Search results for "statistical"
showing 10 items of 4960 documents
Scaled factorial moments and split-bin correlation functions. A thermodynamic model comparison
1991
Abstract We compare the scaled factorial moments to the recently proposed split-bin correlation functions, using the thermodynamic model for heavy ion collisions that was recently demonstrated to exhibit power-law growth of the scaled factorial moments as a function of bin size. We find that the split-bin correlation functions are superior for experimental use, as they are intensitive to fictitious correlations due to limited resolving power. In addition, after correction for non-flat single-particle distributions, the split-bin correlation functions provide an unambiguous signal for correlations. As a result, they may provide more powerful evidence for new phenomena like fractal structure …
Monte Carlo estimation of transverse and longitudinal correlation functions in the model
2010
Abstract Monte Carlo simulations of the three-dimensional O ( 4 ) model in the ordered phase are performed to study the Goldstone mode effects. Our data show a distinct scaling region, where the Fourier-transformed transverse correlation function behaves as ∝ k − λ ⊥ with λ ⊥ 2 ( λ ≃ 1.95 ), in disagreement with the standard theoretical prediction λ ⊥ = 2 .
Longitudinal quantitative MRI assessment of cortical damage in multiple sclerosis: A pilot study
2017
PURPOSE Quantitative MRI (qMRI) allows assessing cortical pathology in multiple sclerosis (MS) on a microstructural level, where cortical damage has been shown to prolong T1 -relaxation time and increase proton density (PD) compared to controls. However, the evolution of these changes in MS over time has not been investigated so far. In this pilot study we used an advanced method for the longitudinal assessment of cortical tissue change in MS patients with qMRI in comparison to cortical atrophy, as derived from conventional MRI. MATERIALS AND METHODS Twelve patients with relapsing-remitting MS underwent 3T T1 /PD-mapping at two timepoints with a mean interval of 12 months. The respective co…
Wavelet analysis of baryon acoustic structures in the galaxy distribution
2011
Baryon Acoustic Oscillations (BAO) are a feature imprinted in the density field by acoustic waves travelling in the plasma of the early universe. Their fixed scale can be used as a standard ruler to study the geometry of the universe. BAO have been previously detected using correlation functions and power spectra of the galaxy distribution. In this work, we present a new method for the detection of the real-space structures associated with this feature. These baryon acoustic structures are spherical shells with a relatively small density contrast, surrounding high density central regions. We design a specific wavelet adapted to the search for shells, and exploit the physics of the process b…
Euclid preparation XV. Forecasting cosmological constraints for the Euclid and CMB joint analysis
2022
The combination and cross-correlation of the upcoming $Euclid$ data with cosmic microwave background (CMB) measurements is a source of great expectation since it will provide the largest lever arm of epochs, ranging from recombination to structure formation across the entire past light cone. In this work, we present forecasts for the joint analysis of $Euclid$ and CMB data on the cosmological parameters of the standard cosmological model and some of its extensions. This work expands and complements the recently published forecasts based on $Euclid$-specific probes, namely galaxy clustering, weak lensing, and their cross-correlation. With some assumptions on the specifications of current and…
The ALHAMBRA survey: Estimation of the clustering signal encoded in the cosmic variance
2015
[Aims]: The relative cosmic variance (σv) is a fundamental source of uncertainty in pencil-beam surveys and, as a particular case of count-in-cell statistics, can be used to estimate the bias between galaxies and their underlying dark-matter distribution. Our goal is to test the significance of the clustering information encoded in the σv measured in the ALHAMBRA survey. [Methods]: We measure the cosmic variance of several galaxy populations selected with B-band luminosity at 0.35 ≤ z< 1.05 as the intrinsic dispersion in the number density distribution derived from the 48 ALHAMBRA subfields. We compare the observational σv with the cosmic variance of the dark matter expected from the theory…
CMB spectral distortions in generic two-field models
2017
We investigate the CMB $\mu$ distortion in models where two uncorrelated sources contribute to primordial perturbations. We parameterise each source by an amplitude, tilt, running and running of the running. We perform a detailed analysis of the distribution signal as function of the model parameters, highlighting the differences compared to single-source models. As a specific example, we also investigate the mixed inflaton-curvaton scenario. We find that the $\mu$ distortion could efficiently break degeneracies of curvaton parameters especially when combined with future sensitivity of probing the tensor-to-scalar ratio $r$. For example, assuming bounds $\mu < 0.5 \times 10^{-8}$ and $r<0.0…
Morphostatistical characterization of the spatial galaxy distribution through Gibbs point processes
2021
This paper proposes a morpho-statistical characterisation of the galaxy distribution through spatial statistical modelling based on inhomogeneous Gibbs point processes. The galaxy distribution is supposed to exhibit two components. The first one is related to the major geometrical features exhibited by the observed galaxy field, here, its corresponding filamentary pattern. The second one is related to the interactions exhibited by the galaxies. Gibbs point processes are statistical models able to integrate these two aspects in a probability density, controlled by some parameters. Several such models are fitted to real observational data via the ABC Shadow algorithm. This algorithm provides …
A search for light dark matter in XENON10 data
2011
We report results of a search for light (3.5x10^{-42} cm^2, for a dark matter particle mass m_{\chi}=8 GeV. We find that our data strongly constrain recent elastic dark matter interpretations of excess low-energy events observed by CoGeNT and CRESST-II, as well as the DAMA annual modulation signal.
In the realm of the Hubble tension—a review of solutions
2021
The $\Lambda$CDM model provides a good fit to a large span of cosmological data but harbors areas of phenomenology. With the improvement of the number and the accuracy of observations, discrepancies among key cosmological parameters of the model have emerged. The most statistically significant tension is the $4-6\sigma$ disagreement between predictions of the Hubble constant $H_0$ by early time probes with $\Lambda$CDM model, and a number of late time, model-independent determinations of $H_0$ from local measurements of distances and redshifts. The high precision and consistency of the data at both ends present strong challenges to the possible solution space and demand a hypothesis with en…