arXiv subjects

Ji-Chong Yang

Publications and source records attributed to Ji-Chong Yang.

At least 19 recordsLinked to original sources

arXiv2026

Probing Neutral Triple Gauge Couplings at e- p colliders

The Standard Model Effective Field Theory~(SMEFT) has attracted much attention as a model-independent way for probing new physical signals. In the SMEFT framework, $e^{-}p$ colliders can be used to study new interactions of gauge bosons, such as neutral Triple Gauge Couplings~(nTGCs). We study the signals and backgrounds of six different processes at the Future Circular Collider-hadron electron~(FCC-he) and propose different event selection strategies. The expected constraints on the coefficients of the dimension-8 operators for each process, as well as the combined constraints are obtained. The results show that the sensitivity of $e^{-}p$ colliders to nTGCs is similar to the current Large Hadron Collider~(LHC) experiments and is more competitive than that of Circular Electron Positron Collider~(CEPC) experiments.

hep-ph↗

arXiv2026

Enhancing the sensitivity to FCNC top decays $t\to cH $ and $t\to cS $ in the boosted regime at CLIC

The top quark, having the largest Yukawa coupling to the Higgs sector, provides a unique window into electroweak symmetry breaking and possible new physics beyond the Standard Model. Searches for rare top-quark processes are thus powerful probes of new physics. In this work, we investigate the flavor-changing neutral-current (FCNC) top-quark decays $t\to cH$ and $t\to cS$, where $S$ denotes a light scalar, at the Compact Linear Collider (CLIC) with a center-of-mass energy of $\sqrt{s}=1.5~\mathrm{TeV}$. Our analysis focuses on a kinematic regime distinct from most previous studies, in which the top quarks are typically highly boosted. To enhance signal discrimination in the boosted regime, we construct multi-channel jet images and employ a convolutional neural network (CNN) classifier to capture jet-substructure patterns relevant to the FCNC signals. Assuming an integrated luminosity of $4~\mathrm{ab}^{-1}$, we obtain the expected $95\%$ C.L. upper limit $\mathrm{BR}(t\to cH)\times \mathrm{BR}(H\to b\bar b)<5.27\times10^{-5}$. For the exotic scalar singlet, expected $95\%$ C.L. upper limits between $3.25\times10^{-5}$ and $5.26\times10^{-5}$ are obtained for $\mathrm{BR}(t\to cS)\times \mathrm{BR}(S\to b\bar b)$, for scalar masses between $30$ and $80~\mathrm{GeV}$.

hep-ph↗

arXiv2026

State-Dependent Visibility of Non-Commutative Ordering in Quantum Dynamics

A nonzero commutator proves that two orderings differ as operators, but it does not ensure that a physical state can reveal the difference. We ask when non-Abelian ordering information becomes dynamically invisible. For Hermitian operators $B$ and $C$, we compare the evolutions generated by the opposite-order products $M=(B+iC)(B-iC)$ and $\widetilde M=(B-iC)(B+iC)$, and define their operational visibility from the minimum overlap of the output states over a normalized time window. This visibility bounds the difference produced by the two orderings in every observable on the chosen state. An exact one-qubit solution shows that the same fixed pair can be perfectly invisible in one state and visible in another. We then keep the ordered generators fixed and vary only the many-body ground state across a quantum phase transition. The same ordering difference is nearly invisible in one regime and clearly visible in the other. Moreover, states with identical leading quadratic decay can develop sharply different finite-time visibility because their first distinction appears at higher order. The effect persists across distinct operator pairs and coefficient perturbations. Thus dynamical Abelianization is a property of the state-dependent process, i.e., non-Abelian ordering information can become operationally inaccessible even though the underlying operators remain non-commuting.

quant-ph↗

arXiv2026

SMEFT-Pheno-Agent: a natural-language-driven AI agent for machine-learning-assisted Standard Model Effective Field Theory phenomenology

We present SMEFT-Pheno-Agent, a Python workflow guided by a natural-language AI agent to perform machine-learning-assisted Standard Model Effective Field Theory (SMEFT) phenomenology at high-energy colliders. The software coordinates twelve automated execution phases spanning configuration intake, environment validation, event generation, machine-learning selection, statistical inference, and final audit. At each phase boundary, the agent interprets natural-language intent to generate runnable parameter files and adapter invocations required for subsequent execution. Once the detector-level events are written, the agent automatically proposes key kinematic observables alongside candidate machine-learning algorithms suited to the specific data structure and analysis objectives. All numerical calculations are delegated strictly to validated domain tools, with MadGraph5_aMC@NLO, Pythia, Delphes generating collider simulations, and MLAnalysis extracting features. The agent cannot modify physical parameters outside the locked configuration, and all LLM-produced artifacts, including parameter files, observable choices, algorithm selections, and prose drafts, are documented in machine-readable phase manifests prior to execution. These manifests establish complete reproducibility and audit traceability for SMEFT phenomenology studies.

