3,072 research outputs found

    Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. V. A New Size-Luminosity Scaling Relation for the Broad-Line Region

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    This paper reports results of the third-year campaign of monitoring super-Eddington accreting massive black holes (SEAMBHs) in active galactic nuclei (AGNs) between 2014-2015. Ten new targets were selected from quasar sample of Sloan Digital Sky Survey (SDSS), which are generally more luminous than the SEAMBH candidates in last two years. Hβ\beta lags (τHβ\tau_{_{\rm H\beta}}) in five of the 10 quasars have been successfully measured in this monitoring season. We find that the lags are generally shorter, by large factors, than those of objects with same optical luminosity, in light of the well-known RHβL5100R_{_{\rm H\beta}}-L_{5100} relation. The five quasars have dimensionless accretion rates of M˙=10103\dot{\mathscr{M}}=10-10^3. Combining measurements of the previous SEAMBHs, we find that the reduction of Hβ\beta lags tightly depends on accretion rates, τHβ/τRLM˙0.42\tau_{_{\rm H\beta}}/\tau_{_{R-L}}\propto\dot{\mathscr{M}}^{-0.42}, where τRL\tau_{_{R-L}} is the Hβ\beta lag from the normal RHβL5100R_{_{\rm H\beta}}-L_{5100} relation. Fitting 63 mapped AGNs, we present a new scaling relation for the broad-line region: RHβ=α144β1min[1,(M˙/M˙c)γ1]R_{_{\rm H\beta}}=\alpha_1\ell_{44}^{\beta_1}\,\min\left[1,\left(\dot{\mathscr{M}}/\dot{\mathscr{M}}_c\right)^{-\gamma_1}\right], where 44=L5100/1044erg s1\ell_{44}=L_{5100}/10^{44}\,\rm erg~s^{-1} is 5100 \AA\ continuum luminosity, and coefficients of α1=(29.62.8+2.7)\alpha_1=(29.6_{-2.8}^{+2.7}) lt-d, β1=0.560.03+0.03\beta_1=0.56_{-0.03}^{+0.03}, γ1=0.520.16+0.33\gamma_1=0.52_{-0.16}^{+0.33} and M˙c=11.196.22+2.29\dot{\mathscr{M}}_c=11.19_{-6.22}^{+2.29}. This relation is applicable to AGNs over a wide range of accretion rates, from 10310^{-3} to 10310^3. Implications of this new relation are briefly discussed.Comment: 15 pages, 9 figures, 5 table, accepted for publication in The Astrophysical Journa

    A Multicenter prospective study of poor-grade aneurysmal subarachnoid hemorrhage (AMPAS): observational registry study

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    BACKGROUND: Poor-grade aneurysmal subarachnoid hemorrhage (aSAH) is associated with very high mortality and morbidity. Our limited knowledge on predictors of long-term outcome in poor-grade patients with aSAH definitively managed comes from retrospective and prospective studies of small case series of patients in single center. The purpose of the AMPAS is to determine the long-term outcomes in poor-grade patients with different managements within different time after aSAH, and identify the independent predictors of the outcome that help guide the decision on definitive management. METHODS/DESIGN: The AMPAS study is a prospective, multicenter, observational registry of consecutive hospitalized patients with poor grade aSAH (WFNS grade IV and V). The aim is to enroll at least 226 poor-grade patients in 11 high-volume medical centers (eg, >150 aSAH cases per year) affiliated to different universities in China. This study will describe poor grade patients and aneurysm characteristics, treatment strategies (modality and time of definitive management), hospitalization complications and outcomes evolve over time. The definitive management is ruptured aneurysm treatment. Outcomes at 3, 6, 12 months after the management were measured using the Glasgow Outcome Scale and the Modified Rankin Scale. DISCUSSION: The AMPAS is the first prospective, multicenter, observational registry of poor grade aSAH with any management. This study will contribute to a better understanding of significant predictors of outcome in poor grade patients and help guide future treatment of the worst patients after aSAH. TRIAL REGISTRATION: Chinese Clinical Trial Registry: ChiCTR-TNRC-10001041

