EPJA Topical Collection: CompOSE: a repository for Neutron Star Equations of State and Transport Properties

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Published on 14 February 2023

Guest Editors: Danai Antonopoulou, Enrico Bozzo, Chikako Ishizuka, Ian Jones, Micaela Oertel, Constança Providencia, Laura Tolos and Stefan Typel

The CompOSE Topical Collection is a compendium of several works on neutron star equations of state (EoS) and transport properties related to the online repository CompOSE (CompStar Online Supernovae Equations of State).

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EPJ A Topical Collection: Light Clusters in Nuclei and Nuclear Matter: Nuclear Structure and Decay, Heavy Ion Collisions, and Astrophysics

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Published on 02 February 2023

Guest Editors: David Blaschke, Hisashi Horiuchi, Masaaki Kimura, Gerd Röpke and Peter Schuck

Clustering in nuclei and nuclear matter is an interesting aspect which was intensely worked out during the last two decades. It concerns not only exotic nuclei such as Hoyle-like states, but leads to a better description of general aspects of nuclear structure and reactions. In particular, clustering is essential to understand fission and alpha decay, as well as heavy ion collisions from low to highest energies. In astrophysics, the thermodynamic properties of stellar matter below saturation density, transport properties, and the evolution of compact stellar objects are determined by clustering of nuclear matter. Contributions of this emerging field are collected in this Topical Collection.

EPJA Topical Collection: The QCD Phase Diagram in Strong Magnetic Fields

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Published on 03 November 2022

Guest Editors: Pedro Costa, Débora Peres Menezes, Vladimir Skokov and Carsten Urbach

Read all articles of this topical collection for free until 2nd January 2023!

In recent years, the impact of strong magnetic fields on the strongly interacting matter phase diagram has been a very active field of research with important developments. The presence of these strong magnetic fields modifies the dynamics of quarks, gluons and hadrons and is expected to have an enormous influence over all regions of the phase diagram: from the first stages of the Universe to the physics of neutron stars and the quark gluon plasma.

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EPJ A Topical Issue: An Experimental Program with Positron Beams at Jefferson Lab

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Published on 14 April 2022

The perspective of high energy and high duty cycle polarized positron beams in complement to the existing CEBAF (Continuous Electron Beam Accelerator Facility) electron beams is attracting a lot of interest. Following the proof-of-principle PEPPo (Polarized Electrons for Polarized Positrons) experiment demonstrating a new scheme for producing highly polarized positrons, the Jefferson Lab (JLab) Positron Working Group (PWG) engaged in the thorough development of the experimental program that would be achieved at JLab with such beams. It encompasses the determination of the physics quantities that characterize nucleons and nuclei structure: electromagnetic form factors, generalized polarizabilities, parton distributions, and generalized parton distributions. It also concerns some of the hottest questions of the field as the charge radius of the proton and the occurrence of physics beyond the standard model through the search of low mass dark matter particles, the measurement of weak neutral-current couplings, and the investigation of charged lepton flavour violation.

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EPJA appoints Patrizia Rossi as Managing Editor for Reviews and Letters to the Editor (experiment)

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Published on 13 December 2021

The publishers of The European Physical Journal A: Hadrons and Nuclei are pleased to announce the appointment of Dr Patrizia Rossi as Managing Editor for Reviews and Letters to the Editor (experiment) as of 1 January 2022.

Patrizia Rossi is the Deputy Associate Director for Nuclear Physics at Jefferson Lab (JLab), Research Professor at George Washington University, and Research Director at the Frascati National Laboratories of INFN-Italy (on leave). Her scientific research focuses on hadron and nuclear physics using electromagnetic probes. This research aims to study the structure of the nucleon and the nature of the strong interaction in terms of fundamental constituents of QCD. Her most recent investigations are related to the study of the transverse momentum parton distribution functions for which she is co-spokesperson for several experiments.

EPJ A Highlight - Celebrating the impacts of Jacques Raynal’s work in the development of nuclear reaction formalism, codes and analysis

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Published on 08 November 2021

This topical article edition of EPJ A is dedicated to the memory of French nuclear physicist Jacques Raynal, who passed away on April 10th, 2020.

