arXiv subjects

D. M. Asner

Publications and source records attributed to D. M. Asner.

At least 523 records · Page 29Linked to original sources

arXiv2012

Search for Time-Dependent CPT Violation in Hadronic and Semileptonic B Decays

We report a new sensitive search for CPT violation, which includes improved measurements of the CPT-violating parameter z and the total decay-width difference normalized to the averaged width DeltaGamma_d/Gamma_d of the two Bd mass eigenstates. The results are based on a data sample of 535 x 10^6 BBbar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^+e^- collider. We obtain Re(z) = [+1.9 +/- 3.7 (stat) +/- 3.3 (syst)] x 10^{-2}, Im(z) = [-5.7 +/- 3.3 (stat) +/- 3.3 (syst)] x 10^{-3}, and DeltaGamma_d/Gamma_d = [-1.7 +/- 1.8 (stat) +/- 1.1 (syst)] x 10^{-2}, all of which are consistent with zero. This is the most precise single measurement of these parameters in the neutral B-meson system to date.

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arXiv2012

Phase Difference Between the Electromagnetic and Strong Amplitudes for psi(2S) and J/psi Decays into Pairs of Pseudoscalar Mesons

Using the data for 24.5x10^6 psi(2S) produced in e^+e^- annihilations at sqrt{s}=3686 MeV at the CESR-c e^+e^- collider and 8.6x10^6 J/psi produced in the decay psi(2S)->pi^+pi^-J/psi, the branching fractions for psi(2S) and J/psi decays to pairs of pseudoscalar mesons, pi^+pi^-, K^+K^-, and K_S K_L, have been measured using the CLEO-c detector. We obtain branching fractions Br(psi(2S)->pi^+pi^-)=(7.6+-2.5+-0.6)x10^-6, Br(psi(2S)->K^+K^-)=(74.8+-2.3+-3.9)x10^-6, Br(psi(2S)->K_S K_L)=(52.8+-2.5+-3.4)x10^-6, and Br(J/psi->pi^+pi^-)=(1.47+-0.13+-0.13)x10^-4, Br(J/psi->K^+K^-)=(2.86+-0.09+-0.19)x10^-4, Br(J/psi+-K_S K_L)=(2.62+-0.15+-0.14)x10^-4, where the first errors are statistical and the second errors are systematic. The phase differences between the amplitudes for electromagnetic and strong decays of psi(2S) and J/psi to 0^{-+} pseudoscalar pairs are determined by a Monte Carlo method to be δ(psi(2S)_{PP}=(110.5^{+16.0}_{-9.5})^o and δ(J/psi)_{PP}=(73.5^{+5.0}_{-4.5})^o. The difference between the two is Δδ= δ(psi(2S))_{PP}-δ(J/psi)_{PP} =(37.0^{+16.5}_{-10.5})^o.

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arXiv2012

Measurement of $B^0 \to J/ψη^{(}{}'{}^{)}$ and Constraint on the $η-η'$ Mixing Angle

We measure the branching fractions of $B^{0} \to J/ψη^{(}{}'{}^{)}$ decays with the complete Belle data sample of $772 \times 10^{6}$ $B\bar{B}$ events collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. The results for the branching fractions are: ${\cal B}(B^{0} \to J/ψη)=(12.3 \pm ^{1.8}_{1.7} \pm 0.7) \times 10^{-6}$ and ${\cal B}(B^{0} \to J/ψη') < 7.4 \times 10^{-6}$ at 90% confidence level. The $η-η'$ mixing angle is constrained to be less than $ 42.2^{\circ}$ at 90% confidence level.

