1,498 research outputs found
Dark energy, cosmological constant and neutrino mixing
The today estimated value of dark energy can be achieved by the vacuum
condensate induced by neutrino mixing phenomenon. Such a tiny value is
recovered for a cut-off of the order of Planck scale and it is linked to the
sub eV neutrino mass scale. Contributions to dark energy from auxiliary fields
or mechanisms are not necessary in this approach.Comment: 10 pages, 2 figure
A new perspective in the dark energy puzzle from particle mixing phenomenon
We report on recent results on particle mixing and oscillations in quantum
field theory. We discuss the role played in cosmology by the vacuum condensate
induced by the neutrino mixing phenomenon. We show that it can contribute to
the dark energy of the universe.Comment: 11 pages, to be published on the review book "Dark Energy-Current
Advances and Ideas
Contact interaction in an unitary ultracold Fermi gas
An ultracold Fermi atomic gas at unitarity presents universal properties that
in the diluted limit can be well described by a contact interaction. By
employing a guide function with correct boundary conditions and making simple
modifications to the sampling procedure we are able to handle for the first
time a true contact interaction in a quantum Monte Carlo calculation. The
results are obtained with small variances. Our calculations for the Bertsch and
contact parameters are in excellent agreement with published experiments. The
possibility of using a more faithfully description of ultracold atomic gases
can help uncover features yet unknown of the ultracold atomic gases. In
addition, this work paves the way to perform quantum Monte Carlo calculations
for systems interacting with contact interactions, where in many cases the
description using potentials with finite effective range might not be accurate
Efficient Implementation Of The Hellmann-feynman Theorem In A Diffusion Monte Carlo Calculation.
Kinetic and potential energies of systems of (4)He atoms in the solid phase are computed at T = 0. Results at two densities of the liquid phase are presented as well. Calculations are performed by the multiweight extension to the diffusion Monte Carlo method that allows the application of the Hellmann-Feynman theorem in a robust and efficient way. This is a general method that can be applied in other situations of interest as well.13405410
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