280 research outputs found

    Constraints on neutron skin thickness and nuclear deformations using relativistic heavy-ion collisions from STAR

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    In these proceedings, we present the measurements of neutron skin thickness and nuclear deformation using isobar 4496^{96}_{44}Ru+4496^{96}_{44}Ru and 4096^{96}_{40}Zr+4096^{96}_{40}Zr collisions at sNN=200\sqrt{s_{_{\rm NN}}}=200 GeV by the STAR detector. The significant deviations from unity of the isobar ratios of elliptic flow v2v_{2}, triangular flow v3v_{3}, mean pTp_{\rm T} fluctuations δpT2/pT2\langle\delta p_{\rm T}^{2}\rangle/\langle p_{\rm T}\rangle^{2}, and asymmetric cumulant ac2{3}{\rm ac}_{2}\{3\} indicate large differences in their quadrupole and octuple deformations. The significant deviations of the isobar ratios of produced hadron multiplicity NchN_{\rm ch}, mean transverse momentum pT\langle p_{\rm T}\rangle, and net charge number ΔQ\Delta Q indicate a halo-type neutron skin for the Zr nucleus, much thicker than for the Ru nucleus, consistent with nuclear structure calculations. We discuss how we extract the neutron skin thickness, the symmetry energy slope parameter, and deformation parameters from data.Comment: Presented at Quark Matter 2022, Karkow, Poland, April 4-10, 202

    Correlations of flow harmonics in 2.76A TeV Pb--Pb collisions

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    Using the event-by-event viscous hydrodynamics VISH2+1 with MC-Glauber, MC-KLN, and AMPT initial conditions, we investigate the correlations of flow harmonics, including the symmetric cumulants SCv(m,n)SC^{v}(m, n), the normalized symmetric cumulants NSC(m,n)NSC(m, n), and the Pearson correlation coefficients C(vm2,vn2)C(v_{m}^{2}, v_{n}^{2}) in 2.76A TeV Pb--Pb collisions. We find SCv(m,n)SC^{v}(m, n) is sensitive to both initial conditions and the specific shear viscosity η/s\eta/s. A comparison with the recent ALICE data show that our hydrodynamic calculations can qualitatively describe the data of SCv(3,2)SC^{v}(3, 2) and SCv(4,2)SC^{v}(4, 2) for various initial conditions, which demonstrate that v2v_2, v4v_4 are correlated and v2v_2, v3v_3 are anti-correlated. Meanwhile, the predicted symmetric cumulants SCv(5,2)SC^{v}(5, 2), SCv(5,3)SC^{v}(5, 3), and SCv(4,3)SC^{v}(4, 3) reveal that v2v_2 and v5v_5, v3v_3 and v5v_5 are correlated, v3v_3 and v4v_4 are anti-correlated in most centrality classes. We also find NSCv(3,2)NSC^{v}(3, 2) and C(v32,v22)C(v_{3}^{2}, v_{2}^{2}), which are insensitive to η/s\eta/s, are mainly determined by corresponding NSCε(3,2)NSC^{\varepsilon}(3, 2) and C(ε32,ε22)C(\varepsilon_{3}^{2}, \varepsilon_{2}^{2}) correlators from the initial state. In contrast, other NSCv(m,n)NSC^{v}(m, n) and C(vm2,vn2)C(v_{m}^{2}, v_{n}^{2}) correlators are influenced by both initial conditions and η/s\eta/s, which illustrates the non-linear mode couplings in higher flow harmonics with n4n \geq 4.Comment: 10 pages, 7 figure

    Investigating the correlations of flow harmonics in 2.76A TeV Pb--Pb collisions

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    This proceeding briefly summarizes our recent investigations on the correlations of flow harmonics in 2.76A TeV Pb--Pb collisions with viscous hydrodynamics {\tt VISH2+1}. We calculated both the symmetric cumulants SCv(m,n)SC^{v}(m, n) and the normalized symmetric cumulants NSCv(m,n)NSC^{v}(m, n), and found v2v_{2} and v4v_{4}, v2v_{2} and v5v_{5}, v3v_{3} and v5v_{5} are correlated, v2v_{2} and v3v_{3}, v3v_{3} and v4v_{4} are anti-correlated. We also found NSCv(3,2)NSC^{v}(3, 2) are insensitive to the QGP viscosity, which are mainly determined by the initial conditions.Comment: SQM2016 proceeding, 4pages, 2 figure

    Intelligent optical performance monitor using multi-task learning based artificial neural network

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    An intelligent optical performance monitor using multi-task learning based artificial neural network (MTL-ANN) is designed for simultaneous OSNR monitoring and modulation format identification (MFI). Signals' amplitude histograms (AHs) after constant module algorithm are selected as the input features for MTL-ANN. The experimental results of 20-Gbaud NRZ-OOK, PAM4 and PAM8 signals demonstrate that MTL-ANN could achieve OSNR monitoring and MFI simultaneously with higher accuracy and stability compared with single-task learning based ANNs (STL-ANNs). The results show an MFI accuracy of 100% and OSNR monitoring root-mean-square error of 0.63 dB for the three modulation formats under consideration. Furthermore, the number of neuron needed for the single MTL-ANN is almost the half of STL-ANN, which enables reduced-complexity optical performance monitoring devices for real-time performance monitoring

