3 SEP 2025
14:00 - 15:00

Investigation of heat transport in micro/nanoscale semiconductor structures owing to their application especially in transistor technology, is a matter of interest. There exist atomistic and phenomenological macroscopic methods for heat transport study in semiconductor nanodevices. The atomistic models are more complicated, computationally expensive and simultaneously very accurate. Meanwhile, the macroscopic heat transfer models in support of less computational cost and acceptable but not very precise results, are introduced. The Dual Phase Lag (DPL) model presenting two phase lags, is one of the popular macroscopic schemes. It is obtained that using the DPL model for studying the temperature and heat flux behavior through the nanostructures, results in data which are almost near to that of the atomistic phonon Boltzmann equation (PBE). The present study tries to justify why DPL results are not very accurate and introduces the non-locality as a solution. The studied case is a silicon MOSFET. It is obtained that implementing the non-locality in heat flux is “the missing piece of the puzzle”. While the conventional DPL presents not perfect but almost good results for high Knudsen number systems, including the non-locality makes the results, also for High Kn numbers, very close to that of the PBE data. The newly non-dimensional parameter γ, presenting the strength of the nonlocality, is utilized through the nonlocal DPL modeling. The factor γ is found to have a linear relationship with Knudsen (Kn) number, being 3.5 and 1.5 for Kn=10 and also 0.035 and 0.015 for Kn=0.1, respectively, in one/two dimension. Hence, it is obtained that intruding γ is critical for obtaining accurate temperature and heat flux distributions that are very close to the practical results of the Phonon Boltzmann equation. .




Venue: Room D, 3rd Floor, Farmanieh Building, IPM
Link: https://vmeeting2.ipm.ir/b/nan-gkn-wmh-exh

27 AUG 2025
11:00 - 12:00

Abstract:

We consider the running coupling constant in holographic models supported by Einstein-dilaton-Maxwell action for heavy and light quarks. To obtain the dependence of the running coupling constant α on temperature and chemical potential we impose boundary conditions on the dilaton field that depend on the position of the horizon. We use two types of boundary conditions: a simple boundary condition with the dilaton field vanishing at the horizon and a boundary condition that ensures an agreement with lattice calculations of string tension between quarks at zero chemical potential. The location of the first order phase transitions in the (mu,T)-plane does not depend on the dilaton boundary conditions for light and heavy quarks. At these phase transitions, the function α undergoes jumps depending on temperature and chemical potential. We also show that for the second boundary conditions the running coupling decreases with a temperature increase, and the dependence on temperature and chemical potential both for light and heavy quarks is actually specified in quark-gluon plasma (QGP) phase by functions of one variable, demonstrating in this sense automodel behavior.

Indico Link:
https://indico.hep.ipm.ir/e/A.Hajilo

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

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

27 AUG 2025
14:00 - 15:00

Quantum batteries are an emerging concept at the intersection of quantum physics and energy technology. In this talk, I will present a simple but powerful scheme for a cavity-based quantum battery, where an atom interacts with a cavity under a structured environment. I will show how the presence or absence of environmental memory can dramatically affect the charging process. Remarkably, memory-assisted environments enable the battery to store more energy and deliver more useful work than memory-less ones. Beyond the theoretical results, I will also discuss the physical feasibility of realizing such systems in modern quantum optics laboratories, pointing to a future where quantum-enhanced energy storage may become practical.

Based on : https://advanced.onlinelibrary.wiley.com/doi/abs/10.1002/qute.202400115


Venue: Room D, 3rd Floor, Farmanieh Building, IPM
Link: https://vmeeting2.ipm.ir/b/nan-gkn-wmh-exh

25 AUG 2025
11:00 - 12:00

Abstract:

In modern collider experiments, the quest to explore fundamental interactions between elementary particles has reached unparalleled levels of precision. Signatures from particle physics detectors are low-level objects (such as energy depositions or tracks) encoding the physics of collisions (the final state particles of hard scattering interactions). The complete simulation of them in a detector is a computational and storage-intensive task. To address this computational bottleneck in particle physics, alternative approaches have been developed, introducing additional assumptions and trade off accuracy for speed. The field has seen a surge in interest in surrogate modeling the detector simulation, fueled by the advancements in deep generative models. This talk will focus on using deep generative models as a surrogate for traditional event generators and detector simulators.

Based on:
https://doi.org/10.1016/j.revip.2024.100092

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

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

20 AUG 2025
14:00 - 15:00

This talk explores extreme near-field thermal transport between two parallel plates made of silica (SiO2) and gold, with gap distances ranging from approximately 0.5 nm to 2 nm. While recent experiments have shown that several orders of magnitude can enhance radiative heat flux between planar surfaces at gaps around 10 nm, the regime of sub-10 nm separations remains largely unexplored. Here, non-equilibrium molecular dynamics (NEMD) simulations are employed to investigate heat transfer between silica plates in both amorphous and crystalline forms, as well as between two planar gold surfaces. The simulation results are compared with predictions from fluctuational electrodynamics, showing generally good agreement- particularly for larger gap sizes. By performing a spectral analysis of the heat transfer coefficients across a range of temperatures, we identify the contributions of different transport modes and provide new insights into the mechanisms governing nanoscale energy transfer. These findings offer valuable guidance for future experimental and theoretical studies in extreme near-field heat transfer.




