30 JUL 2025
11:00 - 12:00

Abstract:

Collinear parton distribution functions (cPDFs) and transverse momentum dependent distributions (TMDs) are essential for calculating cross sections in high-energy physics, particularly within collinear and -factorization frameworks. Currently, there exists two libraries, such as LHAPDF and TMDLib, to obtain these physical objects. However, there are limitations in both libraries, especially for TMDs, such as restricted customization and extensibility. Users are limited to the implementations provided by these libraries and cannot easily support unconventional PDFs. Additionally, no standard TMD library currently supports calculations of QCD coupling and uncertainties, which are crucial for precise phenomenological studies. To address these shortcomings, we introduce PDFxTMDLib, a modern C++ library designed to offer a robust and flexible solution. This library supports both collinear PDFs and TMDs while allowing greater customization. It also opens the way to support higher-order distributions. In this article, we describe the structure of PDFxTMDLib. We also demonstrate its validity and performance by integrating it into the PYTHIA Monte Carlo event generator to compute Drell-Yan cross sections. Additionally, comparisons of PDFs obtained from PDFxTMDLib with those from LHAPDF.and TMDLib confirm the reliability of PDFxTMDLib's results.

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

Meeting Place:
Virtual Format

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

30 JUL 2025
14:00 - 15:00

We have considered the spin-1/2 XXZ chain model which is exactly solvable with the Bethe anzats method. It is shown adding a single defect away from edges is sufficient to see a chaos signature in the model. In this work, we have studied the time behavior of the Loschmidt-echo (LE) by considering domain-wall and Neel states as two product initial states and also a Bell state as an entangled initial state. We have used the numerical full diagonalization method to have full spectrum of the model. It is shown that very short times behavior of the LE is independent from defect and initial state, and the decay is quadratic. Moreover, results show that in the chaotic regime and for intermediate times, the exponential decay behavior of the LE shows some changes by removing defect from the chain in the domain-wall and Bell states, while no changes is seen in the Neel state. To get some intuition of these changes, we have addressed the relation between the dynamics of the LE and the local density of states features..

Based on : https://iopscience.iop.org/article/10.1088/1402-4896/ab0582


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

29 JUL 2025
14:00 - 15:00

Date and time

Tuesday, July 29th, 2025 (7 Mordad), 2:00 pm (Tehran zone)




Link

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


Abstract
The ATOMKI collaboration measured excesses in electron-positron production from nuclear transitions of beryllium, helium and carbon nuclei. All these excesses are compatible with the emission of a new boson with mass around 17 MeV, denoted X17. An independent search for this particle, harnessing a particle physics experiment, was performed at the Positron Annihilation into Dark Matter Experiment (PADME), where a positron beam collided against a diamond target expecting to produce resonantly the X17 particle. Given the presumably narrow width of this particle, a precise theoretical computation of the signal shape was required to account for electron motion within the target. After including the theoretical modelling of this effect in their analysis, the PADME collaboration has reported an excess in electron-positron events centered around 17 MeV. This excess was later independently shown to largely reduce the uncertainty on the expected X17 mass when combined with nuclear observables. As a byproduct of these studies, electron motion in large Z materials has been shown to enhance centre-of-mass energy in fixed-target experiments and allow for a new energy scan mechanism relevant for the measurement of the hadronic vacuum polarization contribution to the muon anomalous magnetic moment.

28 JUL 2025
11:00 - 12:00

Abstract:

In this talk, I will present a recent paper from the STAR Collaboration, which reports the first observation of a positive spin correlation between Lambda and anti-Lambda hyperon pairs. This finding provides a direct link, via quantum entanglement, between the spin-entangled strange quark pairs of the QCD vacuum and their final-state hadron counterparts, offering crucial insights into the behavior of matter at its most fundamental level.

Based on:
https://arxiv.org/abs/2506.05499

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

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

22 JUL 2025
11:00 - 12:00

Date and time

Tuesday, July 22nd, 2025 (31 Tir), 11:00 AM (Tehran zone)




Link

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


Abstract


This talk addresses the intersection of physics at the smallest and largest scales, where quantum mechanics meets cosmology. We highlight the relevance of this interplay to foundational problems in both cosmology and high energy physics. Our discussion spans the potential quantum features manifesting at galactic or cosmological scales, as well as the role of quantum interferometry in enabling ultra-sensitive measurements in high-energy experiments. These experimental advances not only push the boundaries of precision measurement (such as the detection of gravitational waves), but also open promising avenues for probing quantum aspects of gravity, one of the most profound unresolved questions in theoretical physics.

21 JUL 2025
11:00 - 12:00

Abstract:

Inspired by the “What is…?” column in the Notices of the AMS, this talk provides an informal, nontechnical overview of the core ideas behind different characterizations of anomalies. In the first part, I will briefly survey several mathematical perspectives on the classification and characterization of anomalies in quantum field theories. The second part of the talk focuses on the specific example of the conformal anomaly in two dimensions, illustrating the general concepts with explicit computations and highlighting connections to 2D induced gravity and the AdS_3/CFT_2 correspondence where appropriate.



