389 research outputs found
Absolute Energy Calibration of X-ray TESs with 0.04 eV Uncertainty at 6.4 keV in a Hadron-Beam Environment
A performance evaluation of superconducting transition-edge sensors (TESs) in
the environment of a pion beam line at a particle accelerator is presented.
Averaged across the 209 functioning sensors in the array, the achieved energy
resolution is 5.2 eV FWHM at Co (6.9 keV) when the pion beam is
off and 7.3 eV at a beam rate of 1.45 MHz. Absolute energy uncertainty of
0.04 eV is demonstrated for Fe (6.4 keV) with in-situ energy
calibration obtained from other nearby known x-ray lines. To achieve this small
uncertainty, it is essential to consider the non-Gaussian energy response of
the TESs and thermal cross-talk pile-up effects due to charged-particle hits in
the silicon substrate of the TES array.Comment: Accepted for publication in J. Low Temperature Physics, special issue
for the proceedings of the Low Temperature Detectors 16 conferenc
Observation of a new charged charmoniumlike state in B -> J/psi K pi decays
We present the results of an amplitude analysis of anti-B0 -> J/psi K- pi+
decays. A new charged charmoniumlike state Zc(4200)+ decaying to J/psi pi+ is
observed with a significance of 6.2 sigma. The mass and width of the Zc(4200)+
are 4196 +31-29 +17-13 MeV/c^2 and 370 +70-70 +70-132 MeV, respectively; the
preferred assignment of the quantum numbers is J^P = 1^+. In addition, we find
evidence for Zc(4430)+ -> J/psi pi+. The analysis is based on a 711 fb^-1 data
sample collected by the Belle detector at the asymmetric-energy e+ e- collider
KEKB.Comment: 14 pages, 13 figure
Measurement of the lepton polarization and in the decay with one-prong hadronic decays at Belle
With the full data sample of pairs recorded by
the Belle detector at the KEKB electron-positron collider, the decay is studied with the hadronic
decays and . The polarization in two-body hadronic
decays is measured, as well as the ratio of the branching fractions , where
denotes an electron or a muon. Our results, and , are consistent with the theoretical
predictions of the Standard Model. The polarization values of are excluded at the 90\% confidence level.Comment: 17 pages, 11 figures, submitted to Physical Review
Studies of charmed strange baryons in the final state at Belle
We report the discovery of , observed by its decay into
the final state , and present the first observation and evidence
of the decays of and into .
We also perform a combined analysis of the with the
and decay modes to measure
the ratios of branching fractions, masses and widths with improved accuracy. We
measure the ratios of branching fractions , , and , where the uncertainties are
statistical and systematic. The analysis is performed using a 980 fb
data sample collected with the Belle detector at the KEKB asymmetric-energy
collider.Comment: Submitted to PR
Search for and a measurement of the branching fraction for
We search for the decay and measure the
branching fraction for using
121.4~ of data collected at the
resonance with the Belle detector at the KEKB asymmetric-energy
collider. The branching fraction is measured
to be , where is the fraction of
in events. Our result is in good
agreement with the theoretical predictions as well as with a recent measurement
from LHCb. We observe no statistically significant signal for the decay
and set a confidence-level upper
limit on its branching fraction at . This constitutes a
significant improvement over the previous result.Comment: 6 pages, 3 figure
Search for decays with semileptonic tagging at Belle
We present the results of a search for the rare decays , where stands for and . The results are
obtained with pairs collected with the Belle
detector at the KEKB collider. We reconstruct one meson in a
semileptonic decay and require a single meson but nothing else on the
signal side. We observe no significant signal and set upper limits on the
branching fractions. The limits set on the , , , ,
, and channels
are the world's most stringent.Comment: Submitted to PR
First model-independent Dalitz analysis of , decay
We report a measurement of the amplitude ratio of
and decays with a Dalitz analysis of decays, for the first time using a model-independent method.
We set an upper limit at the 68\% confidence level, using the full
data sample of pairs collected at the
resonance with the Belle detector at the KEKB collider. This result is
obtained from observables , , and , where , and
is the weak (strong) phase difference between and .Comment: arXiv admin note: substantial text overlap with arXiv:1502.0755
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