316 research outputs found

    Testing for rational speculative bubbles in the Brazilian residential real-estate market

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    Speculative bubbles have been occurring periodically in local or global real estate markets and are considered a potential cause of economic crises. In this context, the detection of explosive behaviors in the financial market and the implementation of early warning diagnosis tests are of critical importance. The recent increase in Brazilian housing prices has risen concerns that the Brazilian economy may have a speculative housing bubble. In the present paper, we employ a recently proposed recursive unit root test in order to identify possible speculative bubbles in data from the Brazilian residential real-estate market. The empirical results show evidence for speculative price bubbles both in Rio de Janeiro and Sao Paulo, the two main Brazilian cities

    Evidence for Neutrinoless Double Beta Decay

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    The data of the Heidelberg-Moscow double beta decay experiment for the measuring period August 1990 - May 2000 (54.9813 kg y or 723.44 molyears), published recently, are analyzed using the potential of the Bayesian method for low counting rates. First evidence for neutrinoless double beta decay is observed giving first evidence for lepton number violation. The evidence for this decay mode is 97% (2.2\sigma) with the Bayesian method, and 99.8% c.l. (3.1\sigma) with the method recommended by the Particle Data Group. The half-life of the process is found with the Bayesian method to be T_{1/2}^{0\nu} = (0.8 - 18.3) x 10^{25} y (95% c.l.) with a best value of 1.5 x 10^{25} y. The deduced value of the effective neutrino mass is, with the nuclear matrix elements from [Sta90,Tom91] = (0.11 - 0.56) eV (95% c.l.), with a best value of 0.39 eV. Uncertainties in the nuclear matrix elements may widen the range given for the effective neutrino mass by at most a factor 2. Our observation which at the same time means evidence that the neutrino is a Majorana particle, will be of fundamental importance for neutrino physics. PACS. 14.69.Pq Neutrino mass and mixing; 23.40.Bw Weak-interaction and lepton (including neutrino) aspects 23.40.-s Beta decay; double beta decay; electron and muon capture.Comment: 14 pages, psfile, 7 figures, Published in Modern Physics Letters A, Vol. 16, No. 37 (2001) 2409-2420, World Scientific Publishing Company, Home Page: http://ejournals.wspc.com.sg/mpla/16/1637/S0217732301005825.html, Home Page of Heidelberg Non-Accelerator Particle Physics Group: http://www.mpi-hd.mpg.de/non_acc

    Transverse Enhancement Model and MiniBooNE Charge Current Quasi-Elastic Neutrino Scattering Data

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    Recently proposed Transverse Enhancement Model of nuclear effects in Charge Current Quasi-Elastic neutrino scattering [A. Bodek, H. S. Budd, and M. E. Christy, Eur. Phys. J. C{\bf 71} (2011) 1726] is confronted with the MiniBooNE high statistics experimental data. It is shown that the {\it effective} large axial mass model leads to better agreement with the data.Comment: 4 pages, 6 figure

    Kepler Presearch Data Conditioning II - A Bayesian Approach to Systematic Error Correction

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    With the unprecedented photometric precision of the Kepler Spacecraft, significant systematic and stochastic errors on transit signal levels are observable in the Kepler photometric data. These errors, which include discontinuities, outliers, systematic trends and other instrumental signatures, obscure astrophysical signals. The Presearch Data Conditioning (PDC) module of the Kepler data analysis pipeline tries to remove these errors while preserving planet transits and other astrophysically interesting signals. The completely new noise and stellar variability regime observed in Kepler data poses a significant problem to standard cotrending methods such as SYSREM and TFA. Variable stars are often of particular astrophysical interest so the preservation of their signals is of significant importance to the astrophysical community. We present a Bayesian Maximum A Posteriori (MAP) approach where a subset of highly correlated and quiet stars is used to generate a cotrending basis vector set which is in turn used to establish a range of "reasonable" robust fit parameters. These robust fit parameters are then used to generate a Bayesian Prior and a Bayesian Posterior Probability Distribution Function (PDF) which when maximized finds the best fit that simultaneously removes systematic effects while reducing the signal distortion and noise injection which commonly afflicts simple least-squares (LS) fitting. A numerical and empirical approach is taken where the Bayesian Prior PDFs are generated from fits to the light curve distributions themselves.Comment: 43 pages, 21 figures, Submitted for publication in PASP. Also see companion paper "Kepler Presearch Data Conditioning I - Architecture and Algorithms for Error Correction in Kepler Light Curves" by Martin C. Stumpe, et a

    Search for correlation between GRB's detected by BeppoSAX and gravitational wave detectors EXPLORER and NAUTILUS

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    Data obtained during five months of 2001 with the gravitational wave (GW) detectors EXPLORER and NAUTILUS were studied in correlation with the gamma ray burst data (GRB) obtained with the BeppoSAX satellite. During this period BeppoSAX was the only GRB satellite in operation, while EXPLORER and NAUTILUS were the only GW detectors in operation. No correlation between the GW data and the GRB bursts was found. The analysis, performed over 47 GRB's, excludes the presence of signals of amplitude h >=1.2 * 10^{-18}, with 95 % probability, if we allow a time delay between GW bursts and GRB within +-400 s, and h >= 6.5 * 10^{-19}, if the time delay is within +- 5 s. The result is also provided in form of scaled likelihood for unbiased interpretation and easier use for further analysis.Comment: 14 pages, 7 figures. Latex file, compiled with cernik.cls (provided in the package