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arXiv2012

Measurement of the CP-violation Parameter sin2$ϕ_1$ with a New Tagging Method at the $Υ(5S)$ Resonance

We report a measurement of the CP-violation parameter sin2$ϕ_1$ at the $Υ(5S)$ resonance using a new tagging method, called "$B$-$π$ tagging." In $Υ(5S)$ decays containing a neutral $B$ meson, a charged $B$, and a charged pion, the neutral $B$ is reconstructed in the $J/ψK_S^0$ CP-eigenstate decay channel. The initial flavor of the neutral $B$ meson at the moment of the $Υ(5S)$ decay is opposite to that of the charged $B$ and may thus be inferred from the charge of the pion without reconstructing the charged $B$. From the asymmetry between $B$-$π^+$ and $B$-$π^-$ tagged $J/ψK_S^0$ yields, we determine sin2$ϕ_1$ = 0.57 $\pm$ 0.58(stat) $\pm$ 0.06(syst). The results are based on 121 fb$^{-1}$ of data recorded by the Belle detector at the KEKB $e^+ e^-$ collider.

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arXiv2012

Amplitude analyses of the decays chi_c1 -> eta pi+ pi- and chi_c1 -> eta' pi+ pi-

Using a data sample of 2.59 x 10^7 psi(2S) decays obtained with the CLEO-c detector, we perform amplitude analyses of the complementary decay chains chi_c1 -> eta pi+ pi- and chi_c1 -> eta' pi+ pi-. We find evidence for a P-wave eta' pi scattering amplitude, which, if interpreted as a resonance, would have exotic J^PC = 1^-+ and parameters consistent with the pi_1(1600) state reported in other production mechanisms. We also make the first observation of the decay a_0(980) -> eta' pi and measure the ratio of branching fractions B(a_0(980) -> eta' pi)/B(a_0(980) -> eta pi) = 0.064 +- 0.014 +- 0.014. The pi pi spectrum produced with a recoiling eta is compared to that with eta' recoil.

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arXiv2011

First Measurement of the Form Factors in the Decays D0 to rho- e+ nu_e and D+ to rho0 e+ nu_e

Using the entire CLEO-c psi(3770) to DDbar event sample, corresponding to an integrated luminosity of 818 pb^-1 and approximately 5.4 x 10^6 DDbar events, we measure the form factors for the decays D0 to rho- e+ nu_e and D+ to rho0 e+ nu_e for the first time and the branching fractions with improved precision. A four-dimensional unbinned maximum likelihood fit determines the form factor ratios to be: V(0)/A_1(0) = 1.48 +- 0.15 +- 0.05 and A_2(0)/A_1(0)= 0.83 +- 0.11 +- 0.04. Assuming CKM unitarity, the known D meson lifetimes and our measured branching fractions we obtain the form factor normalizations A_1(0), A_2(0), and V(0). We also present a measurement of the branching fraction for D^+ to omega e^+ nu_e with improved precision.

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arXiv2011

Search for CP Violation in D Meson Decays to phi pi+

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-pi+ and the Cabibbo-favored decays Ds -> K+K-pi+ in the K+K- mass region of the phi resonance. Using 955/fb of data collected with the Belle detector we obtain A_CP(D+ -> phi pi+) = (+0.51 +- 0.28 +- 0.05)%. The measurement improves the sensitivity of previous searches by more than a factor of five. We find no evidence for direct CP violation.

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arXiv2011

Observation of the h_c(1P) using e^+e^- collisions above DDbar threshold

Using 586pb^-1 of e^+e^- collision data at E_CM = 4170MeV, produced at the CESR collider and collected with the CLEO-c detector, we observe the process e^+e^- --> pi^+ pi^- h_c(1P). We measure its cross section to be 15.6+-2.3+-1.9+-3.0pb, where the third error is due to the external uncertainty on the branching fraction of psi(2S) --> pi^0 h_c(1P), which we use for normalization. We also find evidence for e^+e^- --> eta h_c(1P) at 4170MeV at the 3sigma level, and see hints of a rise in the e^+e^- --> pi^+ pi^- h_c(1P) cross section at 4260MeV.

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arXiv2011

Branching fractions for Y(3S) -> pi^0 h_b and psi(2S) -> pi^0 h_c

Using e^+e^- collision data corresponding to 5.88M Y(3S) [25.9M psi(2S)] decays and acquired by the CLEO III [CLEO-c] detectors operating at CESR, we study the single-pion transitions from Y(3S) [psi(2S)] to the respective spin-singlet states h_{b[c]}. Utilizing only the momentum of suitably selected transition-pi^0 candidates, we obtain the upper limit B(Y(3S) -> pi^0 h_b) < 1.2\times 10^{-3} at 90% confidence level, and measure B(psi(2S) -> pi^0 h_c) = (9.0+-1.5+-1.3)\times 10^{-4}. Signal sensitivities are enhanced by excluding very asymmetric pi^0 -> gamma gamma candidates.

