295 research outputs found
Constraints on neutron skin thickness and nuclear deformations using relativistic heavy-ion collisions from STAR
In these proceedings, we present the measurements of neutron skin thickness
and nuclear deformation using isobar Ru+Ru and
Zr+Zr collisions at GeV by
the STAR detector. The significant deviations from unity of the isobar ratios
of elliptic flow , triangular flow , mean
fluctuations ,
and asymmetric cumulant indicate large differences in their
quadrupole and octuple deformations. The significant deviations of the isobar
ratios of produced hadron multiplicity , mean transverse momentum
, and net charge number 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
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 , the normalized
symmetric cumulants , and the Pearson correlation coefficients
in 2.76A TeV Pb--Pb collisions. We find is sensitive to both initial conditions and the specific shear viscosity
. A comparison with the recent ALICE data show that our hydrodynamic
calculations can qualitatively describe the data of and
for various initial conditions, which demonstrate that ,
are correlated and , are anti-correlated. Meanwhile, the
predicted symmetric cumulants , , and reveal that and , and are correlated, and
are anti-correlated in most centrality classes. We also find and , which are insensitive to , are
mainly determined by corresponding and
correlators from the initial
state. In contrast, other and
correlators are influenced by both initial conditions and , which
illustrates the non-linear mode couplings in higher flow harmonics with .Comment: 10 pages, 7 figure
Investigating the correlations of flow harmonics in 2.76A TeV Pb--Pb collisions
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
and the normalized symmetric cumulants , and
found and , and , and are
correlated, and , and are anti-correlated. We
also found 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
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
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
Infinite families of MDS and almost MDS codes from BCH codes
In this paper, the sufficient and necessary condition for the minimum
distance of the BCH codes over with length and designed
distance 3 to be 3 and 4 are provided. Let be the minimum distance of the
BCH code . We prove that (1) for any , if
and only if ; (2) for odd, if and only if
. By combining these conditions with the dimensions of these
codes, the parameters of this BCH code are determined completely when is
odd. Moreover, several infinite families of MDS and almost MDS (AMDS) codes are
shown. Furthermore, the sufficient conditions for these AMDS codes to be
distance-optimal and dimension-optimal locally repairable codes are presented.
Based on these conditions, several examples are also given
Constraining the HI-Halo Mass Relation From Galaxy Clustering
We study the dependence of galaxy clustering on atomic gas mass using a
sample of 16,000 galaxies with redshift in the range of
and HI mass of , drawn from the 70% complete sample
of the Arecibo Legacy Fast ALFA survey. We construct subsamples of galaxies
with 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 . For HI
mass thresholds below , 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
- …