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EPJ ST Highlight - Many-body interactions feel the heat: Introducing thermal field theory
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- Published on 01 August 2023
Thermal field theory seeks to explain many-body dynamics at non-zero temperatures not considered in conventional quantum field theory.
Quantum field theory is a framework used by physicists to describe a wide range of phenomena in particle physics and is an effective tool to deal with complicated many-body problems or interacting systems.
Conventional quantum field theory describes systems and interactions at zero temperature and zero chemical potential, and interactions in the real world certainly do occur at non-zero temperatures. That means scientists are keen to discover what effects may arise as a result of non-zero temperature and what new phenomena could arise due to a thermal background. In order to understand this, physicists turn to a recipe for quantum field theory in a thermal background — thermal field theory.
In a new paper in EPJ ST, Munshi G. Mustafa, Senior Professor at the Saha Institute of Nuclear Physics, Kolkata, India, introduces a thermal field theory in a simple way weaving together the details of its mathematical framework and its application.
EPJ Plus Focus Point Issue: Advances in Cryogenic Detectors for Dark Matter, Neutrino Physics, and Astrophysics
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- Published on 28 July 2023
Guest Editor: Luca Pattavina
The papers included in this Focus Point collection offer a glimpse of the very broad range of applications of low-temperature detectors. This class of detectors has seen in recent years a boost in its performance and in the achieved background levels. Nowadays, cryogenic detectors are considered a leading technology in the investigation of the fundamental properties of the most abundant particles in the Universe: neutrinos and Dark Matter, and their applications reach out to nuclear, particle, and astroparticle physics. The papers included in the collection cover the most recent technological progress of low-temperature detectors, from different perspectives (e.g. computational approach, material development). The research groups that contributed to this collection show the range of methods available to tackle the latest experimental challenges of the community.
All articles are available here and are freely accessible until 27 September 2023. For further information, read the Editorial.
EPJ ST Highlight - Investigating the Ising model with magnetisation
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- Published on 27 July 2023
Researchers have explored the evolution of systems of interacting spins, as they transition from random to orderly alignments. Through new simulations, they show that this evolution can be investigated by measuring the changing strength of the system’s magnetism.
The Ising model describes systems of interacting atomic spins relaxing from a ‘paramagnetic’ state – whose spins point in random directions, to a ‘ferromagnetic’ state – whose spins spontaneously align with each other. So far, the nonequilibrium dynamics of this transition has been studied by measuring the growth of regions, or ‘domains’ of aligned spins. In new research published in EPJ ST, researchers led by Wolfhard Janke at the University of Leipzig, Germany, show how this can be done far more easily by measuring the strength of the system’s magnetisation. The team’s discovery could help researchers to better understand the atomic-scale interactions underlying many different phenomena in nature: from electrostatic forces, to neuroscience and economics.
EPJ D Highlight - Looking deeper into graphene using rainbow scattering
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- Published on 24 July 2023
New research uses protons to shine a light on the structure and imperfections of this two-dimensional wonder material
Graphene is a two-dimensional wonder material that has been suggested for a wide range of applications in energy, technology, construction, and more since it was first isolated from graphite in 2004.
This single layer of carbon atoms is tough yet flexible, light but with high resistance, with graphene calculated to be 200 times more resistant than steel and five times lighter than aluminium.
Graphene may sound perfect, but it very literally is not. Isolated samples of this 2D allotrope aren’t perfectly flat, with its surface rippled. Graphene can also feature structural defects that can, in some cases, be deleterious to its function and, in other instances, can be essential to its chosen application. That means that the controlled implementation of defects could enable fine-tuning of the desired properties of two-dimensional crystals of graphene.
In a new paper in EPJ D, Milivoje Hadžijojić and Marko Ćosić, both of the Vinča Institute of Nuclear Sciences, University of Belgrade, Serbia, examine the rainbow scattering of photons passing through graphene and how it reveals the structure and imperfections of this wonder material.
EPJ B Highlight - How a molecular motor moves in a network
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- Published on 24 July 2023
A new study determines the efficiency of a single-molecule heat engine by considering a series of ratchets that transfer energy along a network.
From internal combustion engines to household refrigerators, heat engines are a ubiquitous component of daily life. These machines convert heat into usable energy which can then be used to do work. Heat engines can be as small as a single molecule whose random movements exchange energy with the environment. But determining the efficiency of a molecular heat engine is no simple task. In a study published in EPJ B, Mesfin Asfaw Taye, of West Los Angeles College, California, USA now calculates the performance of a molecular heat engine in terms of a series of molecular ratchets that transfer energy, step-wise, in one direction. He shows and discusses how to manipulate such a system for transporting a particle along a complex path.
