Are supersymmetric particles made up of quarks

Supersymmetry

Supersymmetry is about nothing less than overcoming the strict separation between matter and forces. The price: With supersymmetry, the number of particles would double. So far, nothing has been seen of the second half.

Many physicists want the universe to be as simple as possible. Not because the researchers are lazy. Rather, they hope that the laws of the universe are particularly elegant. And such elegance, they also wish, should appear in the smallest possible number of different building blocks.

Union of the forces of nature

Although the Standard Model has already brought some order into the original confusion of particles, the search for the primal principle from which the entire diversity of the universe is derived is far from over. At the beginning of the 1970s, a number of theoretical physicists had come a huge step closer to this goal. At that time they discovered a possible regularity - a symmetry - in the universe with which the strict separation between matter and forces could perhaps be dissolved. This “supersymmetry” could unite what still separates the standard model.

According to the Standard Model, the world consists of matter and force particles: matter particles such as electrons and quarks form composite objects such as atoms and people. And for each of the known forces there are force particles through which particles interact. These two types of particles are very different in their behavior. According to supersymmetry, however, there are now supersymmetric partners for all matter particles that behave like force particles and vice versa. The rigid separation of matter and forces would be abolished and the search for the original principle would go one step further.

Symmetries in the natural sciences

In the natural sciences, especially in physics, symmetries play a role that should not be underestimated. It sounds obvious, but for the development of any theory there is one assumption that is crucial: the laws of nature are the same at all times, in all places and in every direction.

This does not mean that the universe is the same in all places, at all times and in all directions. The universe is of course and obviously not the same everywhere, but the same laws apply everywhere.

In this context, physicists speak of symmetries: if, for example, one can move a place in the universe or the zero point of time and the same laws still apply everywhere.

The symmetries of space and time are therefore among the most fundamental in physics. Until the 1970s it was assumed that all symmetries had been discovered. However, a few resourceful physicists took another closer look and discovered that a possible symmetry had previously been neglected. This oversight could be excused: it had something to do with a property of particles that is known to be strange: spin.

The spin

From various experiments, the quantum physicists were able to conclude that elementary particles have a property that bodies of everyday size do not have. They called this spin. The mathematical description of this property is somewhat successful if one imagines the particles rotating around themselves. Like many other quantum theoretical properties, the spin is quantized, that is, it can only assume certain values. In the imagination this means that the axis of rotation around which the particle rotates can only point in certain directions.

For example, electrons only have two spin settings available. Either up or down. There is no in between. Quarks also have two such settings. But there are also particles that can choose from three or more possible settings. And then there are those who only have one attitude.

Physicists assign different spin values ​​to the particles, which represent a kind of measure of the speed of rotation. Matter particles such as electrons and quarks have the spin value 1/2, the interaction particles, through whose exchange the forces function, have the spin value 1.

Supersymmetrical partner particles

Supersymmetrical partner particles

Supersymmetry is a symmetry that is closely related to the spin of the particles. Unfortunately, like most things in the quantum world, it is much more difficult to imagine than a shift in space and time. What is easy to imagine, however, are the consequences that result from supersymmetry and that could in principle be demonstrated in particle accelerators: If our universe is supersymmetric, then there is a supersymmetric partner for each of the known particles. For example, there would be super-symmetrical spin-0 particles for the spin-1/2 particles and, conversely, for the spin-1 particles, there would be supersymmetrical spin-1/2 partners. This would connect the world of matter particles with that of force particles. The price for this elegance: the number of different particles doubles.

But no matter how hard the researchers have tried so far and no matter how big their particle accelerators have become, if there is supersymmetry, then physicists have remained hidden to this day a whole half of the universe. They try to explain this with the mass of the supersymmetrical particles: They are simply too heavy to be generated and detected in today's particle accelerators.

According to the name given by the theorists, the supersymmetric partners for the matter particles are prefixed with an "s" - as in Selektron or Squark. The supersymmetrical versions of the interaction particles get an “ino” at the end: Photino, Gluino and so on.

The supersymmetry has great advantages. With their help, the different forces can be combined much better into a single force that dominated the universe shortly after the Big Bang. Over time, the universe has cooled down and the various manifestations of the forces known to us today are said to have been “flocculated” from the one elemental force.

So far, supersymmetry has only existed on paper. Neither does there have to be a primal force or even a primal principle. And the reason why no supersymmetric particles have been found so far does not necessarily have to be their too large mass. A simpler answer could be “There is no such thing as supersymmetry”.