arXiv subjects

Chong-Xing Yue

Publications and source records attributed to Chong-Xing Yue.

At least 19 recordsLinked to original sources

arXiv2026

Probing axion-like particle couplings to leptons via the $γγjj$ signal at the FCC-ee

We study the sensitivity of the Future Circular Collider in electron-positron mode (FCC-ee) to the axion-like particle (ALP) couplings with leptons via the process $e^{+}e^{-} \rightarrow γγjj$ at the center-of-mass energy $\sqrt{s}=91$ GeV with the integrated luminosity $\mathcal{L}=150~\text{ab}^{-1}$. We analyze three scenarios, $\mathbf{c}_R=0$, $\mathbf{c}_L=0$ and $\mathbf{c}_R=\mathbf{c}_L$, for both unpolarized and polarized beams with $(P_{e^-}, P_{e^+}) = (+80\%, -80\%)$, and derive projected lower limits on the effective coupling strengths. The polarized case provides higher sensitivity than the unpolarized case. Specifically, for the $\mathbf{c}_R=0$ scenario (probing the ALP-neutrino coupling $\text{Tr}(g_{aνν})/f_a$), the projected sensitivity in the polarized case reaches approximately $0.0105~\text{GeV}^{-1}$ for the ALP mass in the range $10$--$24$ GeV; for $\mathbf{c}_L=0$ (probing the ALP-charged lepton coupling $\text{Tr}(g_{a\ell\ell})/f_a$), it reaches $0.0174~\text{GeV}^{-1}$ in the $10$--$27$ GeV range; and for $\mathbf{c}_R=\mathbf{c}_L$ (probing the ALP-neutrino coupling $\text{Tr}(g_{aνν})/f_a$), it reaches $0.00394~\text{GeV}^{-1}$ in the $45$--$80$ GeV range. In these ALP mass ranges, our projected sensitivities are complementary to the projected sensitivities from other search channels at future colliders.

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arXiv2026

Probing the ALP--Photon--Dark Photon Interaction through the Mono-Photon plus Missing-Energy Signature at a Muon Collider

The dark axion portal provides a well-motivated framework for new physics beyond the Standard Model (SM), in which an axion-like particle (ALP) couples simultaneously to a photon and a dark photon, leading to distinctive collider signatures. In this work, we investigate the sensitivity to the $a$--$γ$--$γ'$ interaction via the mono-photon channel arising from $μ^{+}μ^{-} \to a γ'$ with $a \to γγ'$ at the $1.5~\mathrm{TeV}$ muon collider with an integrated luminosity of $\mathcal{L}=500~\mathrm{fb}^{-1}$ for the polarized and unpolarized beam configurations, $P(μ^+,μ^-)=(-100\%,+100\%)$ and $P(μ^+,μ^-)=(0,0)$, using detector-level simulation. The signal is characterized by a single energetic photon accompanied by missing energy as the dark photons escape detection. The projected sensitivity reaches the $\mathcal{O}(10^{-5})~\mathrm{GeV}^{-1}$ level for ALP masses in the range $1~\mathrm{GeV}\leq m_a\leq1200~\mathrm{GeV}$ for $P(μ^+,μ^-)=(-100\%,+100\%)$, while for $P(μ^+,μ^-)=(0,0)$ the projected sensitivity reaches the $\mathcal{O}(10^{-4})~\mathrm{GeV}^{-1}$ level for the same ALP mass range. These results demonstrate that the mono-photon signature at a muon collider provides a sensitive probe of the $a$--$γ$--$γ'$ interaction over a wide mass range.

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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.

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arXiv2026

Prospects for probing light photophobic axion-like particles via displaced vertex signals at the CEPC

