arXiv subjects

K. Inami

Publications and source records attributed to K. Inami.

At least 199 records · Page 11Linked to original sources

arXiv2017

Search for the $0^{--}$ Glueball in $Υ(1S)$ and $Υ(2S)$ decays

We report the first search for the $J^{PC}=0^{--}$ glueball in $Υ(1S)$ and $Υ(2S)$ decays with data samples of $(102\pm2)$ million and $(158\pm4)$ million events, respectively, collected with the Belle detector. No significant signals are observed in any of the proposed production modes, and the 90\% credibility level upper limits on their branching fractions in $Υ(1S)$ and $Υ(2S)$ decays are obtained. The inclusive branching fractions of the $Υ(1S)$ and $Υ(2S)$ decays into final states with a $χ_{c1}$ are measured to be $\BR(Υ(1S)\to χ_{c1}+ anything) = (1.90\pm 0.43(stat.)\pm 0.14(syst.))\times 10^{-4}$ with an improved precision over prior measurements and $\BR(Υ(2S)\to χ_{c1}+ anything) = (2.24\pm 0.44(stat.)\pm 0.20(syst.))\times 10^{-4}$ for the first time.

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arXiv2016

Lepton-Flavor-Dependent Angular Analysis of $B\to K^\ast \ell^+\ell^-$

We present a measurement of angular observables and a test of lepton flavor universality in the $B\to K^\ast \ell^+\ell^-$ decay, where $\ell$ is either $e$ or $μ$. The analysis is performed on a data sample corresponding to an integrated luminosity of $711~\mathrm{fb}^{-1}$ containing $772\times 10^{6}$ $B\bar B$ pairs, collected at the $Υ(4S)$ resonance with the Belle detector at the asymmetric-energy $e^+e^-$ collider KEKB. The result is consistent with Standard Model (SM) expectations, where the largest discrepancy from a SM prediction is observed in the muon modes with a local significance of $2.6σ$.

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arXiv2016

Measurement of the branching ratio of $\bar{B}^0 \rightarrow D^{+} τ^- \barν_τ$ relative to $\bar{B}^0 \rightarrow D^{+} \ell^- \barν_{\ell}$ decays with a semileptonic tagging method

We report a measurement of the ratio ${\cal R}(D^*) = {\cal B}(\bar{B}^0 \rightarrow D^{*+} τ^- \barν_τ)/{\cal B}(\bar{B}^0 \rightarrow D^{*+} \ell^- \barν_{\ell})$, where $\ell$ denotes an electron or a muon. The results are based on a data sample containing $772\times10^6$ $B\bar{B}$ pairs recorded at the $Υ(4S)$ resonance with the Belle detector at the KEKB $e^+ e^-$ collider. We select a sample of $B^0 \bar{B}^0$ pairs by reconstructing both $B$ mesons in semileptonic decays to $D^{*\mp} \ell^{\pm}$. We measure ${\cal R}(D^*)= 0.302 \pm 0.030({\rm stat)} \pm 0.011({\rm syst)}$, which is within $1.6 σ$ of the Standard Model theoretical expectation, where the standard deviation $σ$ includes systematic uncertainties. We use this measurement to constrain several scenarios of new physics in a model-independent approach.

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arXiv2016

Search for a dark vector gauge boson decaying to $π^+ π^-$ using $η\rightarrow π^+π^- γ$ decays

We report a search for a dark vector gauge boson $U^\prime$ that couples to quarks in the decay chain $D^{*+} \to D^0 π^+, D^0 \to K^0_S η, η\to U^\prime γ$, $U^\prime \to π^+ π^-$. No signal is found and we set a mass-dependent limit on the baryonic fine structure constant of $10^{-3} - 10^{-2}$ in the $U^\prime$ mass range of 290 to 520 MeV/$c^2$. This analysis is based on a data sample of 976 fb$^{-1}$ collected by the Belle experiment at the KEKB asymmetric-energy $e^+e^-$ collider.

