HOLISMOKES Cañameras, R.; Schuldt, S.; Shu, Y. ...
Astronomy and astrophysics (Berlin),
09/2021, Letnik:
653
Journal Article
Recenzirano
Odprti dostop
We have carried out a systematic search for galaxy-scale strong lenses in multiband imaging from the Hyper Suprime-Cam (HSC) survey. Our automated pipeline, based on realistic strong-lens ...simulations, deep neural network classification, and visual inspection, is aimed at efficiently selecting systems with wide image separations (Einstein radii θ E ∼ 1.0–3.0″), intermediate redshift lenses ( z ∼ 0.4–0.7), and bright arcs for galaxy evolution and cosmology. We classified gri images of all 62.5 million galaxies in HSC Wide with i -band Kron radius ≥0.8″ to avoid strict preselections and to prepare for the upcoming era of deep, wide-scale imaging surveys with Euclid and Rubin Observatory. We obtained 206 newly-discovered candidates classified as definite or probable lenses with either spatially-resolved multiple images or extended, distorted arcs. In addition, we found 88 high-quality candidates that were assigned lower confidence in previous HSC searches, and we recovered 173 known systems in the literature. These results demonstrate that, aided by limited human input, deep learning pipelines with false positive rates as low as ≃0.01% can be very powerful tools for identifying the rare strong lenses from large catalogs, and can also largely extend the samples found by traditional algorithms. We provide a ranked list of candidates for future spectroscopic confirmation.
We report measurements of the inclusive J/ψ yield and average transverse momentum as a function of charged-particle pseudorapidity density dNch/dη in p–Pb collisions at √sNN = 5.02 TeV with ALICE at ...the LHC. The observables are normalised to their corresponding averages in non-single diffractive events. An increase of the normalised J/ψ yield with normalised dNch/dη, measured at mid-rapidity, is observed at mid-rapidity and backward rapidity. At forward rapidity, a saturation of the relative yield is observed for high charged-particle multiplicities. The normalised average transverse momentum at forward and backward rapidities increases with multiplicity at low multiplicities and saturates beyond moderate multiplicities. In addition, the forward-to-backward nuclear modification factor ratio is also reported, showing an increasing suppression of J/ψ production at forward rapidity with respect to backward rapidity for increasing charged-particle multiplicity.
The invariant differential cross sections for inclusive
π
0
and
η
mesons at midrapidity were measured in pp collisions at
s
=
2.76
TeV for transverse momenta
0.4
<
p
T
<
40
GeV/
c
and
0.6
<
p
T
<
...20
GeV/
c
, respectively, using the ALICE detector. This large range in
p
T
was achieved by combining various analysis techniques and different triggers involving the electromagnetic calorimeter (EMCal). In particular, a new single-cluster, shower-shape based method was developed for the identification of high-
p
T
neutral pions, which exploits that the showers originating from their decay photons overlap in the EMCal. Above 4 GeV/
c
, the measured cross sections are found to exhibit a similar power-law behavior with an exponent of about 6.3. Next-to-leading-order perturbative QCD calculations differ from the measured cross sections by about 30% for the
π
0
, and between 30–50% for the
η
meson, while generator-level simulations with PYTHIA 8.2 describe the data to better than 10–30%, except at
p
T
<
1
GeV/
c
. The new data can therefore be used to further improve the theoretical description of
π
0
and
η
meson production.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We report measurements of the inclusive J/ψ yield and average transverse momentum as a function of charged-particle pseudorapidity density dNch/dη in p–Pb collisions at √sNN=5.02 TeVwith ALICE at the ...LHC. The observables are normalised to their corresponding averages in non-single diffractive events. An increase of the normalised J/ψ yield with normalised dNch/dη, measured at mid-rapidity, is observed at mid-rapidity and backward rapidity. At forward rapidity, a saturation of the relative yield is observed for high charged-particle multiplicities. The normalised average transverse momentum at forward and backward rapidities increases with multiplicity at low multiplicities and saturates beyond moderate multiplicities. In addition, the forward-to-backward nuclear modification factor ratio is also reported, showing an increasing suppression of J/ψ production at forward rapidity with respect to backward rapidity for increasing charged-particle multiplicity.
