Nikolaos Mavromatos of King's College London and colleagues in Athens and Texas obtained their result by studying a special "off-shell" time-dependent term (due to the dilaton) in the Boltzmann equation that describes the evolution of hot matter density as the Universe cooled down. "The formalism that this work used was developed in partial collaboration with John Ellis of CERN and Vasiliki Mitsou of IFIC, Valencia, and is a version of 'non-critical string theory'", said Mavromatos.
All the matter and radiation in the universe is thought to have been created by the Big Bang. The radiation stopped interacting with the matter some 400,000 years later -- when the universe had cooled down enough for electrons and protons to form hydrogen atoms. The density of dark matter particles such as the neutralino (a dark matter candidate favoured by many of the current "supersymmetric" approaches to particle physics) was therefore "frozen" at this time -- the so-called relic abundance.
The researchers say that the neutralino relic abundance is reduced by as much as a factor of ten in their models due to dilaton effects, as compared to standard cosmology theories. In contrast, the relic abundance of "ordinary" matter, which makes up stars, planets and humans, is only slightly diluted. The new model also agrees with the established model of nucleosynthesis (the way in which light elements were created during the first few minutes of the universe).
The new result is important for both cosmology and particle physics, says Mavromatos. Indeed, such non-equilibrium string cosmology models are on an equal footing with the standard cosmological cold dark matter model (called Lambda-CDM). For particle physics, the findings are relevant for future supersymmetric searches in colliders such as the Large Hadron Collider, due to come on-line at CERN early next year. The supersymmetric theory, one of the facets of string theory, postulates that every particle has a massive "shadow" particle partner.
Dark matter is fundamentally different from normal, luminous matter and is invisible to modern telescopes, giving off no light or heat. It appears to interact with normal matter only through gravity. Most cosmologists believe dark matter, currently thought to make up 95% of all matter in the universe, plays a crucial role in how large structures such as galaxies emerged after the Big Bang.
Charlotte Webber | EurekAlert!
Only an atom thick: Physicists succeed in measuring mechanical properties of 2D monolayer materials
17.01.2018 | Universität des Saarlandes
Black hole spin cranks-up radio volume
15.01.2018 | National Institutes of Natural Sciences
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.
Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...
The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
18.01.2018 | Life Sciences
18.01.2018 | Life Sciences
18.01.2018 | Earth Sciences