20 FEB 2025
-

Winter school on Physics of Complex Fluids (PCF)
School of Physics, IPM
February 19-20, 2025 (Esfand 1-2, 1403)


The Winter School on Complex Fluids aims to enhance the knowledge of postdoctoral researchers and graduate students, particularly at the doctoral level, in the physics of fluids and complex systems. This program provides an in-depth exploration of the physics of complex fluids and hydrodynamic phenomena in soft and dispersed materials, delivering a solid foundation in these fields. The school covers a diverse range of materials with physical and mechanical properties between those of liquids and solids, including macromolecules (e.g., polymers in solution or melt, liquid crystals), suspensions, dispersions (colloids, emulsions, foams, immersed granular materials), dry granular materials, biological fluids, and self-assembling fluids like surfactants. These systems have applications in numerous scientific and industrial fields.

The curriculum combines experimental techniques with theoretical research to uncover fundamental mechanisms governing the dynamics of complex fluids. Participants will also gain practical experience with measurement techniques for dynamic and static parameters and explore simulation methods for modeling natural and industrial systems. Additionally, the school emphasizes applied fluids, addressing critical challenges in energy transition and biological sciences.







The deadline for registration is 3th of February, 2025 (15 Bahman, 1403).

20 FEB 2025
14:00 - 16:00

We will introduce a class of models of Axiom of Determinacy that we call Nairian Models and will explain their role in set theory.

Zoom room information:
https://us06web.zoom.us/j/81916335336?pwd=5zQT4lutMiBoY5Xp1pkFGtbqiaGozg.1
Meeting ID: 819 1633 5336
Passcode: 559618
Venue: Niavaran, Lecture Hall 1

19 FEB 2025
-

Winter school on Physics of Complex Fluids (PCF)
School of Physics, IPM
February 19-20, 2025 (Esfand 1-2, 1403)


The Winter School on Complex Fluids aims to enhance the knowledge of postdoctoral researchers and graduate students, particularly at the doctoral level, in the physics of fluids and complex systems. This program provides an in-depth exploration of the physics of complex fluids and hydrodynamic phenomena in soft and dispersed materials, delivering a solid foundation in these fields. The school covers a diverse range of materials with physical and mechanical properties between those of liquids and solids, including macromolecules (e.g., polymers in solution or melt, liquid crystals), suspensions, dispersions (colloids, emulsions, foams, immersed granular materials), dry granular materials, biological fluids, and self-assembling fluids like surfactants. These systems have applications in numerous scientific and industrial fields.

The curriculum combines experimental techniques with theoretical research to uncover fundamental mechanisms governing the dynamics of complex fluids. Participants will also gain practical experience with measurement techniques for dynamic and static parameters and explore simulation methods for modeling natural and industrial systems. Additionally, the school emphasizes applied fluids, addressing critical challenges in energy transition and biological sciences.


The deadline for registration is 3th of February, 2025 (15 Bahman, 1403).

19 FEB 2025
11:00 - 12:00

Abstract:

We revisit the canonical quantization of free bosonic closed string theory and observe that the physicality of states requires vanishing of the worldsheet Virasoro algebra generators sandwiched between any two physical states. This requirement yields four classes of physical states, depending on discrete worldsheet symmetries: parity and time reversal. The usual string states which are highest weight states of the Virasoro algebra, preserve both, while the other new three classes break one or both. We initiate the quantization of a null p-brane in light-cone gauge using the idea of sandwich quantum constraints and show that solutions to the sandwich conditions are classified into p+1 distinct classes, which we completely specify.

