arXiv subjects

Zhi-Wei Liu

Publications and source records attributed to Zhi-Wei Liu.

At least 37 records · Page 2Linked to original sources

arXiv2025

Energy-Workload Coupled Migration Optimization Strategy for Virtual Power Plants with Data Centers Considering Fuzzy Chance Constraints

This paper proposes an energy-workload coupled migration optimization strategy for virtual power plants (VPPs) with data centers (DCs) to enhance resource scheduling flexibility and achieve precise demand response (DR) curve tracking. A game-based coupled migration framework characterized by antisymmetric matrices is first established to facilitate the coordination of cross-regional resource allocation between VPPs. To address the challenge posed to conventional probabilistic modeling by the inherent data sparsity of DC workloads, deterministic equivalent transformations of fuzzy chance constraints are derived based on fuzzy set theory, and non-convex stochastic problems are transformed into a solvable second-order cone program. To address the multi-player interest coordination problem in cooperative games, an improved Shapley value profit allocation method with the VPP operator as intermediary is proposed to achieve a balance between theoretical fairness and computational feasibility. In addition, the alternating direction method of multipliers with consensus-based variable splitting is introduced to solve the high-dimensional non-convex optimization problem, transforming coupled antisymmetric constraints into separable subproblems with analytical solutions. Simulations based on real data from Google's multiple DCs demonstrate the effectiveness of the proposed method in improving DR curve tracking precision and reducing operational costs.

eess.SY↗

arXiv2025

Femtoscopy can tell whether $Z_c(3900)$ and $Z_{cs}(3985)$ are resonances or virtual states

There have been extended and heated discussions on the nature of the two exotic states, $Z_c(3900)$ and $Z_{cs}(3985)$, particularly whether they are near-threshold resonances, virtual states, or bound states. In this work, we demonstrate for the first time that the femtoscopic technique can be employed to distinguish between these three scenarios. More concretely, based on the Koonin-Pratt formula with a Gaussian source, we show that the low-momentum $D^0D^{*-}$/$D^0D_s^{*-}$ correlation functions significantly differ in the three scenarios. The high-momentum results exhibit distinct characteristics in the resonant and virtual state scenarios, especially in small collision systems of 1 fm, as produced in $pp$ collisions at the LHC. We hope that these discoveries will stimulate further experimental studies and help clarify the nature of the many exotic states that have been discovered.

hep-ph↗

arXiv2025

Hypernuclear structure with the new leading order covariant chiral hyperon-nucleon force

We have studied single-$Λ$ finite hypernuclear systems spanning from light to heavy masses, employing a new microscopic Lambda-N interaction derived from in-medium interactions within relativistic Brueckner-Hartree-Fock calculations using the leading-order covariant chiral hyperon-nucleon force. Without any adjustable parameters, we have successfully reproduced the experimental results for the single-Lambda binding energies. Although some discrepancies persist in light hypernuclei, the overall calculated binding energies show excellent agreement with the experimental data, and outperforming other microscopic interactions. This study further demonstrates the validity of the leading-order covariant chiral hyperon-nucleon potential and provides a practical set of microscopic interactions for the Skyrme-Hartree-Fock framework.

nucl-th↗

arXiv2025

Charmonium-nucleon femtoscopic correlation function

This study investigates the femtoscopic correlation functions of charmonium-nucleon pairs, utilizing the lattice QCD phase shifts provided by the HAL QCD Collaboration. A ``model-independent'' formalism is employed to transform scattering phase shifts directly into momentum correlation functions, thereby circumventing the approximations inherent in traditional methods, such as the Lednický-Lyuboshits model. The $J/ψ$-$p$ correlation functions, including spin-averaged and partial-wave results, are predicted using near-physical pion mass lattice results. The $η_c$-$p$ correlation function is calculated for the first time. The derived correlation functions provide critical references for future experiments, such as those at the LHC, where high-precision measurements of charmonium-nucleon correlations could unveil valuable insights into non-perturbative QCD dynamics.

