15 MAR 2023
17:30 - 19:00

Modular forms continue to attract attention for decades with many different application areas. To study statistical properties of modular forms, including for instance Sato-Tate like problems, it is essential to be able to compute a large number of Fourier coefficients. In this talk, we will show that this can be achieved in level 4 for a large range of half-integral weights by making use of one of three explicit bases, the elements of which can be calculated via fast power series operations.
This is joint work with Gabor Wiese (Luxembourg).

Zoom Meeting ID: 856 1386 0958
Passcode: 513992
ICS-File: https://researchseminars.org/seminar/FGC-IPM/ics

14 MAR 2023
14:00 - 15:00

Date and time

Tuesday, 14th of March 2023 (23th of Esfand, 1401), 2:00 pm (Tehran zone)



Link

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



Abstract

A star cluster is a group of stars that shares a common origin and is gravitationally bound for some length of time. Star clusters are ideal astrophysical systems whose long-term evolution is determined by several internal and external processes, like mass loss due to stellar evolution and the energy-equipartition processes as well as tidal removal of star. It is well known that the internal properties of GCs can undergo significant changes at birth but also during the course of the cluster’s dynamical evolution. It is therefore essential to specify to what extent the present-day properties of GCs, such as their physical sizes and masses are imprinted by early evolution and formation processes and to what extent they are the outcome of long-term dynamical evolution. In this talk, I will present the main mechanisms that play a role in the dynamical evolution of star clusters emphasizing the importance of the early evolution. Next, I will review the current state of this field and review some open problems and give examples of recent theoretical findings.

9 MAR 2023
11:00 - 12:00

Abstract:

Chiral symmetry is an approximate symmetry of Quantum chromodynamics (QCD). At low temperatures and density, this symmetry is spontaneously broken. However, by increasing the temperatures or density, the chiral broken phase goes to the normal phase. Exploring the phase diagram of QCD is of fundamental interest. The aim is to understand the condensed matter, or many-body properties, of strong interaction. Heavy-ion collisions program aims to achieve this goal experimentally.
Recent observation on the spin polarization of Lambda particles indicates the matter produced at these collisions carries a large angular momentum. Moreover, since the colliding nuclei are charged particles we expect an enormous magnetic field to be generated at the early stage of collision. Studying the properties of matter under such extreme conditions give us some insight into the phase structure of quark matter.
In this talk, after providing a review on some general ideas as well as the heavy-ion collision program, I will present some of our latest results on the effect of rotation on the chiral symmetry breaking of a magnetized quark matter.

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

7 MAR 2023
14:00 - 15:00

Date and time

Tuesday, 7th of March 2023 (16th of Esfand, 1401), 2:00 pm (Tehran zone)



Link

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



Abstract

The quantum gauge theory is the current basis for explaining the interactions of elementary

particles. Among the four fundamental interactions: electromagnetic, weak, strong, and

gravitational, for the last two, a proper mathematical construction does not yet exist. Quantum gauge theory is based on three different branches of mathematics: 1) geometry, 2) group theory, and 3) functional analysis.

The strong interactions are studied in the SU(3) quantum Yang-Mills theory but an axiomatic

QFT with the mass gap and color confinement does not yet exist. In the classical field theory

model, the gluon is a massless particle but one can not see the color charge of a particle in nature, and then the gluons must be in the bound states, forming massive particles. This is the mass gap problem. The mass gap is the difference in energy between the vacuum and the next lowest energy state. The energy of the vacuum is zero by definition, and the mass gap is the mass of the lightest particle. However, the color confinement postulated permits only bound states of gluons, it is an obvious contradiction.

In this presentation, I would like to discuss the fact that if we replace: 1) Minkowskian

geometry with the de Sitterian geometry, 2) Poincare group with the de Sitter group and

3) Hilbert space quantization with the Krein space quantization, an axiomatic quantum Yang-Mills theory with a mass gap and the color confinement can be constructed. It is important to note that the ambient space formalism allows us to make this construction possible.


[1] M.V. Takook, J.P. Gazeau, Nucl. Phys. B 980, 115811 (2022) Quantum Yang-Mills theory in de Sitter ambient space formalism, [arXiv:2112.02651v2].

[2] M.V. Takook, Europhys. Lett. 1410, 22003 (2023) Axiomatic de Sitter quantum Yang-Mills theory with color confinement and mass gap, [arXiv:2211.16060].

