Towards φ3/γ extraction in a study of D∗ρ at Belle

We report on progress in an angular time-dependent analysis of the B0 → D∗∓ρ± decay at the Belle experiment. The study aims to establish a novel method for studying CP violation using this decay by measuring 2φ1 + φ3 (2β + γ) of the Unitarity Triangle

Search for D0D^{0} decays to invisible final states at Belle

We report the result from the first search for $D^0$ decays to invisible final states. The analysis is performed on a data sample of 924 $\rm{fb}^{-1}$ collected at and near the $\Upsilon(4S)$ and $\Upsilon(5S)$ resonances with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. The absolute branching fraction is determined using an inclusive $D^0$ sample, obtained by fully reconstructing the rest of the particle system including the other charmed particle. No significant signal yield is observed and an upper limit of $9.4\times 10^{-5}$ is set on the branching fraction of $D^0$ to invisible final states at 90\% confidence level.Comment: 17 pages, 4 figures, submitted to PRD(RC

Energy scan of the e+e−→hb(nP)π+π−e^+e^- \to h_b(nP)\pi^+\pi^- (n=1,2)(n=1,2) cross sections and evidence for Υ(11020)\Upsilon(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 $e^+e^- \to h_b(nP)\pi^+\pi^-$ $(n=1,2)$ cross sections from thresholds up to $11.02\,$GeV. We find clear $\Upsilon(10860)$ and $\Upsilon(11020)$ peaks with little or no continuum contribution. We study the resonant substructure of the $\Upsilon(11020) \to h_b(nP)\pi^+\pi^-$ 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.Comment: 8 pages, 4 figures, submitted to Physical Review Letter

Study of e+e- => B(*) B(*)-bar pi+- at sqrt(s)=10.866 GeV

We report the analysis of the three-body e+e- => B B-bar pi, B B*-bar pi, and B* B*-bar pi processes, including the first observation of the Zb+-(10610) =>[B B*-bar+c.c.]+- and Zb+-(10650) => [B*B*-bar]+- transitions. We measure visible cross sections for the three-body production of sigma_vis(e+e- => [B B*-bar+c.c.]+-pi-+=(11.2+-1.0(stat.)+-1.2(syst.)) pb and sigma_vis(e+e- => [B*B*-bar]+-pi-+)=(5.61+-0.73(stat.)+-0.66(syst.)) pb and set a 90% C.L. upper limit of sigma_vis(e+e- => [BB-bar]+-pi-+)<2.1 pb. The results are based on a 121.4 1/fb data sample collected with the Belle detector at a center-of-mass energy near the Y(5S) peak.Comment: 8 pages, 2 figure

Measurements of the masses and widths of the Σc(2455)0/++\Sigma_{c}(2455)^{0/++} and Σc(2520)0/++\Sigma_{c}(2520)^{0/++} baryons

