258 research outputs found
Coherent Excitation of the Highly Forbidden Electric Octupole Transition in Yb+ 172
We report on the first coherent excitation of the highly forbidden S21/2?F27/2 electric octupole (E3) transition in a single trapped Yb+172 ion, an isotope without nuclear spin. Using the transition in Yb+171 as a reference, we determine the transition frequency to be 642 116 784 950 887.6(2.4) Hz. We map out the magnetic field environment using the forbidden S21/2?D25/2 electric quadrupole (E2) transition and determine its frequency to be 729 476 867 027 206.8(4.4) Hz. Our results are a factor of 1×105 (3×105) more accurate for the E2 (E3) transition compared to previous measurements. The results open up the way to search for new physics via precise isotope shift measurements and improved tests of local Lorentz invariance using the metastable F27/2 state of Yb+. © 2020 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI
De geprotocolleerde Interapy-behandeling van depressie via het internet; resultaten van een gerandomiseerde trial
Psychologische behandelingen via internet bieden een nieuwe mogelijkheid voor de geestelijke gezondheidszorg. In samenwerking met de Stichting Mentrum ggz Amsterdam heeft Interapy een behandeling voor depressie via internet opgezet. De behandeling bestaat uit cognitief-gedragstherapeutische interventies, zoals psycho-educatie, schrijfopdrachten, registratie, activatie, het uitdagen van negatieve automatische gedachten en terugvalpreventie. Dit artikel beschrijft de procedure, de behandeling en de resultaten van een vergelijkende studie onder cliënten die matig tot ernstig depressief waren. De cliënten die direct actief werden behandeld (N = 32) verbeterden significant meer dan de cliënten in de psycho-educatieconditie (N = 14). Deze tweede groep kreeg de actieve behandeling ongeveer twaalf weken later. De effecten waren groot. In de actief behandelde groep liet 75 procent van de cliënten klinisch relevante verbetering zien, in de psycho-educatieconditie was dat percentage 36. Uit de follow-up na zes weken bleek dat de verbeteringen standhielden
Precise measurement of hadronic tau-decays with an eta meson
We have studied hadronic tau decay modes involving an eta meson using 490
fb^{-1} of data collected with the Belle detector at the KEKB asymmetric-energy
e+e- collider. The following branching fractions have been measured: B(tau- ->
K- eta nu)=(1.58 +- 0.05 +- 0.09)x 10^{-4}, B(tau- -> K- pi0 eta nu)=(4.6 +-
1.1 +- 0.4)x 10^{-5}, B(tau- -> pi- pi0 eta nu)=(1.35 +- 0.03 +- 0.07)x
10^{-3}, B(tau- -> pi- KS eta nu)=(4.4 +- 0.7 +- 0.2)x 10^{-5}, and B(tau- ->
K^{*-} eta nu)=(1.34 +- 0.12 +- 0.09)x 10^{-4}. These results are substantially
more precise than previous measurements. The new measurements are compared with
theoretical calculations based on the CVC hypothesis or the chiral perturbation
theory. We also set upper limits on branching fractions for tau decays into K-
KS eta nu, pi- KS pi0 eta nu, K- eta eta nu, pi- eta eta nu and non-resonant K-
pi^0 eta nu final states.Comment: 24 pages, 7 figure
Evidence of the Purely Leptonic Decay B- --> tau- nu_tau-bar
We present the first evidence of the decay B- --> tau- nu_tau-bar using 414
fb^-1 of data collected at the Upsilon(4S) resonance with the Belle detector at
the KEKB asymmetric-energy e+e- collider. Events are tagged by fully
reconstructing one of the B mesons in hadronic modes. We detect the signal with
a significance of 3.5 standard deviations including systematics, and measure
the branching fraction to be Br(B- --> tau- nu_tau-bar) = (1.79
+0.56-0.49(stat) +0.46-0.51(syst))*10^-4. This implies that f_B = 0.229
+0.036-0.031(stat) +0.034-0.037(syst) GeV and is the first direct measurement
of this quantity.Comment: 6 pages, 3 figures, to appear in Physical Review Letter
Measurement of the near-threshold cross section using initial-state radiation
We report measurements of the exclusive cross section for , where or , in the center-of-mass energy range from the threshold to with initial-state radiation. The
analysis is based on a data sample collected with the Belle detector with an
integrated luminosity of 673 .Comment: Presented at EPS07 and LP07 conferences, published in PRD(RC
Search for Lepton-Flavor-Violating tau Decays into a Lepton and an f0(980) Meson
We search for lepton-flavor-violating tau decays into a lepton (electron or
muon) and an f0(980) meson using 671 fb-1 of data collected with the Belle
detector at the KEKB asymmetric-energy e+e- collider. No events are observed
and we set the following 90% C.L. upper limits on the branching fraction
products: B(tau- -> e-f0(980))*B(f0(980)->pi+pi-)
mu-f0(980))*B(f0(980) -> pi+pi-)<3.4x10^-8. This is the first search performed
for these modes.Comment: 10 pages, 4 figures, submitted to Phys. Lett.
Observation of the and the Y(2175) in
The cross sections for and e^+ e^- \to \phi
\fzero are measured from threshold to using
initial state radiation. The analysis is based on a data sample of 673
fb collected on and below the resonance with the Belle
detector at the KEKB asymmetric-energy collider. First measurements
are reported for the resonance parameters of the in the
mode: MeV/ and MeV/. A structure at ,
corresponding to the so called Y(2175), is observed; its mass and width are
determined to be MeV/ and , respectively.Comment: 11 pages, 6 figures. Add one plot. Accepted by Phys.Rev.D(RC
Moments of the Hadronic Invariant Mass Spectrum in B --> X_c l nu Decays at Belle
We present a measurement of the hadronic invariant mass squared (M^2_X)
spectrum in charmed semileptonic B meson decays B --> X_c l nu based on 140
fb^-1 of Belle data collected near the Y(4S) resonance. We determine the first,
the second central and the second non-central moments of this spectrum for
lepton energy thresholds ranging between 0.7 and 1.9 GeV. Full correlations
between these measurements are evaluated.Comment: published version of the paper (one figure added, minor changes in
the text); 16 pages, 3 figures, 10 table
Observation of Ds1(2536)+ -> D+pi-K+ and angular decomposition of Ds1(2536)+ -> D*+K0S
Using 462/fb of e+e- annihilation data recorded by the Belle detector, we
report the first observation of the decay Ds1(2536)+ -> D+pi-K+. The ratio of
branching fractions B(Ds1+ -> D+pi-K+)/B(Ds1+ -> D*+K0) is measured to be
(3.27+-0.18+-0.37)%. We also study the angular distributions in the Ds1(2536)+
-> D*+K0S decay and measure the ratio of D- and S-wave amplitudes. The S-wave
dominates, with a partial width of Gamma_S/Gamma_total=0.72+-0.05+-0.01.Comment: Submitted to Phys.Rev.D 16 pages, 6 figures, 3 table
Search for lepton-flavor-violating decays at Belle
We have searched for neutrinoless lepton decays into and ,
where stands for an electron or muon, and for a vector meson
(, , , or ), using 543 fb
of data collected with the Belle detector at the KEKB asymmetric-energy
collider. No excess of signal events over the expected background has
been observed, and we set upper limits on the branching fractions in the range
at the 90% confidence level. These upper limits
include the first results for the mode as well as new limits that
are significantly more restrictive than our previous results for the , , and modes.Comment: 7 pages, 16 figure
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