scholarly journals Entropy production from stochastic dynamics in discrete full phase space

2012 ◽  
Vol 86 (2) ◽  
Author(s):  
Ian J. Ford ◽  
Richard E. Spinney
Keyword(s):  
Phase Space ◽  
Entropy Production ◽  
Stochastic Dynamics ◽  
Full Phase Space

scholarly journals Optimal Shadowing Filter for a Positioning and Tracking Methodology with Limited Information

Sensors ◽  
2019 ◽  
Vol 19 (4) ◽  
pp. 931 ◽  
Author(s):  
Ayham Zaitouny ◽  
Thomas Stemler ◽  
Shannon Algar
Keyword(s):  
Phase Space ◽  
Real Life ◽  
Positional Information ◽  
Irregular Sampling ◽  
Moving Target ◽  
Limited Information ◽  
Uncorrelated Noise ◽  
Full Phase Space

Positioning and tracking a moving target from limited positional information is a frequently-encountered problem. For given noisy observations of the target’s position, one wants to estimate the true trajectory and reconstruct the full phase space including velocity and acceleration. The shadowing filter offers a robust methodology to achieve such an estimation and reconstruction. Here, we highlight and validate important merits of this methodology for real-life applications. In particular, we explore the filter’s performance when dealing with correlated or uncorrelated noise, irregular sampling in time and how it can be optimised even when the true dynamics of the system are not known.

scholarly journals Leaves on trees: identifying halo stars with extreme gradient boosted trees

2018 ◽  
Vol 621 ◽  
pp. A13 ◽  
Author(s):  
Jovan Veljanoski ◽  
Amina Helmi ◽  
Maarten Breddels ◽  
Lorenzo Posti
Keyword(s):  
Phase Space ◽  
New Era ◽  
Massive Galaxies ◽  
Full Phase Space ◽  
Halo Stars ◽  
Machine Learning Model ◽  
Data Release ◽  
Stellar Halo ◽  
Red Giant ◽  
Galactic Astronomy

Context. Extended stellar haloes are a natural by-product of the hierarchical formation of massive galaxies like the Milky Way. If merging is a non-negligible factor in the growth of our Galaxy, evidence of such events should be encoded in its stellar halo. The reliable identification of genuine halo stars is a challenging task, however. Aims. With the advent of the Gaia space telescope, we are ushered into a new era of Galactic astronomy. The first Gaia data release contains the positions, parallaxes, and proper motions for over two million stars, mostly in the solar neighbourhood. The second Gaia data release will enlarge this sample to over 1.5 billion stars, the brightest ~ 5 million of which will have full phase-space information. Our aim for this paper is to develop a machine learning model for reliably identifying halo stars, even when their full phase-space information is not available. Methods. We use the Gradient Boosted Trees algorithm to build a supervised halo star classifier. The classifier is trained on a sample of stars extracted from the Gaia Universe Model Snapshot, which is also convolved with the errors of the public TGAS data, which is a subset of Gaia DR1, as well as with the expected uncertainties for the upcoming Gaia DR2 catalogue. We also trained our classifier on a dataset resulting from the cross-match between the TGAS and RAVE catalogues, where the halo stars are labelled in an entirely model-independent way. We then use this model to identify halo stars in TGAS. Results. When full phase-space information is available and for Gaia DR2-like uncertainties, our classifier is able to recover 90% of the halo stars with at most 30% distance errors, in a completely unseen test set and with negligible levels of contamination. When line-of-sight velocity is not available, we recover ~ 60% of such halo stars, with less than 10% contamination. When applied to the TGAS catalogue, our classifier detects 337 high confidence red giant branch halo stars. At first glance this number may seem small, however, it is consistent with the expectation from the models, given the uncertainties in the data. The large parallax errors are in fact the biggest limitation in our ability to identify a large number of halo stars in all the cases studied.

scholarly journals Charged-Particle Multiplicity Moments as Described by Shifted Gompertz Distribution in e+e−, pp¯, and pp Collisions at High Energies

2020 ◽  
Vol 2020 ◽  
pp. 1-24
Author(s):  
Aayushi Singla ◽  
M. Kaur
Keyword(s):  
Charged Particle ◽  
Phase Space ◽  
Center Of Mass ◽  
Particle Multiplicity ◽  
Charged Particle Multiplicity ◽  
Distribution Analysis ◽  
Factorial Moments ◽  
Hadronic Interactions ◽  
Gompertz Distribution ◽  
Full Phase Space

