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Yisong Zhang

Publications and source records attributed to Yisong Zhang.

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A Systematic Survey on Large Language Models for Evolutionary Optimization: From Modeling to Solving

Large language models (LLMs) are increasingly integrated with evolutionary computation to support optimization tasks. This survey primarily focuses on evolutionary optimization, i.e., optimization based on evolutionary computation. For brevity, we use the term optimization throughout to denote this scope. However, existing surveys typically examine isolated roles of LLMs and do not provide a unified view that connects optimization modeling with optimization solving. To address this gap, we systematically review recent developments through a workflow-oriented framework. First, we organize the literature into two primary stages: LLMs for optimization modeling and LLMs for optimization solving (in this survey, the terms optimization modeling and optimization solving are used as concise forms of optimization problem modeling and optimization problem solving, respectively). Second, we divide the solving stage into three paradigms according to the role of the LLM: stand-alone optimizers, low-level components embedded in optimization algorithms, and high-level managers for algorithm selection and generation. Third, we analyze representative methods, identify their technical limitations, and clarify their relationships with traditional optimization approaches. We further substantiate this taxonomy through benchmark systematization, baseline comparisons, and practitioner-oriented guidance, and we review interdisciplinary applications across the natural sciences, engineering, and machine learning. Based on the resulting analysis, we identify research directions toward dynamic, self-evolving, and agentic optimization ecosystems. An up-to-date collection of related literature is maintained at https://github.com/ishmael233/LLM4OPT.

cs.NE

Scalars at the Cosmological Collider: Full Shapes of Tree Diagrams and Bispectrum Searches using Planck Data

The Cosmological Collider (CC) provides a unique opportunity to probe the particle spectrum and fundamental interactions at extremely high energies. Massive particles, via their decay into inflaton quanta, can induce a non-analytic, oscillatory, primordial non-Gaussianity (NG), including the bispectrum. At tree level, three classes of such processes contribute to the bispectrum: 'single exchange', 'double exchange', and 'triple exchange', depending on the number of massive particle propagators. We provide a unified evaluation of all three diagrams and derive the explicit shape functions for the bispectrum, valid across the entire kinematic space. We perform a search for these three processes with the Planck data, finding no evidence for NG. We also consider simple extensions of the minimal scenario that can counter the exponential suppression of the non-analytic signature, and produce on-shell particles with masses $M\gg H$, the Hubble scale during inflation. In particular, we focus on the 'scalar chemical potential' mechanism and extend our previous search to a wider range of chemical potential ($ω$) and $M$, finding global 1.5$σ$ evidence for non-zero NG for the parameter space $ω- M \simeq 3H$.

hep-ph

Cosmological Collider Searches beyond the Hubble Scale with Planck Data

Searches for primordial non-Gaussianity (NG) has the potential to not only reveal the physics of cosmic inflation, but also the structure of fundamental interactions at the highest energies. The cosmological collider (CC) physics program exemplifies this possibility and demonstrates how searches for oscillatory NG can lead to mass-spin spectroscopy of extremely heavy states. Adopting an effective field theory approach, we find the class of Feynman diagrams that can give the largest NG mediated by a heavy scalar particle with mass $M\sim H$, the inflationary Hubble scale. We compute the full shape of the NG and perform the first search for this shape using Planck data, finding no evidence for NG. This search loses its sensitivity as $M\gg H$ since quantum vacuum fluctuations cannot efficiently produce such heavier particles. We then focus on a mechanism where a chemical potential excites on-shell scalar particles with mass $M\gg H$. Computing the full shapes, we perform the first CC search for particles parametrically heavier than $H$ using Planck data. For a range of chemical potential $ω$ and $M$ satisfying $ω-M \simeq 3H$, we find a global $1.7σ$ evidence for non-zero NG, after taking into account the look-elsewhere effect.

hep-ph

OCEL (Object-Centric Event Log) 2.0 Specification

Object-Centric Event Logs (OCELs) form the basis for Object-Centric Process Mining (OCPM). OCEL 1.0 was first released in 2020 and triggered the development of a range of OCPM techniques. OCEL 2.0 forms the new, more expressive standard, allowing for more extensive process analyses while remaining in an easily exchangeable format. In contrast to the first OCEL standard, it can depict changes in objects, provide information on object relationships, and qualify these relationships to other objects or specific events. Compared to XES, it is more expressive, less complicated, and better readable. OCEL 2.0 offers three exchange formats: a relational database (SQLite), XML, and JSON format. This OCEL 2.0 specification document provides an introduction to the standard, its metamodel, and its exchange formats, aimed at practitioners and researchers alike.

cs.DB

Giant adiabatic spin torque in magnetic tunnel junctions with a hybrid free layer structure

The discovery of spin torque transfer (STT) has lead to a significant advance in the development of spintronic devices. Novel structures and materials have been studied in order to improve the performance of the magnetic tunnel junctions (MTJs) performances and understand the fundamental physics in spin torque transfer. The adiabatic spin torque effect, which is due to the spatial non-uniformity of magnetic properties, has been predicted in theory and demonstrated experimentally in magnetic nanowires. However, this important spin torque has been rarely concerned in the magnetic tunnel junctions (MTJ) because of its extremely weak effect in conventional MTJs. This paper reports for the first time a giant adiabatic spin torque in MTJ devices with a hybrid free layer structure. The generation of the giant adiabatic spin torque was realized through the introduction of a spatial magnetic non-uniformity in a hybrid free layer along the current direction. It is observed that the giant adiabatic spin torque can substantially promote the current-induced switching process in the MTJ devices: the adiabatic spin torque can be larger than the in-plane spin torque, which allows for the switching with a single-polar current under different bias fields. Moreover, the adiabatic spin torque, which is proportional to the level of spatial non-uniformity, increases during the switching process. The observed effects are confirmed by numerical simulations. These results have far-reaching implications for the future of high-density STT-MRAM devices.

cond-mat.mes-hall