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Thermalization at the femtoscale seen in high-energy Pb+Pb collisions

Physical Review C 2024年第5期109卷 L051902-L051902页

作者： Rupam Samanta Somadutta Bhatta Jiangyong Jia Matthew Luzum Jean-Yves Ollitrault AGH University of Science and Technology Faculty of Physics and Applied Computer Science Aleja Mickiewicza 30 30-059 Cracow Poland Université Paris Saclay CNRS CEA Institut de Physique Théorique 91191 Gif-sur-Yvette France Department of Chemistry Stony Brook University Stony Brook New York 11794 USA Physics Department Brookhaven National Laboratory Upton New York 11976 USA Instituto de Física Universidade de São Paulo Rua do Matão 1371 Butantã 05508-090 São Paulo Brazil

A collision between two atomic nuclei accelerated at a speed close to that of light creates a dense system of quarks and gluons. Interactions among them are so strong that they behave collectively like a droplet of fluid of ten-femtometer size, which expands into the vacuum and eventually fragments into thousands of particles. We report a new manifestation of thermalization in recent data from the Large Hadron Collider. Our analysis is based on results from the ATLAS Collaboration, which has measured the variance of the momentum per particle across Pb+Pb collision events with the same particle multiplicity. This variance decreases steeply over a narrow multiplicity range corresponding to central collisions. We provide a simple explanation of this newly observed phenomenon: For a given multiplicity, the momentum per particle increases with increasing impact parameter. Since a larger impact parameter goes along with a smaller collision volume, this in turn implies that the momentum per particle increases as a function of density, which is a generic consequence of thermalization. Our analysis provides the first direct evidence of this phenomenon at the femtoscale.

关键词： Charged-particle multiplicity Collective flow Particle correlations & fluctuations Quark-gluon plasma

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Enhanced Emotion Recognition Using a Hybrid Autoencoder-LSTM Model Optimized with a Hybrid ACO-WOA Algorithm for Hyperparameter Tuning

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International Journal of Advanced computer science and Applications 2025年第4期16卷 861-876页

作者： Waiker, Vinod Ramesh, Janjhyam Venkata Naga Bala, Ms Kiran Krishnaiah, V.V. Jaya Rama Jackulin, T. Muniyandy, Elangovan Shahin, Osama R. Datta Meghe Institute of Management Studies Maharashtra Nagpur India Department of CSE Graphic Era Hill University Dehradun248002 India Department of CSE Graphic Era Deemed To Be University Uttarakhand Dehradun248002 India Department of Computer Science College of Engineering and Computer Science Jazan University Jazan Saudi Arabia Department of Computer Science and Engineering Koneru Lakshmaiah Education Foundation Andhra Pradesh Vaddeswaram India Department of CSE Panimalar Engineering College Tamil Nadu Chennai India Department of Biosciences-Saveetha School of Engineering Saveetha Institute of Medical and Technical Sciences Chennai602 105 India Applied Science Research Center Applied Science Private University Amman Jordan Department of Computer Science College of Computer and Information Sciences Jouf University Saudi Arabia Physics and Mathematics Department Faculty of Engineering Helwan University Helwan Egypt

Emotion recognition is vital in the human computer interaction because it improves interaction. Therefore, this paper proposes an improved method for emotion recognition regarding the Hybrid Autoencoder-Long Short-Term Memory (LSTM) model and the newly developed hybrid approach of the Ant Colony Optimization (ACO) and Whale Optimization Algorithm (WOA) for hyperparameters tuning. In this case, Autoencoder can reduce input data dimensionality for input data and find the features relevant for the model’s work. In addition, LSTM is able to work with temporal structures of sequential inputs like speech and videos. The contribution of this research lies in the novel combination method of ACO-WOA which aims at tweaking hyperparameters of Autoencoder-LSTM model. Global aspect of ACO and WOA thereby improve the search efficiency and the accuracy of the proposed emotion recognition system and its generalization capacity. In context with the benchmark dataset for the experimentations of emotion recognition, it has established the efficiency of the proposed model in terms of the conventional methods. Recall rates in recognitive intended various emotions and different modalities were also higher in the hybrid Autoencoder-LSTM model. The optimization algorithms like the ACO-WOA also supported in reducing the computational cost which arose due to hyperparameters tuning. The implementation of this paper is done through Python Software. This implementation shows a high accuracy of 94.12% and 95.94% for audio datasets and image datasets respectively when compared with other deep learning models of Conv LSTM and VGG16. Therefore, the research shows that the presented hybrid approach can be a useful solution for successfully employing emotion recognition for enhancing the creation of the empathetic AI systems and for improving user interactions within various fields including healthcare, entertainment, and customer support. © (2025), (science and Information Organization). All rights