We present measurements of the masses and decay widths of the baryonic states $\Sigma_{c}(2455)^{0/++}$ and $\Sigma_{c}(2520)^{0/++}$ using a data sample corresponding to an integrated luminosity of 711 fb$^{-1}$ collected with the Belle detector at the KEKB $e^{+}e^{-}$ asymmetric-energy collider operating at the $\Upsilon(4S)$ resonance. We report the mass differences with respect to the $\Lambda_{c}^{+}$ baryon $M(\Sigma_{c}(2455)^{0})-M(\Lambda_{c}^{+}) = 167.29\pm0.01\pm0.02$ MeV/$c^{2}$, $M(\Sigma_{c}(2455)^{++})-M(\Lambda_{c}^{+}) = 167.51\pm0.01\pm0.02$ MeV/$c^{2}$, $M(\Sigma_{c}(2520)^{0})-M(\Lambda_{c}^{+}) = 231.98\pm0.11\pm0.04$ MeV/$c^{2}$, $M(\Sigma_{c}(2520)^{++})-M(\Lambda_{c}^{+}) = 231.99\pm0.10\pm0.02$ MeV/$c^{2}$, and the decay widths $\Gamma(\Sigma_{c}(2455)^{0}) = 1.76\pm0.04^{+0.09}_{-0.21}$ MeV/$c^{2}$, $\Gamma(\Sigma_{c}(2455)^{++}) = 1.84\pm0.04^{+0.07}_{-0.20}$ MeV/$c^{2}$, $\Gamma(\Sigma_{c}(2520)^{0}) = 15.41\pm0.41^{+0.20}_{-0.32}$ MeV/$c^{2}$, $\Gamma(\Sigma_{c}(2520)^{++}) = 14.77\pm0.25^{+0.18}_{-0.30}$ MeV/$c^{2}$, where the first uncertainties are statistical and the second are systematic. The isospin mass splittings are measured to be $M(\Sigma_{c}(2455)^{++})-M(\Sigma_{c}(2455)^{0})=0.22\pm0.01\pm0.01$ MeV/$c^{2}$ and $M(\Sigma_{c}(2520)^{++})-M(\Sigma_{c}(2520)^{0})=0.01\pm0.15\pm0.03$ MeV/$c^{2}$. These results are the most precise to date.Comment: 13 pages, 4 figures, Submitted to PRD(RC

Observation of an alternative χc0(2P)\chi_{c0}(2P) candidate in e+e−→J/ψDDˉe^+ e^- \rightarrow J/\psi D \bar{D}

We perform a full amplitude analysis of the process $e^+ e^- \rightarrow J/\psi D \bar{D}$, where $D$ refers to either $D^0$ or $D^+$. A new charmoniumlike state $X^*(3860)$ that decays to $D \bar{D}$ is observed with a significance of $6.5\sigma$. Its mass is ($3862^{+26}_{-32}{}^{+40}_{-13}$) MeV/$c^2$ and width is ($201^{+154}_{-67}{}^{+88}_{-82}$) MeV. The $J^{PC}=0^{++}$ hypothesis is favored over the $2^{++}$ hypothesis at the level of $2.5\sigma$. The analysis is based on the 980 $\mathrm{fb}^{-1}$ data sample collected by the Belle detector at the asymmetric-energy $e^+ e^-$ collider KEKB.Comment: 17 pages, 11 figure

Measurement of the CKM Matrix Element ∣Vcb∣|V_{cb}| from B0→D∗−ℓ+νℓB^{0} \to D^{*-} \ell^+ \nu_\ell at Belle

We present a new measurement of the CKM matrix element $|V_{cb}|$ from $B^{0} \to D^{*-} \ell^+ \nu_\ell$ decays, reconstructed with the full Belle data set of $711 \, \rm fb^{-1}$ integrated luminosity. Two form factor parameterizations, originally conceived by the Caprini-Lellouch-Neubert (CLN) and the Boyd, Grinstein and Lebed (BGL) groups, are used to extract the product $\mathcal{F}(1)\eta_{\rm EW}|V_{cb}|$ and the decay form factors, where $\mathcal{F}(1)$ is the normalization factor and $\eta_{\rm EW}$ is a small electroweak correction. In the CLN parameterization we find $\mathcal{F}(1)\eta_{\rm EW}|V_{cb}| = (35.06 \pm 0.15 \pm 0.56) \times 10^{-3}$, $\rho^{2}=1.106 \pm 0.031 \pm 0.007$, $R_{1}(1)=1.229 \pm 0.028 \pm 0.009$, $R_{2}(1)=0.852 \pm 0.021 \pm 0.006$. For the BGL parameterization we obtain $\mathcal{F}(1)\eta_{\rm EW}|V_{cb}|= (34.93 \pm 0.23 \pm 0.59)\times 10^{-3}$, which is consistent with the World Average when correcting for $\mathcal{F}(1)\eta_{\rm EW}$. The branching fraction of $B^{0} \to D^{*-} \ell^+ \nu_\ell$ is measured to be $\mathcal{B}(B^{0}\rightarrow D^{*-}\ell^{+}\nu_{\ell}) = (4.90 \pm 0.02 \pm 0.16)\%$. We also present a new test of lepton flavor universality violation in semileptonic $B$ decays, $\frac{{\cal B }(B^0 \to D^{*-} e^+ \nu)}{{\cal B }(B^0 \to D^{*-} \mu^+ \nu)} = 1.01 \pm 0.01 \pm 0.03~$. The errors correspond to the statistical and systematic uncertainties respectively. This is the most precise measurement of $\mathcal{F}(1)\eta_{\rm EW}|V_{cb}|$ and form factors to date and the first experimental study of the BGL form factor parameterization in an experimental measurement

