Randall–Sundrum model

The Randall - Sundrum model is in modern theoretical physics a mathematical approach for a uniform description of the fundamental forces in the universe. It has been suggested by physicists Lisa Randall and Raman Sundrum in 1999 and describes the universe with the introduction of an additional fifth dimension as a curved space-time model, specifically as an anti- de Sitter spacetime ( AdS5 abbreviated ).

Relevance

The Randall - Sundrum model is the first model of Branenkosmologie and thus allows first an infinitely large, so do not kompaktifizierte ( tiny rolled-up ), extra dimension. (This tiny rolled-up dimensions had Oskar Klein in 1926 proposed to describe all the known fundamental forces in a world formula, his proposal was taken up later in string theory and extended. )

In this way, it provides the opportunity to solve several fundamental problems in physics:

• It explains with the help of the Higgs mechanism, why elementary particles have mass, gravity, however - compared to the other interaction forces - is weaker by a multiple.

• In addition, it describes a consistent model, which enables the unification of all hitherto known fundamental forces, regardless of the string theory and supersymmetry. This showed works by Lisa Randall and Matthew Schwartz and Alex Pomarol.

Genesis

The Randall - Sundrum model, by Randall as a 5- dimensional warped geometry theory refers to ( a five-dimensional space geometry dtsch theory ), was created as a solution to test the hierarchy problem in the Standard Model of particle physics. The theory is based on previous work by Petr Horava and Edward Witten for the Horava -Witten model. In fact, actually, there are two Randall - Sundrum models RS-1 and RS-2, the second is an extension of the first approach.

RS-1 model

As in the Horava -Witten model are also in the Randall - Sundrum model 1, the known from the Standard Model ago elementary particles in one of two four-dimensional boundary worlds ( branes with three spatial and one temporal dimension ), which are located at the opposite ends of an extra dimension.

Our visible universe, including three of the fundamental forces acting therein ( electromagnetic, weak and strong interactions ) is then one of these two border worlds. The other frontier world and the intervening empty space (bulk) are hidden, as elementary particles and light can not pass into the space. Only the graviton, which transmits the force of gravity as the fourth fundamental force can penetrate the bulk and combine matter in both border worlds.

In the Randall - Sundrum model 1, the fifth dimension has a finite extent.

RS-2 model

The expanded later developed Randall - Sundrum model 2 and simplifies the Randall - Sundrum model 1 in an essential detail, in which it takes two branes do with one. Here, the fifth dimension is unlimited. The probability of gravitons in the fifth dimension is concentrated in the vicinity of our world and also takes off exponentially. The extent of the effect of gravity on an unlimited fifth dimension could explain why the gravity is thus several orders of magnitude weaker than the rest of the forces of interaction.

Experimental Evidence

Since the experimental proof of the predicted by string theory effects only at excessively high energy ranges is possible, the currently known methods for particle acceleration would need equipment, the dimensions required by the order of our galaxy. For this reason string theory was considered for many years as not verifiable.

The Randall - Sundrum model provides in contrast to predictions ( eg, the existence of Kaluza-Klein particles ) that can be checked with the Large Hadron Collider at the European Organization for Nuclear Research CERN in Geneva.

Development

Over the last years, many other models have been developed, which differ significantly in their effects (eg, on the expansion of the universe ) in part by the Randall - Sundrum model. So, adopted in RS model empty bulk by models was extended with a scalar field in the bulk, as in Ekpyrotischen scenario and the cyclic universe. Here, the branes are dynamically interacting with the scalar field can oscillate against each other and even penetrate.