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arXiv2016

Study of $\mathbf{B^{0}\rightarrowρ^{+}ρ^{-}}$ decays and implications for the CKM angle $\mathbf{ϕ_2}$

We present a measurement of the branching fraction and the longitudinal polarization fraction of $B^{0}\rightarrowρ^+ρ^-$ decays, as well as the time-dependent $CP$ violating parameters in decays into longitudinally polarized $ρ^{+}ρ^{-}$ pairs with Belle's final data set of $772\times 10^6$ $B\bar{B}$ pairs, at the $Υ(4S)$ resonance, collected at the asymmetric-energy $e^+ e^-$ collider KEKB. We obtain ${\cal B}(B^0 \rightarrow ρ^+ ρ^-)=(28.3\pm 1.5\;(\rm stat) \pm 1.5\;(\rm syst))\times 10^{-6}$, $f_L = 0.988\pm 0.012\;(\rm stat ) \pm0.023\;(\rm syst)$, ${\cal A}_{CP} = 0.00\pm0.10\;(\rm stat ) \pm0.06\;(\rm syst)$, ${\cal S}_{CP} = -0.13\pm0.15\;(\rm stat ) \pm0.05\;(\rm syst).$ We perform an isospin analysis to constrain the CKM angle $ϕ_2$ and obtain two solutions with \begin{eqnarray} ϕ_{2} = (93.7\pm10.6)^{\circ},\nonumber \end{eqnarray} being most compatible with other Standard-Model based fits to the data.

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arXiv2016

Measurements of the $Υ(10860)$ and $Υ(11020)$ resonances via $σ(e^+e^-\rightarrowΥ(n{\rm S})π^+π^-)$

We report new measurements of the total cross sections for $e^+e^-\to Υ(n{\rm S})π^+π^-$ ($n$ = 1, 2, 3) and $e^+e^-\to b\bar b$ from a high-luminosity fine scan of the region $\sqrt{s} = 10.63$-$11.05$ GeV with the Belle detector. We observe that the $Υ(n{\rm S})π^+π^-$ spectra have little or no non-resonant component and extract from them the masses and widths of $Υ(10860)$ and $Υ(11020)$ and their relative phase. We find $M_{10860}=(10891.1\pm3.2^{+0.6}_{-1.7})$ MeV/$c^2$ and $Γ_{10860}=(53.7^{+7.1}_{-5.6}\,^{+1.3}_{-5.4})$ MeV and report first measurements $M_{11020}=(10987.5^{+6.4}_{-2.5}\,^{+9.0}_{-2.1})$ MeV/$c^2$, $Γ_{11020}=(61^{+9}_{-19}\,^{+2}_{-20})$ MeV, and $ϕ_{\rm 11020}-ϕ_{\rm 10860} = (-1.0\pm0.4\,^{+1.4}_{-0.1})$ rad.

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arXiv2016

Measurement of the CKM angle $φ_1$ in $B^0\to\bar{D}{}^{(*)0}h^0$, $\bar{D}{}^0\to K_S^0π^+π^-$ decays with time-dependent binned Dalitz plot analysis

We report a measurement of the CP violation parameter $φ_1$ obtained in a time-dependent analysis of $B^0\to\bar{D}{}^{(*)0}h^0$ decays followed by $\bar{D}{}^0\to K_S^0π^+π^-$ decay. A model-independent measurement is performed using the binned Dalitz plot technique. The measured value is $φ_1 = 11.7^{\circ}\pm7.8^{\circ}({\rm stat.})\pm 2.1^{\circ}({\rm syst.})$. Treating $\sin{2φ_1}$ and $\cos{2φ_1}$ as independent parameters, we obtain $\sin{2φ_1} = 0.43\pm 0.27({\rm stat.})\pm 0.08({\rm syst.})$ and $\cos{2φ_1} = 1.06\pm 0.33({\rm stat.})^{+0.21}_{-0.15}({\rm syst.})$. The results are obtained with a full data sample of $772 \times 10^6 B\bar{B}$ pairs collected near the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider.

