Particle physicist Harvey Meyer of Mainz University investigates the matter that emerged after the Big Bang as a result of the strong interaction of quarks and gluons
28 February 2018
Particle physicist Professor Harvey Meyer of Johannes Gutenberg University Mainz (JGU) has received a grant from the European Research Council supporting his research on fundamental questions of physics with the help of highly complex calculations. One of those questions he is exploring is whether so-called sterile neutrinos could be candidates for dark matter. The starting point for his calculations is the so-called strong interaction, one of the four fundamental forces, which is responsible for binding quarks and gluons in the nucleus of atoms. Over the next five years, the European Research Council (ERC) will be funding his Strong-interaction matter coupled to electroweak probes and dark matter candidates (SIMDAMA) project to the tune of EUR 1.7 million. The ERC Consolidator Grant is one of the most richly endowed EU funding awards.
Harvey Meyer has been PRISMA Professor of Theoretical Particle Physics at Mainz University since April 2014. One of the aims of the ERC sponsored project is to identify possible dark matter candidates with the aid of computer-assisted calculations based on the theory of the strong interaction.
Visible matter accounts for only approximately 15 percent of the total matter in the universe. The rest is dark matter, which emits no radiation and is therefore invisible to us. "However, we know from astrophysical observations that dark matter must exist," explained Meyer. Dark matter, like visible matter, is subject to gravity, clumps together, and thus influences the way that galaxies and galaxy clusters rotate. It has so far proved impossible to determine what dark matter is made of. One hypothesis is that it consists of sterile neutrinos, i.e., theoretical particles whose existence still has to be demonstrated.
Calculating the total energy of sterile neutrinos
With the support of the ERC Consolidator Grant, Meyer is aiming to calculate how many sterile neutrinos may have been created in the early universe, a period when the most common particles were quarks and gluons. This would allow for comparing the total energy of the sterile neutrinos with the known energy of dark matter. "If the total energy of the sterile neutrinos is greater than that of dark matter, then these particles are almost certainly not constituents of dark matter," Meyer explained. On the other hand, if the corresponding number of sterile neutrinos turns out to be relatively lower, the possibility remains that dark matter may not be composed solely of this one type of particle but of several different constituents.
However, sterile neutrinos are hard to detect. According to the hypothesis, they are only subject to gravity and not the other three fundamental forces of the Standard Model of particle physics. Meyer's work is based on quantum chromodynamics, the fundamental theory describing the forces between quarks and gluons, discretized on a space-time lattice. He assumes for the purposes of his calculations that sterile neutrinos exhibit the oscillation phenomenon that allows them to turn into the three known types of neutrinos, i.e., the electron neutrino, the muon neutrino, and the tau neutrino, which themselves interact with quarks via the weak interaction.
Using photons to cross-check the calculations
Meyer intends to also shed light on a related topic using very similar calculations: the production of photons by the quark-gluon plasma. This type of plasma, which existed in the first microseconds after the Big Bang, can be generated today through the collision of heavy ions such as lead or gold in accelerators. This creates particles of light, which can be measured fairly precisely in the experiments. "Using our methods, we can theoretically calculate the production of photons and then compare this result with the data from experiments. If the figures match, this would strongly indicate that our calculations with regard to sterile neutrinos are also correct," Meyer stated.
Both the calculations on the production of sterile neutrinos and on the generation of photons from the quark-gluon plasma are to be undertaken using complex Monte Carlo simulations on high-performance computers such as the MOGON II facility at Mainz University. "Solving the puzzle of dark matter, measuring the parameters of neutrino oscillations, and testing the Standard Model are among the top priorities of fundamental physics today," said Meyer. "Our project will provide us with the opportunity of making significant contributions to all three of these fields."
Harvey Meyer was appointed Junior Professor of Theoretical Nuclear and Hadron Physics at Johannes Gutenberg University Mainz in April 2010. Four years later, in April 2014, he became Professor of Theoretical Particle Physics at the PRISMA Cluster of Excellence and the Faculty of Physics, Mathematics, and Computer Science at JGU. In his research, he employs computer-based methods to calculate the dynamic properties of strongly-interacting particles.
The ERC Consolidator Grant is one of the most richly endowed funding awards given by the EU to researchers. The European Research Council uses these grants to support excellent researchers at the start of their independent careers, usually at a time 7 to 12 years after they have finished their doctorates when they are developing their own research programs. In order to be awarded a grant, applicants must not only demonstrate excellence in research but must additionally provide evidence of the pioneering nature of their project and its feasibility.