EPJ E Highlight - Exploring the elasticity of colloidal suspensions
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- Published on 21 July 2023
Author: Zephyris, CC BY-SA 3.0 https://creativecommons.org/ licenses/by-sa/3.0, via Wikimedia Commons
Experiments reveal that under the right conditions, the elasticity of colloidal suspensions will peak at a certain value, which depends both on the deformation applied to the material and the strength of attraction between its solid particles.
The behaviours of colloidal materials – where tiny solid particles are suspended in fluid – depend strongly on how the particles interact with each other. Through new research published in EPJ E, a team led by Pascal Hébraud at the University of Strasbourg, France, show how under certain conditions, the elasticity of silica-based colloids subjected to oscillating flows will peak at a certain value. Their discovery could lead to improved techniques for manipulating the behaviour of colloidal materials, used in fields as wide-ranging as materials science, food technology, construction, and nanotechnology.
EPJ B Highlight - Calculating thermal properties from phonon behaviours
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- Published on 21 July 2023
A new study determines the thermal properties of advanced solid materials, based on first-principles calculations of quantum vibrations.
As the energy demands of our modern world continue to grow, there is a crucial need to understand how heat flows through the materials we use to build our technology. Through new research published in EPJ B, Vinod Solet and Sudhir Pandey at the Indian Institute of Technology Mandi have accurately estimated the thermal properties of a particularly promising alloy, based on first-principles calculations of phonons. Composed of scandium (Sc), silver (Ag), and carbon (C), this alloy could soon become a key component of devices which convert heat into electricity, while its low reflectivity and strong photon absorption would make it especially well-suited for highly efficient solar cells.
EPJ D Highlight - Looking deeper into violent neutron star collisions to find the origins of heavy elements
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- Published on 21 July 2023
The gold that makes up your most precious jewellery may have been forged in a violent cosmic collision millions or billions of light years away between two neutron stars. New research seeks to better understand this process.
There is only a single confirmed site in the Universe capable of generating conditions extreme enough to initiate the production process for many of the heaviest elements in the Universe, including gold, platinum, uranium – neutron star mergers. These mergers are the only event observed to-date that can produce the incredible densities and temperatures needed to power the rapid neutron capture process.
In a new paper in EPJ D, Andrey Bondarev, a postdoc researcher at Helmholtz Institute Jena, James Gillanders a postdoc researcher in Rome, and their colleagues examine the spectra from the kilonova AT2017gfo to investigate the presence of forged tin, by looking for spectral features caused by its forbidden transitions.
EPJ E Highlight - Measuring nanocomposite structures with neutron and x-ray scattering
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- Published on 17 July 2023
Experiments with state-of-the-art scattering instruments reveal an absence of specific patterns in the x-rays scattered by nanocomposite materials. With the help of advanced simulation techniques, a new study suggests that attractive interactions between nanoparticles with diverse shapes and sizes are most likely responsible for this behaviour.
Small-angle scattering of x-rays and neutrons is a useful tool for studying molecular and nanoparticle structures. So far, however, experiments have revealed a surprising lack of nanoparticle structure in certain nanocomposite materials – whose molecular skeletons are reinforced with nanoparticles previously treated with polymer adsorption. In a new approach detailed in EPJ E, Anne-Caroline Genix and Julian Oberdisse at the University of Montpellier, France, show that these patterns can only be produced through attractive interactions between nanoparticles with a diverse array of shapes and sizes. The duo’s results highlight the rapidly improving capabilities of small-angle scattering instruments, and could also help researchers to improve their techniques for studying nanocomposites – with applications in areas including miniaturised electronics, biological tissue engineering, and strong, lightweight materials for aircraft.
EPJ D Topical Issue: Precision Physics of Simple Atomic Systems
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- Published on 17 July 2023
Guest Editors: Krzysztof Pachucki, Thomas Udem, Wim Ubachs, Paolo Crivelli & Stefan Ulmer
This EPJD special issue dedicated to the field of precision physics of simple atomic systems includes several important peer-reviewed contributions, presented on the 11th edition of the PSAS conference —initially planned to take place in May 2020 in Wuhan, China (only to be rescheduled 2 years later, in May 2022, due to the COVID-19 pandemic, in Warsaw, Poland).
The aim of the PSAS conference is to gather scientists from all over the world working on precise calculations and measurements, with the goal to test fundamental physics, to verify laws of physics, and to determine fundamental constants. Correspondingly, a mix of theoretical, numerical and experimental works spanning the fields of spectroscopy of atomic and molecular hydrogen, QED of few-electron bound systems, exotic atoms and ions, searches for BSM physics with atoms and antimatter, clocks, measurements of g-2 and alpha, originating from several of the major groups in this field, are reported here, making the current collection of interest for both the younger generation entering this research field and experts for efficient access on recent developments.
All articles are available here and are freely accessible until 29 August 2023. For further information read the Editorial.
