Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Microscopic Universe Provides Insight Into Life and Death of a Neutron

01.06.2018

Experiments on the lifetime of a neutron reveal surprising and unexplained deviations. In order to address this problem of subatomic physics, a team of physicists from Jülich, the UK, and the USA created a simulation of a microscopic universe. They were thus able to calculate a fundamental natural constant of nuclear physics for the first time – a milestone in this field of research. The results of their work were published today in the renowned journal Nature.

A neutron “lives” for almost 15 minutes before it decays. The elementary particles remain stable as long as they are in the atomic nuclei. In isolation, however, they decay after just under 15 minutes into other particles – protons, electrons, and antineutrinos.


A neutron decays into a proton, an electron, and an antineutrino. In the QCD lattice approach, a discrete space is used for the calculation.

Evan Berkowitz

To determine the lifetime of the neutrons, scientists observe either the emergence of these decay products or the disappearance of the neutrons. However, these two varying experiments deliver different results. The deviation is less than nine seconds. This might not appear to be much, but the conflicts between the experimental measurements could answer key questions about a new physics beyond the known particles and processes in the universe.

For the first time, an international team of scientists used supercomputers to calculate a quantity that is crucial for understanding the lifetime of neutrons: the axial coupling constant of the weak interaction, or gA for short. “It determines the force with which the particles are bound together in the atomic nucleus as well as the radioactive decay rate of the neutron,” explains Evan Berkowitz from the Nuclear Physics Institute (IKP).

“We were able to calculate the coupling constant with unprecedented precision and our method is paving the way towards further improvements that may explain the experimental discrepancy in the lifetime of neutrons.”

Space and time on a lattice

For their calculation, the researchers turned to a key feature of the standard model of particle physics: quantum chromodynamics (QCD). This theory describes how quarks and gluons – the building blocks for nuclear particles such as protons and neutrons – interact with each other. These interactions determine the mass of the nuclear particles, the strength of their coupling, and, therefore, the value of the coupling constants.

However, QCD calculations are extremely complex. For their calculations, the researchers therefore used a numerical simulation known as lattice QCD. “In this simulation, space and time are represented by points on a lattice,” explains Berkowitz. “Through this construction, a calculation of the relations between the elementary particles is fundamentally possible – but only with the aid of powerful supercomputers.” The scientists used the Titan supercomputer at the Oak Ridge National Laboratory in Tennessee for their simulations.

Microscopic universe

The coupling constant, which previously could only be derived from neutron decay experiments, was thus determined directly from the standard model for the first time. To this end, the researchers created a simulation of a microscopic part of the universe measuring just a few neutrons wide – much smaller than the smallest atom. The model universe contains a single neutron in the middle of a “sea” of gluons and pairs of quarks and their antiparticles, antiquarks. In this microcosm, the scientists simulated the decay of a neutron to predict what happens in nature.

Berkowitz explains that this allows two results for gA from completely independent sources – those from the neutron decay experiments and those using the standard model – to be compared with each other for the first time. “Even the smallest deviations between the values could lead to new discoveries related to dark matter, the asymmetry between matter and antimatter, and other fundamental questions concerning the nature of the universe.”

A new era

“Through our simulation, we were also able to show that the lattice QCD approach can be applied to basic research on the physics of atomic nuclei,” explains Berkowitz. The methods have so far mainly been used for elementary particle physics, i.e. the physics of quarks and gluons , and of short-lived particles found in collider experiments. “These calculations ring in a new era. We can now determine parameters of nuclear physics with greater precision without having to resort to experimental measurement data or phenomenological models.”

Original publication: A per-cent-level determination of the nucleon axial coupling from Quantum Chromodynamics, by C.C. Chang, A. N. Nicholson, E. Rinaldi, E. Berkowitz, N. Garron, D.A. Brantley, H. Monge-Camacho, C. Monahan, C. Bouchard, M.A. Clark, B. Joó, T. Kurth, K. Orginos, P. Vranas, and A. Walker-Loud, Nature,
DOI: 10.1038/s41586-018-0161-8

Contact:
Dr. Evan Berkowitz
Nuclear Physics Institute – Theory of the Strong Interactions (IKP-3/IAS-4)
Tel.: +49 2462 62-4161
Email: e.berkowitz@fz-juelich.de

Press contact:
Dr. Regine Panknin
Press officer
Tel: +49 2461 61-9054
Email: r.panknin@fz-juelich.de

Weitere Informationen:

http://www.fz-juelich.de/ikp/ikp-3/EN/Home/TheorieDerStarkenWechselwirkung.html Nuclear Physics Institute – Theory of the Strong Interactions (IKP-3/IAS-4)

Dipl.-Biologin Annette Stettien | Forschungszentrum Jülich

More articles from Life Sciences:

nachricht Small but ver­sat­ile; key play­ers in the mar­ine ni­tro­gen cycle can util­ize cy­anate and urea
10.12.2018 | Max-Planck-Institut für Marine Mikrobiologie

nachricht Carnegie Mellon researchers probe hydrogen bonds using new technique
10.12.2018 | Carnegie Mellon University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Researchers develop method to transfer entire 2D circuits to any smooth surface

What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.

Rice engineers led by materials scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices...

Im Focus: Three components on one chip

Scientists at the University of Stuttgart and the Karlsruhe Institute of Technology (KIT) succeed in important further development on the way to quantum Computers.

Quantum computers one day should be able to solve certain computing problems much faster than a classical computer. One of the most promising approaches is...

Im Focus: Substitute for rare earth metal oxides

New Project SNAPSTER: Novel luminescent materials by encapsulating phosphorescent metal clusters with organic liquid crystals

Nowadays energy conversion in lighting and optoelectronic devices requires the use of rare earth oxides.

Im Focus: A bit of a stretch... material that thickens as it's pulled

Scientists have discovered the first synthetic material that becomes thicker - at the molecular level - as it is stretched.

Researchers led by Dr Devesh Mistry from the University of Leeds discovered a new non-porous material that has unique and inherent "auxetic" stretching...

Im Focus: The force of the vacuum

Scientists from the Theory Department of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science (CFEL) in Hamburg have shown through theoretical calculations and computer simulations that the force between electrons and lattice distortions in an atomically thin two-dimensional superconductor can be controlled with virtual photons. This could aid the development of new superconductors for energy-saving devices and many other technical applications.

The vacuum is not empty. It may sound like magic to laypeople but it has occupied physicists since the birth of quantum mechanics.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

Expert Panel on the Future of HPC in Engineering

03.12.2018 | Event News

 
Latest News

Small but ver­sat­ile; key play­ers in the mar­ine ni­tro­gen cycle can util­ize cy­anate and urea

10.12.2018 | Life Sciences

New method gives microscope a boost in resolution

10.12.2018 | Physics and Astronomy

Carnegie Mellon researchers probe hydrogen bonds using new technique

10.12.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>