Does Heavy Dark Matter Hide In the Shadows?

Scientists currently propose that the Universe was born almost 14 billion years ago in the wild exponential inflation of the Big Bang, when it emerged from a tiny Patch that was smaller than a proton to reach macroscopic size in the smallest fraction of a second. The original Patch is thought to have been so extremely hot and dense that everything we are and everything that we can ever know was born from it. The Universe has been expanding and cooling off ever since. We can now observe from where we are situated on our small rocky planet, the dying fires of cosmic birth. Most of the Universe is hidden in the shadows–a mysterious form of invisible matter that is called dark matter accounts for most of its matter content. The dark matter is transparent because it does not dance with light–although its gravitational influence on objects that can be seen reveals its ghostly presence. Scientists do not know what composes the bizarre non-atomic dark matter, and its identity has long eluded those who have tried to understand it. However, in August 2019, astronomers from the Max Planck Institute for Computational Physics in Potsdam, Germany, and the University of Warsaw in Poland, have proposed a new and unusual dark matter candidate–a superheavy gravitino.

The gravitino is a hypothetical fermion, associated with graviton theories of supergravity. The graviton is also hypothetical but dark web sites
, if it does exist, it is an elementary particle that mediates the force of gravity. Fermions are subatomic particles.

The Universe itself is almost completely composed of dark energy (~68%), dark matter (~27%), and so-called “ordinary” atomic matter (~5%). Other contents include electromagnetic radiation (~0. 005%-0. 01%) and antimatter. Dark matter is thought to be composed of unidentified non-atomic particles, and it is a substance whose powerful gravitational pull serves as the “glue” that holds galaxies together. The identity of the dark energy is also unknown, but it is considered to be the mysterious substance responsible for causing the Universe to accelerate in its expansion–and it is possibly a property of space itself. While “ordinary” atomic matter accounts for much less of the Universe than dark matter and dark energy, it is the part of the Universe that we are most familiar with. Extraordinary “ordinary” matter accounts for literally every element listed in the familiar Periodic Table, and without its presence, we would not be here.

Dr. Hermann Nicolai, Director of the Max Planck Institute for Gravitational Physics, and his colleague Dr. Krzysztrof Meissner from the University of Warsaw, note that the existence of the still-hypothetical superheavy gravitino follows from a hypothesis that seeks to explain how the observed spectrum of quarks and leptons in the standard model of particle physics might emerge from a fundamental theory. Furthermore, the two scientists describe a possible method for actually tracking down this elusive possible particle.

The standard model of particle physics includes the building blocks of matter and the forces that bind them together. It proposes that there are a half-dozen different quarks and a half-dozen leptons that are grouped into a trio of “families”. Quarks are any one of numerous subatomic particles carrying a fractional electric charge, and are postulated as the building blocks of hadrons. The most stable hadrons are protons and neutrons (baryons), which are the components of atomic nuclei. The six types of quarks are: up, down, strange, charm, bottom and top. Leptons are elementary particles that do not experience strong interactions.

We are, ourselves–as well as the matter that surrounds us–made up of only three particles: the up and down quarks and electrons. The electron is a member of the lepton family.

Until now, the long-established standard model of particle physics has not changed. The Large Hadron Collider (LHC) at CERN in Switzerland began operating about a decade ago with the primary purpose of hunting for what may reside beyond. Alas, despite expectations to the contrary, after ten years of obtaining data scientists have not detected any new elementary particles–with the important exception of the Higgs boson, the so-called “god particle”, responsible for providing particles with mass. Hence, until now, measurements with the LHC have failed to provide any evidence at all of the greatly anticipated “new physics” beyond the standard model. This new research provides a dramatic contrast.

In a previous paper published in Physical Review Letters, Dr. Nicolai and Dr. Meissner proposed a new theory seeking to explain why only the already-known elementary particles emerge as the basic building blocks of matter provided by Mother Nature–and, also, why no new particles should be expected to show up in the energy range accessible to current or conceivable future experiments. In order to provide a solution, the two scientists studied the possible existence of superheavy gravitinos–and their real existence in nature would make them fascinating, albeit unusual, candidates for dark matter.

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