Alexandre Pombo successfully finished his Physics M.Sc. at Aveiro University, on October 10th 2017, by defending a thesis with title "Q-balls spectroscopy and construction of boson stars". This thesis was supervised by Gr@v researchers and examined by Prof. Yves Brihaye, from the University of Mons, Belgium. Well done Alexandre!
Helgi Rúnarsson successfully defended his PhD thesis "Kerr black holes with scalar and Proca hair". The exam took place at the University of Aveir, on October 9th 2017. The thesis was supervised by Gr@v members C. Herdeiro and E. Radu and former member J. C. Degollado, now at UNAM (Mexico). Congratulations Helgi!
Gr@v member António P. Morais gave a talk at Escola Secundária José Régio in Vila do Conde with title "Do Infinitamente Grande ao Infinitamente Pequeno - uma jornada pelas interações fundamentais na natureza". António was an invited speaker to participate in a sequence of seminars entitled "A Biblioteca convida...", and presented to 11th and 12th grade Science and Technology students the four fundamental interactions in nature and how have they shaped our Universe.
Abstract: I will present the influence of the chiral anomaly on the evolution of magnetohydrodynamics. In the early universe, before electroweak symmetry breaking, and in systems at high enough temperatures such that the electron mass can be ignored, the general description of a charged plasma needs to take into account the triangle anomaly. The interplay between turbulence and chiral magnetic effect can have important consequences on the evolution of magnetic fields, leading to the creation of maximally-helical fields from initially non-helical ones. Chiral effects can support a turbulent inverse cascade, causing a slower decrease of magnetic field with time and a faster growth of correlation length, when compared to the evolution predicted by the standard magnetohydrodynamical description. Using the weak anomaly approximation, specific solutions for the inverse cascade regime that show how chiral effects support it are derived.
Gr@v member Carlos Herdeiro was one of the invited speakers of the 5th UTQuest workshop, with the theme "Hidden Sector Physics and Cosmophysics", that took place at the Yukawa Insitute for Theoretical Physics, Kyoto University, Kyoto, Japan.
The article "Warm Little Inflaton", co-authored by Gr@v member João G. Rosa and collaborators Mar Bastero-Gil (Granada U.), Arjun Berera (Edinburgh U.) and Rudnei O. Ramos (U.E. Rio de Janeiro) has been published in Physical Review Letters and selected as one of the Editors' Suggestions (a distinction given to about 1 in 6 papers).
Abstract: We discuss the possibility that dark matter corresponds to an oscillating scalar field coupled to the Higgs boson. We argue that the initial field amplitude should generically be of the order of the Hubble parameter during inflation, as a result of its quasi-de Sitter fluctuations. This implies that such a field may account for the present dark matter abundance for masses in the range 10^−6–10^−4 eV, if the tensor-to-scalar ratio is within the range of planned CMB experiments. We show that such mass values can naturally be obtained through either Planck-suppressed non-renormalizable interactions with the Higgs boson or, alternatively, through renormalizable interactions within the Randall–Sundrum scenario, where the dark matter scalar resides in the bulk of the warped extra-dimension and the Higgs is confined to the infrared brane.
Our group coordinated the "Numerical Relativity and High Energy Physics" IRSES network (2012-2015). Here is a list of the global network meetings organized: