arXiv subjects

D. Joffe

Publications and source records attributed to D. Joffe.

90 records · Page 5Linked to original sources

arXiv2015

Observation of $X(3872)$ in $B \to X(3872) Kπ$ decays

We report the first observation of $B^0 \to X(3872) (K^{+}π^{-})$ and evidence for $B^+ \to X(3872) (K^{0}π^{+})$. We measure the product of branching fractions for the former to be ${\cal B}(B^0 \to X(3872) (K^+ π^-)) \times {\cal B}(X(3872) \to J/ψπ^+ π^-) = (7.9 \pm 1.3(\mbox{stat.})\pm 0.4(\mbox{syst.})) \times 10^{-6}$ and find that $B^{0}\to X(3872) K^{*}(892)^{0}$ does not dominate the $B^{0}\to X(3872)K^{+}π^{-}$ decay mode. We also measure ${\cal B}(B^+ \to X(3872) (K^0 π^+)) \times {\cal B}(X(3872) \to J/ψπ^+ π^-) = (10.6 \pm 3.0(\mbox{stat.}) \pm 0.9(\mbox{syst.})) \times 10^{-6}$. This study is based on the full data sample of 711~fb$^{-1}$ ($772\times 10^6 B\bar B$ pairs) collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB collider.

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arXiv2015

Measurements of $B\rightarrow \bar{D} D_{s0} ^{+}(2317)$ decay rates and a search for isospin partners of the $D_{s0}^{+} (2317)$

We report improved measurements of the product branching fractions ${\mathcal B}(B^+\rightarrow\bar{D}^0 D_{s0}^{*+} (2317))\times{\mathcal B}( D_{s0} ^{*+}(2317)\rightarrow D_s^{+}π^0) =(8.0^{+1.3}_{-1.2} \pm 1.1 \pm 0.4)\times 10^{-4}$ and ${\mathcal B}(B^0\rightarrow D^- D_{s0} ^{*+}(2317))\times{\mathcal B}(D_{s0}^{*+}(2317)\rightarrow D_s^{+}π^0) =(10.2^{+1.3}_{-1.2} \pm 1.0 \pm 0.4)\times 10^{-4}$, 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 ${\mathcal B}(B^0 \rightarrow D^0 z^0)\times{\mathcal B}(z^0\rightarrow D_s^{+}π^-)$ and ${\mathcal B}(B^+\rightarrow D^- z^{++})\times{\mathcal B}(z^{++}\rightarrow D_s^{+}π^+)$ 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 $B\bar{B}$ meson pairs collected at the $Υ(4S)$ resonance in the Belle detector at the KEKB collider.

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arXiv2015

Study of $D^{**}$ production and light hadronic states in the $\bar{B}^0 \to D^{*+} ωπ^-$ decay

We report on the first observations of $\bar{B}^0 \to D_1(2430)^0 ω$, $\bar{B}^0 \to D_1(2420)^0 ω$ and $\bar{B}^0 \to D^*_2(2460)^0 ω$ decays. The $\bar{B}^0 \to D^{*+} ρ(1450)^-$ decay is also observed. The branching fraction measurements are based on $(771.6 \pm 10.6)\times 10^6$ $B\bar{B}$ events collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. The fractions of longitudinal polarization of the $D^{**}$ states as well as partial wave fractions of the $D_1(2430)^0$ are obtained. We also set a $90\%$ confidence level upper limit for the product of branching fractions of $\mathcal{B}(\bar{B}^0 \to D^{*+} b_1(1235)^-) \times \mathcal{B}(b_1(1235)^- \to ωπ^-)$. The measurements show evidence of nontrivial final-state interaction phases for the $ρ$-like amplitudes.

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arXiv2015

Measurement of $e^+e^- \to γχ_{cJ}$ via initial state radiation at Belle

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

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arXiv2015

First observation of the hadronic transition $ Υ(4S) \to ηh_{b}(1P)$ and new measurement of the $h_b(1P)$ and $η_b(1S)$ parameters

