21 JUN 2021
11:00 - 12:00

Based on
https://link.springer.com/content/pdf/10.1140/epjc/s10052-020-7676-5.pdf


Abstract: The energy-momentum tensor or gravitational form factors of nucleons are calculated in light cone QCD. The obtained results are compared with the results of lattice QCD and (existing) data provided by JLAB. As a by-product, some mechanical properties of the nucleon like the pressure and energy density at the center of nucleon as well as its mechanical radius are also calculated and their results are compared with other existing theoretical predictions. We compare the mass or gravitational radius of nucleon with its charge radius, which leads to a puzzle!!!!.


https://meet.google.com/anh-ditu-htd

22 JUN 2021
17:30 - 19:30

We use potential modularity theorems to prove, for a class of smooth projective hyperbolic curves, effective height bounds for all rational points on such curves which are defined over an odd-degree totally real field. (Over such fields and for such curves this amounts to an unconditional effectivization of Faltings' theorem.) We do this by proving effective height bounds for S-integral K-points on Hilbert modular varieties when K is totally real of odd degree (a familiar hypothesis from the theory of Hilbert modular forms), and then deducing a height bound for rational points on complete curves inside such varieties. The curves C_t : x^6 + 4y^3 = t^2 (with t a nonzero totally real algebraic number of odd degree, e.g. t = 1) are examples of curves to which this method applies.
Zoom Meeting link:
https://zoom.us/j/9299700405?pwd=QXZJYTVkeHpJWDE4SGVTbkVzZmJxQT09
Meeting ID: 929 970 0405
Passcode: 210609

22 JUN 2021
14:00 - 15:00

Abstract:

If the electroweak Higgs vacuum expectation value $v$ in early universe is $\sim 1 \%$ higher than its present value $v_0=246$ GeV, the $^7$Li puzzle in BBN and the CMB/$\Lambda$CDM tension with late-universe measurements on Hubble parameter are mitigated. We propose a model of an axion coupled to the Higgs field, named ``axi-Higgs'', with its mass $m_a \sim 10^{-30} - 10^{-29}\,{\rm eV}$ and decay constant $f_a \sim 10^{17} - 10^{18}\,{\rm GeV}$, to achieve this goal. The axion initial value $a_{\rm ini}$ yields an initial $\Delta v_{\rm ini}/v_0 \sim 0.01$ throughout the BBN-recombination epoch and a percent level contribution to the total matter density today. Because of its very large de Broglie wavelength, this axion matter density $\omega_a$ suppresses the matter power spectrum, alleviating the CMB/$\Lambda$CDM $S_8/\sigma_8$ tension with the weak-lensing data. It also explains the recently reported isotropic cosmic birefringence by its coupling with photons. Adding the axion ($m \sim 10^{-22}\,$eV) in the fuzzy dark matter model to the axi-Higgs model allows bigger $\Delta v_{\rm rec}$ and $\omega_a$ to address the Hubble and $S_8/\sigma_8$ tensions simultaneously. The model predicts that $\Delta v$ may be detected by the spectral measurements of quasars, while its oscillation may be observed in the atomic clock measurements.



Date: Tuesday, June 22th

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

Zoom. (click)

Meeting ID: 881 3325 0645

Passcode: 078775

23 JUN 2021
11:00 - 12:00

Abstract: We explore the potential of the LHC to measure the rate of proton-proton collisions through the process of central exclusive production $ pp -> p WW \gamma p$ and prob the triple and quartic anomalous gauge boson couplings contributing to this process at the center of mass energy 13 TeV and integrated luminosity 300 fb^(-1). In addition to the presence of two opposite sign leptons, a photon, and missing energy, the distinctive signature of this process is the presence of two intact protons flying few millimeters from the initial beam direction in both sides of the interaction point which suppress the background process effectively. To exploit this feature of signal we benefit from forward detectors (FDs) placed about 200 meters from the interaction point to register the kinematics of tagged protons. The obtained expected limits show very good improvements for dimension-8 quartic couplings and competitive bounds on dimension-6 anomalous triple couplings w.r.t the current experimental limits.
https://link.springer.com/article/10.1007/JHEP07(2020)191


Indico: https://indico.particles.ipm.ir/indico/event/416

https://meet.google.com/vax-dyjg-wju

23 JUN 2021
13:30 - 15:00

In this talk firstly I will briefly review the inflationary cosmology as the most successful model describing the quantum perturbations in the early universe. Then I will explain the stochastic method as a powerful tool to describe these quantum perturbations. In the third part I will talk about the magnetogensis problem in cosmology. Moreover the past efforts such as using a parity violation model in the context of early universe cosmology are going to be discussed as probable solutions. As we will see these efforts are not totally successful to solve the problem without taking into account all quantum effects. As an attempt to solve the problem the stochastic method will be used as an effective theory. By exploiting the stochastic method we will see the results are consistent with observation and we are a step closer to the final solution.

23 JUN 2021
14:00 - 15:00

Abstract:
We study an antisymmetric spin-orbit coupling of a two-dimensional single-band Hubbard Hamiltonian. We propose that this is the most basic paradigm for understanding the electrical characteristics of locally noncentrosymmetric transition metal (TM) oxides like Sr2IrO4. Based on exact diagonalizations of small clusters and the random-phase approximation, we investigate the correlation effects on charge and magnetic order as a function of doping and of the TM-oxygen-TM bond angle. For small doping and small-angle, we find dominant commensurate in-plane antiferromagnetic fluctuations, while ferromagnetic fluctuations dominate for larger angles. Moderately strong nearest-neighbor Hubbard interactions can also stabilize a charge density wave order. Furthermore, we compare the dispersion of magnetic excitations for the hole-doped case to resonant inelastic x-ray scattering data and find good qualitative agreement.


Date: Wednesday, June 23, 2021

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

3 JUL 2021
13:00 - 21:00

Workshop (online)
July 3 , 2021 from 13 to 21

8 JUL 2021
15:00 - 18:00

The SLH webinar series will focus on the latest applications of synchrotron light in various diciplines of health sciences
The first session from this series will be held on Thursday, July 8th, 2021, 10:30-13:30 (GMT) and is dedicated to Micro & Nano Imaging and consists of four talks delivered by experienced scientists from CHU Grenoble-Alpes and CNRS, France.
These webinars are jointly held by the School of Advanced Technologies in Medicine (SATiM) in Tehran University of Medical Sciences, and the Iranian Light Source Facility (ILSF) in Institute for Research in Fundamental Sciences (IPM), Iran.
Registration is free for all medical students and scientists around the world and all participants will be given Certification of Attendance. For registration and more information, please visit our website or contact us on social media.

9 NOV 2021
09:00 - 16:00

Join the community of synchrotron radiation users sharing their knowledge and experiences.

10 NOV 2021
09:00 - 16:00

Join the community of synchrotron radiation users sharing their knowledge and experiences.