关键词： Ant colony optimization

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Ultra-low power 10-bit 50-90 MSps SAR ADCs in 65 nm CMOS for multi-channel ASICs

arXiv

引用

arXiv 2023年

作者： Firlej, Miroslaw Fiutowski, Tomasz Idzik, Marek Moroń, Jakub Świentek, Krzysztof AGH University of Krakow Faculty of Physics and Applied Computer Science Al. Mickiewicza 30 Kraków30-059 Poland

The design and measurement results of ultra-low power, fast 10-bit Successive Approximation Register (SAR) Analog-to-Digital Converter (ADC) prototypes in 65 nm CMOS technology are presented. Eight prototype ADCs were designed using two different switching schemes of capacitive Digital-to-Analog Converters (DACs), based on MIM or MOM capacitors, and controlled by standard or low-power SAR logic. The layout of each ADC prototype is drawn in 60 um pitch to make it ready for multi-channel implementation. A series of measurements have been made confirming that all prototypes are fully functional, and six of them achieve very good quantitative performance. Five out of eight ADCs show both integral (INL) and differential (DNL) nonlinearity errors below 1 LSB. In dynamic measurements performed at 0.1 Nyquist input frequency, the effective number of bits (ENOB) between 8.9–9.3 was obtained for different ADC prototypes. Standard ADC versions work up to 80–90 MSps with ENOB between 8.9–9.2 bits at the highest sampling rate, while the low-power versions work up to above 50 MSps with ENOB around 9.3 bits at 40 MSps. The power consumption is linear with the sample rate and at 40 MSps it is around 400 μW for the low-power ADCs and just over 500 μW for the standard ADCs. At 80 MSps the standard ADCs consume about 1 mW. Copyright © 2023, The Authors. All rights reserved.

关键词： VLSI circuits

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Honeycomb antidot artificial lattice as a prototypical correlated Dirac fermion system

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Physical Review B 2023年第23期108卷 235119-235119页

作者： A. Biborski M. Zegrodnik P. Wójcik M. P. Nowak Academic Centre for Materials and Nanotechnology AGH University of Krakow Al. Mickiewicza 30 30-059 Krakow Poland Faculty of Physics and Applied Computer Science AGH University of Krakow Al. Mickiewicza 30 30-059 Krakow Poland

We study theoretically the electronic properties of the artificial quantum dot honeycomb lattice defined in a two-dimensional electron gas, focusing on the possibility of achieving a regime in which electronic correlations play a dominant role. At first, we establish a noninteracting model compatible with recently studied experimentally devices. According to the values of the obtained electron-electron interaction integrals, we postulate that the inclusion of inherent electron-gas self-screening is indispensable to reconstruct the experimental observations. Applying the Thomas-Fermi type of screening, we show that the radius of the antidot is crucial to achieve a correlated state in which phenomena like antiferromagnetic ordering and interaction-induced insulating state appear. We estimate the conditions for which the electronically correlated state in an artificial honeycomb lattice can be realized.