hep-ph↗

arXiv2026

Expressibility and trainability of a two-dimensional pairwise quantum-circuit ansatz

Parameterized quantum circuits~(PQCs) constitute a central building block of variational quantum algorithms~(VQAs) and quantum machine learning~(QML) methods. Existing ansatz designs often adopt hardware-agnostic or simplified 1D chain/ring entanglement patterns. However, as quantum hardware continues to develop, native 2D connectivity patterns, such as planar superconducting-qubit architectures, are becoming increasingly important. Inspired by this hardware structure, we construct a native 2D pairwise ansatz and compare its expressibility and trainability with representative 1D ansatze at identical layer depths, despite their different circuit depths. For the fixed 16-qubit system, the 2D ansatz has the smallest KL divergence at $L=1$ and $2$, and its second-order frame potential approaches the theoretical lower bound more rapidly at shallow layer counts than the frame potentials of the three 1D ansatze. We also evaluate the gradient variance of the Pauli-$Z$-string expectation value $\langle Z_0\otimes\cdots\otimes Z_{15}\rangle$ with respect to the first $R_y$ angle. For this Pauli-$Z$ string and fixed parameter, the gradient variance is smaller for the 2D circuit at $L=1$--$4$. The differences narrow at $L=5$, and the four ansatze yield statistically compatible variances at $L=6$.

quant-ph↗

arXiv2026

A collider as a quantum computer

Scattering processes in high-energy physics are inherently quantum mechanical, yet are typically analyzed at the level of final states, where entanglement appears as a property of the outcome rather than a consequence of the underlying dynamics. We reformulate scattering at the level of the process itself by representing helicity transition matrices as quantum circuits. Once the kinematic configuration and scattering channel are fixed, the problem reduces to a finite-dimensional quantum map, making a circuit description natural. Within this framework, an example of the process $e^+e^-\to μ^+μ^-$ is shown, which decomposes into unitary and non-unitary components, corresponding to coherent mixing and postselection effects. This representation reorganizes the amplitude into distinct operational elements, providing a perspective in which collider processes can be viewed as constrained quantum circuits and their entanglement structure can be understood in terms of the underlying circuit dynamics, opening the door to analyzing their properties using the language of quantum information.

hep-ph↗

arXiv2026

Mesonic screening correlators in an external imaginary electric field at finite temperature

External electromagnetic fields provide a useful probe of QCD matter, but real electric fields are hindered by the sign problem, motivating studies with imaginary electric fields. We investigate mesonic screening correlators in lattice QCD at finite temperature in the presence of such a background using staggered fermions. At low temperature, scalar screening masses increase with the field strength, while pseudo-scalar masses remain largely unchanged, and charge-asymmetric channels show additional structure. At high temperature, the correlators exhibit clear spatial oscillations with frequencies set by the quark electric charges. These results demonstrate nontrivial modifications of screening properties induced by external electric fields.

hep-lat↗

arXiv2026

Wilson loops with oppositely oriented plaquettes as a probe of center vortex structure

We study Wilson loops with a nontrivial orientation structure in lattice gauge theory as a probe of the center vortex picture. The observable is a single Wilson loop containing two plaquettes with opposite orientations, realized in two geometries referred to as the vertical and parallel configurations. The vertical case behaves consistently with expectations from the vortex picture. In contrast, the parallel configuration shows a deviation from the naive area-law expectation which cannot be explained solely by the opposite orientations of the plaquettes. We introduce a simple qualitative vortex model which accounts for this behavior and shows that the observed effect can still be understood within the vortex framework.