Indico Link:
https://indico.hep.ipm.ir/e/i.rasulian

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

Link to Join Virtually:
https://www.skyroom.online/ch/ipm-particles/weekly-seminar

19 FEB 2025
17:30 - 19:00

We discuss construction of a derived Lagrangian intersection theory of moduli spaces of perfect complexes, with support on divisors on compact Calabi Yau threefolds. Our goal is to compute deformation invariants associated to a fixed linear system of divisors in CY3. We apply a Tyurin degeneration of the CY3 into a normal-crossing singular variety composed of Fano threefolds meeting along their anti-canonical divisor. We show that the moduli space over the Fano 4 fold given by total space of degeneration family satisfies a relative Lagrangian foliation structure which leads to realizing the moduli space as derived critical locus of a global (-1)-shifted potential function. We construct a flat Gauss-Manin connection to relate the periodic cyclic homology induced by matrix factorization category of such function to the derived Lagrangian intersection of the corresponding ?Fano moduli spaces?. The later provides one with categorification of DT invariants over the special fiber (of degenerating family). The alternating sum of dimensions of the categorical DT invariants of the special fiber induces numerical DT invariants. If there is time, we show how in terms of ?non-derived? virtual intersection theory, these numerical DT invariants relate to counts of D4-D2-D0 branes which are expected to have modularity property by the S-duality conjecture. This talk is based on joint work with Ludmil Katzarkov and Maxim Kontsevich, recent work with Jacob Krykzca, and former work with Vladimir Baranovsky.

https://zoom.us/join
Meeting ID: 9086116889
Passcode: 362880
Website: http://math.ipm.ac.ir/agnt/
Venue: Niavaran, Lecture Hall 1

19 FEB 2025
15:30 - 17:00

The pants graph of a compact orientable surface S, introduced by Hatcher and Thurston, is a simplicial graph whose vertices are maximal essential multicurves on S and whose edges correspond to certain local moves on multicurves. The importance of the pants graph comes from a theorem of Brock showing that the pants graph is a good combinatorial model for the Teichmuller space with the Wiel-Petersson metric, which is the space of hyperbolic metrics on S up to isotopy. In joint work with Marc Lackenby, we give upper bounds for distance in the pants graph and derive applications for distance in the Teichmuller space and also for volumes of hyperbolic 3-manifolds. I will give an overview of these results, no prior familiarity with the Teichmuller is needed for the talk.

Online via Zoom:
Meeting ID: 908 611 6889
Passcode: 362880
Venue: Niavaran, Lecture Hall 1

19 FEB 2025
14:00 - 15:00

Many combinatorial optimization problems have been studied in the prize collecting setting, where the coverage requirement for an entity can be relaxed by paying a predefined penalty. This resembles the classical Lagrangian relaxation, and is natural in many practical applications. In this talk we discuss approximation algorithms for the prize-collecting version of the Traveling Salesman Problem (TSP) and some of its generalizations.

Zoom room information:
https://us06web.zoom.us/j/84906984159?pwd=BCWaIbXBuku3A5I84zNg9mHFxVZjXD.1
Meeting ID: 849 0698 4159
Passcode: 362880
Venue: Niavaran, Lecture Hall 1

19 FEB 2025
14:00 - 15:00

Cancer cells exhibit a high degree of plasticity, a characteristic that enables them to adapt and thrive in diverse environments. This plasticity is closely linked to stemness, with cancer cells possessing stem-like properties often displaying enhanced invasion, proliferation, and resistance to conventional therapies. Differentiation therapy offers a promising strategy to target this unique feature by inducing cancer cells to mature into less malignant, more functional states. By reducing their stemness, tumorigenic potential, and likelihood of resistance, differentiation therapy creates a more favorable context for integration with conventional cancer treatments such as chemotherapy and radiotherapy, paving the way for improved therapeutic outcomes.



This Seminar is free, hybrid, and open to the public.

You can join with this link:

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

18 FEB 2025
11:00 - 13:00

Low-mass dense cores are known as the birthplace of low-mass stars. In this study, we concentrate on Isothermal, low-mass clouds that experience quasi-static contraction, a slow and gradual process that allows the system to maintain near-equilibrium conditions. We specifically analyze steady-state spherically symmetric, magnetized clouds containing a central protostar, with gas accreting onto it from the cloud’s outer boundary. We aim to elucidate the effects of magnetic fields and spherical symmetry on the gas accretion in these clouds. In our analysis, we consider the magnetic field to be toroidal. By incorporating the parameter λ, which represents the ratio of magnetic pressure to gas pressure, we can effectively evaluate the influence of this toroidal magnetic field on the gas accretion processes within these clouds. Our results show that roughly 30% of the cloud’s radius exhibits supersonic motion, with approximately half of the cloud’s mass accumulating within this region. Furthermore, the sonic point’s expansion speed varies between and the mass accretion rates varies from , reflecting the values considered in this study. The toroidal magnetic field is found to be insufficient in suppressing high mass accretion rates, implying the involvement of additional factors in regulating gas accretion onto the central star.
Keywords: Sonic transition, Low-mass star formation, Magnetic field effects

