EPJ C Highlight - Factoring in gravitomagnetism could do away with dark matter

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The rotational curve of the galaxy Messier 33 shows the difference between observations and what should be expected from models of gravity. Until now, this disparity has been explained by ‘dark matter’ but a new paper suggests an alternative explanation. Credit: Mario De Leo, CC BY-SA 4.0, via Wikimedia Commons

Models of galactic rotation curves built of a general relativistic framework could use gravitomagnetism to explain the effects of dark matter.

Observations of galactic rotation curves give one of the strongest lines of evidence pointing towards the existence of dark matter, a non-baryonic form of matter that makes up an estimated 85% of the matter in the observable Universe. Current assessments of galactic rotation curves are based upon a framework of Newtonian accounts of gravity, a new paper published in EPJ C, by Gerson Otto Ludwig, National Institute for Space Research, Brazil, suggests that if this is substituted with a general relativity-based model, the need to recourse to dark matter is relieved, replaced by the effects of gravitomagnetism.

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EPJ C Highlight - Placing cosmological constraints on quantum gravity phenomenology

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Hawking radiation is still poorly understood. Source https://en.wikipedia.org/wiki/ Black_hole#/media/File: IonringBlackhole.jpeg

Researchers have used cosmological data to place stringent new limits on a model which emerges in attempts to reconcile gravity with the principles of quantum mechanics.

A description of gravity compatible with the principles of quantum mechanics has long been a widely pursued goal in physics. Existing theories of this ‘quantum gravity’ often involve mathematical corrections to Heisenberg’s Uncertainty Principle (HUP), which quantifies the inherent limits in the accuracy of any quantum measurement. These corrections arise when gravitational interactions are considered, leading to a ‘Generalized Uncertainty Principle’ (GUP). Two specific GUP models are often used: the first modifies the HUP with a linear correction, while the second introduces a quadratic one. Through new research published in EPJ C, Serena Giardino and Vincenzo Salzano at the University of Szczecin in Poland have used well-established cosmological observations to place tighter constraints on the quadratic model, while discrediting the linear model.

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EPJ C Highlight - Tracking the evolution Maxwell knots

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The evolution of maxwell knots over time, with the smaller yellow knot changing to the larger red knot. The trajectories of the knots are marked in green.

New research investigates the properties of particular solutions of Maxwell equations, tracking their evolution over time and determining a route to combine them with other systems.

Maxwell equations govern the evolution of electromagnetic fields with light being a particular solution of these equations in spaces devoid of electric charge. A new study published in EPJ C by Alexei Morozov and Nikita Tselousov, from the Moscow Institute of Physics and Technology and the Institute of Transmission Problems, Russia, respectively, details peculiar solutions to the Maxwell equations—so-called Maxwell knots. The research could have applications in the fields of mathematical physics and string theory.

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EPJ C: Jocelyn Monroe new Editor-in-Chief for Experimental Physics II: Astroparticle Physics

The publishers of The European Physical Journal C – Particles and Fields are pleased to announce the appointment of Professor Jocelyn Monroe as new Editor-in-Chief for Experimental Physics II: Astroparticle Physics replacing Professor Laura Baudis.

Jocelyn Monroe, head of the Astroparticle Physics Group at Royal Holloway, University of London, is an expert on dark matter direct detection and the interface with neutrino physics. Her research interests include experimental dark matter searches, low-energy neutrino physics and detector development for rare event searches.

EPJ C Highlight - Detecting solar neutrinos with the Borexino experiment

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Distribution of best-fit results of 210Bi and CNO neutrinos interaction rates obtained fitting thousands of simulated datasets under different assumptions of 210Bi backgrounds.

Neutrinos produced by the CNO cycle within the core of the Sun are being hunted by the Borexino experiment so that we may learn more about this important nuclear process.

Neutrinos are chargeless particles with about a mass about a millionth that of an electron that are created by the nuclear processes that occur in the Sun and other stars. These particles are often colourfully described as the ‘ghosts’ of the particle zoo because they interact so weakly with matter. A paper published in EPJ C by the Borexino collaboration – including XueFeng Ding, Postdoc Associate of Physics at Princeton University, United States – documents the attempts of the Borexino experiment to measure low-energy neutrinos from the Sun’s carbon-nitrogen-oxygen (CNO) cycle for the first time.

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EPJ C Highlight - Weak equivalence principle violated in gravitational waves

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Gravitational waves influence Fisher information. MoocSummers, wikimedia commons (CC BY-SA 4.0)

Calculations reveal that a key principle of classical physics is broken by quantum particles as they pass through ripples in spacetime.

