10,852 research outputs found
Circle bundles over 4-manifolds
Every 1-connected topological 4-manifold M admits a -covering by
#_{r-1}S^{2}\times S^{3}, where rankH^{2}(M;\QTR{Bbb}{Z}).Comment: 6 pages to appear in Archiv der Mat
Trapped ion quantum computation with transverse phonon modes
We propose a scheme to implement quantum gates on any pair of trapped ions
immersed in a large linear crystal, using interaction mediated by the
transverse phonon modes. Compared with the conventional approaches based on the
longitudinal phonon modes, this scheme is much less sensitive to ion heating
and thermal motion outside of the Lamb-Dicke limit thanks to the stronger
confinement in the transverse direction. The cost for such a gain is only a
moderate increase of the laser power to achieve the same gate speed. We also
show how to realize arbitrary-speed quantum gates with transverse phonon modes
based on simple shaping of the laser pulses.Comment: 5 page
Study of the quasi-two-body decays B^{0}_{s} \rightarrow \psi(3770)(\psi(3686))\pi^+\pi^- with perturbative QCD approach
In this note, we study the contributions from the S-wave resonances,
f_{0}(980) and f_{0}(1500), to the B^{0}_{s}\rightarrow \psi(3770)\pi^
{+}\pi^{-} decay by introducing the S-wave \pi\pi distribution amplitudes
within the framework of the perturbative QCD approach. Both resonant and
nonresonant contributions are contained in the scalar form factor in the S-wave
distribution amplitude \Phi^S_{\pi\pi}. Since the vector charmonium meson
\psi(3770) is a S-D wave mixed state, we calculated the branching ratios of
S-wave and D-wave respectively, and the results indicate that f_{0}(980) is the
main contribution of the considered decay, and the branching ratio of the
\psi(2S) mode is in good agreement with the experimental data. We also take the
S-D mixed effect into the B^{0}_{s}\rightarrow \psi(3686)\pi^ {+}\pi^{-} decay.
Our calculations show that the branching ratio of B^{0}_{s}\rightarrow
\psi(3770)(\psi(3686))\pi^ {+}\pi^{-} can be at the order of 10^{-5}, which can
be tested by the running LHC-b experiments.Comment: 10 pages, 3 figure
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