Dimensionless ratios: characteristics of quantum liquids and their phase transitions

Dimensionless ratios of physical properties can characterize low-temperature phases in a wide variety of materials. As such, the Wilson ratio (WR), the Kadowaki-Woods ratio and the Wiedemann\--Franz law capture essential features of Fermi liquids in metals, heavy fermions, etc. Here we prove that the phases of many-body interacting multi-component quantum liquids in one dimension (1D) can be described by WRs based on the compressibility, susceptibility and specific heat associated with each component. These WRs arise due to additivity rules within subsystems reminiscent of the rules for multi-resistor networks in series and parallel --- a novel and useful characteristic of multi-component Tomonaga-Luttinger liquids (TLL) independent of microscopic details of the systems. Using experimentally realised multi-species cold atomic gases as examples, we prove that the Wilson ratios uniquely identify phases of TLL, while providing universal scaling relations at the boundaries between phases. Their values within a phase are solely determined by the stiffnesses and sound velocities of subsystems and identify the internal degrees of freedom of said phase such as its spin-degeneracy. This finding can be directly applied to a wide range of 1D many-body systems and reveals deep physical insights into recent experimental measurements of the universal thermodynamics in ultracold atoms and spins.Comment: 12 pages (main paper), (6 figures

Satellite Alignment: I. Distribution of Substructures and Their Dependence On Assembly History From N-Body Simulations

Observations have shown that the spatial distribution of satellite galaxies is not random, but aligned with the major axes of central galaxies. This alignment is dependent on galaxy properties, such that red satellites are more strongly aligned than blue satellites. Theoretical work done to interpret this phenomena has found that it is due to the non-spherical nature of dark matter halos. However, most studies over-predict the alignment signal under the assumption that the central galaxy shape follows the shape of the host halo. It is also not clear whether the color dependence of alignment is due to an assembly bias or an evolution effect. In this paper we study these problems using a cosmological N-body simulation. Subhalos are used to trace the positions of satellite galaxies. It is found that the shape of dark matter halos are mis-aligned at different radii. If the central galaxy shares the same shape as the inner host halo, then the alignment effect is weaker and agrees with observational data. However, it predicts almost no dependence of alignment on the color of satellite galaxies, though the late accreted subhalos show stronger alignment with the outer layer of the host halo than their early accreted counterparts. We find that this is due to the limitation of pure N-body simulations that satellites galaxies without associated subhalos ('orphan galaxies') are not resolved. These orphan (mostly red) satellites often reside in the inner region of host halos and should follow the shape of the host halo in the inner region.Comment: 12 pages, 11 figures, Published on Ap

The Distribution of Satellites Around Central Galaxies in a Cosmological Hydrodynamical Simulation

Observations have shown that the spatial distribution of satellite galaxies is not random, but rather is aligned with the major axes of central galaxies (CGs). The strength of the alignment is dependent on the properties of both the satellites and centrals. Theoretical studies using dissipationless N-body simulations are limited by their inability to directly predict the shape of CGs. Using hydrodynamical simulations including gas cooling, star formation, and feedback, we carry out a study of galaxy alignment and its dependence on the galaxy properties predicted directly from the simulations.We found that the observed alignment signal is well produced, as is the color dependence: red satellites and red centrals both show stronger alignments than their blue counterparts. The reason for the stronger alignment of red satellites is that most of them stay in the inner region of the dark matter halo where the shape of the CG better traces the dark matter distribution. The dependence of alignment on the color of CGs arises from the halo mass dependence, since the alignment between the shape of the central stellar component and the inner halo increases with halo mass. We also find that the alignment of satellites is most strongly dependent on their metallicity, suggesting that the metallicity of satellites, rather than color, is a better tracer of galaxy alignment on small scales. This could be tested in future observational studies.Comment: ApJ Letter, accepted. Four figures, no table. The resolution of Fig 1 was downgraded due to the limitation of file size. Updated to match the version in pres

Continuation Path Learning for Homotopy Optimization

Homotopy optimization is a traditional method to deal with a complicated optimization problem by solving a sequence of easy-to-hard surrogate subproblems. However, this method can be very sensitive to the continuation schedule design and might lead to a suboptimal solution to the original problem. In addition, the intermediate solutions, often ignored by classic homotopy optimization, could be useful for many real-world applications. In this work, we propose a novel model-based approach to learn the whole continuation path for homotopy optimization, which contains infinite intermediate solutions for any surrogate subproblems. Rather than the classic unidirectional easy-to-hard optimization, our method can simultaneously optimize the original problem and all surrogate subproblems in a collaborative manner. The proposed model also supports real-time generation of any intermediate solution, which could be desirable for many applications. Experimental studies on different problems show that our proposed method can significantly improve the performance of homotopy optimization and provide extra helpful information to support better decision-making.Comment: Accepted by the 40th International Conference on Machine Learning (ICML 2023

The Power of Unrequited Love: The Parasocial Relationship, Trust, and Organizational Identification Between Middle-Level Managers and CEOs

Previous studies have found that CEOs manage their firms through traditional methods such as leadership and management practices. In this study, we investigate how the parasocial relationship (PSR) between middle-level managers and CEOs affects the organizational trust and the organizational identification (OI) of middle managers. We find that the PSR between middle managers and CEOs has a positive effect on the OI of middle managers, which is mediated by the organizational trust of middle managers. Purpose: Middle managers and CEOs are the key components of a firm and are crucial to firm strategies and control systems. Middle managers play a vital role in information transmission like in the organizational hierarchy while CEOs influence low-level employees through middle managers. In this study, we investigate how the PSR between middle managers and CEOs affects organizational trust and OI. Design/Methodology: In this study, the data concerning OI, integrity perception, and organizational trust are derived from a survey conducted by the internal control research group of the China Securities Regulatory Commission (CSRC). The research group began the survey on September 5, 2014, for the firms listed in the A-share market, accounting firms with securities and future practice qualifications, and institutional investors through the accounting department of the CSRC, the Shanghai Stock Exchange, the Shenzhen Stock Exchange, and the Asset Management Association of China. The research group members surveyed 2,536 A-share firms listed on the Shanghai Stock Exchange and Shenzhen Stock Exchange. As of October 31, 2014, 2,154 sets of questionnaires with a total of 12,551 questionnaires were received, with a response rate of 84.95%. The financial and accounting data are from the China Stock Market and Accounting Research (CSMAR) database. Findings: We find that the PSR between middle managers and CEOs has a positive effect on the OI of middle managers, which is mediated by the organizational trust of middle managers. This study extends the application of the parasocial interaction (PSI) theory, organizational trust theory, and social identity theory in listed firms. Practical Implication: There are practical implications for internal relationship management, corporate governance, and performance management. CEOs should value the influence of organizational trust and improve his/her own social and work abilities on middle-level managers as the organizational trust of middle-level managers has a significant positive impact on their sense of responsibility, ethical behavior, organizational commitment, job satisfaction, and performance. CEOs should adopt various methods to influence different managers because organizational trust mediates the relationship between the PSR and OI. Originality/Value: Our study is one of the first attempts to apply the PSI theory to the corporate world. Given the dynamics of present-day markets and changing stakeholder demands, there is little insight into how this relationship affects organizational health and functioning. Much less what a PSR between CEO and middle management looks like in practice. Our study attempts to fill the gap by investigating how CEOs might come to affect middle managers through their practices and behaviors