It illustrates, through a series of peer-reviewed articles, the various facets of what Raynal and his colleagues accomplished, as well as the profound influence of his results in several domains of nuclear reactions, both for theory formalism and for the analysis and understanding of experimental observables. The articles also demonstrate how his work paved the way for the future development of concepts and numerical codes for nuclear reaction calculations.

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EPJ A Highlight - Celebrating the life and work of Mahir Hussein through cutting-edge research

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Published on 27 July 2021

A new collection of papers focusing on the dynamics of nuclei pays fitting tribute to Iraqi/Brazilian physicist Mahir Saleh Hussein.

On 16th May 2019 Iraqi/ Brazilian physicist Mahir Saleh Hussein passed away leaving behind a distinguished career of achievements in a broad range of physics disciplines. There is, perhaps, no better way of paying tribute to this influential figure in physics than presenting a collection of cutting-edge, peer-reviewed papers. A special edition of EPJ A, edited by Valdir Guimarães, Universidade de São Paulo Instituto de Física, Brazil, Carlos Bertulani, Department of Physics of the Texas A&M University-Commerce, USA, and Nicolas Alamanos, Deputy Director of the Institute of Research into the Fundamental Laws of the Universe (IRFU), France, brings together a collection of papers focusing on nuclei clustering and dynamics as a fitting tribute to Hussein.

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EPJ A Highlight - THOR: Driving collaboration in heavy-ion collision research

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Published on 02 June 2021

As an expansive platform for collaboration between different research groups, the THOR COST Action has enabled hundreds of physicists studying the aftermath of high-energy collisions between heavy ions to improve their predictions.

In the universe’s earliest moments, particles existed in an unimaginably hot plasma, whose behaviour was governed by deeply complex webs of interaction between individual particles. Today, researchers can recreate these exotic conditions through high-energy collisions between heavy ions, whose products can tell us much about how hot, strongly-interacting matter behaves. Yet without extensive, highly coordinated collaborations between researchers across many different backgrounds, studies like this simply wouldn’t be possible. This Topical Issue of EPJ A draws together a large collection of papers inspired by the theory of hot matter and relativistic heavy-ion collisions (THOR) European Cooperation in Science and Technology (COST) Action. Running between November 2016 and April 2021, THOR has provided a way for over 300 researchers involved in heavy-ion collision analysis to freely exchange their ideas, leading to exciting new advances in the wider field of particle physics.

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EPJ A Highlight - Paving the way for effective field theories

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Published on 01 February 2021

A detailed analysis of theories which approximate the underlying properties of physical systems could lead to new advances in studies of low-energy nuclear processes

Over the past century, a wide variety of models have emerged to explain the complex behaviours which unfold within atomic nuclei at low energies. However, these theories bring up deep philosophical questions regarding their scientific value. Indeed, traditional epistemological tools have been rather elaborated to account for a unified and stabilised theory rather than to apprehend a plurality of models. Ideally, a theory is meant to be reductionist, unifying and fundamentalist. In view of the intrinsic limited precision of their prediction and of the difficulty in assessing a priori their range of applicability, as well as of their specific and disconnected character, traditional nuclear models are necessarily deficient when analysed by means of standard epistemological interpretative frameworks.

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EPJ A Highlight - Automated symmetry adaption in nuclear many-body theory

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Published on 10 December 2020

The extreme cost of solving the A-nucleon Schrödinger equation can be minimized by leveraging rotational symmetry and, thus, enable the computation of observables in heavy nuclei and/or with high precision.

The associated reduction process, which amounts to re-expressing the working equations in terms of rotationally-invariant objects, requires lengthy symbolic manipulations of elaborate algebraic identities.

For the first time, this involved process is automated by a powerful graph-theory-based tool, the AMC code, which condenses months of error-prone derivations into a simple computational task performed within seconds.

The AMC program tightens the gap for a full automation of the many-body workflow, thereby lowering the time required to build and test novel quantum many-body formalisms.