Dark energy from the motions of neutrinos

Carlos Peña Garay

Instituto de Física Corpuscular, UV/CSIC, Valencia

 

Dark energy is at the core of the infrared behavior of our theory. It raises questions on the vacuum
chosen to build our successful ultraviolet physics. Alternatively,  a scalar field may play the role of dark energy, but if it possesses a potential that is either extraordinarily flat or fine-tuned. I will discuss a new avenue that lifts these restrictions when the scalar field undergoes persistent energy exchange with another fluid. The field may come to rest while displaced from the local minimum of its potential. Dark energy can therefore be formed from any potential, regardless of its shape. If the rate of energy transfer is modulated by the scalar's acceleration, the field undergoes a rapid process of freezing, after which the field's equation of state mimics that of a cosmological constant. As an example, I will discuss a physically motivated realization in the form of a derivative neutrino-majoron coupling, which avoids the dynamical instabilities associated with mass-varying neutrino models.