In recent years, long-lived particles (LLPs) have attracted increasing attention in searches for physics beyond the Standard Model (SM). In this paper, we investigate the discovery prospects for light, long-lived ALPs predicted by the photophobic ALP scenario through displaced-vertex signals at the CEPC, with a center-of-mass energy of $\sqrt{s}=91.2 $ GeV and an integrated luminosity of $\mathcal{L}=$ $100$ ab$^{-1}$. After comparing several possible single-production processes for the photophobic ALP, we focus on the dominant process $e^+ e^- \to Z \to a γ$, in which the ALP $a$ subsequently decays into a pair of charged leptons at a displaced vertex. Dedicated Monte Carlo simulations are performed for the $μ^+ μ^- γ$ and $τ_h^+ τ_h^- E\mkern-10.5 mu/_T γ$ signals. For the $μ^+μ^-γ$ signal, the CEPC is sensitive to the parameter region $g_{aWW} \in [1.27\times10^{-3},6.80\times10^{-1}]~\mathrm{TeV}^{-1}$ for $m_a \in [1,4]~\mathrm{GeV}$. For the $τ_h^+τ_h^- E\mkern-10.5 mu/_T γ$ signal, the accessible region is $g_{aWW} \in [7.00\times10^{-4},9.40\times10^{-3}]~\mathrm{TeV}^{-1}$ for $m_a \in [4,9]~\mathrm{GeV}$. These results demonstrate the substantial potential of the CEPC to explore light, long-lived ALPs through displaced-vertex signals, providing complementary coverage to existing searches at LEP and the LHC, as well as to the projected reach of the HL-LHC.

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arXiv2026

Prospects for probing neutral vector-like leptons via pair production at muon collider

Vector-like leptons (VLLs) are well-motivated candidates for physics beyond the Standard Model. We investigate the sensitivity of the $6$ TeV muon collider to the neutral doublet VLL (denoted as $N$) via its pair production within a general VLL framework. Taking vector-like muon as a case study, we study the subsequent decay $N\rightarrow W^+ μ$ and analyze two representative signals, namely $4j2μ$ and $2\ell2μE\mkern-10.5 mu/$, arising from the hadronic and leptonic decays of the $W$ boson, respectively. The signal and background events are simulated within a complete Monte Carlo framework, and a cut-based analysis is performed at the $6$ TeV muon collider with an integrated luminosity $\mathcal{L}=4$ ab$^{-1}$ and beam polarizations $(P_{μ^+},P_{μ^-})=(-1,1)$. We consider VLL masses in the range of $1300-3000$ GeV and evaluate the corresponding search sensitivity. Our results show that the future $6$ TeV muon collider can effectively probe neutral doublet VLLs through the $4j2μ$ and $2\ell2μE\mkern-10.5 mu/$ signals, with statistical significances exceeding $5σ$ over a broad mass range. These results demonstrate that the future $6$ TeV muon collider has excellent potential to search neutral doublet VLLs.

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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↗

arXiv2026

Searching for long-lived axion-like particles via displaced vertices at the HL-LHC

Axion-like particles (ALPs) are well-motivated extensions of the standard model (SM) that appear in numerous new physics scenarios. In this paper, we concentrate on searches for long-lived ALPs predicted by the photophobic scenario at the HL-LHC with the center-of-mass energy $\sqrt{s}=14$ TeV and the integrated luminosity $\mathcal{L}=$ $3$ ab$^{-1}$. We consider the process $pp \to γa$ with the ALP $a$ decaying into a pair of displaced charged leptons and perform a detailed analysis of two types of signals: $π^+ π^- γE\mkern-10.5 mu/_T $ and $\ell^+ \ell^- γE\mkern-10.5 mu/_T $. For the $π^+ π^- γE\mkern-10.5 mu/_T $ signal, we find that the prospective sensitivities of the HL-LHC can reach $g_{aWW}\in [8.72 \times 10^{-3}, 6.42 \times 10^{-2}]$ TeV$^{-1}$ for the ALP mass $m_a \in [4, 10]$ GeV. While for the $\ell^+ \ell^- γE\mkern-10.5 mu/_T $ signal, the HL-LHC can probe a broader parameter space, with the sensitivities covering $m_a \in [4, 10]$ GeV and $g_{aWW} \in [4.17 \times 10^{-3}, 2.00 \times 10^{-1}]$ TeV$^{-1}$. These long-lived searches complement some previous prompt decay studies from LEP and LHC experiments, extending the parameter space explored by the LHCb collaboration. Our results show that the HL-LHC has significant potential to probe long-lived ALPs via their displaced vertex signatures.

