Showing papers by "J. Haba published in 2015"

Measurement of e+e- →π+π-ψ (2S) via initial state radiation at Belle

Abstract: We report measurement of the cross section of e(+)e(-) -> pi(+)pi(-)psi(2S) between 4.0 and 5.5 GeV, based on an analysis of initial state radiation events in a 980 fb(-1) data sample recorded with the Belle detector. The properties of the Y(4360) and Y(4660) states are determined. Fitting the mass spectrum of pi(+)pi(-)psi(2S) with two coherent Breit-Wigner functions, we find two solutions with identical mass and width but different couplings to electron-positron pairs: M-Y(4360) = (4347 +/- 6 +/- 3) MeV/c(2), Gamma(Y(4360)) = (103 +/- 9 +/- 5) MeV, M-Y(4660) = (4652 +/- 10 +/- 8) MeV/c(2), Gamma(Y(4660)) = (68 +/- 11 +/- 1) MeV; and B[Y(4360) -> pi(+)pi(-)psi(2S)] . Gamma(e+e-)(Y(4360)) = (10.9 +/- 0.6 +/- 0.7) eV and B[Y(4660) -> pi(+)pi(-)psi(2S)] . Gamma(e+e-)(Y(4660)) = (8.1 +/- 1.1 +/- 0.5) eV for one solution; or B[Y(4360) -> pi(+)pi(-)psi(2S)] . Gamma(e+e-)(Y(4360)) = (9.2 +/- 0.6 +/- 0.6) eV and B[Y(4660) -> pi(+)pi(-)psi(2S)] . Gamma(e+e-)(Y(4660)) = (2.0 +/- 0.3 +/- 0.2) eV for the other. Here, the first errors are statistical and the second systematic. Evidence for a charged charmoniumlike structure at 4.05 GeV/c(2) is observed in the pi(+/-)psi(2S) intermediate state in the Y(4360) decays.

Amplitude analysis of e+e-→ (nS)π+π-at s =10.866GeV

Abstract: We report results on studies of the e(+)e(-) annihilation into three-body Upsilon(nS)pi(+)pi(-) (n = 1, 2, 3) final states including measurements of cross sections and the full amplitude analysis. The cross sections measured at root s = 10.866 GeV and corrected for the initial state radiation are sigma(e(+)e(-) --> Upsilon(1S)pi(+)pi(-)) = (2.27 +/- 0.12 +/- 0.14) pb, sigma(e(+)e(-) --> Upsilon(2S)pi(+)pi(-)) = (4.07 +/- 0.16 +/- 0.45) pb, and sigma(e(+)e(-) --> Upsilon(3S)pi(+)pi(-)) = (1.46 +/- 0.09 +/- 0.16) pb. Amplitude analysis of the three-body Upsilon(nS)pi(+)pi(-) final states strongly favors I-G(J(P)) = 1(+)(1(+)) quantum-number assignments for the two bottomonium-like Z(b)(+/-) states, recently observed in the Upsilon(nS)pi(+) and h(b)(mP)pi(+)(m = 1, 2) decay channels. The results are obtained with a 121.4 fb(-1) data sample collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider.

Measurement of the B ¯ →xsγ branching fraction with a sum of exclusive decays MEASUREMENT of THE. T. SAITO et al.

Abstract: We use 772×106 BB¯ meson pairs collected at the ?(4S) resonance with the Belle detector to measure the branching fraction for B¯→Xsγ. Our measurement uses a sum-of-exclusives approach in which 38 of the hadronic final states with strangeness equal to +1, denoted by Xs, are reconstructed. The inclusive branching fraction for MXs<2.8GeV/c2, which corresponds to a minimum photon energy of 1.9 GeV, is measured to be B(B¯→Xsγ)=(3.51±0.17±0.33)×10-4, where the first uncertainty is statistical and the second is systematic.