关键词： Antiferromagnetism Electronic structure Flat bands Bloch wave theory Electron-correlation calculations Free-electron model Hubbard model Materials modeling Tight-binding model Trial wave functions Variational approach Variational wave functional methods Wannier function methods

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Factorization breaking for higher moments of harmonic flow

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Physical Review C 2022年第3期105卷 034904-034904页

作者： Piotr Bożek Rupam Samanta AGH University of Science and Technology Faculty of Physics and Applied Computer Science Aleja Mickiewicza 30 30-059 Cracow Poland

We study correlations between harmonic flow vectors squared measured at different transverse momenta. One of the flow harmonics squared is taken at a fixed transverse momentum and correlated to the momentum-averaged harmonic flow squared of the same order. Such four-particle correlators, dependent on transverse momentum, have been recently measured experimentally. Factorization coefficients based on the ratio of such four-particle correlators allow the independent measurement of the flow vector and the flow magnitude factorization-breaking coefficient. Moreover, the correlation of the angles of flow harmonics as a function of transverse momentum can be extracted. Results are compared to preliminary data of the ALICE Collaboration. We also present predictions for the momentum-dependent factorization-breaking coefficient between mixed flow harmonics. The correlators with squares of mixed harmonics can serve as a way to independently measure the flow vector, the flow magnitude, and the flow angle correlations and could be used to gain additional information on the fluctuating initial state and the dynamics in heavy-ion collisions.

关键词： Collective flow Hydrodynamic models Particle correlations & fluctuations Relativistic heavy-ion collisions

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Enhanced Explanations for Knowledge-Augmented Clustering using Subgroup Discovery 10

Enhanced Explanations for Knowledge-Augmented Clustering usi...

引用

10th IEEE International Conference on Data science and Advanced Analytics, DSAA 2023

作者： Szelazek, MacIej Hudson, Dan Bobek, Szymon Nalepa, Grzegorz J. Atzmueller, Martin Agh University Faculty of Applied Computer Science Kraków Poland Institute of Applied Computer Science Jagiellonian University Jagiellonian Human-Centered Artificial Intelligence Laboratory Mark Kac Center for Complex Systems Research Kraków Poland Osnabrück University Semantic Information Systems Group Osnabrück Germany Osnabrück Germany

ISBN: (纸本)9798350345032

Contemporary machine learning techniques are capable of extracting complex structure from data in a way that complements or exceeds manual examination, yet, as is welldocumented, many of these techniques suffer from a lack of interpretability. This paper extends previous work on explainable and interpretable machine learning, in particular on the 'Knowledge-Augmented Clusters (KnAC)' approach, allowing human users to benefit from uninterpretable 'black box' models to extract structure from datasets by clustering and to make this better understandable. One of the key functions of KnAC is to relate expert-annotated clusters to clusters that have been identified by a machine learning method, and then provide a comprehensible explanation, thus clarifying the relationships that KnAC discovered. Our novel contribution in this paper is to examine the usefulness of subgroup discovery as a way to generate comprehensible explanations within KnAC, and to compare this to the existing approach based on the XAI algorithm Anchors through a detailed evaluation. We find that the approach using subgroup discovery performs equally or better in our extensive experimentation testing this on six different datasets. © 2023 IEEE.

关键词： Machine learning

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Chern-Simons gravitational term coupled to an isocurvature field

arXiv

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arXiv 2025年

作者： Orlando, Giorgio Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University Krakow30-348 Poland

The Chern-Simons gravitational term during inflation is usually coupled to the inflaton field. The resulting theory suffers from ghost-field formation in the tensor sector, which limits the observational effects of P-violation on cosmological correlators. In this work, we consider the Chern-Simons term coupled to an isocurvature component in a multi-field model of inflation. Since the resulting theory does not affect the quadratic action of tensor perturbations, ghost fields do not appear. This operator provides (P-violating) interactions between the isocurvature perturbation and the curvature and tensor perturbations. We show that combining these couplings with interactions between the curvature and isocurvature components coming from a turning trajectory, the resulting 〈sst〉PV non-Gaussianities can reach fNLsst,PV = BPVζζh(k, k, k)/Pζ2(k) ∼ O(1) within the parameter space of the theory. Our result motivates the systematic study of the Chern-Simons gravitational term coupled to isocurvature fields in multi-field models of inflation with couplings between the curvature and isocurvature fields or other mechanisms that transfer effects on the isocurvature field into the curvature field. Copyright © 2025, The Authors. All rights reserved.