Using a sample of $771.6 \times 10^{6}$ $Υ(4S)$ decays collected by the Belle experiment at the KEKB $e^+e^-$ collider, we observe for the first time the transition $Υ(4S) \to ηh_b(1P)$ with the branching fraction ${\cal B}[Υ(4S) \to ηh_b(1P)]= (2.18 \pm 0.11 \pm 0.18) \times 10^{-3}$ and we measure the $h_b(1P)$ mass $M_{h_{b}(1P)} = (9899.3 \pm 0.4 \pm 1.0)$ MeV/$c^{2}$, corresponding to the hyperfine splitting $ΔM_{\mathrm HF}(1P) = (0.6 \pm 0.4 \pm 1.0)$ MeV/$c^{2}$. Using the transition $h_b(1P) \to γη_b(1S)$, we measure the $η_b(1S)$ mass $M_{η_{b}(1S)} = (9400.7 \pm 1.7 \pm 1.6)$ MeV/$c^{2}$, corresponding to $ΔM_{\mathrm HF}(1S) = (59.6 \pm 1.7 \pm 1.6)$ MeV/$c^{2}$, the $η_b(1S)$ width $Γ_{η_{b}(1S)} = (8 ^{+6}_{-5} \pm 5)$ MeV/$c^{2}$ and the branching fraction ${\cal B}[h_b(1P) \to γη_b(1S)]= (56 \pm 8 \pm 4) \%$.

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arXiv2015

Measurement of the direct $CP$ asymmetry in $\bar{B}\rightarrow X_{s+d}γ$ decays with a lepton tag

We report the measurement of the direct $CP$ asymmetry in the radiative $\bar{B}\rightarrow X_{s+d}γ$ decay using a data sample of $(772 \pm 11)\times 10^6$ $B\bar{B}$ pairs collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. The $CP$ asymmetry is measured as a function of the photon energy threshold. For $E^{\rm{*}}_γ \geq 2.1~{\rm{GeV}}$, where $E^{\rm{*}}_γ$ is the photon energy in the center-of-mass frame, we obtain $\mathcal{A}_{CP}(\bar{B}\rightarrow X_{s+d}γ)= (2.2 \pm 3.9 \pm 0.9) \%$, consistent with the Standard Model prediction.

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arXiv2015

Search for B+ -> l+ nu gamma decays with hadronic tagging using the full Belle data sample

We search for the decay B+ -> l+ nu gamma with l+ = e+ or mu+ using the full Belle data set of 772 x 10^6 BBbar 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 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 BR(B+ -> e+ nu gamma) < 6.1 x 10^-6, BR(B+ -> mu+ nu gamma) < 3.4 x 10^-6, and BR(B+ -> l+ nu gamma) < 3.5 x 10^-6 at 90 % credibility level.

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arXiv2015

Search for the decay $B^+\rightarrow\overline{K}{}^{0}K^{+}$ at Belle

We report a search for the rare charmless decay $B^+\rightarrow\overline{K}{}^{*0}K^{*+}$ using a data sample of $772\times10^6$ $B\bar{B}$ pairs collected at the $Υ(4S)$ 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 as $ \mathcal{B}(B^+\rightarrow\overline{K}{}^{*0}K^{*+}) <1.31\times 10^{-6}$.

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arXiv2014

Search for $B_{s}^{0}\rightarrowγγ$ and a measurement of the branching fraction for $B_{s}^{0}\rightarrowϕγ$

We search for the decay $B_{s}^{0}\rightarrowγγ$ and measure the branching fraction for $B_{s}^{0}\rightarrowϕγ$ using 121.4~$\textrm{fb}^{-1}$ of data collected at the $Υ(\mathrm{5}S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. The $B_{s}^{0}\rightarrowϕγ$ branching fraction is measured to be $(3.6 \pm 0.5 (\mathrm{stat.}) \pm 0.3 (\mathrm{syst.}) \pm 0.6 (f_{s})) \times 10^{-5}$, where $f_{s}$ is the fraction of $B_{s}^{(*)}\bar{B}_{s}^{(*)}$ in $b\bar{b}$ events. Our result is in good agreement with the theoretical predictions as well as with a recent measurement from LHCb. We observe no statistically significant signal for the decay $B_{s}^{0}\rightarrowγγ$ and set a $90\%$ confidence-level upper limit on its branching fraction at $ 3.1 \times 10^{-6}$. This constitutes a significant improvement over the previous result.