hep-ph↗

arXiv2025

Deuteron-Deuteron Interaction and Correlation Function

The interaction between deuterons ($d$-$d$) is pivotal for understanding the characteristics of certain light nuclei from the perspective of the deuteron cluster and achieving a precise reproduction of $d$-$d$ fusion cross sections. In this work, we construct a new set of elastic $d$-$d$ interactions by fitting the phase shifts using potentials parameterized in a Woods-Saxon shape. Then, the correlation functions are calculated with the obtained potential and compared with the recent measurements by the STAR collaboration. We find that the $d$-$d$ phase shifts and the correlation functions are internally consistent, confirming that correlation functions can provide cross-check for the $d$-$d$ interaction. In addition, both the $^1S_0$ bound state and the repulsive $^5S_2$ interaction contribute to the observed suppression in the measured correlation function. Moreover, we demonstrate that the $P$-wave contribution of the correlation functions cannot be neglected, especially in determining the source size.

nucl-th↗

arXiv2025

Perspectives for hyperon and hypernuclei physics

Hypernuclei, nuclei containing one or more hyperons, serve as unique laboratories for probing the non-perturbative quantum chromodynamics (QCD). Recent progress in hypernuclear physics, driven by advanced experimental techniques and theoretical innovations, is briefly reviewed with a focus on key findings and unresolved challenges, such as the precise determination of the hypertriton binding energy, investigations of charge symmetry breaking in mirror hypernuclei, and the search for exotic systems, including the neutral nn$Λ$ state. Experimental breakthroughs, including invariant-mass analyses and femtoscopy studies in heavy-ion collisions, as well as high-resolution $γ$-spectroscopy, have enabled precise studies of light hypernuclei and offered critical insights into the hyperon-nucleon interaction. Theoretical progress, including ab initio calculations based on chiral effective field theory and lattice QCD, has further enhanced our understanding of hyperon-nucleon and hyperon-hyperon interactions.

nucl-th↗

arXiv2025

In-medium $ΛN$ interactions with leading order covariant chiral hyperon/nucleon-nucleon forces

In-medium $ΛN$ interactions are crucial in hypernuclei and neutron star physics. In this work, we study the in-medium $ΛN$ interaction within the relativistic Brueckner-Hartree-Fock (RBHF) framework, employing the leading-order covariant chiral hyperon/nucleon-nucleon forces for the first time. We demonstrate that a consistent description of both the experimental cross-section data and the `empirical value' of the $Λ$ single-particle potential can be achieved. This contrasts with the majority of studies in the non-relativistic framework, where higher-order two-body chiral forces are typically required. This study offers a new perspective on the in-medium $ΛN$ interactions, urgently needed in relativistic \textit{ab initio} hypernuclear physics studies.

nucl-th↗

arXiv2025

Relativistic chiral nuclear forces: status and prospects

Understanding nuclear structure, reactions, and the properties of neutron stars from \textit{ab initio} calculations from the nucleon degrees of freedom has always been a primary goal of nuclear physics, in which the microscopic nuclear force serves as the fundamental input. So far, the Weinberg chiral nuclear force, first proposed by the Nobel laureate Weinberg, has become the \textit{de facto} standard input for nuclear \textit{ab initio} studies. However, compared to their non-relativistic counterparts, relativistic \textit{ab initio} calculations, which describe better nuclear observables, have only begun. The lack of modern relativistic nucleon-nucleon interactions is an important issue restricting their development. In this work, we briefly review the development and status of the Weinberg chiral nuclear force, as well as its limitations. We further present a concise introduction to the relativistic chiral nuclear force, show its description of the scattering phase shifts and observables such as differential cross sections, and demonstrate its unique features. Additionally, we show that the relativistic framework could be naturally extended to the antinucleon-nucleon interaction.

nucl-th↗

arXiv2024

Three ways to decipher the nature of exotic hadrons: multiplets, three-body hadronic molecules, and correlation functions

