21 SEP 2023
11:00 - 12:00

Abstract:

Inertia is the intrinsic tendency of matter to remain in a given condition. The state of a particle in spacetime is determined by its mass and spin, which characterize the irreducible unitary representations of the inhomogeneous Lorentz group. Therefore, the inertial attributes of a particle are determined by its mass and spin. The inertial properties of mass are well known; hence, I concentrate on the inertial properties of intrinsic spin.

Meeting Place:
Seminar Room, School of Particles and Accelerators, IPM

21 SEP 2023
10:00 - 12:00

Let $R$ be a commutative Noetherian ring and $M$ be an $R$-module. The trace of $M$, denoted by $ r_R(M)$, is defined as the sum of ideals $phi(M)$, where the sum is taken over all $R$-module homomorphisms $phi:Mlongrightarrow R$. The trace of a module have been considered in various contexts, in particular to better understand the center of the ring of endomorphisms of a module. When the canonical module $omega_R$ of $R$ exists, the significance of the trace of $omega_R$ arises from the fact that it describes the non-Gorenstein locus of $R$. The study of commutative rings lying between Gorenstein and Cohen-Macaulay rings has been very intense in the last years. There are several different ways to approach this study. One of them was recently initiated by Herzog, Hibi, and Stamate in [2] introducing the notion of nearly Gorenstein ring. A Cohen-Macaulay local ring $R$ admitting a canonical module $omega_R$ is said to be nearly Gorenstein if $ r(omega_R)$ contains the maximal ideal (there is a similar notion for positively graded algebras over a field). In these talks, we study the trace ideal of semidualizing modules, give some characterizations of them and compare them with annihilators of specific Ext modules. Then, two new classes of rings, namely quasi nearly Gorenstein and weakly nearly Gorenstein, are introduced as generalizations of nearly Gorenstein rings; [1].
references:
1. M. Bagherpoor and A. Taherizadeh. Trace ideals of semidualizing modules and two generalizations of nearly Gorenstein rings, Communications in Algebra {51}(2) (2023), 446-463.
2. J. Herzog, T. Hibi, and D. I. Stamate. The trace of the canonical module. Isr. J. Math. 233 (2019), 133-165.
3. H. Lindo, Trace ideals and centers of endomorphism rings of modules over commutative rings, Journal of Algebra {482} (2017), 102-130.
online in Zoom: https://zoom.us/join
Meeting ID: 9086116889
Passcode: 362880
Venue: Niavaran, Lecture Hall 2

20 SEP 2023
11:00 - 12:00

Abstract:

For operating the particle accelerators, providing the required vacuum pressure is crucial. In practice, the vacuum is needed to minimize the beam-gas interaction which has a significant impact on the beam lifetime, luminosity, intensity, and instability. The vacuum is also needed to avoid electrical discharge in high voltage instruments, reduce contamination of optics, prevent the material from corrosion and damage, thermally isolate cryogenic devices, and reduce the induced radioactivity and noises in detectors.
In this presentation, an overview of ultra-high vacuum systems that are used in charge particle accelerators will be presented which include a brief introduction of some vacuum equipment, the gas sources in particle accelerators, design and modeling of the vacuum system and requirements to achieve the Ultra-High Vacuum (UHV) pressure. Finally, as a special case, the design and modeling of the vacuum system for Iranian Light Source Facility will be presented.

Indico Link:
https://indico.hep.ipm.ir/e/h.karimi

Meeting Place:
Seminar Room, School of Particles and Accelerators, IPM

Link to join virtually:
https://meet.google.com/fnv-dfkk-ghb

20 SEP 2023
14:00 - 15:00

Macroscale chains have been proposed to give insight into the physics of molecular polymer systems. However, using the concept of thermodynamics for such macroscopic out-of-equilibrium systems is a matter of open debate. On the other hand, understanding the rheological response of systems of quasi-one-dimensional semiflexible materials, such as bead-chain packings, is currently a great challenge. In this talk, we study the dynamics of a single macro scale chain and an assembly of entangled chains in two different geometries and try to compare our findings with polymer physics when it is possible. For the entangled chain system, we observe a universal transition from localized to wide shear zones, that occurs upon shearing the system. We show that the nonlinear rheological response is governed by the interplay between increasing stored elastic forces due to entanglements and interlocking between chains. The insight from this study can be used as a guide to design the microstructure of new materials with peculiar mechanical responses.


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https://www.skyroom.online/ch/schoolofnanoscience/weeklyseminars

18 SEP 2023
11:00 - 12:00

Abstract:

Quantum chromodynamics (QCD) is the theory of the strong interaction. The fundamental particles of QCD, quarks and gluons, carry colour charge and form colourless bound states at low energies. The hadronic bound states of primary interest to us are the mesons and the baryons. From knowledge of the meson spectrum, we use neural networks and Gaussian processes to predict the masses of baryons with 90.3% and 96.6% accuracy, respectively. These results compare favourably to the constituent quark model. We as well predict the masses of pentaquarks and other exotic hadrons.