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arXiv2016

Measurement of $e^+e^- \to π^+π^-ψ(2S)$ via Initial State Radiation at Belle

We report measurement of the cross section of $e^+e^-\to π^+π^-ψ(2S)$ between 4.0 and $5.5 {\rm GeV}$, based on an analysis of initial state radiation events in a $980 \rm fb^{-1}$ data sample recorded with the Belle detector. The properties of the $Y(4360)$ and $Y(4660)$ states are determined. Fitting the mass spectrum of $π^+π^-ψ(2S)$ with two coherent Breit-Wigner functions, we find two solutions with identical mass and width but different couplings to electron-positron pairs: $M_{Y(4360)} = (4347\pm 6\pm 3) {\rm MeV}/c^2$, $Γ_{Y(4360)} = (103\pm 9\pm 5) {\rm MeV}$, $M_{Y(4660)} = (4652\pm10\pm 8) {\rm MeV}/c^2$, $Γ_{Y(4660)} = (68\pm 11\pm 1) \rm MeV$; and ${\cal{B}}[Y(4360)\to π^+π^-ψ(2S)]\cdot Γ_{Y(4360)}^{e^+e^-} = (10.9\pm 0.6\pm 0.7) \rm eV$ and ${\cal{B}}[Y(4660)\to π^+π^-ψ(2S)]\cdot Γ_{Y(4660)}^{e^+e^-} = (8.1\pm 1.1\pm 0.5) \rm eV$ for one solution; or ${\cal{B}}[Y(4360)\to π^+π^-ψ(2S)]\cdot Γ_{Y(4360)}^{e^+e^-} = (9.2\pm 0.6\pm 0.6) \rm eV$ and ${\cal{B}}[Y(4660)\to π^+π^-ψ(2S)]\cdot Γ_{Y(4660)}^{e^+e^-} = (2.0\pm 0.3\pm 0.2) \rm eV$ for the other. Here, the first errors are statistical and the second systematic. Evidence for a charged charmoniumlike structure at $4.05 {\rm GeV}/c^2$ is observed in the $π^{\pm}ψ(2S)$ intermediate state in the $Y(4360)$ decays.

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arXiv2016

Energy scan of the $e^+e^- \to h_b(nP)π^+π^-$ $(n=1,2)$ cross sections and evidence for $Υ(11020)$ decays into charged bottomonium-like states

Using data collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider, we measure the energy dependence of the $e^+e^- \to h_b(nP)π^+π^-$ $(n=1,2)$ cross sections from thresholds up to $11.02\,$GeV. We find clear $Υ(10860)$ and $Υ(11020)$ peaks with little or no continuum contribution. We study the resonant substructure of the $Υ(11020) \to h_b(nP)π^+π^-$ transitions and find evidence that they proceed entirely via the intermediate isovector states $Z_b(10610)$ and $Z_b(10650)$. The relative fraction of these states is loosely constrained by the current data: the hypothesis that only $Z_b(10610)$ is produced is excluded at the level of 3.3 standard deviations, while the hypothesis that only $Z_b(10650)$ is produced is not excluded at a significant level.

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arXiv2016

Search for a massive invisible particle $X^0$ in $B^{+}\to e^{+}X^{0}$ and $B^{+}\to μ^{+}X^{0}$ decays

We present a search for a non-Standard-Model invisible particle $X^0$ in the mass range $0.1\textrm{-}1.8 \,{\rm GeV}/{c^2}$ in $B^{+}\to e^{+} X^{0}$ and $B^{+}\to μ^{+} X^{0}$ decays. The results are obtained from a $711~{\rm fb}^{-1}$ data sample that corresponds to $772 \times 10^{6} B\bar{B}$ pairs, collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB $e^+ e^-$ collider. One $B$ meson is fully reconstructed in a hadronic mode to determine the momentum of the lepton of the signal decay in the rest frame of the recoiling partner $B$ meson. We find no evidence of a signal and set upper limits on the order of $10^{-6}$.

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arXiv2016

Observation of the decay $B_s^0\rightarrow K^0\overline{K}^0$

We measure the decay $B_s^0\rightarrow K^0\overline{K}^0$ using data collected at the $Υ(5S)$ resonance with the Belle detector at the KEKB $e^+e^-$ collider. The data sample used corresponds to an integrated luminosity of 121.4 ${\rm fb^{-1}}$. We measure a branching fraction $\mathcal{B}(B_s^0\rightarrow K^0\overline{K}^0) = [19.6\,^{+5.8}_{-5.1}({\rm stat.})\,\pm1.0({\rm sys.})\,\pm 2.0(N^{}_{B_s^0\overline{B}_s^0})]\times 10^{-6}$ with a significance of 5.1 standard deviations. This measurement constitutes the first observation of this decay.

