2,815 research outputs found
Nonparaxial shape-preserving Airy beams with Bessel signature
Spatially accelerating beams that are solutions to the Maxwell equations may
propagate along incomplete circular trajectories, after which diffraction
broadening takes over and the beams spread out. Taking these truncated Bessel
wave fields to the paraxial limit, some authors sustained that it is recovered
the known Airy beams (AiBs). Based on the angular spectrum representation of
optical fields, we demonstrated that the paraxial approximation rigorously
leads to off-axis focused beams instead of finite-energy AiBs. The latter will
arise under the umbrella of a nonparaxial approach following elliptical
trajectories in place of parabolas. Deviations from full-wave simulations
appear more severely in beam positioning rather than its local profile
Direct detection of fermion dark matter in the radiative seesaw model
We consider the scenario in the radiative seesaw model where the dark matter
particle is the lightest -odd fermion. We identify the regions of the
parameter space of the model compatible with neutrino oscillation data, with
the upper limits from rare charged lepton decays and with the observed dark
matter abundance via thermal freeze-out, and we compute the dark matter
scattering cross section with nuclei via the one-loop exchange of a photon, a
-boson or a Higgs boson. We find that the predicted spin-independent cross
section lies below the current LUX limit, although, for some choices of
parameters, above the expected sensitivity of XENON1T or LZ.Comment: 22 pages, 4 figure
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