730,435 research outputs found
Gauge-Higgs Unification and Quark-Lepton Phenomenology in the Warped Spacetime
In the dynamical gauge-Higgs unification of electroweak interactions in the
Randall-Sundrum warped spacetime the Higgs boson mass is predicted in the range
120 GeV -- 290 GeV, provided that the spacetime structure is determined at the
Planck scale. Couplings of quarks and leptons to gauge bosons and their
Kaluza-Klein (KK) excited states are determined by the masses of quarks and
leptons. All quarks and leptons other than top quarks have very small couplings
to the KK excited states of gauge bosons. The universality of weak interactions
is slightly broken by magnitudes of , and for
-, - and -, respectively. Yukawa couplings become
substantially smaller than those in the standard model, by a factor |\cos
\onehalf \theta_W| where is the non-Abelian Aharonov-Bohm phase
(the Wilson line phase) associated with dynamical electroweak symmetry
breaking.Comment: 34 pages, 7 eps files, comments and a reference adde
Spontaneous two photon emission from a single quantum dot
Spontaneous two photon emission from a solid-state single quantum emitter is
observed. We investigated photoluminescence from the neutral biexciton in a
single semiconductor quantum dot coupled with a high Q photonic crystal
nanocavity. When the cavity is resonant to the half energy of the biexciton,
the strong vacuum field in the cavity inspires the biexciton to simultaneously
emit two photons into the mode, resulting in clear emission enhancement of the
mode. Meanwhile, suppression was observed of other single photon emission from
the biexciton, as the two photon emission process becomes faster than the
others at the resonance.Comment: 13 pages, 4 figure
Electromagnons in the multiferroic state of perovskite manganites with symmetric-exchange striction
We have investigated electrically-active magnetic excitations
(electromagnons) in perovskite manganites with the -type (up-up-down-down)
spin structure by terahertz spectroscopy. EuYMnO (0.11) and YLuMnO (01) without magnetic -moments,
which host collinear sinusoidal, -type, cycloidal, and -type spin orders,
are used to examine the systematics of possible electromagnons. Three-peak
structures (23, 35, 45 cm) of magnetic origin show up in the -type
phase with little composition () dependence of frequencies, making a
contrast with the electromagnons observed in the cycloidal-spin ()
phases. One of these electromagnon is ascribed to the zone-edge magnon mode
based on the calculated magnon dispersions.Comment: 5 pages, 4 figure
Electromagnons in the multiferroic state of perovskite manganites with symmetric-exchange striction
We have investigated electrically-active magnetic excitations
(electromagnons) in perovskite manganites with the -type (up-up-down-down)
spin structure by terahertz spectroscopy. EuYMnO (0.11) and YLuMnO (01) without magnetic -moments,
which host collinear sinusoidal, -type, cycloidal, and -type spin orders,
are used to examine the systematics of possible electromagnons. Three-peak
structures (23, 35, 45 cm) of magnetic origin show up in the -type
phase with little composition () dependence of frequencies, making a
contrast with the electromagnons observed in the cycloidal-spin ()
phases. One of these electromagnon is ascribed to the zone-edge magnon mode
based on the calculated magnon dispersions.Comment: 5 pages, 4 figure
Participatory variety selection and scaling: Small grain cereals
United States Agency for International Developmen
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