"onig graphs, we introduce graded ideals of K"onig type with respect to a monomial order $<$. It turns out that if $I$ is of K"onig type, then the Cohen--Macaulay property of $ini_<(I)$ does not depend on the characteristic of the base field. This happens to be the case also for $I$ itself when $I$ is a monomial ideal or a binomial edge ideal. We consider the ideals of K"onig type among the edge ideals, binomial edge ideals and the toric ideal of a Hibi ring and use the König property to determine explicitly their canonical module.
This is based on a joint work with Jürgen Herzog and Takayuki Hibi

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Meeting ID: 929 970 0405
Passcode: 210406

21 APR 2021
13:30 - 15:00

Abstract
The XENON1T collaboration recently reported the excess of events from recoil electrons which may be sign of a fundamental new discovery about our universe. In this talk, I will review the current status of different dark matter (DM) direct detection experiments towards ultimate DM detector. I will show that sterile neutrinos with masses around 90 keV and specific effective coupling can explain the XENON1T anomaly preserving DM astrophysical and cosmological constraints, and it possibly describes the anomalies in other experiments. At the end I will try to explain how one can be convinced that DM has been discovered or not from observing an unexplained excess?
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