Search NASA⌕ Search

Engineering topics

Sanuki, T.

Publications and source records attributed to Sanuki, T..

14 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Azimuthal asymmetries of back-to-back π ± - ( π 0 , η , π ± ) pairs in e + e - annihilation

This work reports the first observation of azimuthal asymmetries around the thrust axis in e + e – annihilation of pairs of back-to-back charged pions in one hemisphere, and π 0 and η mesons in the opposite hemisphere. These results are complemented by a new analysis of pairs of back-to-back charged pions. The π 0 and η asymmetries rise with the relative momentum z of the detected hadrons as well as with the transverse momentum with respect to the thrust axis. These asymmetries are sensitive to the Collins fragmentation function $H$ $^{1}_{⊥}$ and provide complementary information to previous measurements with charged pions and kaons in the final state. In particular, the η final states will provide additional information on the flavor structure of $H$ $^{1}_{⊥}$. This is the first measurement of the explicit transverse-momentum dependence of the Collins fragmentation function from Belle data. It uses a dataset of 980.4 fb –1 collected by the Belle experiment at or near a center- of-mass energy of 10.58 GeV.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

Search for the Dark Photon and the Dark Higgs Boson at Belle

The dark photon A ' and the dark Higgs boson h ' are hypothetical constituents featured in a number of recently proposed dark sector models. Assuming prompt decays of both dark particles, we search for their production in the so-called Higgstrahlung channel e + e - → A ' h ' , with h ' → A ' A ' . We investigate ten exclusive final states with A ' → e + e - , μ + μ - , or π + π - in the mass ranges 0.1 GeV / c 2 < m A ' < 3.5 GeV / c 2 and 0.2 GeV / c 2 < m h ' < 10.5 GeV / c 2 . We also investigate three inclusive final states 2 ( e + e - ) X , 2 ( μ + μ - ) X , and ( e + e - ) ( μ + μ - ) X , where X denotes a dark photon candidate detected via missing mass, in the mass ranges 1.1 GeV / c 2 < m A ' < 3.5 GeV / c 2 and 2.2 GeV / c 2 < m h ' < 10.5 GeV / c 2 . Using the entire 977 fb - 1 data set collected by Belle, we determine no significant signal. Here, we obtain individual and combined 90% credibility level upper limits on the branching fraction times the Born cross section, B × σ Born , on the Born cross section σ Born , and on the dark photon coupling to the dark Higgs boson times the kinetic mixing between the standard model photon and the dark photon, α D × ε 2 . These limits improve upon and cover wider mass ranges than previous experiments. The limits from the final states 3 ( π + π - ) and 2 ( e + e - ) X are the first placed by any experiment. For α D equal to 1 / 137 , m h ' < 8 GeV / c 2 , and m A ' < 1 GeV / c 2 , we exclude values of the mixing parameter ε above ~ 8×10 -4 .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Search for the decay B + → K ¯ * 0 K * + at Belle

We report a search for the rare charmless decay B+ → K¯ *0 K *+ using a data sample of 772 × 10 6 BB¯ pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e + e – collider. Here, no statistically significant signal is found and a 90% confidence-level upper limit is set on the decay branching fraction of B(B + → K¯K *0 K *+ ) < 1.31 × 10 –6 .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Search for the process e + e $-$ → J / ψ X ( 1835 ) at s ≈ 10.6 GeV

We report the results of a search for the X(1835) state in the process e + e - →J/ψX(1835) using a data sample of 672 fb -1 collected with the Belle detector at and near the Υ(4S) resonance at the KEKB asymmetric-energy e + e - collider. No significant evidence is found for this process, and an upper limit is set on its cross section times the branching fraction: σ Born (e + e - →J/ψX(1835))•B(X(1835)→≥3 charged tracks)<1.3 fb at 90% confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Observation of ψ ( 4040 ) and ψ ( 4160 ) decay into η J / ψ

The cross section for $e^+e^-$ $\to$ $\eta J/\psi$ between $\sqrt{s}=3.8 GeV/c^2$ and 5.3 $GeV/c^2$ is measured via initial state radiation using 980 $fb^{-1}$ of data on and around the $\Upsilon(nS)(n=1,2,3,4,5)$ resonances collected with the Belle detector at KEKB. Two resonant structures at the $\psi(4040)$ and $\psi(4160)$ are observed in the $\eta J/\psi$ invariant mass distribution. Fitting the mass spectrum with the coherent sum of two Breit-Wigner functions, one obtains $B$($\psi(4040)\to\eta J/\psi$)$ \cdot\Gamma_{e^+e^-}^{\psi(4040)}$ = ($4.8\pm0.9\pm1.4$) eV and $B$($\psi(4160)\to\eta J/\psi)\cdot\Gamma_{ee}^{\psi(4160)}$ = ($4.0\pm0.8\pm1.4$) eV for one solution and $B$($\psi(4040)\to\eta J/\psi$)$\cdot\Gamma_{ee}^{\psi(4040)}$ = ($11.2\pm1.3\pm1.9$) eV and $B$($\psi(4160)\to\eta J/\psi$)$\cdot\Gamma_{ee}^{\psi(4160)}$ = ($13.8\pm1.3\pm2.0$) eV for the other solution, where the first errors are statistical and the second are systematic. This is the first measurement of this hadronic transition mode of these two states, and the partial widths to $\eta J/\psi$ are found to be about 1 MeV. There is no evidence for the $Y(4260)$, $Y(4360)$, $\psi(4415)$, or $Y(4660)$ in the $\eta J/\psi$ final state, and upper limits of their production rates in $e^+e^-$ annihilation are determined.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Search for lepton-flavor and lepton-number-violating τ → ℓ h h ' decay modes

We search for lepton-flavor-violating and lepton-number-violating τ decays into a lepton (ℓ = electron or muon) and two charged mesons (h, h' = π ± or K ± ) using 854 fb -1 of data collected with the Belle detector at the KEKB asymmetric-energy e + e - collider. We obtain 90% confidence level upper limits on the τ → ℓhh' branching fractions in the range (2.0-8.4)×10 -8 . These results improve upon our previously published upper limits by factors of about 1.8 on average.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Search for CP violation in D ± meson decays to Φπ±

We search for CP violation in Cabibbo-suppressed charged D meson decays by measuring the difference between the CP-violating asymmetries for the Cabibbo-suppressed decays D ± →K⁺ K⁻ π ± and the Cabibbo-favored decays D s ± → K⁺K⁻ π ± in the K⁺K⁻ mass region of the Φ resonance. Using 955 fb⁻¹ of data collected with the Belle detector, we obtain A CP D⁺ →Φπ⁺ = (+0.51±0.28±0.05)%. The measurement improves the sensitivity of previous searches by more than a factor of 5.We find no evidence for direct CP violation.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2010

ATF2 Commissioning

ATF2 is a final-focus test beam line that attempts to focus the low-emittance beam from the ATF damping ring to a beam size of about 37 nm, and at the same time to demonstrate nm beam stability, using numerous advanced beam diagnostics and feedback tools. The construction is well advanced and beam commissioning of ATF2 has started in the second half of 2008. ATF2 is constructed and commissioned by ATF international collaborations with strong US, Asian and European participation.

Seryi, Andrei↗