18 APR 2024
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"HEPCo@physics school" stands for High Energy Physics and Cosmology at physics school.
18 April 2024 (30 Farvardin 1403)
Deadline for registration: 16 Farvardin 1403

17 APR 2024
11:00 - 12:00

Abstract:

Luminosity, along with the center of mass energy, is the most important figure of merit of any particle collider. It quantifies the power of a machine to squeeze particles through a given space in a given time. The precision luminosity measurement is crucial as it directly affects the other physics parameters like physics process's production cross section. In this talk the luminosity is first introduced. Then the technique used to measure this quantity is presented, which yields in determining a calibration constant; so-called \sig_{visible}, via some specific van-der-Meer (vdM) scans. Finally, the contribution from several sources of systematic uncertainties on the measurement of the luminosity is discussed.

Indico Link:
https://indico.hep.ipm.ir/e/m.zeinali

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

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

17 APR 2024
13:30 - 15:00

This talk is devoted to giving non-specialists an idea of how modern theoretical astrophysicists approach modelling astronomical phenomena. This will be achieved by using the problem of binary stellar evolution as a case study. After a brief introduction on the current relevance of accurately simulating binary stars and a quick glance at stellar evolution, I will discuss several codes that could be used to simulate binary stars, as well as their shortcomings. Then, I will introduce a novel method we devised that could be used to simulate the gravitational fields of binary systems in one-dimensional codes. Afterwards, I will describe a numerical integrator we created which was used to produce a database of properties needed when simulating binary stars. Finally, I will go through the different procedures we carried out in order to verify the values tabulated in our database. This publicly available database can be coupled to stellar evolution codes in order to simulate the evolution of binary stars

17 APR 2024
14:00 - 15:00

The classical Tverberg's theorem of 1966 states that any set of size (d+1)(q-1)+1 in the Euclidean space of dimension d can be partitioned into q parts whose convex hulls intersect. In this talk, I will talk about many variants of this theorem and a conjecture by Engstrom and Noren that was recently proved with the aid of Najafian, ALipour, and Mazidi.

Zoom room information is:
https://us06web.zoom.us/j/89600366073?pwd=RMHt0eGdvGtkaDBG1Me3y8bOLgooGh.1
Meeting ID : 896 0036 6073
Passcode : 290109
Venue: Niavaran, Lecture Hall 1

17 APR 2024
17:30 - 19:00

The geometry of moduli spaces and stacks of vector bundles on curves have been intensively studied from different perspectives; for example, via point counting over finite fields by Harder and Narasimhan, and gauge theoretically by Atiyah and Bott over the complex numbers. Following Grothendieck's vision that a motive of an algebraic variety should capture many of its cohomological invariants, Voevodsky introduced a triangulated category of motives which partially realises this idea. After describing some properties of this category, I will present a formula for the motive of the moduli stack of vector bundles on a smooth projective curve; this formula is compatible with classical computations of invariants of this stack due to Harder, Atiyah--Bott and Behrend--Dhillon. The proof involves rigidifying this stack using Flag-Quot schemes parametrising Hecke modifications as well as a motivic version of an argument of Laumon and Heinloth on the cohomology of small maps, which is closely related to the Grothendieck-Springer resolution. I will explain how to extend this to a formula for the stack of coherent sheaves and, if there is time, I will give an overview of other motivic descriptions of closely related moduli spaces. This is joint work with Simon Pepin Lehalleur.

https://zoom.us/join
Meeting ID: 9086116889
Passcode: 362880
Venue: , (Zoom Lecture)

15 APR 2024
16:00 - 18:00

Against the Extension of Perception in Quantum Mechanics

15 APR 2024
11:00 - 12:00

Abstract:

In this talk we would like to speak about measurement of the energy spectrum of a linear accelerator. Photons with energy totaling more than 10 MeV provide efficient treatment for deeply seated tumors but interact with the nuclei of high-Z materials constituting a head of the linac. These interactions result in photoneutrons that deliver an additional out-of-field dose to the patient, which increases the risk of radiation-induced cancer. Monte Carlo simulation is an accurate strategy for estimating the effective photoneutron dose for a patient. In the current study, the possibility of using GEANT4 to calculate the photoneutron spectrum from the medical linac was investigated. Validation of the simulated model was carried out based on a comparison of simulated and measured percentage depth–dose curves from photons in the water phantom. The obtained photoneutron spectrum was compared with the previously measured spectrum at the Varian Thilogy linac. GEANT4 may improve the accuracy of calculations of the effective dose based on photoneutrons.

Based on:
https://doi.org/10.3390/qubs7030027

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

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

14 APR 2024
15:00 - 16:00

Abstract:

The approach to thermal equilibrium, or thermalization, in isolated quantum systems, is among the fundamental problems. Recent theoretical studies have revealed that thermalization in quantum systems has several remarkable features. In this talk, I will briefly review thermalization in the isolated quantum system. It has been demonstrated that two distinct thermalization regimes, strong and weak, occur for different initial states. I will discuss some candidates to probe strong and weak thermalization. finally, I will review the recursive procedure to produce the Krylov space and apply it to explore quantum thermalization. In particular, we would like to understand to what extent the nature of thermalization may be explored in this context.