Observation of B0→pΛˉD(∗)−B^{0} \rightarrow p\bar{\Lambda} D^{(*)-}

We report the first observation of the decays $B^0 \rightarrow p\bar{\Lambda} D^{(*)-}$. The data sample of $711$ fb$^{-1}$ used in this analysis corresponds to $772$ million $B\bar{B}$ pairs, collected at the $\Upsilon(4S)$ resonance by the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. We observe $19.8\sigma$ and $10.8\sigma$ excesses of events for the two decay modes and measure the branching fractions of $B^0 \rightarrow p\bar{\Lambda} D^{-}$ and $B^0 \rightarrow p\bar{\Lambda} D^{*-}$ to be $(25.1\pm2.6\pm3.5)\times10^{-6}$ and $(33.6\pm6.3\pm4.4)\times10^{-6}$, 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 di-baryon ($p\bar{\Lambda}$) system is observed, consistent with that observed in similar $B$ decays.Comment: 16 pages, 3 figures and 3 tables, submitted to PR

Inclusive cross sections for pairs of identified light charged hadrons and for single protons in e+e−e^+e^- at s=\sqrt{s}= 10.58 GeV

We report the first double differential cross sections of two charged pions and kaons ($e^+e^- \rightarrow hhX$) 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 di-hadron 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 di-hadron 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 di-hadron results are obtained from a $655\,{\rm fb}^{-1}$ data sample collected near the $\Upsilon(4S)$ 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 ($e^+e^- \rightarrow pX$) cross sections are extracted from a $159\,{\rm fb}^{-1}$ data sub-sample.Comment: submitted to PR

Observation of D0→ρ0γD^0\to \rho^0\gamma and search for CPCP violation in radiative charm decays

We report the first observation of the radiative charm decay $D^0 \to \rho^0 \gamma$ and the first search for $CP$ violation in decays $D^0 \to \rho^0 \gamma$, $\phi\gamma$, and $\overline{K}{}^{*0} \gamma$, using a data sample of 943 fb$^{-1}$ collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. The branching fraction is measured to be $\mathcal{B}(D^0 \to \rho^0 \gamma)=(1.77 \pm 0.30 \pm 0.07) \times 10^{-5}$, where the first uncertainty is statistical and the second is systematic. The obtained $CP$ asymmetries, $\mathcal{A}_{CP}(D^0 \to \rho^0 \gamma)=+0.056 \pm 0.152 \pm 0.006$, $\mathcal{A}_{CP}(D^0 \to \phi \gamma)=-0.094 \pm 0.066 \pm 0.001$, and $\mathcal{A}_{CP}(D^0 \to \overline{K}{}^{*0} \gamma)=-0.003 \pm 0.020 \pm 0.000$, are consistent with no $CP$ violation. We also present an improved measurement of the branching fractions $\mathcal{B}(D^0 \to \phi \gamma)=(2.76 \pm 0.19 \pm 0.10) \times 10^{-5}$ and $\mathcal{B}(D^0 \to \overline{K}{}^{*0} \gamma)=(4.66 \pm 0.21 \pm 0.21) \times 10^{-4}$