3,081 research outputs found
Command Interneurons in the Crayfish Central Nervous System
The motor effects evoked by stimulation of each of eight command fibres in the circumoesophageal commissures of the crayfish are described. The fibres obtained appeared to have widespread connexions in all or most of the lower ganglia. For certain fibres the response was stronger on the homolateral side of the animal; for others it was symmetrical. The frequency of stimulation of a command fibre generally had a pronounced influence on the speed of the evoked response. In addition, segments of the total response could be elicited selectively by alteration of the frequency and duration of stimulation. Although the responses associated with most of the fibres were not sensitive to the fine temporal pattern of the applied stimulation, for one fibre the motor output depended clearly on the spacing of the stimulating pulses
Desperately Seeking Non-Standard Phases via Direct CP Violation in Process
Attributing the recent CLEO discovery of to originate
(primarily) from the fragmentation of an off-shell gluon () via , , we emphasize that many such states () should
materialize. Indeed the hadronic fragments () of states are closely
related to those seen in . A particular
final state of considerable interest is . Signals from such states
in decays can be combined to provide a very sensitive search for CP
violating phase(s) from non-standard physics. The method should work even if
the contribution of these source(s) to the rates is rather small () to
the point that a comparison between theory and experiment may find it extremely
difficult to reveal the presence of such a new physics.Comment: 16 pages, 5 figure
Texture of Yukawa coupling matrices in general two-Higgs-doublet model
We discuss possible parallel textures of the Yukawa coupling matrices in the
generaltwo-Higgs-doublet model (2HDM). In those textures the flavor changing
neutral currentsare naturally suppressed. Motivated by a phenomenologically
successful texturewith four texture zeros in the standard model, we propose a
predictive ansatz for the Yukawa coupling matrices with the same texture in the
general 2HDM. Compared with the six texture-zero based ansatz proposed by Cheng
and Sher, it is in a better agreement with the data of quark mixings and CP
violation. The four texture-zero based ansatz predicts a different hierarchy in
the Yukawa coupling matrix elements. As a consequence, in the lepton sector,
the related Yukawa couplings are less constrained by the experimental upper
bound of , which allows significantly larger predictions for
other processes. The contributions from neutral scalar interactions to the
lepton number violation decay modes are
calculated in both ansatz. It is shown that the predictions from the four
texture-zero based ansatz could be two order of magnitude greater than that
from the six texture-zero based one. The branching ratio of and
can reach and 1.3\tiems 10^{-10}
respectively. The predicted ratio of is also
larger and almost parameter independent. Those differences make the two ansatz
to be easily distinguished by the future experiments.Comment: 12 pages, 2 figure
at Hadron Colliders
We study the observability for a lepton flavor-changing decay of a Higgs
boson at hadron colliders. Flavor-changing couplings of a Higgs
boson exist at tree level in models with multiple Higgs doublets. The
coupling is particularly motivated by the favorable intepretation of
oscillation. We find that at the Tevatron Run II the unique
signature could serve as the Higgs discovery channel, surpassing
expectations for Higgs boson searches in the SM and in a large parameter region
of the MSSM. The sensitivity will be greatly improved at the LHC, beyond the
coverage at a muon collider Higgs factory.Comment: Version to appear in PR
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