3,137 research outputs found
Supersymmetric Higgs Bosons and Beyond
We consider supersymmetric models that include particles beyond the Minimal
Supersymmetric Standard Model (MSSM) with masses in the TeV range, and that
couple significantly to the MSSM Higgs sector. We perform a model-independent
analysis of the spectrum and couplings of the MSSM Higgs fields, based on an
effective theory of the MSSM degrees of freedom. The tree-level mass of the
lightest CP-even state can easily be above the LEP bound of 114 GeV, thus
allowing for a relatively light spectrum of superpartners, restricted only by
direct searches. The Higgs spectrum and couplings can be significantly modified
compared to the MSSM ones, often allowing for interesting new decay modes. We
also observe that the gluon fusion production cross section of the SM-like
Higgs can be enhanced with respect to both the Standard Model and the MSSM.Comment: References added. Mistake in Eq. 14 corrected, conclusions unchanged.
Typos corrected. Version accepted for publication in PRD. 50 pages, 29
figure
Cataract production in mice by heavy charged particles
The cataractogenic effects of heavy charged particles are evaluated in mice in relation to dose and ionization density. The relative biological effectiveness in relation to linear energy transfer for various particles is considered. Results indicated that low single doses (5 to 20 rad) of Fe 56 or Ar 40 particles are cataractogenic at 11 to 18 months after irradiation; onset and density of the opacification are dose related and cataract density (grade) at 9, 11, 13, and 16 months after irradiation shows partial linear energy transfer dependence. The severity of cataracts is reduced significantly when 417 rad of Co 60 gamma radiation is given in 24 weekly 17 rad fractions compared to giving this radiation as a single dose, but cataract severity is not reduced by fractionation of C12 doses over 24 weeks
Geometric phases in semiconductor spin qubits: Manipulations and decoherence
We describe the effect of geometric phases induced by either classical or
quantum electric fields acting on single electron spins in quantum dots in the
presence of spin-orbit coupling. On one hand, applied electric fields can be
used to control the geometric phases, which allows performing quantum coherent
spin manipulations without using high-frequency magnetic fields. On the other
hand, fluctuating fields induce random geometric phases that lead to spin
relaxation and dephasing, thus limiting the use of such spins as qubits. We
estimate the decay rates due to piezoelectric phonons and conduction electrons
in the circuit, both representing dominant electric noise sources with
characteristically differing power spectra.Comment: 17 pages, 8 figures, published versio
Geometrical spin dephasing in quantum dots
We study spin-orbit mediated relaxation and dephasing of electron spins in
quantum dots. We show that higher order contributions provide a relaxation
mechanism that dominates for low magnetic fields and is of geometrical origin.
In the low-field limit relaxation is dominated by coupling to electron-hole
excitations and possibly noise rather than phonons.Comment: Replaced with final published versio
Report on the rare quagga cat shark landed
Quagga catshark, Halaelurus quagga (Alcock,
1899) one of the rarest sharks in the family
Scyliorhinidae (Order Carcharhiniformes) was
observed at Muttom landing centre, Tamil Nadu on
June 5 2017. It was landed as a bycatch in the
demersal-trawl operated off Muttom at 150-200 m
depths. The male specimen collected measured 298
mm in total length (TL) and its morphometrics were
recorde
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