First Observation of the Hadronic Transition Γ (4S) →ηhb (1P) and New Measurement of the hb (1P) and ηb (1S) Parameters

Abstract: Using a sample of 771.6×10(6) ϒϒ(4S) decays collected by the Belle experiment at the KEKB e(+)e(-) collider, we observe, for the first time, the transition ϒ(4S)→ηh(b)(1P) with the branching fraction B[ϒ(4S)→ηh(b)(1P)]=(2.18±0.11±0.18)×10(-3) and we measure the h(b)(1P) mass M(h(b)(1P))=(9899.3±0.4±1.0) MeV/c(2), corresponding to the hyperfine (HF) splitting ΔM(HF)(1P)=(0.6±0.4±1.0) MeV/c(2). Using the transition h(b)(1P)→γη(b)(1S), we measure the η(b)(1S) mass M(η(b)(1S))=(9400.7±1.7±1.6) MeV/c(2), corresponding to ΔM(HF)(1S)=(59.6±1.7±1.6) MeV/c(2), the η(b)(1S) width Γ(η(b)(1S))=(8(-5)(+6)±5) MeV/c(2) and the branching fraction B[h(b)(1P)→γη(b)(1S)]=(56±8±4)%.

Observation of X (3872) in B →x (3872)Kπ decays

Abstract: We report the first observation of B-0 -> X(3872)(K+pi(-)) and evidence for B+ -> X(3872)(K-0 pi(+)). We measure the product of branching fractions for the former to be B(B-0 -> X(3872)(K+pi(-)) x B(X(3872) -> J/psi pi(+)pi(-)) = (7.9 +/- 1.3(stat) +/- 0.4(syst) x 10(-6) and find that B-0 -> X(3872)K*(892)(0) does not dominate the B-0 -> X(3872)K+pi(-) decay mode. We also measure B(B+ -> X(3872)(K-0 pi(+))) x B(X(3872) -> J/psi pi(+)pi(-)) = (10.6 +/- 3.0(stat) +/- 0.9(syst) x 10(-6). This study is based on the full data sample of 711 fb(-1) (772 x 10(6)B (B) over bar pairs) collected at the Upsilon(4S) resonance with the Belle detector at the KEKB collider.

Search for B+ →a+νaγ decays with hadronic tagging using the full Belle data sample

Abstract: We search for the decay B+ -> l(+)nu(l)gamma with l(+) = e(+) or mu(+) using the full Belle data set of 772 x 10(6) B (B) over bar 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(l)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 B(B+ -> e(+)nu(e)gamma) mu(+)nu(mu)gamma) l(+)nu(l)gamma) < 3.5 x 10(-6) at 90% credibility level.

Inclusive cross sections for pairs of identified light charged hadrons and for single protons in e + e − at s = 10.58 GeV

Abstract: We report the first double differential cross sections of two charged pions and kaons (e(+)e(-) -> hhX) in electron-positron annihilation as a function of the fractional energies of the two hadrons for any charge and hadron combination. The dependence of these dihadron cross sections on the topology (same, opposite hemisphere or anywhere) is also studied with the help of the event shape variable thrust and its axis. The ratios of these dihadron cross sections for different charges and hadron combinations directly shed light on the contributing fragmentation functions. For example, we find that the ratio of same-sign pion pairs over opposite-sign pion pairs drops toward higher fractional energies where disfavored fragmentation is expected to be suppressed. These dihadron results are obtained from a 655 fb(-1) data sample collected near the gamma (4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. Extending the previously published single-pion and single-kaon cross sections, single-proton (e(+)e(-) -> pX) cross sections are extracted from a 159 fb(-1) data subsample.

First Observation of CP Violation in B ¯ 0 → DCP (∗) h0 Decays by a Combined Time-Dependent Analysis of BABAR and Belle Data

Abstract: We report a measurement of the time-dependent CP asymmetry of B0->D(*)CP h0 decays, where the light neutral hadron h0 is a pi0, eta or omega meson, and the neutral D meson is reconstructed in the CP eigenstates K+ K-, K0S pi0 or K0S omega The measurement is performed combining the final data samples collected at the Y(4S) resonance by the BaBar and Belle experiments at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively The data samples contain ( 471 +/- 3 ) x 10^6 BB pairs recorded by the BaBar detector and ( 772 +/- 11 ) x 10^6, BB pairs recorded by the Belle detector We measure the CP asymmetry parameters -eta_f S = +066 +/- 010 (stat) +/- 006 (syst) and C = -002 +/- 007 (stat) +/- 003 (syst) These results correspond to the first observation of CP violation in B0->D(*)CP h0 decays The hypothesis of no mixing-induced CP violation is excluded in these decays at the level of 54 standard deviations