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arXiv2011

Observation of B- to pbar Lambda D0 at Belle

We study B- meson decays to pbar Lambda D(*)0 final states using a sample of 657 * 10^6 B Bbar events collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ e- collider. The observed branching fraction for B- to pbar Lambda D0 is (1.43^ +0.28_-0.25 +- 0.18)*10^-5. with a significance of 8.1 standard deviations, where the uncertainties are statistical and systematic, respectively. Most of the signal events have the pbarLambda mass peaking near threshold. No significant signal is observed for B- to pbar Lambda D*0 and the corresponding upper limit on the branching fraction is 4.8 * 10^-5 at the 90% confidence level.

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arXiv2011

Analysis of the Decay D^0 to K^0_S pi^0 pi^0

We present the results of a Dalitz plot analysis of D^0 to K^0_S pi^0 pi^0 using the CLEO-c data set of 818 inverse pico-barns of e^+ e^- collisions accumulated at sqrt{s} = 3.77 GeV. This corresponds to three million D^0 D^0-bar pairs from which we select 1,259 tagged candidates with a background of 7.5 +- 0.9 percent. Several models have been explored, all of which include the K^*(892), K^*_2(1430), K^*(1680), the f_0(980), and the sigma(500). We find that the combined pi^0 pi^0 S-wave contribution to our preferred fit is (28.9 +- 6.3 +- 3.1)% of the total decay rate while D^0 to K^*(892)^0 pi^0 contributes (65.6 +- 5.3 +- 2.5)%. Using three tag modes and correcting for quantum correlations we measure the D^0 to K^0_S pi^0 pi^0 branching fraction to be (1.059 +- 0.038 +- 0.061)%.

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arXiv2011

Studies of D^+ -> {eta', eta, phi} e^+ nu_e

We report the first observation of the decay D^+ -> eta' e^+ nu_e in two analyses, which combined provide a branching fraction of B(D+ -> eta' e nu) = (2.16 +/- 0.53 +/- 0.07) x 10^{-4}. We also provide an improved measurement of B(D+ -> eta e nu) = (11.4 +/- 0.9 +/- 0.4) x 10^{-4}, provide the first form factor measurement, and set the improved upper limit B(D+ -> phi e nu) < 0.9 x 10^{-4} (90% C.L.).

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arXiv2011

Search for the decay $D^+_{s}\toωe^+ν$

We present the first search for the decay $D^+_{s}\to ωe^{+}ν$ to test the four-quark content of the $D^+_{s}$ and the $ω$-$ϕ$ mixing model for this decay. We use 586 $\mathrm{pb}^{-1}$ of $e^{+}e^{-}$ collision data collected at a center-of-mass energy of 4170 MeV. We find no evidence of a signal, and set an upper limit on the branching fraction of $\mathcal{B}(D^+_{s}\toωe^+ν)<$0.20% at the 90% confidence level.

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arXiv2011

Observation of the Dalitz Decay $D_{s}^{*+} \to D_{s}^{+} e^{+} e^{-}$

Using 586 $\textrm{pb}^{-1}$ of $e^{+}e^{-}$ collision data acquired at $\sqrt{s}=4.170$ GeV with the CLEO-c detector at the Cornell Electron Storage Ring, we report the first observation of $D_{s}^{*+} \to D_{s}^{+} e^{+} e^{-}$ with a significance of $5.3 σ$. The ratio of branching fractions $\calB(D_{s}^{*+} \to D_{s}^{+} e^{+} e^{-}) / \calB(D_{s}^{*+} \to D_{s}^{+} γ)$ is measured to be $[ 0.72^{+0.15}_{-0.13} (\textrm{stat}) \pm 0.10 (\textrm{syst})]%$, which is consistent with theoretical expectations.