    A Unified Approach to the Classical Statistical Analysis of Small Signals

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    We give a classical confidence belt construction which unifies the treatment of upper confidence limits for null results and two-sided confidence intervals for non-null results. The unified treatment solves a problem (apparently not previously recognized) that the choice of upper limit or two-sided intervals leads to intervals which are not confidence intervals if the choice is based on the data. We apply the construction to two related problems which have recently been a battle-ground between classical and Bayesian statistics: Poisson processes with background, and Gaussian errors with a bounded physical region. In contrast with the usual classical construction for upper limits, our construction avoids unphysical confidence intervals. In contrast with some popular Bayesian intervals, our intervals eliminate conservatism (frequentist coverage greater than the stated confidence) in the Gaussian case and reduce it to a level dictated by discreteness in the Poisson case. We generalize the method in order to apply it to analysis of experiments searching for neutrino oscillations. We show that this technique both gives correct coverage and is powerful, while other classical techniques that have been used by neutrino oscillation search experiments fail one or both of these criteria.Comment: 40 pages, 15 figures. Changes 15-Dec-99 to agree more closely with published version. A few small changes, plus the two substantive changes we made in proof back in 1998: 1) The definition of "sensitivity" in Sec. V(C). It was inconsistent with our actual definition in Sec. VI. 2) "Note added in proof" at end of the Conclusio

    Measurement of pretzelosity asymmetry of charged pion production in Semi-Inclusive Deep Inelastic Scattering on a polarized 3^3He target

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    An experiment to measure single-spin asymmetries in semi-inclusive production of charged pions in deep-inelastic scattering on a transversely polarized 3^3He target was performed at Jefferson Lab in the kinematic region of 0.16<x<0.350.16<x<0.35 and 1.4<Q2<2.71.4<Q^2<2.7 GeV2{\rm GeV^2}. The pretzelosity asymmetries on 3^3He, which can be expressed as the convolution of the h1Th^\perp_{1T} transverse momentum dependent distribution functions and the Collins fragmentation functions in the leading order, were measured for the first time. Using the effective polarization approximation, we extracted the corresponding neutron asymmetries from the measured 3^3He asymmetries and cross-section ratios between the proton and 3^3He. Our results show that for both π±\pi^{\pm} on 3^3He and on the neutron the pretzelosity asymmetries are consistent with zero within experimental uncertainties.Comment: 6 pages, 3 figures; enlarged the legends in Fig.3; added 3 citation

    Single Spin Asymmetries in Charged Kaon Production from Semi-Inclusive Deep Inelastic Scattering on a Transversely Polarized 3He^3{\rm{He}} Target

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    We report the first measurement of target single spin asymmetries of charged kaons produced in semi-inclusive deep inelastic scattering of electrons off a transversely polarized 3He^3{\rm{He}} target. Both the Collins and Sivers moments, which are related to the nucleon transversity and Sivers distributions, respectively, are extracted over the kinematic range of 0.1<<xbjx_{bj}<<0.4 for K+K^{+} and KK^{-} production. While the Collins and Sivers moments for K+K^{+} are consistent with zero within the experimental uncertainties, both moments for KK^{-} favor negative values. The Sivers moments are compared to the theoretical prediction from a phenomenological fit to the world data. While the K+K^{+} Sivers moments are consistent with the prediction, the KK^{-} results differ from the prediction at the 2-sigma level.Comment: 6 pages, 3 figure

    Evidence for e+eγχc1,2e^+e^-\to\gamma\chi_{c1, 2} at center-of-mass energies from 4.009 to 4.360 GeV

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    Using data samples collected at center-of-mass energies of s\sqrt{s} = 4.009, 4.230, 4.260, and 4.360 GeV with the BESIII detector operating at the BEPCII collider, we perform a search for the process e+eγχcJe^+e^-\to\gamma\chi_{cJ} (J=0,1,2)(J = 0, 1, 2) and find evidence for e+eγχc1e^+e^-\to\gamma\chi_{c1} and e+eγχc2e^+e^-\to\gamma\chi_{c2} with statistical significances of 3.0σ\sigma and 3.4σ\sigma, respectively. The Born cross sections σB(e+eγχcJ)\sigma^{B}(e^+e^-\to\gamma\chi_{cJ}), as well as their upper limits at the 90% confidence level are determined at each center-of-mass energy.Comment: 8 pages, 7 figures, 3 table

    Observation of χc1\chi_{c1} decays into vector meson pairs ϕϕ\phi\phi, ωω\omega\omega, and ωϕ\omega\phi

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    Decays of χc1\chi_{c1} to vector meson pairs ϕϕ\phi\phi, ωω\omega\omega and ωϕ\omega\phi are observed for the first time using (106±4)×106(106\pm4)\times 10^6 \psip events accumulated at the BESIII detector at the BEPCII e+ee^+e^- collider. The branching fractions are measured to be (4.4±0.3±0.5)×104(4.4\pm 0.3\pm 0.5)\times 10^{-4}, (6.0±0.3±0.7)×104(6.0\pm 0.3\pm 0.7)\times 10^{-4}, and (2.2±0.6±0.2)×105(2.2\pm 0.6\pm 0.2)\times 10^{-5}, for χc1ϕϕ\chi_{c1}\to \phi\phi, ωω\omega\omega, and ωϕ\omega\phi, respectively. The observation of χc1\chi_{c1} decays into a pair of vector mesons ϕϕ\phi\phi, ωω\omega\omega and ωϕ\omega\phi indicates that the hadron helicity selection rule is significantly violated in χcJ\chi_{cJ} decays. In addition, the measurement of χcJωϕ\chi_{cJ}\to \omega\phi gives the rate of doubly OZI-suppressed decay. Branching fractions for χc0\chi_{c0} and χc2\chi_{c2} decays into other vector meson pairs are also measured with improved precision.Comment: 4 pages, 2 figure

