11 SEP 2024
14:00 - 16:00

This talk focuses on pointwise ergodic theorems and their connection to Bourgain's path to his Fields Medal. We aim to cover four key milestones:
Part One: We investigate the norm convergence of ergodic averages, concluding with an explanation of the Baby Spectral Theorem.
Part Two: We examine the pointwise ergodic theorem established by Birkhoff in 1931. Depending on the time available, we will cover at least one proof, exploring Calderon's transference in the process.
Part Three: This section delves into the circle method and its comparison to the continuous Fourier Transform. We will also discuss several properties of prime numbers and provide an approximation for averages along primes.
Part Four: We introduce the concept of oscillation and present a proof of the pointwise ergodic theorem along primes. Time permitting, we will explore further developments post-1990.

The references are uploaded in the following link:
https://drive.google.com/drive/folders/1_zIDuDybfkfYuHhrlLtwe-rd6SdpraPZ?usp=drive_link
Venue: Niavaran, Lecture Hall 1

11 SEP 2024
10:00 - 12:00

This talk focuses on pointwise ergodic theorems and their connection to Bourgain's path to his Fields Medal. We aim to cover four key milestones:
Part One: We investigate the norm convergence of ergodic averages, concluding with an explanation of the Baby Spectral Theorem.
Part Two: We examine the pointwise ergodic theorem established by Birkhoff in 1931. Depending on the time available, we will cover at least one proof, exploring Calderon's transference in the process.
Part Three: This section delves into the circle method and its comparison to the continuous Fourier Transform. We will also discuss several properties of prime numbers and provide an approximation for averages along primes.
Part Four: We introduce the concept of oscillation and present a proof of the pointwise ergodic theorem along primes. Time permitting, we will explore further developments post-1990.

The references are uploaded in the following link:
https://drive.google.com/drive/folders/1_zIDuDybfkfYuHhrlLtwe-rd6SdpraPZ?usp=drive_link
Venue: Niavaran, Lecture Hall 1

11 SEP 2024
11:00 - 12:00

Abstract:

In the Standard Model (SM) of particle physics, gluons are the fundamental particles mediating the strong interaction, as photons do in electromagnetic interactions. Gluons can attract each other to form new bound states called glueballs, which are the only particles in nature entirely composed of force mediators. Finding these gluon bound states is crucial and serves as a fundamental test of the SM. No candidate has yet been unambiguously identified until the new BESIII result to be reported in this presentation.
The Beijing Electron Positron Collider (BEPCII) is a double ring e+e- collider in the 2-5 GeV energy region and the Beijing Spectrometer (BESIII) is a general purpose detector operating at the BEPCII. Decays of J/ψ particle produce a gluon-rich environment and are an ideal place to search for glueball. Discovery of the glueball has been one of the most important scientific goals of the BEPC and BEPCII for decades.
The X(2370) particle was first discovered at the BESIII experiments in 2011. To confirm its pseudoscalar glueball state nature experimentally, the most crucial step is to determine whether the spin parity quantum number of the X(2370) are indeed zero spin and negative parity.
Recently, based on ~10 billion J/ψ decays collected with BESIII, the spin-parity quantum numbers of the X(2370) were firstly measured with a complex partial wave analysis. The experimental results, including quantum numbers, mass, production and decay properties, are consistent with the features of the lightest pseudoscalar glueball. This recent study provides direct and strong experimental evidence for X(2370) being a glueball.

Indico Link:
https://indico.hep.ipm.ir/e/y.huang

Link to Join Virtually:
https://meet.google.com/bda-vsem-tuv

11 SEP 2024
18:00 - 19:30

In this talk, I explore the evolution of types or species in populations from both genetic and genomic perspectives. I first discuss the Fleming-Viot (FV) process in random environment, a measure-valued diffusion modeling the evolution of type-frequencies in countable populations subject to genetic drift, mutation, and selection. The random environment introduces fluctuating fitness among types, meaning their relative strength compared to each other varies stochastically over time. This makes the model significantly more complex than the classical version. I then briefly describe a more general model where multiple FV processes coexist, with interacting and fluctuating fitnesses, allowing competition and collaboration between types and populations. Key results include ergodic behavior and averaging theorems, which are established using dual representations that involve intricate function-valued Markov processes. In the second part, I model genome evolution as continuous-time random walks on groups and graphs, establishing a framework for phylogeny reconstruction of genomes sampled at random from the evolutionary process. A geometric median of a set A in a metric space (S,d) is a point x whose sum of distances to points of A, i.e. ∑_(y∈S)▒d(x,y) , is minimized. I highlight the role of geometric medians in estimating the true ancestor of sampled genomes and present conditions under which medians provide accurate estimations. Finally, I conclude by emphasizing key applications of these models in evolutionary biology and population genetics.

https://us06web.zoom.us/j/86042917248?pwd=YOAG1B0ePOSpipAnqPwM8PDPyiM1ti.1
Meeting ID: 860 4291 7248
Pass Code: 362880
Venue: , (Online)