关键词： Tensors

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Anisotropic, multiband, and strong-coupling superconductivity of the Pb0.64Bi0.36 alloy

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Physical Review B 2024年第21期110卷 214510-214510页

作者： Sylwia Gutowska Karolina Górnicka Paweł Wójcik Tomasz Klimczuk Bartlomiej Wiendlocha University of Vienna Faculty of Physics and Center for Computational Materials Science Kolingasse 14-16 A-1090 Vienna Austria AGH University of Krakow Faculty of Physics and Applied Computer Science Aleja Mickiewicza 30 30-059 Krakow Poland Materials Science and Technology Division Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA Faculty of Applied Physics and Mathematics and Advanced Materials Centre Gdansk University of Technology ul. Narutowicza 11/12 80-233 Gdańsk Poland

This paper presents theoretical and experimental studies on the superconductivity of Pb0.64Bi0.36 alloy, which is a prototype of strongly coupled superconductors and exhibits one of the strongest coupling under ambient pressure among the materials studied so far. The critical temperature, the specific heat in the superconducting state, and the magnetic critical fields are experimentally determined. Deviations from the single-gap s-wave BCS-like behavior are observed. The electronic structure, phonons, and electron-phonon interactions are analyzed in relation to the metallic Pb, explaining why the Pb-Bi alloy exhibits such a large value of the electron-phonon coupling parameter λ≃2. Superconductivity is studied using the isotropic Eliashberg formalism as well as the anisotropic density functional theory for superconductors. We find that while Pb is a two-gap superconductor with well-defined separate superconducting gaps, in the Pb-Bi alloy an overlapped three-gap-like structure is formed with a strong anisotropy. Furthermore, the chemical disorder, inherent to this alloy, leads to strong electron scattering, which is found to reduce the critical temperature.

关键词： Anisotropy

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Primordial full bispectra from the general bounce cosmology

arXiv

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arXiv 2025年

作者： Akama, Shingo Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University Krakow30-348 Poland

Primordial non-Gaussianities are key quantities to test early universe scenarios. In this paper, we compute full bispectra of scalar and tensor perturbations generated during a contracting phase in a general bounce model. The general bounce model consists of two branches: one realizes scale-invariant scalar and tensor power spectra from perturbations whose amplitudes become constant on superhorizon scales, as in de Sitter inflation, while the other realizes scale-invariant power spectra from perturbations whose amplitudes grow on superhorizon scales, as in matter bounce cosmology. We study the auto- and cross-bispectra originating from the scale-invariant scalar and tensor perturbations in these two branches. We investigate the amplitudes and shapes of non-Gaussianities and find that the differences between the two branches manifest for equilateral and squeezed momentum triangle configurations. In particular, one of the branches in which the superhorizon perturbations are conserved reproduces the so-called Maldacena’s consistency relation. By examining perturbativity conditions and considering current observational constraints on primordial non-Gaussianities, we also find a viable parameter space in which both theoretical and observational constraints are satisfied simultaneously. © 2025, CC BY.

关键词： Tensors

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Interpreting pulsar timing array data of gravitational waves with Ekpyrosis-bouncing cosmology

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Physical Review D 2025年第4期111卷 043508-043508页

作者： Taotao Qiu Mian Zhu School of Physics Huazhong University of Science and Technology Wuhan 430074 China Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University 30-348 Krakow Poland

Recent pulsar timing array (PTA) experiments have reported strong evidence of the stochastic gravitational wave background (SGWB). If interpreted as primordial gravitational waves, the signal favors a strongly blue-tilted spectrum. On the other hand, the Ekpyrosis-bouncing cosmology with a strongly blue-tilted gravitational wave spectrum, i.e., nT≃2, offers a potential explanation for the observed SGWB signal. In this paper, we construct a concrete Ekpyrosis-bouncing model, and show its capacity to intepret the PTA result without pathologies. Both tensor and scalar perturbations are analyzed with constraints from the current observations.

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