The Weak Equivalence Principle (WEP) is a key aspect of classical physics. It states that when particles are in freefall, the trajectories they follow are entirely independent of their masses. However, it is not yet clear whether this property also applies within the more complex field of quantum mechanics. In new research published in EPJ C, James Quach at the University of Adelaide, Australia, proves theoretically that the WEP can be violated by quantum particles in gravitational waves – the ripples in spacetime caused by colossal events such as merging black holes.

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EPJ C - New Deputy Editor-in-Chief for Theoretical Physics II

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Dominik Schwarz

The publishers of The European Physical Journal C - Particles and Fields (EPJ C) are pleased to announce the appointment of Professor Dominik Schwarz as Deputy Editor-in-Chief for Theoretical Physics II: Gravitation, Astroparticle Physics and Cosmology, General Aspects of Quantum Field Theories, and Alternatives. He will relieve Professor Kostas Skenderis from submissions in the fields of astroparticle physics and cosmology, serving more and more as connecting elements between the phenomenology of the standard model and more elaborate mathematical theories including gravitation.

Dominik Schwarz, head of the Astroparticle Physics and Cosmology Working Group at Bielefeld University, is an expert on the interface of particle physics with cosmology as well as the interface between modelling and observational cosmology. His research interests include cosmological inflation and the thermal history of the Universe, the cosmic microwave background and large scale structure, dark matter and dark energy.

EPJ C - New Editor-in-Chief for Experimental Physics I: Accelerator Based High-Energy Physics

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Günther Dissertori (© Hostettler DPHYS/ETHZ)

The publishers of The European Physical Journal C – Particles and Fields are pleased to announce the appointment of Professor Günther Dissertori as new Editor-in-Chief for Experimental Physics I: Accelerator Based High-Energy Physics, replacing Professor Jos Engelen as of 1 January 2019.

Günther Dissertori obtained his PhD in Physics for a thesis on theoretical studies and experimental data analyses related to the ALEPH experiment at the CERN electron-positron collider LEP. He is Full Professor and Head of the Institute for Particle Physics and Astrophysics at ETH Zürich. Currently, the main focus of his research group is on the analysis of data taken with the CMS detector and its future upgrade, as well as on applications of particle physics detector technologies to bio-medical imaging, in particular positron emission tomography.

EPJ C - New Editor-in-Chief for Theoretical Physics II

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Kostas Skenderis

The publishers of The European Physical Journal C – Particles and Fields are pleased to announce the appointment of Professor Kostas Skenderis as new Editor-in-Chief for Theoretical Physics II: Gravitation, Astroparticle Physics and Cosmology, General Aspects of Quantum Field Theories, and Alternatives, replacing Professor Ignatios Antoniadis.

Kostas Skenderis is Director of the Southampton Theory Astrophysics and Gravity (STAG) Research Centre and a Professor in Mathematical Sciences at the University of Southampton. His research interests are in high energy theoretical physics and string theory, and in particular in the study of holographic dualities, their foundations and their applications.

EPJ C Highlight - Relativity Matters: Two opposing views of the magnetic force reconciled

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Gilbertian - magnetic dipole, from en.wikipedia.org/wiki/Magnetic dipole

How magnetic force acts on charged subatomic particles near the speed of light

Current textbooks often refer to the Lorentz-Maxwell force governed by the electric charge. But they rarely refer to the extension of that theory required to explain the magnetic force on a point particle. For elementary particles, such as muons or neutrinos, the magnetic force applied to such charges is unique and immutable. However, unlike the electric charge, the magnetic force strength is not quantised. For the magnetic force to act on them, the magnetic field has to be inhomogeneous. Hence this force is more difficult to understand in the context of particles whose speed is near the speed of light. Moreover, our understanding of how a point-particle carrying a charge moves in presence of an inhomogenous magnetic field relied until now on two theories that were believed to differ. The first stems from William Gilbert's study of elementary magnetism in 16th century, while the second relies on André-Marie Ampère electric currents. In a new study just published in EPJ C, the authors Johann Rafelski and colleagues from the University of Arizona, USA, succeeded in resolving this ambiguity between Ameperian and Gilbertian forms of magnetic force. Their solution makes it possible to characterise the interaction of particles whose speed is close to the speed of light in the presence of inhomogeneous electromagnetic fields.

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ISSN: 2195-7045 (Electronic Edition)

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