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

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

16 JUL 2025
14:00 - 15:00

We study the impact of noise on the dynamics of entanglement in the transverse-field Ising chain, with the field quenched linearly across one or both of the quantum critical points of the model. Taking concurrence as a measure of entanglement, we find that a quench generates entanglement between nearest- and next-nearest-neighbor spins, with noise reducing the amount of entanglement. Focusing on the next nearest-neighbor concurrence, known to exhibit Kibble-Zurek scaling with the square root of the quench rate in the noiseless case, we find a different result when noise is present: The concurrence now scales logarithmically with the quench rate, with a noise-dependent amplitude. This is also different from the anti-Kibble-Zurek scaling of defect density with quench rate when noise is present, suggesting that noisy entanglement generation is largely independent from the rate of defect formation. Intriguingly, the critical time scale beyond which no entanglement is produced by a noisy quench scales as a power law with the strength of noise, with the same exponent as that which governs the optimal quench time for which defect formation is at a minimum in a standard quantum annealing scheme.

Based on : https://doi.org/10.48550/arXiv.2503.03584


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

16 JUL 2025
11:00 - 12:00

Abstract:

Understanding the fundamental nature of dark matter remains one of the most profound challenges in modern physics. In this talk, I will present how cosmic birefringence—the rotation of the polarization plane of Cosmic Microwave Background (CMB) photons—can serve as a sensitive probe of dark matter phenomenology. I will focus on theoretical frameworks in which dark matter candidates, such as sterile neutrinos, dipolar dark matter, or axion-like fields, induce parity-violating effects that manifest as measurable birefringence. These signatures offer a unique observational window into the interactions between dark matter and Standard Model particles, providing constraints that are complementary to those from conventional direct and indirect detection methods.

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


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

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

15 JUL 2025
14:00 - 15:00

Date and time

Tuesday, July 15th, 2025 (24 Tir), 2:00 pm (Tehran zone)




Link

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


Abstract

In this talk, I will explain a model of warm inflation driven by axion-like particles interacting with $U(1)$ gauge fields, with implications for the early universe's thermal evolution. By extending traditional warm inflation models, we introduce a dissipation mechanism through the thermal fluctuations of electromagnetic fields, leading to a non-trivial backreaction on the inflaton's dynamics. Our results are consistent with CMB observations, even for a natural sub-Plankian Axion decay constant $f

14 JUL 2025
11:00 - 12:00

Abstract:

There is a wide variety of fixed points in many-body quantum systems, including thermal and non-thermal fixed points. These fixed points are characterized by specific exponents and scaling relations. Recently, it has been proposed that relativistic hydrodynamic equations can describe the evolution of fluctuations near non-thermal fixed points far from equilibrium. In this talk, we will first review some fundamental concepts of fixed points and their emergence through renormalization group equations. We will then explore the hydrodynamic equations applicable to these cases.

Based on:
https://doi.org/10.48550/arXiv.2504.18754

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

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

25 JUN 2025
18:00 - 19:30

Date and time,


6-7:30pm, Wednesday 25 June 2025 (4 Tir 1404)


Venue: Online



Link

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



Abstract


Gamma Ray Bursts (GRBs) and Cosmic Rays (CRs) are easily understandable. Solid observations of quasars and micro-quasars show how these objets emit “Cannonballs” (CBs), though the underlying mechanisms are not theoretically well understood. The assumption that core-collapse supernovae emit CBs plus some trivial relativistic kinematics provide a successful understanding of GRBs and CRs. The self-defined “official experts” on these fields resist the evidence, in an explicitly inquisitorial way.

16 JUN 2025
16:00 - 18:00

Some Considerations on the Internal Approach to Interpreting Physical Theories

15 JUN 2025
16:00 - 17:30

12 JUN 2025
14:00 - 16:00

The automorphism group of a countable first-order structure naturally carries the topology of pointwise convergence. In certain cases, this topology can be used to recover/reconstruct the structure up to bi-interpretability. However, it is not the only group topology of interest. In this talk, we explore various group topologies on automorphism groups - particularly minimal group topologies - with a special emphasis on the Zariski topology. This is joint work with Javier de la Nuez González.

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

11 JUN 2025
11:00 - 12:00

Abstract:

In this talk, I will present a series of studies where I explore the quantum properties of gravitational cats (so-called gravcats) modeled by interacting qubits under a variety of physical conditions. My focus is on understanding how gravcats can preserve quantum correlations in the presence of thermal noise, gravitational interactions, and different environmental decoherence mechanisms. I then extend this investigation to more general environments, including classical stochastic, correlated dephasing channels, and power-law noise, as well as weak measurement interventions. These results show that gravcats serve as robust resources for maintaining quantum correlations, particularly in non-Markovian regimes where information backflow can delay decoherence. Altogether, these works contribute new insights into how gravcats can function as reliable carriers of quantum information and highlight the nuanced interplay between gravity, noise, and quantumness in open quantum systems.


Based on:
1. https://journals.aps.org/prd/abstract/10.1103/PhysRevD.111.064077
2. https://www.nature.com/articles/s41598-025-03593-5
3. https://link.springer.com/article/10.1140/epjc/s10052-024-13034-8


Indico Link:
https://indico.hep.ipm.ir/e/S.Haddadi1

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

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