(Phys.org)—A quartet of researchers has boldly proposed the addition of six new particles to the standard model to explain five enduring problems. In their paper published in the journal Physical Review Letters, Guillermo Ballesteros with Université Paris Saclay, Javier Redondo with Universidad de Zaragoza, Andreas Ringwald with Max-Planck-Institut für Physik and Carlos Tamarit with Durham University describe the six particles they would like to add and why.