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4,942 results on '"Lu, Zhen"'

101. Observation of an isothermal glass transition in metallic glasses.

Author

Sun, Yi-Tao, Ding, Da-Wei, Lu, Zhen, Li, Mao-Zhi, Liu, Yan-Hui, and Wang, Wei-Hua

Abstract

Glass transition, commonly manifested upon cooling a liquid, is continuous and cooling rate dependent. For decades, the thermodynamic basis in liquid–glass transition has been at the center of debate. Here, long-time isothermal annealing was conducted via molecular dynamics simulations for metallic glasses to explore the connection of physical aging in supercooled liquid and glassy states. An anomalous two-step aging is observed in various metallic glasses, exhibiting features of supercooled liquid dynamics in the first step and glassy dynamics in the second step, respectively. Furthermore, the transition potential energy is independent of initial states, proving that it is intrinsic for a metallic glass at a given temperature. We propose that the observed dynamic transition from supercooled liquid dynamics to glassy dynamics could be glass transition manifested isothermally. On this basis, glass transition is no longer cooling rate dependent, but is shown as a clear phase boundary in the temperature-energy phase diagram. Hence, a modified out-of-equilibrium phase diagram is proposed, providing new insights into the nature of glass transition. [ABSTRACT FROM AUTHOR]

Published
2024
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103. Topological susceptibility, divergent chiral density and phase diagram of chirally imbalanced QCD medium at finite temperature

Author

Ruggieri, Marco, Chernodub, Maxim N., and Lu, Zhen-Yan

Subjects
High Energy Physics - Phenomenology, High Energy Physics - Lattice, High Energy Physics - Theory, Nuclear Theory
Abstract

We show that the nonlocal two-flavor Nambu--Jona-Lasinio model predicts the enhancement of both chiral and axial symmetry breaking as the chiral imbalance of hot QCD matter, regulated by a chiral chemical potential $\mu_5$, increases. The two crossovers are reasonably close to each other in the range of $\mu_5$ examined here and the pseudocritical temperatures rise with $\mu_5$. The curvatures of the chiral and axial crossovers for the chiral quark chemical potential approximately coincide and give $\kappa_5 \simeq - 0.011$. We point out that the presence of $\mu_5$ in thermodynamic equilibrium is inconsistent with the fact that the chiral charge is not a Noether-conserved quantity for massive fermions. The chiral chemical potential should not, therefore, be considered as a true chemical potential that sets a thermodynamically stable environment in the massive theory, but rather than as a new coupling that may require a renormalization in the ultraviolet domain. The divergence of an unrenormalized chiral density, \corr{coming from zero-point fermionic fluctuations,} is a consequence of this property. We propose a solution to this problem via a renormalization procedure., Comment: 15 pages, 5 figures

Published
2020
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104. QCD $\theta$-vacuum energy and axion properties

Author

Lu, Zhen-Yan, Du, Meng-Lin, Guo, Feng-Kun, Meißner, Ulf-G., and Vonk, Thomas

Subjects
High Energy Physics - Phenomenology, High Energy Physics - Experiment, High Energy Physics - Lattice
Abstract

At low energies, the strong interaction is governed by the Goldstone bosons associated with the spontaneous chiral symmetry breaking, which can be systematically described by chiral perturbation theory. In this paper, we apply this theory to study the $\theta$-vacuum energy density and hence the QCD axion potential up to next-to-leading order with $N$ non-degenerate quark masses. By setting $N=3$, we then derive the axion mass, self-coupling, topological susceptibility and the normalized fourth cumulant both analytically and numerically, taking the strong isospin breaking effects into account. In addition, the model-independent part of the axion-photon coupling, which is important for axion search experiments, is also extracted from the chiral Lagrangian supplemented with the anomalous terms up to $\mathcal{O}(p^6)$., Comment: 22 pages, 1 figure, 2 tables; Version to appear in JHEP

Published
2020
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105. Modeling pressure effects on the turbulent burning velocity for lean hydrogen/air premixed combustion