6 MAR 2023
11:00 - 12:00

Abstract:

The Iranian Light Source Facility (ILSF) is a 3 GeV synchrotron radiation facility, which is in the design stage. The ILSF storage ring design is based on a five-bend achromat lattice providing an ultralow horizontal beam emittance of 0.27 nm-rad. Inevitable errors like imperfection of magnetic field and misalignment of magnets will introduce various destructive effects on the performance of the machine. The possibility of correcting the errors should be thoroughly examined before settling the design. In this paper, we have tried to estimate the errors as realistic as possible based on the results obtained from the simulation of the elements and the accuracy of the predicted equipment for fabrication and alignment. The influence of errors on the lattice is investigated. Closed orbit distortion, beta beating and betatron coupling are corrected and improvement made in the lattice functions and machine performance will be presented

Based on:
https://doi.org/10.1016/j.nima.2019.163180

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

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

2 MAR 2023
11:00 - 12:00

Abstract:

Spacetime wormholes can lead to surprises in black hole physics. We show that a very old black hole can tunnel to a white hole/firewall by emitting a large baby universe. We study the process for a perturbed thermofield double black hole in
Jackiw-Teitelboim (JT) gravity, using the lowest order (genus one) spacetime wormhole that corresponds to single baby-universe emission.

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

2 MAR 2023
09:00 - 20:00

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1 MAR 2023
09:00 - 16:00

The workshop will aim to improve the ethical aspects of using animals for scientific purposes and improve the research integrity of preclinical studies.
The series of workshops are being started from 28/2/2023 and
Access: Free
Content type: Theoretical and practical
For more information, call the number below
26113274

1 MAR 2023
11:00 - 12:00

Abstract:

In this study, we present a new determination of the generalized parton distributions (GPDs) with their uncertainties at zero skewness, $\xi=0$, through a simultaneous analysis of all available experimental data of the nucleon electromagnetic form factors (FFs), nucleon charge and magnetic radii, proton axial FF (AFF), and wide-angle Compton scattering (WACS) cross section for the first time. This can be considered as the most comprehensive analysis of GPDs at $\xi=0$ performed so far. We show that such an analysis provides the simultaneous determination of three kinds of GPDs, namely $H^q$, $\tilde{H}^q$ and $E^q$, considering also the sea quark contributions. As a result, we find that the inclusion of the WACS and AFF data at larger values of the momentum transfer squared can put new constrains on GPDs and change them drastically in some cases. We also indicate that the results for the gravitational $FF$ $M_2$ and the proton total angular momentum $J^p$ calculated using the extracted GPDs are in more agreement with the light-cone QCD sum rules (LCSR) and lattice QCD predictions when all experimental data are included in the analysis simultaneously and the sea quark contributions are considered. This talk is based on arXiv:2211.09522 [hep-ph].

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

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

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

1 MAR 2023
13:30 - 15:00

While at optical wavelengths, galaxy spectra match well with state-of-the-art synthetic stellar population models, the near-infrared (NIR) spectral range poses a challenge: massive early-type galaxies (ETGs) show CO absorption features in their H- and K-band spectra,
which are systematically stronger than all current model predictions. Early studies of ETGs in the NIR attributed the strong CO absorptions to intermediate-mass AGB stars in these galaxies.
This led astronomers to conclude that massive ETGs had long time-scale star formations, in contrast to the constraints from the optical spectral range, where star formation is found
to be less extended in high-mass galaxies relative to low-mass ones. In this talk, I rule out the long belief of the origin of strong CO absorptions
in massive ETGs and reconcile the tension between the galaxy evolution pictures inferred from optical and NIR.

1 MAR 2023
17:30 - 19:00

Grobner bases are a powerful tool in polynomial ideal theory with many applications in various areas of science and engineering. A Grobner basis is a particular generating set for a given ideal which represents many useful properties of the ideal. The general theory of Grobner bases along with the first algorithm for constructing them were introduced by Buchberger in 1965 in his Ph.D. thesis. An staggered linear basis is indeed a linear basis containing a Grobner basis for a given ideal. This notion was first introduced by Gebauer and Moller in 1988, however the algorithm that they described for computing these bases was not complete. In this talk, we first give a brief overview on the theory of Grobner bases (as well as of staggered linear bases) and then present a simple algorithm for computing staggered linear bases.

https://zoom.us/join
Meeting ID: 9086116889
Passcode: 362880

28 FEB 2023
09:00 - 16:00

The workshop will aim to improve the ethical aspects of using animals for scientific purposes and improve the research integrity of preclinical studies.
The series of workshops are being started from 28/2/2023 and
Access: Free
Content type: Theoretical and practical
For more information, call the number below
26113274

28 FEB 2023
14:00 - 15:00

Date and time

Tuesday, 28th of February 2023 (9th of Esfand, 1401), 2:00 pm (Tehran zone)



Link

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



Abstract

Based on spacetime emergence from quantum entanglement, a new complex-valued quantum information measure will be introduced. This quantity will be defined through either the Wick rotation of space to timelike subregions or through the Wick rotation of the coordinates. We argue that this quantity is an example of pseudo entanglement entropy. For holographic states, we define the timelike entanglement entropy as the total complex valued area of a particular stationary combination of both space and timelike extremal surfaces which are homologous to the boundary subregion. We find an explicit matching of our optimization procedure and the careful implementation of the Wick rotation in the boundary CFT in the considered examples. Finally, a relation between this quantity and holographic pseudo entropy in de Sitter space will be addressed.