Researchers from Maastricht University and Nikhef want to use a new experiment to examine one of the mysteries of particle theory. NWO has awarded an M1 grant for this purpose.
The proposal by Nikhef researcher Panos Christakoglou revolves around the extremely strong magnetic field that is created when heavy lead nuclei collide in the ALICE detector at CERN. This field is the strongest known in nature and makes it possible to test the so-called strong CP violation.
According to particle theory, the physical world exists thanks to symmetry violations, which mean that not all possible outcomes of the theory have become reality. One example is the balance of matter and antimatter. In theory, these should have been created in equal amounts in the Big Bang. In reality, the universe consists of matter.
In the Standard Model for particle physics, such a symmetry break can be understood theoretically for both the weak nuclear force and the strong nuclear force. For the weak nuclear force, this has also been measured in experiments at CERN and elsewhere. For the strong nuclear force, there is no experimental evidence of CP violation.
The strong nuclear force is the force that binds quarks in nuclear particles. Quarks are bound in nuclear particles in triplets, but the extreme nuclear collisions in the LHC accelerator at CERN create a plasma of individual quarks and gluons. This Big Bang matter is studied in ALICE.
Christakoglou, senior lecturer in Maastricht and member of the ALICE experiment, expects that the extreme magnetic field created during nuclear collisions in the ALICE detector will enable direct measurement of strong CP violation.
Last year, he predicted in an article in the European Physical Journal that CP asymmetry could cause the quarks in the extreme magnetic fields during nuclear collisions to generate a subtle electric current, which in principle could be measured among all the other signals in the detector.
Cautious indications of this have already been seen in ALICE experiments, but hard evidence is still lacking. With the NWO funding, Christakoglou will be able to appoint a PhD student to study the so-called Chiral Magnetic Effect (CME) in detail.
The strength of the magnetic field will be derived from the behavior of protons and neutrons that do not undergo collision, a technique that has never been tried before.
According to the project proposal, the CME measurements will test the theory that explains CP violation in the strong nuclear force, which dates back to the renowned Russian theorist Andrei Sakharov. The test may also prove that the theory is incorrect.
The project has been awarded more than €400,000 for the next four years of research, which should result in a PhD thesis in due course.
