36,952 research outputs found
Sterile neutrinos, lepton asymmetries, primordial elements: how much of each?
We investigate quantitatively the extent to which having a primordial
leptonic asymmetry (n_nu \neq n_nubar) relaxes the bounds on light sterile
neutrinos imposed by BBN and LSS. We adopt a few assumptions that allow us to
solve the neutrino evolution equations over a broad range of mixing parameters
and asymmetries. For the general cases of sterile mixing with the electron or
muon neutrino, we identify the regions that can be reopened. For the particular
case of a LSND-like sterile neutrino, soon to be rejected or confirmed by
MiniBooNE, we find that an asymmetry of the order of 10^-4 is needed to lift
the conflicts with cosmology.Comment: 18 pages, 2 figures. v2: References and minor comments added. Matches
version published on PR
Effective non-Markovian description of a system interacting with a bath
We study a harmonic system coupled to chain of first neighbor interacting
oscillators. After deriving the exact dynamics of the system, we prove that one
can effectively describe the exact dynamics by considering a suitable shorter
chain. We provide the explicit expression for such an effective dynamics and we
provide an upper bound on the error one makes considering it instead of the
dynamics of the full chain. We eventually prove how error, timescale and number
of modes in the truncated chain are related
Cellular Ability to Sense Spatial Gradients in the Presence of Multiple Competitive Ligands
Many eukaryotic and prokaryotic cells can exhibit remarkable sensing ability
under small gradient of chemical compound. In this study, we approach this
phenomenon by considering the contribution of multiple ligands to the chemical
kinetics within Michaelis-Menten model. This work was inspired by the recent
theoretical findings from Bo Hu et al. [Phys. Rev. Lett. 105, 048104 (2010)],
our treatment with practical binding energies and chemical potential provides
the results which are consistent with experimental observations.Comment: 5 pages, 4 figure
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