117 research outputs found
Improved protocols of secure quantum communication using W states
Recently, Hwang et al. [Eur. Phys. J. D. 61, 785 (2011)] and Yuan et al.
[Int. J. Theo. Phys. 50, 2403 (2011)] have proposed two efficient protocols of
secure quantum communication using 3-qubit and 4-qubit symmetric W state
respectively. These two dense coding based protocols are generalized and their
efficiencies are considerably improved. Simple bounds on the qubit efficiency
of deterministic secure quantum communication (DSQC) and quantum secure direct
communication (QSDC) protocols are obtained and it is shown that dense coding
is not essential for designing of maximally efficient DSQC and QSDC protocols.
This fact is used to design maximally efficient protocols of DSQC and QSDC
using 3-qubit and 4-qubit W states.Comment: 8 page
Measurements of the observed cross sections for exclusive light hadrons containing at , 3.650 and 3.6648 GeV
By analyzing the data sets of 17.3, 6.5 and 1.0 pb taken,
respectively, at , 3.650 and 3.6648 GeV with the BES-II
detector at the BEPC collider, we measure the observed cross sections for
, , ,
and at the three energy
points. Based on these cross sections we set the upper limits on the observed
cross sections and the branching fractions for decay into these
final states at 90% C.L..Comment: 7 pages, 2 figure
Partial wave analysis of J/\psi \to \gamma \phi \phi
Using events collected in the BESII detector, the
radiative decay is
studied. The invariant mass distribution exhibits a near-threshold
enhancement that peaks around 2.24 GeV/.
A partial wave analysis shows that the structure is dominated by a
state () with a mass of
GeV/ and a width of GeV/. The
product branching fraction is: .Comment: 11 pages, 4 figures. corrected proof for journa
Direct Measurements of Absolute Branching Fractions for D0 and D+ Inclusive Semimuonic Decays
By analyzing about 33 data sample collected at and around 3.773
GeV with the BES-II detector at the BEPC collider, we directly measure the
branching fractions for the neutral and charged inclusive semimuonic decays
to be and , and determine the ratio of the two branching
fractions to be
A study of charged kappa in
Based on events collected by BESII, the decay
is studied. In the invariant mass
spectrum recoiling against the charged , the charged
particle is found as a low mass enhancement. If a Breit-Wigner function of
constant width is used to parameterize the kappa, its pole locates at MeV/. Also in this channel,
the decay is observed for the first time.
Its branching ratio is .Comment: 14 pages, 4 figure
Measurements of the observed cross sections for e+e -> exclusive light hadrons containing K^S_0 meson at \sqrt{s} = 3.773 and 3.650 GeV
By analyzing the data sets of 17.3 pb taken at GeV
and of 6.5 pb taken at GeV with the BES-II detector at
the BEPC collider, we measure the observed cross sections for the exclusive
light hadron final states of , ,
, ,
and produced in
annihilation at the two energy points. We set the upper limits on the
observed cross sections and the branching fractions for decay to
these final states at 90% C.L..Comment: 6 pages, 1 figur
Study of J/Psi decays into eta Kstar Kstar-bar
We report the first observation of \mPJpsi \to \mPeta\mPKst\mAPKst decay in
a \mPJpsi sample of 58 million events collected with the BESII detector. The
branching fraction is determined to be . The selected signal event sample is further used to search for the
\mPY resonance through \mPJpsi \to \mPeta \mPY, \mPY\to\mPKst\mAPKst. No
evidence of a signal is seen. An upper limit of \mathrm{Br}(\mPJpsi \to \mPeta
\mPY)\cdot\mathrm{Br}(\mPY\to\mPKst\mAPKst) < 2.52\times 10^{-4} is set at the
90% confidence level.Comment: 11 pages, 4 figure
Curvature-bias corrections using a pseudomass method
Momentum measurements for very high momentum charged particles, such as muons from electroweak vector boson decays, are particularly susceptible to charge-dependent curvature biases that arise from misalignments of tracking detectors. Low momentum charged particles used in alignment procedures have limited sensitivity to coherent displacements of such detectors, and therefore are unable to fully constrain these misalignments to the precision necessary for studies of electroweak physics. Additional approaches are therefore required to understand and correct for these effects. In this paper the curvature biases present at the LHCb detector are studied using the pseudomass method in proton-proton collision data recorded at centre of mass energy √(s)=13 TeV during 2016, 2017 and 2018. The biases are determined using Z→μ + μ - decays in intervals defined by the data-taking period, magnet polarity and muon direction. Correcting for these biases, which are typically at the 10-4 GeV-1 level, improves the Z→μ + μ - mass resolution by roughly 18% and eliminates several pathological trends in the kinematic-dependence of the mean dimuon invariant mass
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