2021 Impact factor 4.991
Particles and Fields


EPJ D Highlight - Astrophysical plasma study benefits from new soft X-ray transition energies benchmark

An artist’s impression of an X-ray binary, the kind of cosmic event that will benefit from a new benchmark in the study of astrophysical plasmas. Credit: Dana Berry/NASA Goddard Space Flight Center

The new benchmark for X-ray transition energies set for neon, carbon dioxide, and sulfur hexafluoride paves a pathway to high accuracy analysis of astrophysical plasmas.

The analysis of astrophysical plasmas is vital in the quest to learn about some of the Universe’s most powerful and mysterious objects and events such as stellar coronae and winds, cataclysmic variables, X-ray binaries containing neutron stars and black holes, supernova remnants, or outflows in active galactic nuclei. The success of such research will lead to future astrophysical X-ray observatories enabling scientists to access techniques that are currently not available to X-ray astronomy. A key requirement for the accurate interpretation of high-resolution X-ray spectra is accurate knowledge of transition energies.

A new paper published in EPJ D authored by J. Stierhof, of the Dr. Karl Remeis-Observatory and Erlangen Centre for Astroparticle Physics of Friedrich-Alexander-Universt Erlangen-Nürnberg, Bamberg, Germany, and coauthors utilizes a newly introduced experimental setup at the BESSY II synchrotron facility to provide precise calibration references in the soft X-ray regime of neon, carbon dioxide, and sulfur hexafluoride gases.


EPJ H Highlight - Documenting the first attempt at a gravitational-wave observatory in Europe

Binary neutrons stars generate ripples in spacetime, gravitational waves, detected here on Earth by interferometers like LIGO. Credits: R. Hurt/Caltech-JPL

EUROGRAV was set to be a network of gravitational wave antennas in Europe. A new paper looks at the reasons it never happened.

First predicted in Einstein’s theory of general relativity, gravitational waves are tiny ripples in spacetime generated by titanic and powerful cosmic events. The great physicist believed that no equipment would ever be sensitive to detect these faint cosmic ripples. Fortunately, Einstein was wrong, but that doesn’t mean that the detection of gravitational waves has been easy.

The history of a planned array interferometer gravitational wave detectors to be built in Europe during the late 1980s, the reasons this failed, and the parallels with current detectors, are documented in a new paper published in EPJ H, authored by Adele La Rana, University of Verona, and INFN Section of Sapienza University, Italy.


EPJ Plus Highlight - Tackling large data sets and many parameter problems in particle physics

The Pandemonium tool links together six clusters of data and provides a graphical interpretation.

A new tool to break down and segment large data set problems and problems with many parameters in particle physics could have a wide range of applications.

One of the major challenges in particle physics is how to interpret large data sets that consist of many different observables in the context of models with different parameters.

A new paper published in EPJ Plus, authored by Ursula Laa from the Institute of Statistics at BOKU University, Vienna, and German Valencia from the School of Physics and Astronomy, Monash University, Clayton, Australia, looks at the simplification of large data set and many parameter problems using tools to split large parameter spaces into a small number of regions.


EPJ H Highlight - Acknowledging Fermi’s contributions to early quantum statistics

Fermi’s research was notably independent. https://en.wikipedia.org/wiki/ Enrico_Fermi#/media/File: Enrico_Fermi_1943-49.jpg

Enrico Fermi’s ideas played a key role in the origins of quantum statistics, but so far, they have been largely overlooked in historical analysis

Within large systems of identical fermions, Fermi-Dirac statistics describes how identical fermions may never occupy the same quantum state. First introduced by Italian physicist, Enrico Fermi, this concept was a key step in our early understanding of quantum mechanics – yet so far, Fermi’s contributions have been largely overlooked in historical analysis. Through new research published in EPJ H, Enric Pérez and Joana Ibáñez, both at the University of Barcelona, Spain, offer a critical analysis of Fermi’s ideas, and assess their immediate impact on our early conceptions of quantum mechanics.


EPJ H Highlight - Assessing the modern relevance of Schrödinger’s time reversal

Schrödinger’s ideas transformed quantum mechanics. https://en.wikipedia.org/wiki/Erwin_ Schrödinger#/media/File:Erwin_ Schrödinger_(1933).jpg

Erwin Schrödinger’s landmark 1931 paper provided a basis for several important conceptions in quantum mechanics, but a new translation and commentary highlights its continuing relevance in modern statistical nanophysics

In 1931, Erwin Schrödinger published a ground-breaking paper, named ‘On the Reversal of the Laws of Nature.’ The study aimed to prove the possibility of a classical structure governed by probability, which displays a property called ‘time reversal symmetry’: where the physical laws underlying the system would remain the same, whether time flowed forwards or backwards. A new English translation of Schrödinger’s paper, published in EPJ H, has now been made by Raphael Chetrite at the University of Nice Sophia Antipolis; Paolo Muratore-Ginanneschi at University of Helsinki; and Kai Schwieger at iteratc GmbH Stuttgart. In an additional commentary, the team emphasise the relevance of his intuitions for modern developments in statistical nanophysics.


