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.

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

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

Link: http://qpm.ipm.ac.ir/