157 research outputs found
Light Gluino, Light Bottom Squark Scenario, and LEP Predictions
The scenario of light gluinos and light sbottoms was advocated to explain the
discrepancy between the measured and theoretical production of quarks at
the Tevatron. This scenario will have model-independent predictions for at the -pole, and at LEPII. We show that the data for at LEPI cannot constrain the scenario, because the ratio
for GeV is smaller than the
uncertainty of the data. However, at LEPII the ratio for GeV, which may give an observable
excess in events; especially, the events.Comment: to match the published version in PR
Superheavy Particle Origin of IceCube PeV Neutrino Events
We interpret the PeV shower events observed by the IceCube collaboration as
an s-channel enhancement of neutrino-quark scattering by a leptoquark that
couples to the tau-flavor and light quarks. With a leptoquark mass of ~ 0.6 TeV
and a steep 1/E^{2.3} neutrino flux, charged-current scattering gives shower
events at ~ 1 PeV and neutral-current scattering gives shower events at ~ 0.5
PeV. This mechanism is also consistent with the paucity of muon-track events
above 100 TeV.Comment: 10 pages, 4 figures. The version appears in Phys. Lett. B, October
201
Electromagnetic properties of dark matter: dipole moments and charge form factor
A neutral dark matter particle may possess an electric dipole moment (EDM) or
a magnetic dipole moment (MDM), so that its scattering with nuclei is governed
by electromagnetic interactions. If the moments are associated with relevant
operators of dimension-5, they may be detectable in direct search experiments.
We calculate complete expressions of the scattering cross sections and the
recoil energy spectra for dark matter with these attributes. We also provide
useful formulae pertinent to dark matter that interacts via an electric charge
form factor (CFF) which is related to the charge radius defined by an effective
dimension-6 operator. We show that a 7 GeV dark matter particle with an EDM,
MDM or CFF easily reproduces the CoGeNT excess while remaining consistent with
null searches.Comment: 10 pages, 1 figure. Version to appear in PL
CP Violating Observables in
We consider various integrated lepton charge-energy asymmetries and azimuthal
asymmetries as tests of CP violation in the process . These
asymmetries are sensitive to different linear combinations of the CP violating
form factors in the three gauge boson production vertex, and can
distinguish dispersive and absorptive parts of the form factors. It makes use
of purely hadronic and purely leptonic modes of 's decays as well as the
mixed modes. The techniques of using the kinematics of jets or missing momentum
to construct CP--odd observables are also employed. These CP violating
observables are illustrated in the generalized Left-Right Model and the Charged
Higgs Model.Comment: 23 pages, plus 11 postscript graphs not posted befor
CP violation in top pair production at an e^+e^- collider
We investigate a possible CP violating effect in annihilation into
top quark pairs. As an illustrative example, we assume the source of
the CP nonconservation is in the Yukawa couplings of a neutral Higgs boson
which contain both scalar and pseudoscalar pieces. One of the interesting
observable effects is the difference in production rates between the two CP
conjugate polarized states.Comment: 9 pages, 3 postscript figures not included but availabel upon
request, CERN-TH.6658/9
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