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arXiv2025

Probing the couplings of an axion-like particle with leptons via three-lepton final state processes at future $e^{-}p$ colliders

The axion-like particle (ALP) is one of the best motivated particles beyond the Standard Model (SM). We explore the possibility of detecting the couplings of ALP with leptons via three-lepton final state processes $e^- p \to e^- j a~(a \to \ell^+ \ell^-)$ at the LHeC (FCC-eh). For completeness, we investigate the cases where the ALP decays not only into electron and muon pairs but also into tau pairs, and perform a detailed simulation for the decays of taus. We find that the prospective sensitivities of the LHeC (FCC-eh) with the center-of-mass energy $\sqrt{s}=1.3~(3.5)$ TeV and the integrated luminosity $\mathcal{L}=1~ (2)$ ab$^{-1}$ to the ALP-lepton couplings are not only stronger than some existing bounds of the LHC and LEP but also complementary to the expected bounds of the CEPC and FCC-ee.

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arXiv2024

Single production of singlet vector-like leptons at the ILC

Vector-like leptons (VLLs) as one kind of interesting new particles can produce rich phenomenology at low- and high-energy experiments. In the framework of the singlet vector-like leptons with scalar (VLS) model, we investigate the discovery potential of VLL via its single production at the International Linear Collider (ILC) with the center of mass energy $\sqrt{s} =$ 1 TeV and the integrated luminosity $\mathcal{L}$ = 1 ab$^{-1}$, taking into account the appropriate polarization. For the signal and standard model (SM) background analysis, we have considered two kinds of decay channels for the W boson, i.e. pure leptonic and fully hadronic decay channels. Our analytic results show that the parameter space $M_{F}\in$ [300, 675] GeV and $κ\in$ [0.0294, 0.1] might be detected by the proposed ILC for pure leptonic decay channel. For fully hadronic decay channel, larger detection region of the parameter space are derived as $M_{F}\in$ [300, 700] GeV and $κ\in$ [0.0264, 0.0941].

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↗

arXiv2024

Prospects for detecting the couplings of axion-like particle with neutrinos at the CEPC

We explore the possibility of detecting the couplings of axion-like particle (ALP) with leptons from their loop-level impact on the ALP couplings to electroweak (EW) gauge bosons via the signal process $e^+ e^- \to γγ{E\mkern-10.5 mu/}$ at the Circular Electron Positron Collider (CEPC) and obtain prospective sensitivities to the ALP-lepton couplings. Our numerical results show that the CEPC with the center of mass energy $\sqrt{s}=240~(91)$ GeV and the integrated luminosity $\mathcal{L}=5.6~(16)$ ab$^{-1}$ might be sensitive for probing the ALP-lepton couplings in the ALP mass range from $10$ GeV to $130~(50)$ GeV, where the prospective sensitivities to the ALP-neutrino coupling $Tr(g_{aνν})/f_a$ can be as low as $0.016~(0.012)$ GeV$^{-1}$ and $0.0031~(2.8 \times 10^{-4})$ GeV$^{-1}$ for $c_{R}=0$ and $c_{R}=c_{L}$, and to the ALP-charged lepton coupling $Tr(g_{a\ell\ell})/f_a$ can be as low as $0.035~(0.07)$ GeV$^{-1}$ for $c_{L}=0$. We find that the prospective sensitivities given by the CEPC are not covered by the current and expected exclusion regions in some ALP mass intervals. The CEPC has the potential for exploring the ALP-neutrino couplings via some promising processes induced by the ALP-EW gauge boson couplings in the future.

hep-ph↗

arXiv2024

Lepton flavour violation Signals of the singly charged scalar singlet at the ILC

The singly charged $SU(2)_L$ singlet scalar is one of the very interesting new particles, as it can generate neutrino masses at loop level, produce contributions to various flavour observables. We study the possibility of detecting this kind of scalar predicted by the singly-charged scalar model at ILC via the lepton flavour violation (LFV) process $e^+e^-\rightarrow S^+S^-\rightarrow μe + {E\mkern-10.5 mu/}$. Considering the constraints on the free parameters, we obtain the expected sensitivities of the ILC with the center of mass energy $\sqrt{s}=1~\mathrm{TeV}$ and the integrated luminosity $\mathcal{L}=$ $1.5~\mathrm{ab}^{-1}$ to the parameter space of the singly-charged scalar model. The prospective excluded mass range at $95\%$ C.L. is $M_S \gtrsim 470~\mathrm{GeV}$, $410~\mathrm{GeV}$ for the branching ratio $\mathcal{B}_{μe}$ = $100\%$ , $50\%$, respectively, while the scalar with $M_S \gtrsim 300~\mathrm{GeV}$ is excluded at $95\%$ C.L. for $\mathcal{B}_{μe}$ = $30\%$.