X-ray generation by inverse Compton scattering at the superconducting RF test facility

Abstract: Quasi-monochromatic X-rays with high brightness have a broad range of applications in fields such as life sciences, bio-, medical applications, and microlithography. One method for generating such X-rays is via inverse Compton scattering (ICS). X-ray generation experiments using ICS were carried out at the superconducting RF test facility (STF) accelerator at KEK. A new beam line, newly developed four-mirror optical cavity system, and new X-ray detector system were prepared for experiments downstream section of the STF electron accelerator. Amplified pulsed photons were accumulated into a four-mirror optical cavity and collided with an incoming 40 MeV electron beam. The generated X-rays were detected using a microchannel plate (MCP) detector for X-ray yield measurements and a new silicon-on-insulator (SOI) detector system for energy measurements. The detected X-ray yield by the MCP detector was 1756.8±272.2 photons/(244 electron bunches). To extrapolate this result to 1 ms train length under 5 Hz operations, 4.60×10 5 photons/1%-bandwidth were obtained. The peak X-ray energy, which was confirmed by the SOI detector, was 29 keV, and this is consistent with ICS X-rays.

Search for B decays to final states with the ηc meson

Abstract: We report a search for B decays to selected final states with the eta (c) meson: B (+/-) -> K (+/-) eta (c) pi (+) pi (-), B-+/- -> K-+/-eta(c)pi(+)pi(-), B-+/- -> K-+/-eta(c)eta and B-+/- -> K-+/-eta(c)pi(0). The analysis is based on 772 x 10(6) B (B) over bar pairs collected at the gamma(4S) resonance with the Belle detector at the KEKB asymmetric-energy e (+)e (-) collider. We set 90% confidence level upper limits on the branching fractions of the studied B decay modes, independent of intermediate resonances, in the range (0.6-5.3) x 10(-4). We also search for molecular-state candidates in the D-0 (D) over bar*(0) - (D) over bar (0) D*(0), D-0 (D) over bar (0) + (D) over bar (0) D-0 and D*(0) (D) over bar*(0) + D*(0) (D) over bar*(0) D*(0) combinations, neutral partners of the Z(3900)(+/-) and Z(4020)(+/-), and a poorly understood state X(3915) as possible intermediate states in the decay chain, and set 90% confidence level upper limits on the product of branching fractions to the mentioned intermediate states and decay branching fractions of these states in the range (0.6-6.9) x 10(-5).

Measurement of e+e- →γχcJ via initial state radiation at Belle

Abstract: The process e(+)e(-) -> gamma chi(cJ) (J = 1, 2) is studied via initial state radiation using 980 fb(-1) of data at and around the Gamma(nS) (n = 1, 2, 3, 4, 5) resonances collected with the Belle detector at the KEKB asymmetricenergy e(+)e(-) collider. No significant signal is observed except from psi(2S) decays. Upper limits on the cross sections between root s = 3.80 and 5.56 GeV are determined at the 90% credibility level, which range from a few pb to a few tens of pb. We also set upper limits on the decay rate of the vector charmonium [psi(4040), psi(4160), and psi(4415)] and charmoniumlike [Y(4260), Y(4360), and Y(4660)] states to gamma chi(cJ).

