Searching for Dark Matter Through the 5th Dimension

Gayatri Sharma

B.Sc 5^th Sem(Physics Major)

Dark Matter:

Dark matter is one of the greatest unsolved mysteries in cosmologies in the present time. It is a form of matter thought of account for approx 85% of matter in universe and about a quarter of total mass- energy density about 2.241×10^-27 kg/ m³. Dark matters are called dark because it does not appear to interact with the electromagnetic field, which means it does not absorb, reflect or emit any EM radiation which makes it difficult to detect. Dark matter has not yet been observed directly, if it exists it must barely interact with ordinary baryonic matter and radiation, except through gravity. Most dark matter is thought to be non-baryonic in nature, it may be composed of some undiscovered subatomic partickles. It can be classified as cold, warm or hot according to its velocity.

Theoretical physicists of the PRISMA+ Cluster of Excellence of Johannes Gutenberg University Mainz are working on a theory that goes beyond the Standard Model of Particle Physics and can answer questions where the Standard Model has to pass – for example, with respect to hierarchies of the masses of the elementary particles or the existence of dark matter. The central element of the theory is an extra dimension in space time. Until now, scientists have faced the problem that the predictions of their theory could not be tested experimentally. They have now overcome this problem.

As early as the 1920s, in an attempt to unify the forces of gravity and EM, Theodon Kaluza and Oskar Klein speculated about the existence of an extra dimension beyond the familiar 3 space dimensions and time- which in physics are combined into 4- dimensional space-time. If it exists, such a new dimension would have to be incredibly tiny and unnoticeable to the human eye. aIn the late 1990s this idea has seen a remarkable renaissance when it was realized that the existence of a 5^th dimension could resolve some of the profound open questions of particle physics. In particular, Yuval Gross man of Stanford University and Matthias Neubert, then a professor at Cornell University, showed in a highly cited publication that the embedding of the Standard Model of particle physics in a 5-dimensional space-time could explain this so far mysterious patterns seen in the masses of elementary particles.

Another 20 years later, the group of Matthias Neubert since 2006 on the faculty of Johannes Gutenberg University in Mainz(Germany) and spokesperson of the PRISMA+ cluster of Excellence made another unexpected discovery; they found that the 5-dimensional field equations predicted the existence of a new, heavy particle with similar properties as the famous Higgs boson but a much heavier mass – so heavy, in fact, that it cannot be produced even at the higher energy particle collider in the world, the Large Hadron Collider(LHC) at the European Center for Nuclear Research CERN near Geneva (Switzwerland). “It was a nightmere”, recalls Javier Castellano Ruiz, a PhD student involved in the research, “We were excited by the idea that our theory predicts a new particle, but it appeared impossibkle to confirm this prediction in any foreseeable experiment.

The Detour through the 5^th Dimension:

In a recent paper published in the European Physical Journal, the researchers found a spectacular resolution to this dilemma. They discovered that their proposed particle would necessarily mediate a new force between the known elementary particles (visible universe) and the mysterious dark matter. Even the abundance of dark matter in the cosmos, as observed in astrophysical experiments, can be explained by their theory. This offers exciting new ways to search for the constituents of the dark matter- literally via a detour through the extra dimension - and obtain clues about the physics at a very early stage in the history of our universe, when the dark matter was produced. "After years of searching for possible confirmations of our theoretical predictions, we are now confident that the mechanism we have discovered would make the dark matter accessible to forthcoming experiments, because the properties of the new interaction between ordinary matter and dark matter - which is mediated by our proposed particle - can be calculated accurately within our theory" says Matthias Neubert, head of the research team. "In the end, so our hope-the new particle may be discovered first through its interactions with the dark sector."