This letter presents the first measurement of jet mass in Pb–Pb and p–Pb collisions at √sNN=2.76TeV and √sNN=5.02TeV, respectively. Both the jet energy and the jet mass are expected to be sensitive ...to jet quenching in the hot Quantum Chromodynamics (QCD) matter created in nuclear collisions at collider energies. Jets are reconstructed from charged particles using the anti-kT jet algorithm and resolution parameter R =0.4. The jets are measured in the pseudorapidity range |ηjet| <0.5 and in three intervals of transverse momentum between 60 GeV/c and 120 GeV/c. The measurement of the jet mass in central Pb–Pb collisions is compared to the jet mass as measured in p–Pb reference collisions, to vacuum event generators, and to models including jet quenching. It is observed that the jet mass in central Pb–Pb collisions is consistent within uncertainties with p–Pb reference measurements. Furthermore, the measured jet mass in Pb–Pb collisions is not reproduced by the quenching models considered in this letter and is found to be consistent with PYTHIA expectations within systematic uncertainties.
We present the first ever measurements of femtoscopic correlations between the K0S and K± particles. The analysis was performed on the data from Pb–Pb collisions at √sNN=2.76TeV measured by the ALICE ...experiment. The observed femtoscopic correlations are consistent with final-state interactions proceeding via the a0(980) resonance. The extracted kaon source radius and correlation strength parameters for K0SK- are found to be equal within the experimental uncertainties to those for K0SK+. Comparing the results of the present study with those from published identical-kaon femtoscopic studies by ALICE, mass and coupling parameters for the a0 resonance are tested. Our results are also compatible with the interpretation of the a0 having a tetraquark structure instead of that of a diquark.
The second and the third order anisotropic flow, V2 and V3, are mostly determined by the corresponding initial spatial anisotropy coefficients, ε2 and ε3, in the initial density distribution. In ...addition to their dependence on the same order initial anisotropy coefficient, higher order anisotropic flow, Vn(n >3), can also have a significant contribution from lower order initial anisotropy coefficients, which leads to mode-coupling effects. In this Letter we investigate the linear and non-linear modes in higher order anisotropic flow Vn for n =4, 5, 6 with the ALICE detector at the Large Hadron Collider. The measurements are done for particles in the pseudorapidity range |η| <0.8 and the transverse momentum range 0.2 <pT<5.0GeV/c as a function of collision centrality. The results are compared with theoretical calculations and provide important constraints on the initial conditions, including initial spatial geometry and its fluctuations, as well as the ratio of the shear viscosity to entropy density of the produced system.
The production of muons from heavy-flavour hadron decays in p–Pb collisions at √s NN =5.02 TeV was studied for 2 < p T < 16 GeV/c with the ALICE detector at the CERN LHC. The measurement was ...performed at forward (p-going direction) and backward (Pb-going direction) rapidity, in the ranges of rapidity in the centre-of-mass system (cms) 2.03 < y cms < 3.53 and -4.46 < y cms < -2.96, respectively. The production cross sections and nuclear modification factors are presented as a function of transverse momentum (p T ). At forward rapidity, the nuclear modification factor is compatible with unity while at backward rapidity, in the interval 2.5 < p T < 3.5 GeV/c, it is above unity by more than 2σ. The ratio of the forward-to-backward production cross sections is also measured in the overlapping interval 2.96 < |y cms | < 3.53 and is smaller than unity by 3.7σ in 2.5 < p T < 3.5 GeV/c. The data are described by model calculations including cold nuclear matter effects.
We present the charged-particle multiplicity distributions over a wide pseudorapidity range (-3.4<η<5.0) for pp collisions at √s=0.9,7, and 8 TeV at the LHC. Results are based on information from the ...Silicon Pixel Detector and the Forward Multiplicity Detector of ALICE, extending the pseudorapidity coverage of the earlier publications and the high-multiplicity reach. The measurements are compared to results from the CMS experiment and to PYTHIA, PHOJET and EPOS LHC event generators, as well as IP-Glasma calculations.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The production cross sections for prompt charmed mesons D 0 , D + , D * + and Ds+ were measured at mid-rapidity in proton–proton collisions at a centre-of-mass energy s=7TeV with the ALICE detector ...at the Large Hadron Collider (LHC). D mesons were reconstructed from their decays D 0 → K - π + , D + → K - π + π + , D * + → D 0 π + , D$+\atop{s}$→K-K+π+, and their charge conjugates.With respect to previous measurements in the same rapidity region, the coverage in transverse momentum (p T ) is extended and the uncertainties are reduced by a factor of about two. The accuracy on the estimated total c$\bar{c}$ production cross section is likewise improved. The measured p T -differential cross sections are compared with the results of three perturbative QCD calculations.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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