hep-lat↗

arXiv2026

A quantum machine learning classifier to search for new physics

Due to the success of the Standard Model~(SM), it is reasonable to anticipate that the signal of new physics~(NP) beyond the SM is small. Consequently, future searches for NP and precision tests of the SM will require high luminosity collider experiments. Moreover, as precision tests advance, rare processes with many final-state particles require consideration which demands the analysis of a vast number of observables. The high luminosity produces a large amount of experimental data spanning a large observable space, posing a significant data-processing challenge. In recent years, quantum machine learning has emerged as a promising approach for processing large amounts of complex data on a quantum computer. In this study, we propose quantum searching neighbor~(QSN) and variational QSN~(VQSN) algorithms to search for NP. The QSN is a classification algorithm. The VQSN introduces variation to the QSN to process classical data. As applications, we apply the (V)QSN in the phenomenological study of the NP at the Large Hadron Collider and muon colliders. Examples are implemented on a real quantum hardware, which confirms reliable performance under noisy conditions. The results indicate that the VQSN demonstrates superior efficiency in the sense of computational complexity to a classical counterpart k-nearest neighbor algorithm, even when dealing with classical data.

hep-ph↗

arXiv2025

Searching for the neutral triple gauge couplings in the process $μ^+μ^-\to γν\barν$ at muon colliders

We investigate the sensitivity of future high-energy muon colliders to neutral triple gauge couplings (nTGCs) through the process $μ^{+}μ^{-}\toγν\barν$ within the Standard Model Effective Field Theory (SMEFT) framework. Extending beyond previous studies, we consider a set of 14 dimension-8 operators, including both Higgs-related and pure gauge structures. By computing the cross sections and performing Monte Carlo simulations at multiple center-of-mass energies (3-30 TeV), we demonstrate that the annihilation process dominates over vector boson fusion (VBF) at TeV scales. We also explore the impact of beam polarization and show that the $(-+)$ polarization enhances sensitivity to several operators. After the study of the event selection strategies, we show that muon colliders can impose stronger expected constraints on nTGCs operators than current LHC bounds, with two of the pure gauge operators yielding the most stringent expected constraints. We also evaluate the contribution of CP-violating pure gauge operators to the electron electric dipole moment (EDM), finding that the expected constraints from muon colliders are stronger than those from EDM measurements.

hep-ph↗

arXiv2025

Search for anomalous quartic gauge couplings in the process $μ^+μ^-\to \barννγγ$ with a nested local outlier factor

In recent years, with the increasing luminosities of colliders, handling the growing amount of data has become a major challenge for future new physics~(NP) phenomenological research. To improve efficiency, machine learning algorithms have been introduced into the field of high-energy physics. As a machine learning algorithm, the local outlier factor~(LOF), and the nested LOF~(NLOF) are potential tools for NP phenomenological studies. In this work, the possibility of searching for the signals of anomalous quartic gauge couplings~(aQGCs) at muon colliders using the NLOF is investigated. Taking the process $μ^+μ^-\to ν\barνγγ$ as an example, the signals of dimension-8 aQGCs are studied, expected coefficient constraints are presented. The event selection strategy uses unsupervised anomaly scores, with supervised optimization for EFT sensitivity. The NLOF algorithm is shown to outperform the k-means based anomaly detection methods, and a traditional counterpart.

hep-ph↗

arXiv2025

Fully strange tetraquark states via QCD sum rules

In this paper, we have systematically explored the mass spectrum of fully strange tetraquark candidates within the framework of QCD sum rules, focusing on states with quantum numbers $J^{PC}=0^{++}$, $0^{-+}$, $0^{--}$, $1^{--}$, $1^{+-}$, and $1^{++}$. The analysis reveals the existence of fully strange tetraquark states with masses ranging from approximately $2.07$ to $3.12$ GeV. These predictions are confronted with existing experimental observations of potential fully strange tetraquark resonances, notably the $X(2300)$ recently reported by the BESIII Collaboration, which may be interpreted as a fully strange tetraquark state. Furthermore, the possible decay modes of these fully strange tetraquark states are analyzed, providing guidance for their identification in current and future high energy experiments such as BESIII, Belle II, and LHCb.

hep-ph↗

arXiv2025

Digit quantum simulation of a fermion field in an expanding universe

Quantum simulation is a rapidly evolving tool with great potential for research at the frontiers of physics, and is particularly suited to be used in computationally intensive lattice simulations, such as problems with non-equilibrium. In this work, a basic scenario, namely free fermions in an expanding universe, is considered and quantum simulations are used to perform the evolution and study the phenomena involved. Using digital quantum simulations with the Jordan-Wigner transformation and Trotter expansion, the evolutions of fermion number density, correlation functions, polarization, and chiral condensation are analyzed. A spread out phenomenon can be observed in the simulation, which is a consequence of momentum redshift. This work also demonstrates the simplicity and convenience of using quantum simulations when studying time-evolution problems.