In the past two decades, a plethora of hadronic states beyond the conventional quark model of $q\bar{q}$ mesons and $qqq$ baryons have been observed experimentally, which motivated extensive studies to understand their nature and the non-perturbative strong interaction. Since most of these exotic states are near the mass thresholds of a pair of conventional hadrons, the prevailing picture is that they are primarily hadronic molecules. In principle, one can verify the molecular nature of these states by thoroughly comparing their masses, decay widths, and production rates in a particular picture with experimental data. However, this is difficult or impossible. First, quantum mechanics allows for the mixing of configurations allowed by symmetries and quantum numbers. Second, data are relatively scarce because of their small production rates and the many difficulties in the experimental measurements. As a result, other alternatives need to be explored. This review summarizes three such approaches that can help disentangle the nature of the many exotic hadrons discovered. In the first approach, based on the molecular interpretations for some exotic states, we study the likely existence of multiplets of hadronic molecules related by various symmetries, such as isospin symmetry, SU(3)-flavor symmetry, heavy quark spin/flavor symmetry, and heavy antiquark diquark symmetry. In the second approach, starting from some hadronic molecular candidates, one can derive the underlying hadron-hadron interactions. With these interactions, one can study related three-body systems and check whether three-body bound states/resonances exist. In the third approach, one can turn to the femtoscopy technique to derive the hadron-hadron interactions, hence inaccessible. This technique provided an unprecedented opportunity to understand the interactions between unstable hadrons.

hep-ph↗

arXiv2024

Online Actuator Selection and Controller Design for Linear Quadratic Regulation with Unknown System Model

We study the simultaneous actuator selection and controller design problem for linear quadratic regulation with Gaussian noise over a finite horizon of length $T$ and unknown system model. We consider both episodic and non-episodic settings of the problem and propose online algorithms that specify both the sets of actuators to be utilized under a cardinality constraint and the controls corresponding to the sets of selected actuators. In the episodic setting, the interaction with the system breaks into $N$ episodes, each of which restarts from a given initial condition and has length $T$. In the non-episodic setting, the interaction goes on continuously. Our online algorithms leverage a multiarmed bandit algorithm to select the sets of actuators and a certainty equivalence approach to design the corresponding controls. We show that our online algorithms yield $\sqrt{N}$-regret for the episodic setting and $T^{2/3}$-regret for the non-episodic setting. We extend our algorithm design and analysis to show scalability with respect to both the total number of candidate actuators and the cardinality constraint. We numerically validate our theoretical results.

math.OC↗

arXiv2024

Implication of a negative effective range on the $D\bar{D}^*$ interaction and the nature of $X(3872)$

A recent analysis of the LHCb data [Phys. Rev. D 105 (2022) L031503] obtained a sizable negative effective range for the $X(3872)$. This has attracted intensive discussions on whether $X(3872)$ can be deemed as a $D\bar{D}^*$ molecular state. This work explicitly demonstrates that the negative effective range of the $X(3872)$ does not contradict the molecular picture, adopting an effective field theory formulation of the $D\bar{D}^*$ interaction that can simultaneously reproduce the binding energy and effective range of the $X(3872)$. We elaborate on the implications of the large negative effective range of $X(3872)$ and the small binding energy on the underlying $D\bar{D}^*$ interaction. Such results are relevant for a better understanding of hadronic molecules and their binding mechanism.

hep-ph↗

arXiv2024

Online Mixed Discrete and Continuous Optimization: Algorithms, Regret Analysis and Applications

We study an online mixed discrete and continuous optimization problem where a decision maker interacts with an unknown environment for a number of $T$ rounds. At each round, the decision maker needs to first jointly choose a discrete and a continuous actions and then receives a reward associated with the chosen actions. The goal for the decision maker is to maximize the accumulative reward after $T$ rounds. We propose algorithms to solve the online mixed discrete and continuous optimization problem and prove that the algorithms yield sublinear regret in $T$. We show that a wide range of applications in practice fit into the framework of the online mixed discrete and continuous optimization problem, and apply the proposed algorithms to solve these applications with regret guarantees. We validate our theoretical results with numerical experiments.

math.OC↗

arXiv2024

Likely existence of bound states and the Efimov effect in the triple-$J/ψ$ system

The ground-breaking discovery of the first fully charmed tetraquark state $X(6900)$ in the $J/ψJ/ψ$ invariant mass distribution by the LHCb collaboration has inspired intensive theoretical studies. Various interpretations, such as molecular states, compact tetraquark states, and coupled-channel effects, have been proposed for these states. Of particular interest is the ongoing search for the triple-$J/ψ$ state--a fully-charmed hexaquark state. To deepen our understanding of the triple-$J/ψ$ state and to guide future experimental searches, we study the triple-$J/ψ$ system in this work employing the Gaussian expansion method and the $J/ψJ/ψ$ potential parameterized to yield a shallow bound state, as suggested in several theoretical works. Our results support a triple-$J/ψ$ bound state, even in cases where the attractive interaction between the two $J/ψ$ mesons is very weak. Moreover, our analysis implies the Efimov effect in the triple-$J/ψ$ system. In addition, we extend our investigation to the triple-$Υ(1S)$ system and obtain results similar to those for the triple-$J/ψ$ system.

