451 research outputs found
Visual SLAM for flying vehicles
The ability to learn a map of the environment is important for numerous types of robotic vehicles. In this paper, we address the problem of learning a visual map of the ground using flying vehicles. We assume that the vehicles are equipped with one or two low-cost downlooking cameras in combination with an attitude sensor. Our approach is able to construct a visual map that can later on be used for navigation. Key advantages of our approach are that it is comparably easy to implement, can robustly deal with noisy camera images, and can operate either with a monocular camera or a stereo camera system. Our technique uses visual features and estimates the correspondences between features using a variant of the progressive sample consensus (PROSAC) algorithm. This allows our approach to extract spatial constraints between camera poses that can then be used to address the simultaneous localization and mapping (SLAM) problem by applying graph methods. Furthermore, we address the problem of efficiently identifying loop closures. We performed several experiments with flying vehicles that demonstrate that our method is able to construct maps of large outdoor and indoor environments. © 2008 IEEE
Search for B+ -> l+ nu gamma decays with hadronic tagging using the full Belle data sample
We search for the decay B+ -> l+ nu gamma with l+ = e+ or mu+ using the full
Belle data set of 772 x 10^6 BBbar pairs, collected at the Y(4S) resonance with
the Belle detector at the KEKB asymmetric-energy e+e- collider. We reconstruct
one B meson in a hadronic decay mode and search for the B+ -> l+ nu gamma decay
in the remainder of the event. We observe no significant signal within the
phase space of E_gamma^sig > 1 GeV and obtain upper limits of BR(B+ -> e+ nu
gamma) mu+ nu gamma) l+ nu
gamma) < 3.5 x 10^-6 at 90 % credibility level.Comment: Submitted to Phys. Rev.
Measurement of via initial state radiation at Belle
The process (=1, 2) is studied via initial
state radiation using 980 fb of data at and around the
(=1, 2, 3, 4, 5) resonances collected with the Belle detector at the KEKB
asymmetric-energy collider. No significant signal is observed except
from decays. Upper limits on the cross sections between
and are determined at the 90% credibility
level, which range from few pb to a few tens of pb. We also set upper limits on
the decay rate of the vector charmonium [), , and
] and charmoniumlike [, , and ] states
to .Comment: Accepted by PR
Measurement of the direct asymmetry in decays with a lepton tag
We report the measurement of the direct asymmetry in the radiative
decay using a data sample of pairs collected at the resonance with
the Belle detector at the KEKB asymmetric-energy collider. The
asymmetry is measured as a function of the photon energy threshold. For
, where is the
photon energy in the center-of-mass frame, we obtain
,
consistent with the Standard Model prediction.Comment: Published at PR
First observation of the hadronic transition and new measurement of the and parameters
Using a sample of decays collected by
the Belle experiment at the KEKB collider, we observe for the first
time the transition with the branching fraction
and we measure the mass MeV/, corresponding to the hyperfine splitting MeV/. Using the transition , we measure the mass MeV/, corresponding to MeV/, the width
MeV/ and the branching
fraction .Comment: 7 pages, 2 figures, submitted to Phys. Rev. Let
Observation of in decays
We report the first observation of and
evidence for . We measure the product of
branching fractions for the former to be {\cal B}(B^0 \to X(3872) (K^+ \pi^-))
\times {\cal B}(X(3872) \to J/\psi \pi^+ \pi^-) = (7.9 \pm 1.3(\mbox{stat.})\pm
0.4(\mbox{syst.})) \times 10^{-6} and find that does not dominate the decay
mode. We also measure {\cal B}(B^+ \to X(3872) (K^0 \pi^+)) \times {\cal
B}(X(3872) \to J/\psi \pi^+ \pi^-) = (10.6 \pm 3.0(\mbox{stat.}) \pm
0.9(\mbox{syst.})) \times 10^{-6}. This study is based on the full data sample
of 711~fb ( pairs) collected at the
resonance with the Belle detector at the KEKB collider.Comment: 7 pages, 3 figure
Study of B^0 -> rho^0 rho^0 decays, implications for the CKM angle phi_2 and search for other B^0 decay modes with a four-pion final state
We present a study of the branching fraction of the decay B^0->rho0rho0 and
the fraction of longitudinally polarized rho0 mesons in this decay. The results
are obtained from the final data sample containing 772 million BBbar pairs
collected at the Y(4S) resonance with the Belle detector at the KEKB
asymmetric-energy e+e- collider. We find 166 +- 59 B^0 -> rho0 rho0 events
(including systematic uncertainties), corresponding to a branching fraction of
B(B^0->rho0rho0) = (1.02 +- 0.30 (stat) +- 0.15 (syst)) x 10^{-6} with a
significance of 3.4 standard deviations and a longitudinal polarization
fraction fL = 0.21^{+0.18}_{-0.22} (stat) +- 0.15 (syst). We use the
longitudinal polarization fraction to determine the Cabibbo-Kobayashi-Maskawa
matrix angle phi_2 = (84.9 +- 13.5) degrees through an isospin analysis in the
B->rhorho system. We furthermore find 149 +- 49 B^0->f0rho0 events,
corresponding to B(B^0->f0rho0) x B(f0->pi+pi-) = (0.78 +- 0.22 (stat) +- 0.11
(syst)) x 10^{-6}, with a significance of 3.1 standard deviations. We find no
other significant contribution with the same final state, and set upper limits
at 90% confidence level on the (product) branching fractions,
B(B^0->pi+pi-pi+pi-)rho0pi+pi-)<12.0 x 10^{-6},
B(B^0->f0pi+pi-) x B(f0->pi+pi-) f0f0) x
B(f0->pi+pi-)^{2} < 0.2 x 10^{-6}.Comment: 21 pages, 20 figures, conference paper for the 2012th CKM workshop,
submitted to PR
Measurement of the CP Violation Parameters in B0 -> pi+ pi- Decays
We present a measurement of the time-dependent charge-parity (CP) violation
parameters in B0 -> pi+ pi- decays. The results are obtained from the final
data sample containing 772 million BBbar pairs collected at the Upsilon(4S)
resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.
We obtain the CP violation parameters Acp = +0.33 +/- 0.06 (stat) +/- 0.03
(syst) and Scp = -0.64 +/- 0.08 (stat) +/- 0.03 (syst), where Acp and Scp
represent the direct and mixing-induced CP asymmetry, respectively. Using an
isospin analysis including results from other Belle measurements, we find 23.8
< phi2 < 66.8 degrees is disfavored at the 1 sigma level, where phi2 is one of
the three interior angles of the CKM unitarity triangle related to B_{u,d}
decays.Comment: 16 pages, 5 figures, CKM2012 conference paper, Submitted to PR
Measurements of the masses and widths of the and baryons
We present measurements of the masses and decay widths of the baryonic states
and using a data sample
corresponding to an integrated luminosity of 711 fb collected with the
Belle detector at the KEKB asymmetric-energy collider operating at
the resonance. We report the mass differences with respect to
the baryon MeV/, MeV/,
MeV/, MeV/, and the decay widths
MeV/,
MeV/,
MeV/,
MeV/,
where the first uncertainties are statistical and the second are systematic.
The isospin mass splittings are measured to be
MeV/ and
MeV/. These results are the most precise to date.Comment: 13 pages, 4 figures, Submitted to PRD(RC
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