Observation ofB0→pΛ¯D(*)−

Abstract: We report the first observation of the decays ${B}^{0}\ensuremath{\rightarrow}p\overline{\mathrm{\ensuremath{\Lambda}}}{D}^{(*)\ensuremath{-}}$. The data sample of $711\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ used in this analysis corresponds to $772\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ pairs, collected at the $\mathrm{\ensuremath{\Upsilon}}(4S)$ resonance by the Belle detector at the KEKB asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider. We observe $19.8\ensuremath{\sigma}$ and $10.8\ensuremath{\sigma}$ excesses of events for the two decay modes and measure the branching fractions of ${B}^{0}\ensuremath{\rightarrow}p\overline{\mathrm{\ensuremath{\Lambda}}}{D}^{\ensuremath{-}}$ and ${B}^{0}\ensuremath{\rightarrow}p\overline{\mathrm{\ensuremath{\Lambda}}}{D}^{*\ensuremath{-}}$ to be $(25.1\ifmmode\pm\else\textpm\fi{}2.6\ifmmode\pm\else\textpm\fi{}3.5)\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}6}$ and $(33.6\ifmmode\pm\else\textpm\fi{}6.3\ifmmode\pm\else\textpm\fi{}4.4)\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}6}$, respectively, where the first uncertainties are statistical and the second are systematic. These results are not compatible with the predictions based on the generalized factorization approach. In addition, a threshold enhancement in the dibaryon ($p\overline{\mathrm{\ensuremath{\Lambda}}}$) system is observed, consistent with that observed in similar $B$ decays.

Measurements of B → D ¯ Ds0∗+ (2317) decay rates and a search for isospin partners of the Ds0∗+ (2317)

Abstract: We report improved measurements of the product branching fractions B(B+ --> (D) over bar D-0(s0)*(+)(2317)) x B(D-s0*(+)(2317) --> D-s(+) pi(0)) (8.0(-1.2)(+1.3) +/- 1.1 +/- 0.4) x 10(-4) and B(B-0 --> D-Ds0*(+)(2317)) x B(D-s0*(+)(2317)) --> D-s(+) pi(0)) = (10.2(-1.2)(+1.3) +/- 1.0 +/- 0.4) x 10(-4) where the first errors are statistical, the second are systematic and the third are from D and D-s(+) branching fractions. In addition, we report negative results from a search for hypothesized neutral (z(0)) and doubly charged (z(++)) isospin partners of the D-s0*(+)(2317) and provide upper limits on the product branching fractions B(B-0 --> D(0)z(0)) x B(z(0) --> D-s(+)pi(-)) and B(B+ --> D(0)z(++) ) x B(z(++) --> D-s(+)pi(+)) that are more than an order of magnitude smaller than theoretical expectations for the hypotheses that the D-s0(*+)(2317) is a member of an isospin triplet. The analysis uses a 711 fb(-1) data sample containing 772 million B (B) over bar -meson pairs collected at the Upsilon(4S) resonance in the Belle detector at the KEKB collider.

Measurement of Azimuthal Modulations in the Cross-Section of Di-Pion Pairs in Di-Jet Production from Electron-Positron Annihilation

Abstract: We present an extraction of azimuthal correlations between two pairs of charged pions detected in opposite jets from electron-positron annihilation. These correlations may arise from the dependence of the di-pion fragmentation on the polarization of the parent quark in the process $e^+e^- \rightarrow q \bar{q}$. Due to the correlation of the quark polarizations, the cross-section of di-pion pair production, in which the pion pairs are detected in opposite jets in a dijet event, exhibits a modulation in the azimuthal angles of the planes containing the hadron pairs with respect to the production plane. The measurement of this modulation allows access to combinations of fragmentation functions that are sensitive to the quark's transverse polarization and helicity. Within our uncertainties we do not observe a significant signal from the previously unmeasured helicity dependent fragmentation function $G_1^\perp$. This measurement uses a dataset of 938~fb$^{-1}$ collected by the Belle experiment at or near $\sqrt{s}\approx10.58$ GeV.

Observation of B-0 -> p(Lambda)over-barD(*)(-)

Abstract: We report the first observation of the decays B^{0}→pΛ[over ¯]D^{(*)-}. The data sample of 711 fb^{-1} used in this analysis corresponds to 772×10^{6} BB[over ¯] pairs, collected at the ϒ(4S) resonance by the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. We observe 19.8σ and 10.8σ excesses of events for the two decay modes and measure the branching fractions of B^{0}→pΛ[over ¯]D^{-} and B^{0}→pΛ[over ¯]D^{*-} to be (25.1±2.6±3.5)×10^{-6} and (33.6±6.3±4.4)×10^{-6}, respectively, where the first uncertainties are statistical and the second are systematic. These results are not compatible with the predictions based on the generalized factorization approach. In addition, a threshold enhancement in the dibaryon (pΛ[over ¯]) system is observed, consistent with that observed in similar B decays.