    Shelf morphology as an indicator of sedimentary regimes: a synthesis from a mixed siliciclastic-carbonate shelf on the eastern Brazilian margin

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    Modern shelf morphology is the result of the interplay between short and long term sedimentary processes. The relation between rates of sediment supply/carbonate growth and accommodation space creation will not only control coastal transgression and regression, but will also define the shelf sedimentary regimes acting to shape the seabed. Herein, shelf morphology and sedimentology are investigated in order to discuss how these characteristics can be representative of distinct sedimentary regimes. The study area is the eastern Brazilian shelf where coastal transgression and regression coexist with the most important coral reef system of the South Atlantic. A compilation of existing published and unpublished data was carried out in order to produce morphological and faciological maps and compare the mapped features with high-resolution seismic and sonographic data. The results show three major regions or morphological compartments: Abrolhos Shelf, Doce River Shelf and the Paleovalleys Shelf. In terms of shelf sedimentary domain, rhodolith beds predominate over the outer shelf along the entire area, coralline reefs are present along the northern Abrolhos inner shelf and a significant terrigenous mud deposit is observed associated to the Doce River adjacent inner shelf beds. The rest of the shelf is composed by bioclastic or terrigenous mud sand and gravel. Terrigenous sedimentation is always restricted to the shoreface or inner shelf shallower areas and carbonate sands and gravels are predominant elsewhere. The Abrolhos shelf shows two distinct sectors; the northern area is a typical mixed sediment environment that has a supply regime along the coast/shoreface, mainly due to longshore transport and a carbonate regime along the inner and outer shelf. The southern shelf morphology and sedimentation are controlled by the antecedent topography and is typically a accommodation regime shelf with associated rhodolith beds. The Doce river shelf is a supply regime environment with the formation of a 5 to 8m thick regressive deposit with downlapping clinoforms. Southward from the Doce river shelf, a significant shift in sedimentary regime is observed as the morphology becomes very irregular with associated hardbottoms and unfilled paleovalleys. This sector of the shelf (Paleovalley shelf) is characterized by an accommodation regime. The interpretation shows that the entire study area can be defined as a mixed sedimentation shelf, showing supply and accommodation regimes. Shelf morphology worked as an indicator of these changes. Carbonate/terrigenous deposition during a highstand/regressive phase coeval along the eastern Brazilian shelf, either laterally and across shelf. This lateral/along coast variation in sediment supply and carbonate production leads to distinct lateral facies and geometry. These spatial changes in morphology and facies, with coexistence of carbonate and siliciclastic sedimentation, are very important for the correlation and interpretation of the geological record, especially stratigraphic surfaces and sequence units

    Precision measurement of the ηπ+ππ0\eta\to\pi^+\pi^-\pi^0 Dalitz plot distribution with the KLOE detector

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    Using 1.61.6 fb1^{-1} of e+eϕηγe^+ e^-\to\phi\to\eta\gamma data collected with the KLOE detector at DAΦ\PhiNE, the Dalitz plot distribution for the ηπ+ππ0\eta \to \pi^+ \pi^- \pi^0 decay is studied with the world's largest sample of 4.7106\sim 4.7 \cdot 10^6 events. The Dalitz plot density is parametrized as a polynomial expansion up to cubic terms in the normalized dimensionless variables XX and YY. The experiment is sensitive to all charge conjugation conserving terms of the expansion, including a gX2YgX^2Y term. The statistical uncertainty of all parameters is improved by a factor two with respect to earlier measurements.Comment: 11 pages, 9 figures, supplement: an ascii tabl

    Redshift Dependence of the CMB Temperature from S-Z Measurements

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    We have determined the CMB temperature, T(z)T(z), at redshifts in the range 0.023-0.546, from multi-frequency measurements of the S-Z effect towards 13 clusters. We extract the parameter α\alpha in the redshift scaling T(z)=T0(1+z)1αT(z)=T_{0}(1+z)^{1-\alpha}, which contrasts the prediction of the standard model (α=0\alpha=0) with that in non-adiabatic evolution conjectured in some alternative cosmological models. The statistical analysis is based on two main approaches: using ratios of the S-Z intensity change, ΔI\Delta I, thus taking advantage of the weak dependence of the ratios on IC gas properties, and using directly the ΔI\Delta I measurements. In the former method dependence on the Thomson optical depth and gas temperature is only second order in these quantities. In the second method we marginalize over these quantities which appear to first order in the intensity change. The marginalization itself is done in two ways - by direct integrations, and by a Monte Carlo Markov Chain approach. Employing these different methods we obtain two sets of results that are consistent with α=0\alpha=0, in agreement with the prediction of the standard model.Comment: Accepted for publication in Ap

    Model-Independent Bounds on a Light Higgs

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    We present up-to-date constraints on a generic Higgs parameter space. An accurate assessment of these exclusions must take into account statistical, and potentially signal, fluctuations in the data currently taken at the LHC. For this, we have constructed a straightforward statistical method for making full use of the data that is publicly available. We show that, using the expected and observed exclusions which are quoted for each search channel, we can fully reconstruct likelihood profiles under very reasonable and simple assumptions. Even working with this somewhat limited information, we show that our method is sufficiently accurate to warrant its study and advocate its use over more naive prescriptions. Using this method, we can begin to narrow in on the remaining viable parameter space for a Higgs-like scalar state, and to ascertain the nature of any hints of new physics---Higgs or otherwise---appearing in the data.Comment: 32 pages, 10 figures; v3: correction made to basis of four-derivative operators in the effective Lagrangian, references adde
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