A group of researchers from the Centre for Theoretical Particle Physics (CFTP) at Instituto Superior Técnico proposed a new solution to open problems in particle and astroparticle physics. The study was led by the CFTP PhD students Aditya Batra and Henrique Câmara in collaboration with their supervisor Filipe Joaquim and the researchers Rahul Srivastava (IISER, Bhopal, India) and José W.F. Valle (IFIC-Valencia University, Spain). The article was published on February 1, in the prestigious journal Physical Review Letters.
The researchers consider the existence of new particles – axions – that carry ‘colour’, a quantum property associated with the strong interaction (the phenomenon responsible for the cohesion of atomic nuclei).
This proposal is based on three unsolved problems – (1) how do neutrinos gain their mass and what makes it so tiny, (2) what is the viable dark-matter candidate and (3) the strong CP problem, related to the fact that the neutron electric dipole moment hasn’t been observed so far. Although these are apparently unrelated problems, the solution proposed by the CFTP researchers is innovative in putting forward axions as a possible link between the three issues.
“The problems of neutrino mass, dark matter and CP problem have intrigued me since the beginning of my PhD,” explains Henrique Câmara. So, “the idea [of this article] provides an interesting solution that links these issues”. Aditya Batra adds “working with internationally renowned supervisors has given me valuable insights into the project” and has helped him improve his communication skills.
According to the Técnico professor Filipe Joaquim, “in addition to the scientific relevance of this work, one of the important aspects is seeing the work of young Portuguese researchers recognised at international level in one of the most-cited journals in physics”. The professor adds, “this recognition is proof that a researcher’s career is on the right track”.
Since this particle couples electromagnetically to photons, axions produced in stars such as the Sun, can be probed experimentally by analysing the solar flux. “Overall, these experiments contribute to our understanding of the role of axions in fundamental physics and their potential connection to dark matter.” This novel idea paves the way for new phenomenological studies with an impact on other aspects of particle and astroparticle physics.