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arXiv2011

Measurements of branching fractions for electromagnetic transitions involving the $χ_{bJ}(1P)$ states

Using 9.32, 5.88 million Upsilon(2S,3S) decays taken with the CLEO-III detector, we obtain five product branching fractions for the exclusive processes Upsilon(2S) => gamma chi_{b0,1,2}(1P) => gamma gamma Upsilon(1S) and Upsilon(3S) => gamma chi_{b1,2}(1P) => gamma gamma Upsilon(1S). We observe the transition chi_{b0}(1P) => gamma Upsilon(1S) for the first time. Using the known branching fractions for B[Upsilon(2S) => gamma chi_{bJ}(1P)], we extract values for B[chi_{bJ}(1P) => gamma Upsilon(1S)] for J=0, 1, 2. In turn, these values can be used to unfold the Upsilon(3S) product branching fractions to obtain values for B[Upsilon(3S) => gamma chi_{b1,2}(1P) for the first time individually. Comparison of these with each other and with the branching fraction B[Upsilon(3S) => gamma chi_{b0}] previously measured by CLEO provides tests of relativistic corrections to electric dipole matrix elements.

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arXiv2010

Upsilon(1S)->gamma+f2'(1525); f2'(1525)->K0sK0s decays

We report on a study of exclusive radiative decays of the Upsilon(1S) resonance into a final state consisting of a photon and two K0s candidates. We find evidence for a signal for Upsilon(1S)->gamma f_2'(1525); f_2'(1525)->K0sK0s, at a rate (4.0+/-1.3+/-0.6)x10^{-5}, consistent with previous observations of Upsilon(1S)->gamma f_2'(1525); f_2'(1525)->K+K-, and isospin. Combining this branching fraction with existing branching fraction measurements of Upsilon(1S)->gamma f_2'(1525) and J/psi->gamma f_2'(1525), we obtain the ratio of branching fractions: B(Upsilon(1S)->gamma f_2'(1525))/B(J/psi->gamma f_2'(1525))=0.09+/-0.02, approximately consistent with expectations based on soft collinear effective theory.

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arXiv2010

Search for rare and forbidden decays of charm and charmed-strange mesons to final states h^+- e^-+ e^+

We have searched for flavor-changing neutral current decays and lepton-number-violating decays of D^+ and D^+_s mesons to final states of the form h^+- e^-+ e^+, where h is either πor K. We use the complete samples of CLEO-c open-charm data, corresponding to integrated luminosities of 818 pb^-1 at the center-of-mass energy E_CM = 3.774 GeV containing 2.4 x 10^6 D^+D^- pairs and 602 pb^-1 at E_CM = 4.170 GeV containing 0.6 x 10^6 D^*+-_s D^-+_s pairs. No signal is observed in any channel, and we obtain 90% confidence level upper limits on branching fractions B(D^+ --> π^+ e^+ e^-) < 5.9 x 10^-6, B(D^+ --> π^- e^+ e^+) < 1.1 x 10^-6, B(D^+ --> K^+ e^+ e^-) < 3.0 x 10^-6, B(D^+ --> K^- e^+ e^+) < 3.5 x 10^-6, B(D^+_s --> π^+ e^+ e^-) < 2.2 x 10^-5, B(D^+_s --> π^- e^+ e^+) < 1.8 x 10^-5, B(D^+_s --> K^+ e^+ e^-) < 5.2 x 10^-5, and B(D^+_s --> K^- e^+ e^+) < 1.7 x 10^-5.

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arXiv2010

Belle II Technical Design Report

The Belle detector at the KEKB electron-positron collider has collected almost 1 billion Y(4S) events in its decade of operation. Super-KEKB, an upgrade of KEKB is under construction, to increase the luminosity by two orders of magnitude during a three-year shutdown, with an ultimate goal of 8E35 /cm^2 /s luminosity. To exploit the increased luminosity, an upgrade of the Belle detector has been proposed. A new international collaboration Belle-II, is being formed. The Technical Design Report presents physics motivation, basic methods of the accelerator upgrade, as well as key improvements of the detector.

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