4 AUG 2020
14:00 - 15:00

Abstract:

In flat spacetime, Poincare group is the Lie group of linear transformations on space-time which keeps the speed of light invariant. This is the corner-stone of special relativity. However, in theories defined such that are only asymptotically flat, it has been shown that the group of physical transformations is larger than Poincare, and it is called the BMS group. I will show that this group of transformations does not keep the speed of light invariant. As a result, one can use this physical observable to distinguish geometries which are related by a BMS transformation to each other, i.e the soft hairs. Moreover, this observable is related to the gravitational memory effect which had been used as an observable for soft hairs.

In my talk, first I will review Asymptotic Symmetry Group (ASG) analysis, BMS_4 group and gravitational memory effect. Then, I will present the results of the analysis of speed of light in this context.


Skype link for emergency

SkypeLink: https://join.skype.com/cm7iyEUWJVCf

4 AUG 2020
19:30 - 21:30

Abstract: In this talk, I will introduce the main properties of the so-called MDCDW phase of dense quark matter and present details on the derivation of the equations of axion electrodynamics that govern its electromagnetic transport. Some important results that have contributed to make the MDCDW a viable candidate for neutron star core matter phases will be discussed. Analogies with condensed matter systems will be underlined.

5 AUG 2020
13:30 - 15:00

The standard model of cosmology, known as LCDM, has a great success in interpretation of the cosmological observations from cosmic microwave background (CMB) radiation to the large scale structure (LSS) observation. However, there are a couple of tensions between the observations and theory. One category of these challenges is in the galactic scale known as "core-cusp", "missing satellite" and too big too fail problems. On the other hand, the measurement of the Hubble parameter from CMB and nearby supernovae are in tension. In this talk, I will present the idea of how the non-linear structure formation and the characteristics of the cosmic web can be used to study these tensions and their probable solutions in more detail. Accordingly, I will introduce the non-Markov version of the excursion set theory as an analytical approach to study the non-linear structures, and then I will show how the idea of the modified initial condition can address the galactic scale challenges of the LCDM. In the next part of the talk I will show, how the Hubble parameter tension can be related to the structure formation history and the merger rate of dark matter halos, which can be considered as a complementary observation to study the tension and its observational consequences in LSS..

5 AUG 2020
14:00 - 15:00

Abstract:

While carbon based materials attract a lot of attention for their remarkable physical and mechanical properties, it is necessary to modify their surface chemistry and wettability with functionalization for successful interaction of these materials with the surrounding medium like air, water and bio-fluids. A functionalization treatment, even small, can drastically alter the physical and chemical properties of carbon-based materials. Among strategies for functionalization, covalent sidewall functionalization is based on the rehybridization of a sp2 carbon atom into a sp3 configuration, is more robust, induces important modifications in the materials properties and exhibits a large range of applications such as broadband electromagnetic devices, ion storage devices, supercapacitor electrodes, sensors, composites, solid lubricants, and water desalination. Here, carbon-based membranes, initially designed and fabricated for water desalination, were functionalized with H2 and SF6 plasma treatments. Interesting morphological impacts of functionalization time and agent on the membranes were captured by molecular dynamic simulations, FESEM imaging, EDAX analyses and Raman spectroscopy. Above and beyond, water contact angle measurements revealed tuneability between hydrophobicity and hydrophilicity of the functionalized membranes. Electrical conductivity measurements further reflected the potential of functionalized carbon based membranes in holding back the salt, allowing fast transport of water, cancelling the conventional trade-off between selectivity and permeability, and presented these materials as candidates for new generation of nanomaterials in water desalination.


Date: Wednesday, 5 Agust 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

5 AUG 2020
11:00 - 12:00

Based on: arXiv:2006.05302


Abstract: In this talk, after a brief review of the strong CP problem and its elegant proposed solution, the Axion model, I will explain how Axion-like Particles (ALPs) come into existence and what motivations are behind them. Furthermore, I will show you that a new expected upper limit on the ALP-gluon coupling can be found by searching for an ALP produced in association with one or two jets in proton-proton collisions. The expected limit obtained in this way is stronger than those already obtained at the LHC searches. The proposed analysis in this talk can thus serve as a tool for probing light ALPs in future searches.


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


Indico: https://indico.particles.ipm.ir/indico/event/367

13 AUG 2020
18:00 - 19:00

One of the most fruitful directions in the study of monomial ideals is finding
topological objects whose chain maps can be adapted to a free resolution of the ideal. The
catalyst of this approach was the Taylor resolution of a monomial ideal, which is supported
on a simplicial complex, but is largely non-minimal. While not all monomial ideals have
minimal free resolutions supported on a simplicial (or even CW) complex, it is known that a
square-free monomial ideal of projective dimension one has a minimal free resolution
supported on a tree. We show that the powers of such an ideal have minimal free resolutions
that are supported on related polyhedral cell complexes, that can be constructed from this
tree. In the process, we provide a full description of the Rees Algebra of the ideal. (This is
joint work with S. Cooper, S. El Khoury, S. Faridi, S. Mayes-Tang, S. Morey and S. Spiroff).


(Access link will be announced by email a day before the webinar dates.)

18 AUG 2020
20:30 - 22:30

Abstract: trong magnetic fields play an important role in the physics of hot quark-gluon plasma produced in heavy-ion collisions. Most interestingly, they can trigger quantum anomalous processes leading to unusual charged-particle correlations in the observable data. The direct verification of the corresponding theoretical prediction is, however, complicated by a large uncertainty in the magnetic field produced in collisions. To constrain the uncertainty, one needs an independent measurement of the field. The direct photon emission could potentially provide such a measurement. In this talk, the recent first-principle calculations of the direct photon emission from a magnetized hot quark-gluon plasma will be reported. As expected, at leading order in the coupling, the emission is determined by the particle-particle and antiparticle-antiparticle scattering processes, as well as by the particle-antiparticle annihilation. The effect of the Landau-level quantization on the angular dependence of the direct photon emission will be discussed.

20 AUG 2020
18:00 - 19:00

Let R be a graded commutative ring generated over a field by finitely many
homogeneous elements of positive degree. Work of Avramov, Buchweitz and Sally shows
that, under certain assumptions, the Laurent series expansions around 1 of the Hilbert series
of two graded R-modules and those of some of their Ext modules are related. When R is a
complete intersection, we show that such relations are connected to the asymptotic behavior
of the Ext modules. (This is joint work with David A. Jorgensen and Peder Thompson.)
School


(Access link will be announced by email a day before the webinar dates.)