quant-ph↗

arXiv2025

Quantum simulation of the phase transition of the massive Thirring model

Recent advancements in quantum computing technology have enabled the study of fermionic systems at finite temperature via quantum simulations. This presents a novel approach to investigating the chiral phase transition in such systems. Among these, the quantum minimally entangled typical thermal states~(QMETTS) algorithm has recently attracted considerable interest. The massive Thirring model, which exhibits a variety of phenomena at low temperatures, includes both a chiral phase transition and a topologically non-trivial ground state. It therefore raises the intriguing question of whether its phase transition can be studied using a quantum simulation approach. In this study, the chiral phase transition of the massive Thirring model and its dual topological phase transition are studied using the QMETTS algorithm. Numerical results are obtained on a classical computer simulating circuit-based quantum computations. The results show that QMETTS is able to accurately reproduce the phase transition and thermodynamic properties of the massive Thirring model.

quant-ph↗

arXiv2025

Enhancing Phase Transition Calculations with Fitting and Neural Network

The computation of bounce action in a phase transition involves solving partial differential equations, inherently introducing non-negligible numerical uncertainty. Deriving characteristic temperatures and properties of this transition necessitates both differentiation and integration of the action, thereby exacerbating the uncertainty. In this work, we fit the action curve as a function of temperature to mitigate the uncertainties inherent in the calculation of the phase transition parameters. We find that, after extracting a factor, the sixth-order polynomial yields an excellent fit for the action in the high temperature approximated potential. In a realistic model, the singlet extension of the Standard Model, this method performs satisfactorily across most of the parameter space after trimming the fitting data. This approach not only enhances the accuracy of phase transition calculations but also systematically reduces computation time and facilitates error estimation, particularly in models involving multiple scalar fields. Furthermore, we discussed the possible of using multiple neural networks to predict the action curve from model parameters.

hep-ph↗

arXiv2025

Detect anomalous quartic gauge couplings at muon colliders with quantum kernel k-means

In recent years, with the increasing luminosities of colliders, handling the growing amount of data has become a major challenge for future New Physics~(NP) phenomenological research. To improve efficiency, machine learning algorithms have been introduced into the field of high-energy physics. As a machine learning algorithm, kernel k-means has been demonstrated to be useful for searching NP signals. It is well known that the kernel k-means algorithm can be carried out with the help of quantum computing, which suggests that quantum kernel k-means~(QKKM) is also a potential tool for NP phenomenological studies in the future. This paper investigates how to search for NP signals using the k-means anomaly detection event selection strategy with quantum kernels. Taking the $μ^+μ^-\to v\bar{v}γγ$ process at a muon collider as an example, the dimension-8 operators contributing to anomalous quartic gauge couplings~(aQGCs) are studied. The expected coefficient constraints obtained using the QKKM of three different forms of quantum kernels and k-means algorithm are presented, it can be shown that QKKM can help to find the signal of aQGCs.

hep-ph↗

arXiv2024

Search for Neutral Triple Gauge Couplings with $ZZ$ Production at Future Electron Positron Colliders

This study investigates Neutral Triple Gauge Couplings (nTGCs) through $ZZ$ production at future electron-positron colliders. The impact of beam polarization on cross section is analyzed. We compare the signals and backgrounds for five different $ZZ$ decay channels and present our event selection strategies for future $e^+e^-$ colliders. The expected coefficient constraints for each decay channels are provided, and final expected constraints are derived by combining results from the different decay patterns. Our analysis indicates that future electron-positron colliders will have significantly enhanced detection capabilities for nTGCs compared to the current LHC experiments, with expected improvements in constraints by one to two orders of magnitude.

hep-ph↗

arXiv2024

Split of the pseudo-critical temperatures of chiral and confine/deconfine transitions by temperature gradient

Searching of the critical endpoint of the phase transition of Quantum Chromodynamics~(QCD) matter in experiments is of great interest. The temperature in the fireball of a collider is location dependent, however, most theoretical studies address the scenario of uniform temperature. In this work, the effect of temperature gradients is investigated using lattice QCD approach. We find that the temperature gradient catalyzes chiral symmetry breaking, meanwhile the temperature gradient increases the Polyakov loop in the confined phase but suppresses the Polyakov loop in the deconfined phase. Furthermore, the temperature gradient decreases the pseudo-critical temperature of chiral transition but increases the pseudo-critical temperature of the confine/deconfine transition.

hep-lat↗