To join the seminar, please click on the following link


https://www.skyroom.online/ch/soa/weekly-seminar

18 FEB 2025
14:00 - 15:00

Date and time

Tuesday, February 18th, 2025 (Bahman 30th, 1403), 2:00 pm (Tehran zone)




Link

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


Abstract
Within the relativistic field theory, CPT is proved to be conserved. However, CP can be broken. The violation of CP can induce electric dipole moment for elementary fermions. Indeed, CP is broken in the Standard Model (SM) of particles. However, the predicted value of the electron electric dipole moment within the SM is too small to be resolvable by present and upcoming experiments. In this talk after a short review of the phenomenological impact of CV-violation, I will discuss our project on the CP-violation carried out in collaboration with late Prof. Demir.

17 FEB 2025
11:00 - 12:00

Abstract:

Atomic nuclei are self-organized, many-body quantum systems bound by strong nuclear forces within femtometer-scale space. These complex systems manifest a variety of shapes, traditionally explored using non-invasive spectroscopic techniques at low energies. However, at these energies, their instantaneous shapes are obscured by long-timescale quantum fluctuations, making direct observation challenging. Here we introduce the collective flow assisted nuclear shape imaging method, which images the nuclear global shape by colliding them at ultrarelativistic speeds and analyzing the collective response of outgoing debris. This technique captures a collision-specific snapshot of the spatial matter distribution within the nuclei, which, through the hydrodynamic expansion, imprints patterns on the particle momentum distribution observed in detectors. We benchmark this method in collisions of ground state Uranium-238 nuclei, known for their elongated, axial-symmetric shape. Our findings show a large deformation with a slight deviation from axial symmetry in the nuclear ground state, aligning broadly with previous low-energy experiments. This approach offers a new method for imaging nuclear shapes, enhances our understanding of the initial conditions in high-energy collisions and addresses the important issue of nuclear structure evolution across energy scales.

Based on:
Nature 635, 67-72 (2024)

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

Link to Join Virtually:
https://www.skyroom.online/ch/ipm-particles/journal-club

12 FEB 2025
15:30 - 17:30

This lecture is a continuation of the lecture of about a year ago with the same title. No familiarity with the last lecture will be assumed and the emphasis will be on topics that were not discussed in the previous lecture and have some novelty.
Venue: Niavaran, Lecture Hall 1

11 FEB 2025
14:00 - 15:00

Date and time

Tuesday, February 11th, 2025 (Bahman 23rd, 1403), 2:00 pm (Tehran zone)




Link

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


Abstract
The cosmological upper bound on the total neutrino mass is the dominant limit on this fundamental parameter. Recent observations have strongly tightened it, approaching the lower limit set by oscillation data. Understanding its physical origin, robustness, and model-independence becomes pressing. In this seminar I will introduce a novel framework to explicitly separate for the first time the two distinct cosmological neutrino-mass effects. On the one hand, the impact on background evolution, related to the energy in neutrino masses; on the other hand, the "kinematic" impact on perturbations, related to neutrino free-streaming. I will didactically explain how these effects separately modify CMB anisotropies, by introducing two effective masses enclosing background and perturbations effects. I will explain the results of analyzing CMB data in this framework, which show that the neutrino-mass bound is mostly a background measurement, i.e., how the neutrino energy density evolves with time. The results also quantify the difficulty of measuring the neutrino "kinematical" mass, whose bound is relaxed by 3 orders of magnitude.

6 FEB 2025
14:00 - 16:00



Zoom room information:
https://us06web.zoom.us/j/81916335336?pwd=5zQT4lutMiBoY5Xp1pkFGtbqiaGozg.1
Meeting ID: 819 1633 5336
Passcode: 559618
Venue: Niavaran, Lecture Hall 1