In continuation of our earlier work, in which we analysed the charged particle multiplicities in leptonic and hadronic interactions at different center-of-mass energies in full phase space as well as in restricted phase space using the shifted Gompertz distribution, a detailed analysis of the normalized moments and normalized factorial moments is reported here. A two-component model in which a probability distribution function is obtained from the superposition of two shifted Gompertz distributions, as introduced in our earlier work, has also been used for the analysis. This is the first analysis of the moments with the shifted Gompertz distribution. Analysis has also been performed to predict the moments of multiplicity distribution for the e+e− collisions at s=500 GeV at a future collider.

scholarly journals Entropy Analysis in Relativistic Heavy-Ion Collisions

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Shakeel Ahmad ◽  
A. Ahmad ◽  
Anuj Chandra ◽  
M. Zafar ◽  
M. Irfan
Keyword(s):  
Phase Space ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collisions ◽  
Strong Correlations ◽  
Entropy Analysis ◽  
Multiphase Transport ◽  
Long Range Correlations ◽  
Ion Collisions ◽  
Full Phase Space ◽  
Multiparticle System

Entropy creation in multiparticle system is investigated by analysing the experimental data on ion-ion collisions at AGS and SPS energies and the results thus obtained are compared with those predicted by multiphase transport and correlation-free Monte Carlo models. Entropies produced in limited- and full-phase space are observed to increase with increasing beam energy. The entropy values, normalized to the maximum rapidity and plotted against pseudorapidity (bin width also normalized to the maximum rapidity), are found to be energy independent, exhibiting a kind of entropy scaling. Such scaling is observed in the full phase space as well as in the regions confined to the forward or backward hemispheres. The findings also reveal that there exist strong correlations amongst the particles produced in the forward and backward hemispheres around the midrapidity. These correlations are found to be of short range in nature, and the contributions from the long-range correlations seem to be absent. PACS numbers: 25.75-q, 25.75.Gz.

scholarly journals Measurements of $${\Xi \left( 1530\right) ^{0}} $$ and $${\overline{\Xi }\left( 1530\right) ^{0}} $$ production in proton–proton interactions at $$\sqrt{s_{NN}}$$ = 17.3 $$\text{ GeV }$$ in the NA61/SHINE experiment

2021 ◽  
Vol 81 (10) ◽  
Author(s):  
A. Acharya ◽  
H. Adhikary ◽  
K. K. Allison ◽  
N. Amin ◽  
E. V. Andronov ◽  
...  
Keyword(s):  
Phase Space ◽  
Transverse Momentum ◽  
Statistical Model ◽  
Beam Momentum ◽  
Proton Proton ◽  
Model Calculations ◽  
Full Phase Space ◽  
Momentum Spectra ◽  
Transverse Momentum Spectra

AbstractDouble-differential yields of $${\Xi \left( 1530\right) ^{0}} $$ Ξ 1530 0 and $${\overline{\Xi }\left( 1530\right) ^{0}} $$ Ξ ¯ 1530 0 resonances produced in p+p interactions were measured at a laboratory beam momentum of 158 $$\text{ GeV }\!/\!c$$ GeV / c . This measurement is the first of its kind in p+p interactions below LHC energies. It was performed at the CERN SPS by the NA61/SHINE collaboration. Double-differential distributions in rapidity and transverse momentum were obtained from a sample of $$26\times 10^6$$ 26 × 10 6 inelastic events. The spectra are extrapolated to full phase space resulting in mean multiplicity of $${\Xi \left( 1530\right) ^{0}} $$ Ξ 1530 0 ($$6.73 \pm 0.25\pm 0.67)\times 10^{-4}$$ 6.73 ± 0.25 ± 0.67 ) × 10 - 4 and $${\overline{\Xi }\left( 1530\right) ^{0}} $$ Ξ ¯ 1530 0 ($$2.71 \pm 0.18\pm 0.18)\times 10^{-4}$$ 2.71 ± 0.18 ± 0.18 ) × 10 - 4 . The rapidity and transverse momentum spectra and mean multiplicities were compared to predictions of string-hadronic and statistical model calculations.

Sign in / Sign up

Export Citation Format

Share Document