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arXiv2014

Measurement of the $\bar{B} \rightarrow X_s γ$ Branching Fraction with a Sum of Exclusive Decays

We use 772$\times 10^6$ $B \bar{B}$ meson pairs collected at the $Υ(4S)$ resonance with the Belle detector to measure the branching fraction for $\bar{B} \rightarrow X_s γ$. Our measurement uses a sum-of-exclusives approach in which 38 of the hadronic final states with strangeness equal to $+1$, denoted by $X_s$, are reconstructed. The inclusive branching fraction for $M_{X_s}<$ 2.8 GeV/$c^2$, which corresponds to a minimum photon energy of 1.9 GeV, is measured to be ${\cal B}(\bar{B} \rightarrow X_s γ)=(3.51\pm0.17\pm0.33)\times10^{-4}$, where the first uncertainty is statistical and the second is systematic.

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arXiv2014

Evidence of $Υ(1S) \to J/ψ+χ_{c1}$ and search for double-charmonium production in $Υ(1S)$ and $Υ(2S)$ decays

Using data samples of $102\times10^6$ $Υ(1S)$ and $158\times10^6$ $Υ(2S)$ events collected with the Belle detector, a first experimental search has been made for double-charmonium production in the exclusive decays $Υ(1S,2S)\rightarrow J/ψ(ψ')+X$, where $X=η_c$, $χ_{cJ} (J=~0,~1,~2)$, $η_c(2S)$, $X(3940)$, and $X(4160)$. No significant signal is observed in the spectra of the mass recoiling against the reconstructed $J/ψ$ or $ψ'$ except for the evidence of $χ_{c1}$ production with a significance of $4.6σ$ for $Υ(1S)\rightarrow J/ψ+χ_{c1}$. The measured branching fraction $\BR(Υ(1S)\rightarrow J/ψ+χ_{c1})$ is $(3.90\pm1.21(\rm stat.)\pm0.23 (\rm syst.))\times10^{-6}$. The $90\%$ confidence level upper limits on the branching fractions of the other modes having a significance of less than $3σ$ are determined. These results are consistent with theoretical calculations using the nonrelativistic QCD factorization approach.

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arXiv2014

Measurement of $B^0 \to D_s^- K^0_Sπ^+$ and $B^+ \to D_s^- K^+K^+$ branching fractions

We report a measurement of the $B^0$ and $B^+$ meson decays to the $D_s^-K^0_S π^+$ and $D_s^- K^+K^+$ final states, respectively, using $657 \times 10^{6} B\overline{B}$ pairs collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. Using the $D_s^-\to ϕπ^-$, $K^{*}(892)^0 K^-$ and $K^0_S K^-$ decay modes for the $D_s$ reconstruction, we measure the following branching fractions: ${\cal B}(B^0\to D_s^{-}K^0_Sπ^+)=[0.47 \pm 0.06 (\mathrm {stat}) \pm 0.05 (\mathrm {syst})]\times 10^{-4}$ and ${\cal B}(B^+\to D_s^-K^+K^+)= [0.93 \pm 0.22 (\mathrm {stat})\pm 0.10 (\mathrm {syst})]\times 10^{-5}$. We find the ratio of the branching fraction of $B^+\to D_s^-K^+K^+$ to that of the analogous Cabibbo favored $B^+\to D_s^-K^+π^+$ decay to be ${\cal R}_{\cal B} = 0.054 \pm 0.013 ({\rm stat}) \pm 0.006 ({\rm syst})$, which is consistent with the na\"ıve factorization model. We also observe a deviation from the three-body phase-space model for both studied decays.

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arXiv2014

Updated Cross Section Measurement of $e^+ e^- \to K^+ K^- J/ψ$ and $K_S^0K_S^0J/ψ$ via Initial State Radiation at Belle

The cross sections of the processes $e^+ e^- \to K^+ K^- J/ψ$ and $K_S^0K_S^0J/ψ$ are measured via initial state radiation at center-of-mass energies between the threshold and 6.0~GeV using a data sample of 980~fb$^{-1}$ collected with the Belle detector on or near the $Υ(nS)$ resonances, where $n=$1, 2, ..., 5. The cross sections for $e^+ e^- \to K^+ K^- J/ψ$ are at a few pb level and the average cross section for $e^+ e^- \to K_S^0K_S^0J/ψ$ is $1.8\pm 0.6 (\rm stat.)\pm 0.3 (\rm syst.)$~pb between 4.4 and 5.2~GeV. All of them are consistent with previously published results with improved precision. A search for resonant structures and associated intermediate states in the cross section of the process $e^+ e^- \to K^+ K^- J/ψ$ is performed.