11 SEP 2024
16:00 - 17:30

In this talk, I will present probabilistic and statistical models addressing problems in population genetics and genome rearrangements. Population models can be classified into two types: those with a constant population size, like the Moran process, and those with a stochastically varying population size, as in branching processes. I will begin by focusing on the structured Moran process, where populations reside on geometric structures (vertices of graphs). These models capture the effects of population geometry on evolutionary dynamics by incorporating frequency-dependent fitness and spatial constraints. I will demonstrate methods for approximating fixation probabilities on star-shaped graphs and other geometric structures using solutions to differential equations, with applications to cancer evolution. I will briefly discuss recent work on modeling the accumulation of genetic variants using branching processes. Finally, I will explore combinatorial problems in genome rearrangements, focusing on the breakpoint median problem, which is central to phylogeny reconstruction. I will explain how to construct approximate medians of random genomes. I will also introduce an algorithm for finding all breakpoint medians and address the challenges in constructing intermediate genomes.
https://us06web.zoom.us/j/86042917248?pwd=YOAG1B0ePOSpipAnqPwM8PDPyiM1ti.1
Meeting ID: 860 4291 7248 Passcode: 362880
Venue: , (Online Seminar)

10 SEP 2024
14:00 - 15:00

Date and time

Tuesday, September 10th, 2024 (Shahrivar 20th, 1403), 2:00 pm (Tehran zone)





Link

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



Abstract
In this talk, I will discuss some properties of the Kerr-Newman (KN) Electromagnetic Fields, which is the G → 0 limit of the KN solution of Einstein-Maxwell equations. In this limit, the electromagnetic sector of the solution survives, while the background becomes locally flat with nontrivial topology. The discussion includes the complex transformation between the non-spinning Coulomb solution and the spinning KN, the g = 2 gyromagnetic ratio of the solution noted by Carter, and the corresponding multipole structure. The topological conserved charges of the electromagnetic field, i.e. the classical helicity and classical spin, are calculated for this solution. Moreover, we studied the interaction of two such solutions by evaluating the Lagrangian for the superposition of those fields. This yields a correction to the interaction potential beyond the Coulomb interaction due to the spin of the fields. The talk is based on: https://arxiv.org/pdf/2405.12602.

9 SEP 2024
11:00 - 12:00

Abstract:

Precise predictions of experimental data at the high energy proton–proton collision are significantly important. Due to the complex nature of proton, where the partons are bound by the strong gluonic force inside the proton, this calculation is not an easy task.
Hence, one cannot calculate the cross section, as simple as, that of the point like particles cross section. Fortunately, the factorization theorem allows us to calculate the cumbersome hadronic differential cross section (DCS) in terms of the elementary partonic cross section, convoluted by the familiar parton distribution functions (PDFs).
In the literature, there can be found different factorization frameworks for calculating the cross section, mostly based on the assumptions of parton behavior inside the proton
, such as the collinear and kt-factorizations (kt is the partonic transverse momentum).
For example, in the collinear factorization, it is assumed that the parton moves collinear to the proton and enters into the hard collision.
Therefore in the collinear factorization theorem, it is supposed that the constituent partons can only have a fraction of the proton momentum, i.e., x,
and these partons do not carry any transverse momentum dependency, i.e. kt.
To describe the distribution of these partons inside the proton, one should use the parton distribution functions (PDFs). However, in the small x limit, the transverse momentum of parton (kt), becomes comparable against the collinear component, i.e., xP (P is the proton momentum). Therefore, the evolution equation of collinear parton, should be generalized by the fact that, parton can also have transverse momentum. This means that the PDFs should have kt dependency. These kt dependent PDFs are called transverse momentum dependent PDFs (TMDs) or unintegrated parton distribution functions (UPDFs).

Link to Join Virtually:
https://meet.google.com/bda-vsem-tuv

28 AUG 2024
11:00 - 12:00

Abstract:

In this talk, I quantify the effects of light spin-zero particles with pseudoscalar couplings to leptons and scalar couplings to nucleons on the evolution of solar neutrinos. I show in this scenario the matter potential sourced by the nucleons in the Sun’s matter gives rise to spin precession of the relativistic neutrino ensemble. For Dirac neutrinos, the spin-flavour precession results in active-sterile oscillations, while for Majorana neutrinos it results in left-handed neutrino to right-handed antineutrino oscillations. In both cases, this leads to distortions in the solar neutrino spectrum which we use to derive constraints on the allowed values of the mediator mass and couplings via a global analysis of the solar neutrino data. In addition for Majorana neutrinos, spin-flavour precession results into a potentially observable flux of solar electron antineutrinos at the Earth which we quantify and constrain with the existing bounds from Borexino and KamLAND.

Indico Link:
https://indico.hep.ipm.ir/e/s.ansarifard1

Link to Join Virtually:
https://meet.google.com/bda-vsem-tuv

28 AUG 2024
09:00 - 10:30

Diagnostic tests that utilize molecular biomarkers in the blood have wide-spread clinical applications. However, early detection of cancer and other devastating diseases is challenging due to the requirement of accurate methods for distinguishing rare molecules carrying disease signals in the background of nondisease associated molecules. Next generation sequencing (NGS) combined with mathematical modelingbased data analysis have proven promising for high accuracy and high throughput diagnostics. Here, I give an overview of the state-of-the-art computational methods that integrate genetic and epigenetic NGS data to extract meaningful signals for diagnosis and disease prevention in cancer screening and other clinical contexts.

This Seminar is free and open to the public.

You can join with this link:

https://www.skyroom.online/ch/arashfj/talk