Based on:
https://arxiv.org/abs/2003.10445

Link to Join Virtually:
https://meet.google.com/fnv-dfkk-ghb

13 SEP 2023
11:00 - 12:00

Abstract:

Collective behavior in many-body systems governed by the strong nuclear force can appear in all energy scales, and it plays an important role in our understanding of the phenomena of such complex systems. The correlations of nucleons in such collective systems lead to a range of fascinating structural properties, such as the deformation of nuclei from the spherical shape. In this talk, I would like to present my recent projects on flow analysis as a probe of nuclear deformation in high energy. I will review n-particle correlation functions and the form of flow probability distribution as two event-by-event flow fluctuation measurements. Then, I will explain their applications in symmetric ion collisions. Finally, I will briefly discuss asymmetric collisions to extract deformation effects analytically in Ultra-central collisions.

Indico Link:
https://indico.hep.ipm.ir/e/h.mehrabpour

Link to join the webinar:
https://meet.google.com/fnv-dfkk-ghb

12 SEP 2023
14:30 - 15:30

Date and time

Tuesday, 12th September 2023 (21th of Shahrivar, 1402), 2:30 pm (Tehran zone)



Link

https://www.skyroom.online/ch/schoolofphysics/highenergyseminar



Abstract
I will discuss a mechanism for baryogenesis from out of equilibrium decays of particles into (unparticle) states of a nearly conformal sector, applicable to composite Higgs model. The generation and evolution of the slowly varying charge and particle number densities can be described by a set “Boltzmann equations” whose coefficients can be expressed in terms of CFT correlation functions. I will apply this formalism to high scale leptogenesis in composite Higgs models and evaluate the asymmetry generation before the confining phase transition (PT) during which the composite Higgs is formed. I will then discuss how the PT may be analyzed and consider its effects on the matter abundances. The cosmological PT in the minimal models tend to complete only after a large period of supercooling, potentially resulting in excessive dilution of matter abundances. However, I will show how generic modification of the minimal models can result in a much faster completion of the PT, allowing for compatibility with baryogenesis before the PT.

5 SEP 2023
14:00 - 15:00

Date and time

Tuesday, 5th September 2023 (14th of Shahrivar, 1402), 2:00 pm (Tehran zone)



Link

https://www.skyroom.online/ch/schoolofphysics/highenergyseminar



Abstract
While early studies of the cosmic microwave background and large-scale structure suggested that primordial fluctuations are both Gaussian and scale-invariant, some alternative classes of inflationary models predict different levels of non-Gaussianities in the primordial gravitational field. Local primordial non-Gaussianity (PNG) generates a primordial bispectrum, which peaks in the squeezed triangle configuration where one of the modes is on a much larger scale than the other two. The long wavelength mode couples with the other two to generate a non-Gaussian signal, which then affects the local number density of galaxies and induces a scale-dependent feature in the two-point function of galaxies. Nevertheless, probing PNG with this technique is limited by various imaging systematic effects that can modulate the galaxy power spectrum on large scales. Systematics cause wide-angle variations in the galaxy density field, and in general, any large-scale variations can translate into an excess signal in the power spectrum, which can be misinterpreted as the signature of non-zero PNG. In this talk, I present a careful study of PNG with photometric galaxies from the Dark Energy Spectroscopic Instrument Legacy Imaging Surveys. I elaborate on statistical tools and simulation-based methods to assess the significance of remaining systematic error and data quality for such a subtle measurement.

4 SEP 2023
11:00 - 12:00

Abstract

In this talk, firstly I will talk about designing of an 11-cell standing wave cavity which I have recently designed by CST. Then, as prospect of our research, I will reveal some conjectures about duality of such systems with some kind of mass spring systems, and also to better deal with space charge effects on beam dynamics, I suggest a problem the solution of which proves a duality between ideal non-neutral plasmas and wave equations. The latter duality, if proved to exist, strictly reduces the computational cost relative to PIC tracking and the former might make the optimization process easier.

Meeting Place:
Seminar Room, School of Particles and Accelerators, IPM

Link to join virtually:
https://meet.google.com/fnv-dfkk-ghb

31 AUG 2023
11:00 - 12:00

Abstract:

In this talk after reviewing some prerequisites, I will discuss how the effect of the environment could be added to the Random Matrix Models and then show how this might affect some quantities like Spectral Form Factor and complexity in these models.

Meeting Place:
Seminar Room, School of Particles and Accelerators, IPM

Link to Join Virtually:
https://meet.google.com/fnv-dfkk-ghb