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arXiv2013

Study of $e^+ e^- \to π^+ π^- J/ψ$ and Observation of a Charged Charmonium-like State at Belle

The cross section for $e^+ e^- \to π^+ π^- J/ψ$ between 3.8 GeV and 5.5 GeV is measured with a 967 fb$^{-1}$ data sample collected by the Belle detector at or near the $Υ(nS)$ ($n = 1,\ 2,\ ...,\ 5$) resonances. The Y(4260) state is observed, and its resonance parameters are determined. In addition, an excess of $π^+ π^- J/ψ$ production around 4 GeV is observed. This feature can be described by a Breit-Wigner parameterization with properties that are consistent with the Y(4008) state that was previously reported by Belle. In a study of $Y(4260) \to π^+ π^- J/ψ$ decays, a structure is observed in the $M(π^\pm\jpsi)$ mass spectrum with $5.2σ$ significance, with mass $M=(3894.5\pm 6.6\pm 4.5) {\rm MeV}/c^2$ and width $Γ=(63\pm 24\pm 26)$ MeV/$c^{2}$, where the errors are statistical and systematic, respectively. This structure can be interpreted as a new charged charmonium-like state.

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arXiv2007

Precision measurements of the total and partial widths of the psi(2S) charmonium meson with a new complementary-scan technique in antiproton-proton annihilations

We present new precision measurements of the psi(2S) total and partial widths from excitation curves obtained in antiproton-proton annihilations by Fermilab experiment E835 at the Antiproton Accumulator in the year 2000. A new technique of complementary scans was developed to study narrow resonances with stochastically cooled antiproton beams. The technique relies on precise revolution-frequency and orbit-length measurements, while making the analysis of the excitation curve almost independent of machine lattice parameters. We study the psi(2S) meson through the processes pbar p -> e+ e- and pbar p -> J/psi + X -> e+ e- + X. We measure the width to be Gamma = 290 +- 25(sta) +- 4(sys) keV and the combination of partial widths Gamma_e+e- * Gamma_pbarp / Gamma = 579 +- 38(sta) +- 36(sys) meV, which represent the most precise measurements to date.

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arXiv2007

Confirmation of a pi_1^0 Exotic Meson in the ηπ^0 System

The exclusive reaction $π^- p \to ηπ^0 n$, $η\to π^+ π^- π^0$ at 18 GeV$/c$ has been studied with a partial wave analysis on a sample of 23~492 $ηπ^0 n$ events from BNL experiment E852. A mass-dependent fit is consistent with a resonant hypothesis for the $P_+$ wave, thus providing evidence for a neutral exotic meson with $J^{PC} = 1^{-+}$, a mass of $1257 \pm 20 \pm 25$ MeV$/c^2$, and a width of $354 \pm 64 \pm 60$ MeV$/c^2$. New interpretations of the meson exotics in neutral $ηπ^0$ system observed in E852 and Crystal Barrel experiments are discussed.

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arXiv2006

Light Quark Resonances in pbar p Annihilations at 5.2 GeV/c

Data from the Fermilab E835 experiment have been used to study the reaction pbar p -> eta eta pi0 at 5.2 GeV/c. A sample of 22 million six photons events has been analyzed to construct the Dalitz plot containing ~80k eta eta pi0 events. A partial wave analysis of the data has been done. Six f_J-states decaying into eta eta and five a_J-states decaying into eta pi0 are identified in the mass region ~1.3 and 2.4 GeV, and their masses, widths and spins are determined by maximum likelihood analysis of the data. Two f_0 states are identified with the popular candidates for the lightest scalar glueball, f_0(1500) and f_0(1710).

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arXiv2005

Measurement of the branching ratios $ψ^\prime \to e^+ e^-$, $ψ^\prime \to J/ψππ$ and $ψ^\prime \to J/ψη$

We have measured several branching ratios for $ψ^\prime$ decay using the data collected by FNAL E835 experiment during year 2000, obtaining ${\cal B}(ψ^\prime \to e^+ e^-) = 0.0068\pm0.0001\pm0.0004$, ${\cal B}(ψ^\prime \to J/ψπ^+ π^-) = 0.292\pm0.005\pm0.018$, ${\cal B}(ψ^\prime \to J/ψπ^0 π^0) = 0.167\pm0.005\pm0.014$ and ${\cal B}(ψ^\prime \to J/ψη) = 0.028\pm0.002\pm0.002$. We also present a measurement of the dipion mass distribution in the decays $ψ^\prime \to J/ψππ$.

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