8,699 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

    Two Photon Decays of ηc\eta_c from Lattice QCD

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    We present an exploratory lattice study for the two-photon decay of ηc\eta_c using Nf=2N_f=2 twisted mass lattice QCD gauge configurations generated by the European Twisted Mass Collaboration. Two different lattice spacings of a=0.067a=0.067fm and a=0.085a=0.085fm are used in the study, both of which are of physical size of 2fmfm. The decay widths are found to be 1.025(5)1.025(5)KeV for the coarser lattice and 1.062(5)1.062(5)KeV for the finer lattice respectively where the errors are purely statistical. A naive extrapolation towards the continuum limit yields Γ1.122(14)\Gamma\simeq 1.122(14)KeV which is smaller than the previous quenched result and most of the current experimental results. Possible reasons are discussed.Comment: 13 pages, 7 figures; matches the published versio

    Machine learning-based volume diagnosis

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    In this paper, a novel diagnosis method is proposed. The proposed technique uses machine learning techniques instead of traditional cause-effect and/or effect-cause analysis. The proposed technique has several advantages over traditional di-agnosis methods, especially for volume diagnosis. In the pro-posed method, since the time consuming diagnosis process is reduced to merely evaluating several decision functions, run time complexity is much lower than traditional diagnosis meth-ods. The proposed technique can provide not only high reso-lution diagnosis but also statistical data by classifying defec-tive chips according to locations of their defects. Even with highly compressed output responses, the proposed diagnosis technique can correctly locate defect locations for most defec-tive chips. The proposed technique correctly located defects for more than 90 % (86 %) defective chips at 50x (100x) out-put compaction. Run time for diagnosing a single simulated defect chip was only tens of milli-seconds.

    NUMERICAL DISTRIBUTION SIMULATION OF TYPHOONS’ WAVE ENERGY IN THE TAIWAN STRAIT AND ITS ADJACENT WATERS

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    As new energy technologies boom in recent years, marine renewable energy, especially wave power is one potential trend. However, few relevant studies focus on extreme sea conditions. In this paper, a numerical model of typhoon waves in the Taiwan Strait is established based on the third-generation ocean wave model SWAN and then calculated by the wave energy empirical equation. Typhoon No. 200808 Fung-wong, strong typhoon No. 200815 Jangmi and strong typhoon No. 201808 Maria are used for verification and analysis. Finally, the results show that most concentrated wave energy values are more than 300 kW/m for typhoon and more than 900 kW/m for strong typhoons, over 60 times and 180 times the annual average (5 kW/m) in the Chinese sea area, respectively. In terms of other locations, corresponding values are more than 50 kW/m and over 100 kW/m. Therefore, typhoons’ wave energy is certainly a huge asset if fully utilized

    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

    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

    Centrality categorization for R_{p(d)+A} in high-energy collisions

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    High-energy proton- and deuteron-nucleus collisions provide an excellent tool for studying a wide array of physics effects, including modifications of parton distribution functions in nuclei, gluon saturation, and color neutralization and hadronization in a nuclear environment, among others. All of these effects are expected to have a significant dependence on the size of the nuclear target and the impact parameter of the collision, also known as the collision centrality. In this article, we detail a method for determining centrality classes in p(d)+A collisions via cuts on the multiplicity at backward rapidity (i.e., the nucleus-going direction) and for determining systematic uncertainties in this procedure. For d+Au collisions at sqrt(s_NN) = 200 GeV we find that the connection to geometry is confirmed by measuring the fraction of events in which a neutron from the deuteron does not interact with the nucleus. As an application, we consider the nuclear modification factors R_{p(d)+A}, for which there is a potential bias in the measured centrality dependent yields due to auto-correlations between the process of interest and the backward rapidity multiplicity. We determine the bias correction factor within this framework. This method is further tested using the HIJING Monte Carlo generator. We find that for d+Au collisions at sqrt(s_NN)=200 GeV, these bias corrections are small and vary by less than 5% (10%) up to p_T = 10 (20) GeV. In contrast, for p+Pb collisions at sqrt(s_NN) = 5.02 TeV we find these bias factors are an order of magnitude larger and strongly p_T dependent, likely due to the larger effect of multi-parton interactions.Comment: 375 authors, 18 pages, 16 figures, 4 tables. Submitted to Phys. Rev. C. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

    Azimuthal anisotropy of pi^0 and eta mesons in Au+Au collisions at sqrt(s_NN)=200 GeV

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    The azimuthal anisotropy coefficients v_2 and v_4 of pi^0 and eta mesons are measured in Au+Au collisions at sqrt(s_NN)=200 GeV, as a function of transverse momentum p_T (1-14 GeV/c) and centrality. The extracted v_2 coefficients are found to be consistent between the two meson species over the measured p_T range. The ratio of v_4/v_2^2 for pi^0 mesons is found to be independent of p_T for 1-9 GeV/c, implying a lack of sensitivity of the ratio to the change of underlying physics with p_T. Furthermore, the ratio of v_4/v_2^2 is systematically larger in central collisions, which may reflect the combined effects of fluctuations in the initial collision geometry and finite viscosity in the evolving medium.Comment: 384 authors, 71 institutions, 11 pages, 9 figures, and 2 tables. Submitted to Physical Review C. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm
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