Venue: Room D, 3rd Floor, Farmanieh Building, IPM
Link: https://vmeeting2.ipm.ir/b/nan-gkn-wmh-exh

20 AUG 2025
11:00 - 12:00

Abstract:

This talk investigates the production of Z bosons in proton-lead collisions at a center of mass energy of $\sqrt{s} = 8.16 TeV$, utilizing various transverse momentum dependent parton distribution functions (TMDs), including the leading order Martin-Ryskin-Watt (LO-MRW), next-to-leading order MRW (NLO-MRW), and parton branching (PB) approaches. By comparing theoretical predictions with experimental data from the CMS collaboration, we assess the performance of these TMD models across different kinematic regions. Our analysis reveals that while both LO-MRW and NLO-MRW models generally align well with experimental data, the LO-MRW model tends to overestimate in certain kinematic regions. The NLO-MRW model, with its strong ordering constraint, provides better agreement in these areas. This study highlights the impact of different impositions of angular and strong ordering constraints in the LO-MRW and NLO-MRW approaches in describing Z boson production.

Indico Link:
https://indico.hep.ipm.ir/e/S.Rezaei

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

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

19 AUG 2025
14:00 - 15:00

Date and time

Tuesday, August 19, 2025 (28 Mordad), 2:00 pm (Tehran time)




Link

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


Abstract
Parton Distribution Functions (PDFs) are key to understanding the momentum and spin distributions of fundamental particles inside the nucleon, and their precise determination is crucial for rigorous tests of the Standard Model and for predicting outcomes in high-energy collider experiments. In this study, we employ Gegenbauer polynomials—a set of orthogonal polynomials with strong convergence properties and superior ability to model the detailed shape of distributions—to parameterize the polarized parton distribution functions (PPDFs). These polynomials are defined by two key parameters, and by fitting experimental data, unknown parameters are extracted that provide deeper insights into the proton’s structure.
By analyzing comprehensive datasets, especially the final JLAB CLAS/EG1b data for proton and deuteron, the essential role of higher twist effects in accurately determining the PPDFs is demonstrated. The polarized structure functions of the proton, neutron, and deuteron are studied at NLO accuracy, both with and without considering higher twist effects. Additionally, the polarized Bjorken sum rule and proton helicity sum rule are examined to validate the fitting results. The findings show strong agreement with existing data and various parameterization models, indicating that this approach effectively decodes the complex structure of the nucleon and opens new horizons in understanding the behavior of fundamental particles at high energies.

13 AUG 2025
11:00 - 12:00

Abstract:

Higher harmonic cavities are widely used in low-emittance and high-current synchrotron storage rings to increase the stored beam's lifetime and vanish the coupled bunch instabilities. These parameters have an essential effect on the quality of synchrotron radiation and the machine's stability. Higher harmonic cavities of the Iranian light source facility are passive, capacitive-loaded structures designed to operate at 300 MHz. These cavities can operate in the beam current range of 50 to 400 mA. This presentation comprehensively discusses analytical calculations and simulations of beam dynamics, electromagnetic, thermomechanical, and vacuum aspects of the Iranian Light Source Facility's higher harmonic cavities. The engineering drawings are finalized after many technical discussions according to the presented results, and the fabrication process of the higher harmonic cavity has been started accordingly. The low-power RF measurement results of the first developed prototype will be reported in the final section.

Indico Link:
https://indico.hep.ipm.ir/e/Sadeghipanah1

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

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

13 AUG 2025
14:00 - 15:00

Entanglement and quantum coherence have pivotal roles in the recent era of quantum technology. However, these unique quantum features are very fragile to inevitable system-environment interaction and decay very fast. Hence, there has been a long-standing debate on finding the procedures to diminish or ideally wash out such deleterious effects. Over the years, the many different approaches have been developed for this purpose, from quantum feedback control to optimal control theory. At the first part of the talk, we establish our general scheme, referred to as process-based optimal control, to control optimally the destructive effects of environment on the dynamics of an open system. This state-independent framework enables us to reexamine the important problems in quantum technology from a different perspective including gate simulation, system-environment decoupling and indirect environment engineering. At the second part, we introduce some quantum features such as purity and coherence of a quantum dynamics/process. By using these properties, we construct a feature-based approach to increase the purity and coherence of an open system dynamics at a given final time.




Venue: Room D, 3rd Floor, Farmanieh Building, IPM
Link: https://vmeeting2.ipm.ir/b/nan-gkn-wmh-exh

12 AUG 2025
14:00 - 15:00

Date and time

Tuesday, August 12, 2025 (21 Mordad), 2:00 pm (Tehran time)




Link

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


Abstract
We entertain the possibility that transient astrophysical sources can produce a flux of dark particles that induce ultra-high-energy signatures at neutrino telescopes such as IceCube and KM3NeT. We construct scenarios where such “dark flux” can produce meta-stable dark particles inside the Earth that subsequently decay to muons, inducing through-going tracks in large-volume neutrino detectors. We consider such a scenario in light of the O(70) PeV ultra-high-energy muon observed by KM3NeT and argue that because of its location in the sky and the strong geometrical dependence of the signal, such events would not necessarily have been observed by IceCube. Our model relies on the upscattering of a new particle X onto new metastable particles that decay to dimuons with decay lengths of O(100) km. This scenario can explain the observation by KM3NeT without being in conflict with the IceCube data.