EPJ Plus Focus Point on Rewriting Nuclear Physics Textbooks: Recent Advances in Nuclear Physics Applications

Guest Editors: Nicolas Alamanos, Carlos Bertulani, Angela Bonaccorso, Angela Bracco, David M. Brink, Giovanni Casini, Maria Agnese Ciocci, Valeria Rosso & Michele Viviani

This collection of articles contains some of the lectures presented at the Summer School ``Re-writing Nuclear Physics textbooks: recent advances in nuclear physics applications" which was held at the INFN Sezione di Pisa and Department of Physics of the University of Pisa in July 2019. The School followed two previous editions dedicated to "30 years with Radioactive Ion Beam Physics" and "Basic Nuclear Interactions and Their Link to Nuclear Processes in the Cosmos and on Earth" also held at the same place in July 2015 and 2017 respectively.


EPJ C Highlight - A cautionary tale of machine learning uncertainty

Underestimating machine learning uncertainty

By decorrelating the performance of machine learning algorithms with imperfections in the simulations used to train them, researchers could be estimating uncertainties that are lower than their true values.

The Standard Model of particle physics offers a robust theoretical picture of the fundamental particles, and most fundamental forces which compose the universe. All the same, there are several aspects of the universe: from the existence of dark matter, to the oscillating nature of neutrinos, which the model can’t explain – suggesting that the mathematical descriptions it provides are incomplete. While experiments so far have been unable to identify significant deviations from the Standard Model, physicists hope that these gaps could start to appear as experimental techniques become increasingly sensitive.

A key element of these improvements is the use of machine learning algorithms, which can automatically improve upon classical techniques by using higher-dimensional inputs, and extracting patterns from many training examples. Yet in new analysis published in EPJ C, Aishik Ghosh at the University of California, Irvine, and Benjamin Nachman at the Lawrence Berkeley National Laboratory, USA, show that researchers using machine learning methods could risk underestimating uncertainties in their final results.


EPJ Plus Focus Point on A Future Higgs & Electroweak Factory (FCC): Challenges towards Discovery

Guest Editors: G. Corti, B. Heinemann, P. Hernandez, P. Koppenburg, M. McCullough, A.-S. Müller, A. Seryi, J. Tanaka

This Focus Point on the FCC-ee maps the current status and the challenges lying forward to realize a future Higgs and electroweak factory like the one envisioned by the Future Circular Collider design study for the post-LHC era. This strategic guideline from the 2020 update of the European Strategy for Particle Physics (ESPP 2020) defines an electron-positron Higgs and electroweak factory "as the highest-priority next collider" that would allow a wide range of precise measurements of the Standard Model parameters including the recently discovered Higgs boson. The proposed FCC-ee best complies with this guideline, and consequently offers, in a cost-effective fashion, the broadest physics discovery potential and the most ambitious perspective towards a 100 TeV high-energy proton collider housed in the same tunnel and profiting from the new infrastructure.

The invited authors evaluate the progress toward the realisation of FCCs since the publication of the FCC Conceptual Design Report. Topics highlight the challenges lying ahead on the accelerator design of FCC-ee, ongoing work for the experiments and detector development, the open theoretical questions informing this endeavour and finally the computational and software challenges that should be tackled. These challenges also set opportunities for a wider community of scientists and engineers who are invited to join the diverse and dynamic environment offered by the FCC collaboration.


EPJ H Highlight - Deciphering Boltzmann’s response to Loschmidt’s paradox

Boltzmann’s reaction has baffled modern readers. https://en.wikipedia.org/wiki/ Ludwig_Boltzmann#

New analysis offers a clarified translation and detailed commentary of Boltzmann’s original reaction to Loschmidt’s paradox

In 1876, Austrian physicist Josef Loschmidt published his ‘reversibility paradox,’ arguing that the time-symmetric processes demanded by fundamental physics are at odds with the second law of thermodynamics. A few months later, Loschmidt’s friend Ludwig Boltzmann, renowned for his statistical interpretation of thermodynamics, published his reaction to the paradox. However, the convoluted nature of his response has long remained baffling to modern readers. Through new analysis published in EPJ H, Olivier Darrigol at the CNRS in France clarifies Boltzmann’s main points, through a new translation and detailed commentary of his 1877 text.


EPJ ST Highlight - An overview of neutrinos and their interactions

A new summary of the study of neutrinos, and the ways in which they interact with regular matter, could inspire both new and senior neutrino researchers to open up new areas of investigation within the field.

The history of our understanding of neutrinos, from their astrophysical origins to their elusive interactions with matter, is full of surprises. Although we know that they are the second most abundant particles in the universe after photons, they are also the least well understood. In this special issue of EPJ ST, M. Sajjad Athar and S.K. Singh at Aligarh Muslim University present a short overview of the study of neutrinos, and the ways in which they interact with other forms of matter at mid-to-high energies.


G. Dissertori, J. Monroe, D. J. Schwarz, K. Skenderis and G. Zanderighi

The author would like to thank two anonymous referees for pointing out several shortcomings in a previous version of this paper and for suggestions to improve its clarity.

J. H. Field

ISSN: 1434-6052 (Electronic Edition)

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