102,650 research outputs found
Dibaryons with two heavy quarks
The relativistic six-quark equations are constructed in the framework of the
dispersion relation technique. The relativistic six-quark amplitudes of
dibaryons including the light , and heavy , quarks are
calculated. The approximate solutions of these equations using the method based
on the extraction of leading singularities of the heavy hexaquark amplitudes
are obtained. The poles of these amplitudes determine the masses of charmed and
bottom dibaryons with the isospins I=0, 1, 2 and the spin-parities ,
, .Comment: 10 pages, types corrected. arXiv admin note: substantial text overlap
with arXiv:1105.081
Heavy dibaryons
The relativistic six-quark equations are found in the framework of the
dispersion relation technique. The approximate solutions of these equations
using the method based on the extraction of leading singularities of the heavy
hexaquark amplitudes are obtained. The relativistic six-quark amplitudes of
dibaryons including the light quarks , and heavy quarks , are
calculated. The poles of these amplitudes determine the masses of charmed and
bottom dibaryons with the isospins 1/2, 3/2, 5/2.Comment: 16 page
Aerodynamic torque on a space vehicle
Aerodynamic torque analysis of reentry vehicle passing through rarefied air at high altitude
An unconventional magnetically-coupled multivibrator
Multivibrator circuit provides a low-frequency sine wave output without using a low-frequency power transformer or filter components. This circuit, utilizing two transistors and a magnetic core, represents a reduction in complexity, size, and weight over similar units
Which hadronic decay modes are good for searching: double or something else?
It has been controversial whether can be discovered in Tevatron Run
2 through the decay followed by . We clear this controversy by an explicit calculation which
predicts to be of order . It is
concluded that observing eta_b through this decay mode in Tevatron Run 2 is
rather unrealistic. The eta_b may be observed in the forthcoming LHC
experiments through the 4-lepton channel, if the background events can be
significantly reduced by imposing some kinematical cuts. By some rough but
plausible considerations, we find that the analogous decay processes eta_b to
VV, D^*\bar{D}^* also have very suppressed branching ratios, nevertheless it
may be worth looking for \eta_b at LHC and Super B factory through the decay
modes \eta_b \to K_S K^{\pm}\pi^{\mp}, D^*\bar{D}.Comment: v2; 28 pages, 2 figures. References added, presentation improved.
Discussion on possible nonperturbative mechanism for eta_b->VV added,
analysis for eta_b->VP updated by incoprating the U-spin violation effec
Single pion electro-- and neutrinoproduction on heavy targets
We present a calculation of single pion electroproduction cross sections on
heavy targets in the kinematic region of the Delta(1232) resonance. Final state
interactions of the pions are taken into account using the pion multiple
scattering model of Adler, Nussinov and Paschos (ANP model). For
electroproduction and neutral current reactions we obtain results for carbon,
oxygen, argon and iron targets and find a significant reduction of the
W-spectra for pi^0 as compared to the free nucleon case. On the other hand, the
charged pion spectra are only little affected by final state interactions.
Measurements of such cross sections with the CLAS detector at JLAB could help
to improve our understanding of pion rescattering effects and serve as
important/valuable input for calculations of single pion neutrinoproduction on
heavy targets relevant for current and future long baseline neutrino
experiments. Two ratios, in Eq. (3.8) and (3.10), will test important
properties of the model.Comment: 21 pages, 8 figure
Spin-polarized electric currents in quantum transport through tubular two-dimensional electron gases
Scattering theory is employed to derive a Landauer-type formula for the spin
and the charge currents, through a finite region where spin-orbit interactions
are effective. It is shown that the transmission matrix yields the spatial
direction and the magnitude of the spin polarization. This formula is used to
study the currents through a tubular two-dimensional electron gas. In this
cylindrical geometry, which may be realized in experiment, the transverse
conduction channels are not mixed (provided that the spin-orbit coupling is
uniform). It is then found that for modest boundary scattering, each step in
the quantized conductance is split into two, and the new steps have a non-zero
spin conductance, with the spin polarization perpendicular to the direction of
the current.Comment: 6 pages, 5 figure
Teleportation of the one-qubit state in decoherence environments
We study standard quantum teleportation of one-qubit state for the situation
in which the channel is subject to decoherence, and where the evolution of the
channel state is ruled by a master equation in the Lindblad form. A detailed
calculation reveals that the quality of teleportation is determined by both the
entanglement and the purity of the channel state, and only the optimal matching
of them ensures the highest fidelity of standard quantum teleportation. Also
our results demonstrated that the decoherence induces distortion of the Bloch
sphere for the output state with different rates in different directions, which
implies that different input states will be teleported with different
fidelities.Comment: 17 pages, 10 figure
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