    Studies of charmed strange baryons in the ΛD\Lambda D final state at Belle

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    We report the discovery of Ξc(3055)0\Xi_{c}(3055)^{0}, observed by its decay into the final state ΛD0\Lambda D^{0}, and present the first observation and evidence of the decays of Ξc(3055)+\Xi_c(3055)^{+} and Ξc(3080)+\Xi_c(3080)^{+} into ΛD+\Lambda D^{+}. We also perform a combined analysis of the ΛD+\Lambda D^{+} with the Σc++K\Sigma_{c}^{++}K^{-} and Σc++K\Sigma_{c}^{\ast ++}K^{-} decay modes to measure the ratios of branching fractions, masses and widths with improved accuracy. We measure the ratios of branching fractions B(Ξc(3055)+ΛD+)/B(Ξc(3055)+Σc++K)=5.09±1.01±0.76{\cal B}(\Xi_{c}(3055)^{+} \to \Lambda D^{+})/{\cal B}(\Xi_{c}(3055)^{+} \to \Sigma_{c}^{++}K^{-})=5.09\pm1.01\pm0.76, B(Ξc(3080)+ΛD+)/B(Ξc(3080)+Σc++K)=1.29±0.30±0.15{\cal B}(\Xi_{c}(3080)^{+} \to \Lambda D^{+})/{\cal B}(\Xi_{c}(3080)^{+} \to \Sigma_{c}^{++}K^{-})=1.29\pm0.30\pm0.15, and B(Ξc(3080)+Σc++K)/B(Ξc(3080)+Σc++K)=1.07±0.27±0.01{\cal B}(\Xi_{c}(3080)^{+} \to \Sigma_{c}^{\ast ++}K^{-})/{\cal B}(\Xi_{c}(3080)^{+} \to \Sigma_{c}^{++}K^{-})=1.07\pm0.27\pm0.01, where the uncertainties are statistical and systematic. The analysis is performed using a 980 fb1^{-1} data sample collected with the Belle detector at the KEKB asymmetric-energy e+ee^{+}e^{-} collider.Comment: Submitted to PR

    Measurement of branching fraction and direct CPCP asymmetry in charmless B+K+Kπ+B^+ \to K^+K^- \pi^+ decays at Belle

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    We report a study of the charmless hadronic decay of the charged BB meson to the three-body final state K+Kπ+K^+ K^- \pi^+. The results are based on a data sample that contains 772×106772\times10^6 BBˉB \bar{B} pairs collected at the Υ(4S)\Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ee^+ e^- collider. The measured inclusive branching fraction and the direct CPCP asymmetry are (5.38±0.40±0.35)×106(5.38\pm0.40\pm0.35)\times 10^{-6} and 0.170±0.073±0.017-0.170\pm0.073\pm0.017, respectively, where the first uncertainties are statistical and the second are systematic. The K+KK^{+}K^{-} invariant mass distribution of the signal candidates shows an excess in the region below 1.51.5 GeV/c2c^2, which is consistent with the previous studies from BaBar and LHCb. In addition, strong evidence of a large direct CPCP asymmetry is found in the K+KK^{+}K^{-} low-invariant-mass region.Comment: 7 pages, 3 figure

    Study of π0\pi^0 pair production in single-tag two-photon collisions

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    We report a measurement of the differential cross section of π0\pi^0 pair production in single-tag two-photon collisions, γγπ0π0\gamma^* \gamma \to \pi^0 \pi^0, in e+ee^+ e^- scattering. The cross section is measured for Q2Q^2 up to 30 GeV2^2, where Q2Q^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 cosθ|\cos \theta^*| < 1.0 for the total energy and pion scattering angle, respectively, in the γγ\gamma^* \gamma center-of-mass system. The results are based on a data sample of 759 fb1^{-1} collected with the Belle detector at the KEKB asymmetric-energy e+ee^+ e^- collider. The transition form factor of the f0(980)f_0(980) and that of the f2(1270)f_2(1270) with the helicity-0, -1, and -2 components separately are measured for the first time and are compared with theoretical calculations.Comment: 36 pages, 37 figures, 11 tables, Belle Preprint 2015-15, KEK Preprint 2015-2
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