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

Abstract: We report a search for the rare charmless decay B+ -> (K) over bar*K-0*(+) using a data sample of 772 x 10(6) B (B) over bar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. No statistically significant signal is found and a 90% confidence- level upper limit is set on the decay branching fraction of B(B+ -> (K) over bar*K-0*(+)) < 1.31 x 10(-6).

Measurement of the direct CP asymmetry in B ¯ →xs+dγ decays with a lepton tag

Abstract: We report the measurement of the direct CP asymmetry in the radiative (B) over bar -> Xs+d gamma decay using a data sample of (772 +/- 11) x 10(6) B (B) over bar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. The CP asymmetry is measured as a function of the photon energy threshold. For E-gamma* >= 2.1 GeV, where E-gamma* is the photon energy in the center-of-mass frame, we obtain A(CP) ((B) over bar -> Xs+d gamma) = (2.2 +/- 3.9 +/- 0.9)%, consistent with the standard model prediction.

Measurement of B0 → D- s K0 S π+ and B+ → D- sK+K+ branching fractions

Abstract: We report a measurement of the B0 and B+ meson decays to the D- sK0 Sπ+ and D- sK+K+ final states, respectively, using 657 × 106BB¯ pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e+ collider. Using the D- s → φ π-, K∗(892)0K- and K0 SK- decay modes for the Ds reconstruction, we measure the following branching fractions: B(B0 → D- sK0 sπ+) = [0.47 ± 0.06(stat) ± 0.05(syst)] × 10-4 and B(B+ → D- sK+K+) = [0.93 ± 0.22(stat) ± 0.10(syst)] × 10-5. We find the ratio of the branching fraction of B+ → D- sK+K+ to that of the analogous Cabibbo-favored B+ → D- sK+π+ decay to be RB = 0.054 ± 0.013(stat) ± 0.006(syst), which is consistent with the naive factorization model. We also observe a deviation of the DsK invariant-mass distribution from the three-body phase-space model for both studied decays.

Measurement of the amplitude ratio of $B^0 \to D^0K^{*0}$ and $B^0 \to \bar{D^0}K^{*0}$ decays with a model-independent Dalitz plot analysis using $D\to K_S^0\pi^+\pi^-$ decays

Abstract: We report a measurement of the amplitude ratio $r_S$ of $B^0 \to D^0K^{*0}$ and $B^0 \to \bar{D^0}K^{*0}$ decays with a model-independent Dalitz plot analysis using $D\to K_S^0\pi^+\pi^-$ decays Using the full data sample of $772\times10^6$ $B\bar{B}$ pairs collected at the $\Upsilon(4S)$ resonance with the Belle detector at KEKB accelerator the upper limit is $r_S < 087$ at the 68 % confidence level This result is the first measurement of $r_S$ with a model-independent Dalitz analysis, and is consistent with results from other analyses The value of $r_S$ indicates the sensitivity of the decay to $\phi_3$ because the statistical uncertainty is proportional to $1/r_S$ The $r_S$ result is obtained from observables ($x_\pm$, $y_\pm$) \begin{eqnarray} x_- &=& +04 ^{+10 +00}_{-06 -01} \pm00 \\ y_- &=& -06 ^{+08 +01}_{-10 -00} \pm01 \\ x_+ &=& +01 ^{+07 +00}_{-04 -01} \pm01 \\ y_+ &=& +03 ^{+05 +00}_{-08 -01} \pm01 \\ , \end{eqnarray} where $x_\pm = r_S \cos(\delta_S \pm \phi_3)$, $y_\pm = r_S \sin(\delta_S \pm \phi_3)$ and $\phi_3 (\delta_S)$ are the weak (strong) phase difference between $B^0 \to D^0K^{*0}$ and $B^0 \to \bar{D^0}K^{*0}$ The first uncertainty is statistical, the second is the experimental systematic and the third is the systematic due to the uncertainties on $c_i$ and $s_i$ parameters measured by CLEO