hep-ph↗

arXiv2023

Correlation function for the $a_0(980)$

We have conducted a model independent analysis of the $K^+ \bar{K}^0$ pair correlation function obtained from ultra high energy $pp$ collisions, with the aim of extracting the information encoded in it related to the $K\bar{K}$ interaction and the coupled channel $π^+ η$. With the present large errors at small relative $K^+\bar{K}^0$ momenta, we find that the information obtained about the scattering matrix suffers from large uncertainties. Even then, we are able to show that the data imply the existence of the $a_0$ resonance, $a_0(980)$, showing as a strong cusp close to the $K\bar{K}$ threshold. We also mention that the measurement of the $π^+ η$ correlation function will be essential in order to constrain more the information on $K\bar{K}$ dynamics that can be obtained from correlation functions.

hep-ph↗

arXiv2023

Distinguishing the spins of $P_c(4440)$ and $P_c(4457)$ with femtoscopic correlation functions

The spins of the pentaquark states $P_c(4440)$ and $P_c(4457)$ play a decisive role in unraveling their nature, but remain undetermined experimentally. Assuming that they are $Σ_c\bar{D}^{*}$ bound states, we demonstrate how one can determine their spins by measuring the $Σ_c^+\bar{D}^{(*)0}$ correlation functions. We show that one can use the $Σ_c^+\bar{D}^0$ correlation function to fix the size of the Gaussian source and then determine the strength of the $Σ_c^+\bar{D}^{*0}$ interaction of spin $1/2$ and $3/2$ and therefore the spins of the $P_c(4440)$ and $P_c(4457)$ states. The method proposed can be applied to decipher the nature of other hadronic molecules and thus deepen our understanding of the nonperturbative strong interaction.

hep-ph↗

arXiv2023

Maximization of Nonsubmodular Functions under Multiple Constraints with Applications

We consider the problem of maximizing a monotone nondecreasing set function under multiple constraints, where the constraints are also characterized by monotone nondecreasing set functions. We propose two greedy algorithms to solve the problem with provable approximation guarantees. The first algorithm exploits the structure of a special class of the general problem instance to obtain a better time complexity. The second algorithm is suitable for the general problem. We characterize the approximation guarantees of the two algorithms, leveraging the notions of submodularity ratio and curvature introduced for set functions. We then discuss particular applications of the general problem formulation to problems that have been considered in the literature. We validate our theoretical results using numerical examples.

math.OC↗

arXiv2023

Study of the $DK$ interaction with femtoscopic correlation functions

The $DK$ interaction in isospin zero is known to be attractive to such an extent that a bound state can be generated, which can be associated with the mysterious $D_{s0}^*(2317)$. In this work, we calculate the $DK$ femtoscopic correlation function in the coupled-channel framework for different source sizes that can directly probe the strongly attractive $DK$ interaction, which is otherwise inaccessible due to the unstable nature of $D$ and $K$ mesons, and therefore can help elucidate the nature of $D_{s0}^*(2317)$. We further generalize the study of source size dependence to various interactions, ranging from repulsive, weakly attractive, moderately attractive, and strongly attractive, in a square-well model. We hope that our study can motivate future experimental measurements of the $DK$ correlation function and other interactions relevant to the understanding of the nature of the many exotic hadrons discovered so far.

hep-ph↗

arXiv2023

Byzantine-Resilient Multi-Agent Distributed Exact Optimization with Less Data

This paper studies the distributed multi-agent resilient optimization problem under the f-total Byzantine attacks. Compared with the previous work on Byzantineresilient multi-agent exact optimization problems, we do not require the communication topology to be fully connected. Under the redundancy of cost functions, we propose the distributed comparative gradient elimination resilient optimization algorithm based on the traditional assumptions on strongly convex global costs and Lipschitz continuous gradients. Under this algorithm, we successfully prove that if the number of inneighbors of each normal agent is greater than some constant and the parameter f satisfies certain conditions, all normal agents' local estimations of the global variable will finally reach consensus and converge to the optimized solution. Finally, the numerical experiments successfully verify the correctness of the results.

math.OC↗