    The Conditional Colour-Magnitude Distribution: I. A Comprehensive Model of the Colour-Magnitude-Halo Mass Distribution of Present-Day Galaxies

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    We formulate a model of the conditional colour-magnitude distribution (CCMD) to describe the distribution of galaxy luminosity and colour as a function of halo mass. It consists of two populations of different colour distributions, dubbed pseudo-blue and pseudo-red, respectively, with each further separated into central and satellite galaxies. We define a global parameterization of these four colour-magnitude distributions and their dependence on halo mass, and we infer parameter values by simultaneously fitting the space densities and auto-correlation functions of 79 galaxy samples from the Sloan Digital Sky Survey defined by fine bins in the colour-magnitude diagram (CMD). The model deprojects the overall galaxy CMD, revealing its tomograph along the halo mass direction. The bimodality of the colour distribution is driven by central galaxies at most luminosities, though at low luminosities it is driven by the difference between blue centrals and red satellites. For central galaxies, the two pseudo-colour components are distinct and orthogonal to each other in the CCMD: at fixed halo mass, pseudo-blue galaxies have a narrow luminosity range and broad colour range, while pseudo-red galaxies have a narrow colour range and broad luminosity range. For pseudo-blue centrals, luminosity correlates tightly with halo mass, while for pseudo-red galaxies colour correlates more tightly (redder galaxies in more massive haloes). The satellite fraction is higher for redder and for fainter galaxies, with colour a stronger indicator than luminosity. We discuss the implications of the results and further applications of the CCMD model.Comment: 32 pages, 26 figures, accepted for publication in MNRA

    Constraining the HI-Halo Mass Relation From Galaxy Clustering

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    We study the dependence of galaxy clustering on atomic gas mass using a sample of \sim16,000 galaxies with redshift in the range of 0.0025<z<0.050.0025<z<0.05 and HI mass of MHI>108MM_{\rm HI}>10^8M_{\odot}, drawn from the 70% complete sample of the Arecibo Legacy Fast ALFA survey. We construct subsamples of galaxies with MHIM_{\rm HI} above different thresholds, and make volume-limited clustering measurements in terms of three statistics: the projected two-point correlation function, the projected cross-correlation function with respect to a reference sample selected from the Sloan Digital Sky Survey, and the redshift-space monopole moment. In contrast to previous studies, which found no/weak HI-mass dependence, we find both the clustering amplitude on scales above a few Mpc and the bias factors to increase significantly with increasing HI mass for subsamples with HI mass thresholds above 109M10^9M_{\odot}. For HI mass thresholds below 109M10^9M_{\odot}, while the measurements have large uncertainties caused by the limited survey volume and sample size, the inferred galaxy bias factors are systematically lower than the minimum halo bias factor from mass-selected halo samples. The simple halo model, in which galaxy content is only determined by halo mass, has difficulties in interpreting the clustering measurements of the HI-selected samples. We extend the simple model by including the halo formation time as an additional parameter. A model that puts HI-rich galaxies into halos that formed late can reproduce the clustering measurements reasonably well. We present the implications of our best-fitting model on the correlation of HI mass with halo mass and formation time, as well as the halo occupation distributions and HI mass functions for central and satellite galaxies. These results are compared with the predictions from semi-analytic galaxy formation models and hydrodynamic galaxy formation simulations.Comment: Accepted for publication in ApJ. The 2PCF measurements are available at http://sdss4.shao.ac.cn/guoh

    Realistic Volume Rendering with Environment-Synced Illumination in Mixed Reality

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    Interactive volume visualization using a mixed reality (MR) system helps provide users with an intuitive spatial perception of volumetric data. Due to sophisticated requirements of user interaction and vision when using MR head-mounted display (HMD) devices, the conflict between the realisticness and efficiency of direct volume rendering (DVR) is yet to be resolved. In this paper, a new MR visualization framework that supports interactive realistic DVR is proposed. An efficient illumination estimation method is used to identify the high dynamic range (HDR) environment illumination captured using a panorama camera. To improve the visual quality of Monte Carlo-based DVR, a new spatio-temporal denoising algorithm is designed. Based on a reprojection strategy, it makes full use of temporal coherence between adjacent frames and spatial coherence between the two screens of an HMD to optimize MR rendering quality. Several MR development modules are also developed for related devices to efficiently and stably display the DVR results in an MR HMD. Experimental results demonstrate that our framework can better support immersive and intuitive user perception during MR viewing than existing MR solutions.Comment: 6 pages, 6 figure