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arXiv2016

First observation of $γγ\to p \bar{p} K^+ K^-$ and search for exotic baryons in $pK$ systems

The process $γγ\to p \bar{p} K^+ K^-$ and its intermediate processes are measured for the first time using a 980~fb$^{-1}$ data sample collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. The production of $p \bar{p} K^+ K^-$ and a $Λ(1520)^0~(\barΛ(1520)^0)$ signal in the $pK^-$~($\bar{p} K^+$) invariant mass spectrum are clearly observed. However, no evidence for an exotic baryon near 1540~MeV/$c^2$, denoted as $Θ(1540)^0$~($\barΘ~(1540)^0$) or $Θ(1540)^{++}$~($Θ(1540)^{--}$), is seen in the $p K^-$~($\bar{p}K^+$) or $pK^+$~($\bar{p} K^-$) invariant mass spectra. Cross sections for $γγ\to p \bar{p} K^+ K^-$, $Λ(1520)^0 \bar{p} K^+ +c.c.$ and the products $σ(γγ\to Θ(1540)^0 \bar{p} K^+ +c.c.)\BR(Θ(1540)^0 \to p K^{-})$ and $σ(γγ\to Θ(1540)^{++} \bar{p} K^- +c.c.)\BR(Θ(1540)^{++}\to p K^{+})$ are measured. We also determine upper limits on the products of the $χ_{c0}$ and $χ_{c2}$ two-photon decay widths and their branching fractions to $p \bar{p} K^+ K^-$ at the 90\% credibility level.

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arXiv2016

Inclusive and exclusive measurements of $B$ decays to $χ_{c1}$ and $χ_{c2}$ at Belle

We report inclusive and exclusive measurements for $χ_{c1}$ and $χ_{c2}$ production in $B$ decays. We measure $\mathcal{B}(B \to χ_{c1} X)$= $(3.03 \pm 0.05(\mbox{stat}) \pm 0.24(\mbox{syst})) \times 10^{-3}$ and $\mathcal{B}(B \to χ_{c2} X)$= $(0.70 \pm 0.06(\mbox{stat}) \pm 0.10(\mbox{syst})) \times 10^{-3}$. For the first time, $χ_{c2}$ production in exclusive $B$ decays in the modes $B^0 \to χ_{c2}π^- K^+$ and $B^+ \to χ_{c2} π^+ π^- K^+$ has been observed, along with first evidence for the $B^+ \to χ_{c2} π^+ K_S^0$ decay mode. For $χ_{c1}$ production, we report the first observation in the $B^+ \to χ_{c1} π^+ π^- K^+$, $B^0 \to χ_{c1} π^+ π^- K_S^0$ and $B^0 \to χ_{c1} π^0 π^- K^+$ decay modes. Using these decay modes, we observe a difference in the production mechanism of $χ_{c2}$ in comparison to $χ_{c1}$ in $B$ decays. In addition, we report searches for $X(3872)$ and $χ_{c1}(2P)$ in the $B^+ \to (χ_{c1} π^+ π^-) K^+$ decay mode. The reported results use $772 \times 10^{6}$ $B\overline{B}$ events collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider.

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arXiv2016

Search for the decay B0 -> phi gamma

We have searched for the decay B0 -> phi gamma using the full Belle data set of 772 x 10^6 BBbar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB e+e- collider. No signal is observed, and we set an upper limit on the branching fraction of B(B0 -> phi gamma) < 1.0 x 10^{-7} at 90% confidence level. This is the most stringent limit on this decay mode to date.

