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23,165 results on '"Zhang Chun"'

223. CFT approach to constraint operators for ($\beta$-deformed) hermitian one-matrix models

Author

Wang, Rui, Zhang, Chun-Hong, Zhang, Fu-Hao, and Zhao, Wei-Zhong

Subjects
High Energy Physics - Theory
Abstract

Since the ($\beta$-deformed) hermitian one-matrix models can be represented as the integrated conformal field theory (CFT) expectation values, we construct the operators in terms of the generators of the Heisenberg algebra such that the constraints can be derived by inserting the constructed operators into the integrated expectation values. We also obtain the second order total derivative operators associating with the derived constraint operators and analyze their properties. We explore the intrinsic connection between the derived constraint operators and $W$-representations of some matrix models. For the Gaussian hermitian one-matrix model in the external field and $\beta$-deformed $N\times N$ complex matrix model, we investigate the superintegrability and derive the corresponding character expansions from their $W$-representations. Moreover a conjectured formula for the averages of Jack polynomials in the literature is proved., Comment: 24 pages. Revised version accepted for publication in Nuclear Physics B

Published
2022
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224. Probing neutron-skin thickness with free spectator neutrons in ultracentral high-energy isobaric collisions

Author

Liu, Lu-Meng, Zhang, Chun-Jian, Zhou, Jia, Xu, Jun, Jia, Jiangyong, and Peng, Guang-Xiong

Subjects
Nuclear Theory, High Energy Physics - Experiment, Nuclear Experiment
Abstract

We show that the yield ratio of free spectator neutrons produced in high-energy $^{96}$Zr+$^{96}$Zr to $^{96}$Ru+$^{96}$Ru collisions is a clean probe of the neutron-skin thickness of colliding nuclei and the slope parameter $L$ of the symmetry energy. The idea is demonstrated based on the proton and neutron density distributions via a state-of-the-art Skyrme-Hartree-Fock-Bogolyubov calculation. Among spectator nucleons given by the Glauber model, free spectator neutrons include those from direct production that survive from clusterization as well as those from deexcitation of heavy clusters described by the popular GEMINI model. More free neutrons are produced in collisions of $^{96}$Zr nucleus due to its larger neutron skin, compared to those produced in collisions of $^{96}$Ru nucleus with a smaller neutron skin. The difference of the free spectator neutron yield is further increased with the increasing difference of the neutron-skin thickness between $^{96}$Zr and $^{96}$Ru with a larger $L$ value, and the increase in ultracentral collisions is particularly insensitive to model details and experimental uncertainties. Since the production of free spectator neutrons is not affected by the complicated dynamics in the mid-rapidity region, the ratio of their multiplicities in ultracentral isobaric collisions is a robust observable for constraining the neutron skin and $L$ value., Comment: 6 pages, 4 figures

Published
2022
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225. Viscous infuences on jetting process from an impacted concave free surface

Author

Cheng, Xiang-Gang, Chen, Xiao-Peng, Ding, Hang, Zhang, Chun-Yu, Guo, Jiao-Jiao, and Jia, Lai-Bing

Subjects
Physics - Fluid Dynamics
Abstract

A focused jet is generated from a concave free surface through an impact of a tube. Experimental and numerical studies were conducted to explore the viscous influences. The results show that a strong vorticity sheet is generated along the free surface just after impact, and the liquid bulk is initialized ($t\le$$10^{-4}$s). After the impact, the liquid surface evolves freely and a jet is ejected ($t\gg$$10^{-4}$s). Pronounced tangential flow is found, and the material in the jet mainly originates from the viscous penetrating layer below the free surface. According to the above observations, a vorticity mechanism of the free surface evolution is proposed. Further, by combining the viscous and interfacial tension effects, a scaling relation estimating the jetting velocity is derived, which agrees with the numerical and experimental results well. The work will be valuable for viscous droplets preparation., Comment: 13 pages, 7 figures

Published
2022

229. Machine Learning-Assisted Identification and Quantification of Hydroxylated Metabolites of Polychlorinated Biphenyls in Animal Samples

Author

Zhang, Chun-Yun, Li, Xueshu, Stietz, Kimberly P Keil, Sethi, Sunjay, Yang, Weizhu, Marek, Rachel F, Ding, Xinxin, Lein, Pamela J, Hornbuckle, Keri C, and Lehmler, Hans-Joachim

Subjects
Analytical Chemistry, Environmental Sciences, Pollution and Contamination, Chemical Sciences, Machine Learning and Artificial Intelligence, Animals, Gas Chromatography-Mass Spectrometry, Hydroxylation, Machine Learning, Mice, Polychlorinated Biphenyls, Tandem Mass Spectrometry, OH-PCBs, GC-MS/MS method, model prediction, relative retention time, relative response factor
Abstract

Laboratory studies of the disposition and toxicity of hydroxylated polychlorinated biphenyl (OH-PCB) metabolites are challenging because authentic analytical standards for most unknown OH-PCBs are not available. To assist with the characterization of these OH-PCBs (as methylated derivatives), we developed machine learning-based models with multiple linear regression (MLR) or random forest regression (RFR) to predict the relative retention times (RRT) and MS/MS responses of methoxylated (MeO-)PCBs on a gas chromatograph-tandem mass spectrometry system. The final MLR model estimated the retention times of MeO-PCBs with a mean absolute error of 0.55 min (n = 121). The similarity coefficients cos θ between the predicted (by RFR model) and experimental MS/MS data of MeO-PCBs were >0.95 for 92% of observations (n = 96). The levels of MeO-PCBs quantified with the predicted MS/MS response factors approximated the experimental values within a 2-fold difference for 85% of observations and 3-fold differences for all observations (n = 89). Subsequently, these model predictions were used to assist with the identification of OH-PCB 95 or OH-PCB 28 metabolites in mouse feces or liver by suggesting candidate ranking information for identifying the metabolite isomers. Thus, predicted retention and MS/MS response data can assist in identifying unknown OH-PCBs.

Published
2022

230. Improving the performance of twin-field quantum key distribution with advantage distillation technology

Author

Li, Hong-Wei, Wang, Rui-Qiang, Zhang, Chun-Mei, and Cai, Qing-Yu

Subjects
Quantum Physics
Abstract

In this work, we apply the advantage distillation method to improve the performance of a practical twin-field quantum key distribution system under collective attack. Compared with the previous analysis result given by Maeda, Sasaki and Koashi [Nature Communication 10, 3140 (2019)], the maximal transmission distance obtained by our analysis method will be increased from 420 km to 470 km. By increasing the loss-independent misalignment error to 12%, the previous analysis method can not overcome the rate-distance bound. However, our analysis method can still overcome the rate-distance bound when the misalignment error is 16%. More surprisingly, we prove that twin-field quantum key distribution can generate positive secure key even if the misalignment error is close to 50%, thus our analysis method can significantly improve the performance of a practical twin-field quantum key distribution system., Comment: accepted by Quantum

Published
2022
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