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

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

9 APR 2024
14:00 - 15:00

Date and time

Tuesday, April 9th, 2024 (Farvardin 21st, 1403), 2:00 pm (Tehran zone)



Link

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



Abstract
Cosmology is a field that deals with a vast amount of data, and it is crucial to ensure consistency and measure the tension between data sets. Tension indicates either discordance between data sets or a problem with the underlying model. One of the most famous examples of tension in cosmology is the Hubble tension, which is a 3.5σ discrepancy between supernovae and CMB data in estimating the age of the Universe. While alternative models have been introduced to resolve this tension, it is necessary to use tension metrics to verify if these data sets are still discordant or in agreement even in alternative models. Furthermore, the existence of different models means that one has to choose the best model among competing models that fits observational data. Nested Sampling, a recent computational algorithm, enables us to perform a model selection approach alongside quantifying tension between different data sets. In this talk, we will discuss the tension metric and the model selection approach in cosmology.

2 APR 2024
14:00 - 15:00

The atmospheric CO2 has reached unprecedented amounts and
the impact of human activities on the current situation is
undeniable. In this talk, I briefly explain the problem of
atmospheric CO2 variation and introduce the main strategies to
control our carbon footprint as a HEPCO researcher according to
the Arxiv 2403.03308

10 MAR 2024
15:00 - 16:00

Abstract:

In this blackboard talk I will explore certain features of complexity in the context of Eigenstate Thermalization Hypothesis

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

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

7 MAR 2024
14:00 - 16:00

Class Field Theory is a profound and significant branch of algebraic number theory, primarily concerned with the study of abelian extensions of local and global fields by utilizing intrinsic objects from the ground field. Through the e x a m i n a t i o n o f c o m p l e x interrelations and principles such as reciprocity laws, conductors, and Lfunctions, this theory illuminates the elegant structures governing global fields. In the forthcoming lecture, our focus will be on number fields, aiming to elucidate the core concepts and methodologies with a keen emphasis on motivational examples and historical context. It is hard to do justice to the field in one lecture, so expect a lot of bias and injustice!!
Venue: Niavaran, Lecture Hall 1

6 MAR 2024
11:00 - 12:00

Abstract:


The study of particle structure is one of the most fundamental and challenging scientific topics that has always maintained its attractiveness among researchers. They have pursued this goal with the development of different tools and methods. One of these methods is by finding particle cross sections, which is accompanied by many complexities. Fortunately, the factorization theorem has made this path easier by providing a solution. In this theory, using collinear and k_t-factorization frameworks we can find the cross section of particle collisions. The k_t-factorization theorem is actually an extension of the collinear factorization theorem, which considers the transverse momentum of a parton in addition to its collinear component. Recently, another approach by extending the k_t-factorization framework is proposed, which is called the (z, k_t)-factorization. In this framework the kinematics of the last step emitted parton in contrast to the k_t-factorization theorem is completely considered, and this parton plays an important role in cross section calculations. In this talk, we investigate the (z, k_t)-factorization framework by considering various hadronic differential cross sections, and also double unintegrated parton distribution functions of different approaches.

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

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

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

6 MAR 2024
14:00 - 15:00

For an arbitrary graph $G$, a hypergraph $mathcal{H}$ is called Berge-$G$ if there is an injection $i: V(G)longrightarrow V(mathcal{H})$ and a bijection $psi :E(G)longrightarrow E(mathcal{H})$ such that for each $e=uvin E(G)$, we have ${i(u),i(v)}subseteq psi (e)$. We denote by $mathcal{B}^rG$, the family of $r$-uniform Berge-$G$ hypergraphs. For families $mathcal{F}_1, mathcal{F}_2,ldots, mathcal{F}_t$ of $r$-uniform hypergraphs, the Ramsey number $R(mathcal{F}_1, mathcal{F}_2,ldots, mathcal{F}_t)$ is the minimum integer $n$ such that in every hyperedge coloring of the complete $r$-uniform hypergraph on $n$ vertices with $t$ colors, there exists $i$, $1leq ileq t$, such that there is a monochromatic copy of a hypergraph in $mathcal{F}_i$ of color $i$.In this lecture, we will first provide a brief history of Ramsey numbers and then focus on Ramsey numbers involving $3$-uniform Berge cycles.

Zoom room information:
https://us06web.zoom.us/j/89600366073?pwd=RMHt0eGdvGtkaDBG1Me3y8bOLgooGh.1 Meeting ID: 896 0036 6073
Passcode: 290109
Venue: Niavaran, Lecture Hall 1