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arXiv2016

First model-independent Dalitz analysis of $B^0 \to DK^{*0}$, $D\to K_S^0π^+π^-$ decay

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 Dalitz analysis of $D\to K_S^0π^+π^-$ decays, for the first time using a model-independent method. We set an upper limit $r_S < 0.87$ at the 68\% confidence level, using the full data sample of $772\times10^6$ $B\bar{B}$ pairs collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB $e^+e^-$ collider. This result is obtained from observables $x_- = +0.4 ^{+1.0 +0.0}_{-0.6 -0.1} \pm0.0$, $y_- = -0.6 ^{+0.8 +0.1}_{-1.0 -0.0} \pm0.1$, $x_+ = +0.1 ^{+0.7 +0.0}_{-0.4 -0.1} \pm0.1$ and $y_+ = +0.3 ^{+0.5 +0.0}_{-0.8 -0.1} \pm0.1$, where $x_\pm = r_S \cos(δ_S \pm ϕ_3)$, $y_\pm = r_S \sin(δ_S \pm ϕ_3)$ and $ϕ_3~(δ_S)$ is the weak (strong) phase difference between $B^0 \to D^0K^{*0}$ and $B^0 \to \bar{D^0}K^{*0}$.

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arXiv2016

Study of $π^0$ pair production in single-tag two-photon collisions

We report a measurement of the differential cross section of $π^0$ pair production in single-tag two-photon collisions, $γ^* γ\to π^0 π^0$, in $e^+ e^-$ scattering. The cross section is measured for $Q^2$ up to 30 GeV$^2$, where $Q^2$ is the negative of the invariant mass squared of the tagged photon, in the kinematic range 0.5 GeV < W < 2.1 GeV and $|\cos θ^*|$ < 1.0 for the total energy and pion scattering angle, respectively, in the $γ^* γ$ center-of-mass system. The results are based on a data sample of 759 fb$^{-1}$ collected with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. The transition form factor of the $f_0(980)$ and that of the $f_2(1270)$ with the helicity-0, -1, and -2 components separately are measured for the first time and are compared with theoretical calculations.

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arXiv2016

Search for $B^0 \to π^- τ^+ ν_τ$ with hadronic tagging at Belle

We search for the process $B^0 \to π^- τ^+ ν_τ$ using the full Belle data set of $711\,{\rm fb}^{-1}$, corresponding to $772 \times 10^6 B\bar{B}$ pairs, collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. We reconstruct one $B$ meson in a hadronic decay and search for the $B^0 \to π^- τ^+ ν_τ$ process in the remainder of the event. No significant signal is observed and an upper limit of $\mathcal{B}(B^0 \to π^- τ^+ ν_τ) < 2.5 \times 10^{-4}$ is obtained at the $90\%$ confidence level.

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arXiv2016

Measurement of the decay $B\to D\ellν_\ell$ in fully reconstructed events and determination of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$

We present a determination of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$ using the decay $B\to D\ellν_\ell$ ($\ell=e,μ$) based on 711 fb$^{-1}$ of $e^+e^-\to Υ(4S)$ data recorded by the Belle detector and containing $772 \times 10^6$ $B\bar{B}$ pairs. One $B$ meson in the event is fully reconstructed in a hadronic decay mode while the other, on the signal side, is partially reconstructed from a charged lepton and either a $D^+$ or $D^0$ meson in a total of 23 hadronic decay modes. The isospin-averaged branching fraction of the decay $B\to D\ellν_\ell$ is found to be $\mathcal{B}(B^0 \to D^- \ell^+ ν_{\ell})=(2.31\pm 0.03(\mathrm{stat})\pm 0.11(\mathrm{syst}))\%$. Analyzing the differential decay rate as a function of the hadronic recoil with the parameterization of Caprini, Lelouch and Neubert and using the form-factor prediction $\mathcal{G}(1)=1.0541\pm 0.0083$ calculated by FNAL/MILC, we obtain $η_\mathrm{EW}|V_{cb}|=(40.12\pm 1.34)\times 10^{-3}$, where $η_\mathrm{EW}$ is the electroweak correction factor. Alternatively, assuming the model-independent form-factor parameterization of Boyd, Grinstein and Lebed and using lattice QCD data from the FNAL/MILC and HPQCD collaborations, we find $η_\mathrm{EW}|V_{cb}|=(41.10 \pm 1.14)\times 10^{-3}$.

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