Author

Lu, Zhen and Yang, Yue

Subjects
Physics - Fluid Dynamics
Abstract

We investigate and model pressure effects on the turbulent burning velocity over a wide range of pressures and turbulence intensities with the direct numerical simulation (DNS) of statistically planar turbulent premixed flames for lean hydrogen/air mixture. DNS results indicate that the stretch factor has an impact on the turbulent burning velocity and flame surface area at elevated pressures. In particular, the enhanced stretch factor at high pressures increases the ratio of turbulent and laminar burning velocities, diminishing the "bending" effect. Based on a good consistency between turbulent and laminar burning velocities with respect to flame stretch, a lookup table formed by laminar flame data is employed to model the stretch factor in turbulent flames at various pressures. A predictive model for the turbulent burning velocity is then developed by combining sub models of the stretch factor and flame surface area. The overall good agreement between model predictions and DNS results demonstrates that the proposed model is able to quantitatively predict the turbulent burning velocity over a wide range of pressures and turbulent intensities in homogeneous isotropic turbulence.

Published
2019

112. Context-dependent neocentromere activity in synthetic yeast chromosome VIII

Author

Anne, Lajari, Barger, James S., Belkaya, Naz, Boulier, Kristin, Butler, Kirk, Callaghan, Melanie, Chang, Calvin, Chen, Janice, Chen, Xueni Jennifer, Cho, In Young, Choi, Elliot, Choi, Woo Jin, Chuang, James, Cook, Ashley L., Cooper, Eric, Culbertson, Nicholas Timothy, Dunn, Jessilyn, Floria, Charlotte, Grogan Anderson, Breeana, Held, Nathalie P., Hsiao, Emily, Igwe, Joseph-Kevin, Kang, Koeun, Karanxha, Joana, Kelly, Marie, Khakhar, Arjun, Khunsriraksakul, Chachrit, Kim, John J., Kim, Dong, Kim, Jin Wan, Lamb, Alex, Lee, David Sung Han, Lee, Yoon Kyung, Lim, Jongseuk, Liu, Steffi, Lopez, Jeremy, Lu, Zhen A., Ma, Henry, Mandel, Jordan A., Mao, Jessica, Matelsky, Jordan, Merran, Jonathan, Mohan, Rishikesh, Montoya, Christopher, Murugan, Sindurathy, Ni, Lisa, Oh, Won Chan, Park, Youngrok, Paulsen, Laura, Phillips, Nick, Pinglay, Sudarshan, Rajan, Vikram Aditya, Ransom, Garrett, Rhoads, Erin, Sanna, Praneeth, Scher, Emily, Shah, Jinesh, Sharma, Ashwyn, Shepardson, Maya C., Song, Joanne, Sontha, Sainikhil, Srinivas, Venkatesh, Tan, Scott, Tu, Ang A., Uhl, Skyler, Xiaoyue, Wang, Yu, Fangzhou, Yu, Justine, Zhu, Amadeus, Lauer, Stephanie, Luo, Jingchuan, Lazar-Stefanita, Luciana, Zhang, Weimin, McCulloch, Laura H., Fanfani, Viola, Lobzaev, Evgenii, Haase, Max A.B., Easo, Nicole, Zhao, Yu, Cai, Jitong, Bader, Joel S., Stracquadanio, Giovanni, and Boeke, Jef D.

Published
2023
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146. Thermodynamics and susceptibilities of isospin imbalanced QCD matter

Author

Lu, Zhen-Yan, Xia, Cheng-Jun, and Ruggieri, Marco

Subjects
High Energy Physics - Phenomenology
Abstract

We study the thermodynamics and the susceptibilities of quark matter in the framework of two-flavor Nambu-Jona-Lasinio model at finite isospin chemical potential and temperature. Isospin number density, normalized energy density and trace anomaly are shown to be in good agreement with the available lattice data as well as with the results from chiral perturbation theory at zero temperature. We also study how susceptibilities depend on the isospin chemical potential and on temperature. We find a peak for the chiral, pion, and isospin susceptibilities at the critical isospin chemical potential, $\mu_I^c(T)$, at the boundary of the phase transition between the normal and pion superfluid phase. Moreover, temperature makes the transition from normal to pion condended phase smoother. We also note that the pion susceptibility always remains zero in the normal phase while it is finite in the superfluid phase., Comment: 8 pages, 6 figures. updated to match EPJC version

Published
2019
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