hep-ph↗

arXiv2024

Searching for singlet vector-like leptons via pair production at ILC

Vector-like leptons (VLLs) as one kind of the most intriguing particles, have been widely concerned in several extensions of the Standard Model (SM). In this work, we explore the discovery potential of VLLs via pair production in the context of models that satisfy asymptotic safety at the International Linear Collider (ILC). The expected sensitivities of the ILC with the center of mass energy $\sqrt{s} =$ 1 TeV and the integrated luminosity $\mathcal{L}$ = 1 ab$^{-1}$ to the parameter space of this kind of VLL models are derived. The results we obtained show that, for the VLL with mass $M_F$ in the region of $M_{F}\in$ [101GeV, 463GeV], the Yukawa coupling $κ$ can be as low as $κ\in$ [0.032, 0.098].

hep-ph↗

arXiv2024

Searching for the light leptophilic gauge boson $Z_x$ via four-lepton final states at the CEPC

We investigate the possibility of detecting the leptophilic gauge boson $Z_x$ predicted by the $U(1)_{L_e-L_μ}$ model via the processes $e^+e^-\rightarrow\ell^+\ell^-Z_x(Z_x\rightarrow \ell^+\ell^-)$ and $e^+e^-\rightarrow \ell^+\ell^-Z_x(Z_x\rightarrow ν_\ell\bar{ν_\ell})$ at the Circular Electron Positron Collider (CEPC) with the center of mass energy $\sqrt s=240$ GeV and the luminosity $\mathcal{L}=5.6$ $\mathrm{ab^{-1}}$. We give the expected sensitivities of the CEPC to the parameter space at $1σ$, $2σ$, $3σ$ and $5σ$ levels.

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arXiv2023

Detecting the coupling of axion-like particles with fermions at the ILC

New pseudoscalars, axion-like particles (ALPs), provide the exciting target for present and future collider-based experiments. Search for ALPs is performed in this paper via the $W^{+}W^{-}$ fusion process $e^{-}e^{+}\rightarrowν_{e}\overline{ν_{e}}a\rightarrowν_{e}\overline{ν_{e}}f\overline{f}$ at the $1$ TeV ILC corresponding to an integrated luminosity of $1$ ab$^{-1}$ and the beam polarization $P(e^{-}$, $e^{+}) = (-80\%$, $+20\%)$. Owing to the good capability of the ILC in performing b-tagging and the sufficiently large branching ratio of the ALP decaying into a pair of b quarks, the decay channel $a\rightarrow{b\overline{b}}$ is mainly concerned. The prospective sensitivities provided by the ILC on the ALP-fermion coupling as low as $1$ TeV$^{-1}$ and $1.75$ TeV$^{-1}$ are derived at $95\%$ confidence level in the ALP mass intervals $37-50$ GeV and $52-300$ GeV, respectively. Our results will help to probe significant parameter space in an unexplored region beyond the existing constraints.

hep-ph↗

arXiv2023

The study of neutral triple gauge couplings in the process $e^+e^-\to Zγ$ including unitarity bounds

The neutral triple gauge couplings~(nTGCs) provide a unique opportunity to probe new physics beyond the Standard Model. The nTGCs can be described by an effective field theory~(EFT), which is valid only under a certain energy scale. One of the signatures that an EFT is no longer valid is the violation of unitarity. We study the partial wave unitarity bounds on the coefficients of nTGCs in the process $e^+e^-\to Zγ$. In the experiments, the constraints obtained should be tighter than the unitarity bounds, otherwise the results are meaningless, therefore there exists a minimal luminosity for a $e^+e^-$ collider such as the CEPC to study the nTGCs. To derive the minimal luminosity, the kinematic features and event selection strategy are studied by Monte-Carlo simulation. Both the processes $e^+e^-\to \ell^+\ell^-γ$ and $e^+e^-\to jjγ$ are studied, event selection strategies are discussed. Based on the statistical significance, the expected constraints in experiments are estimated. The required luminosities for the experiments to reach the unitarity bounds are presented.

hep-ph↗

arXiv2023

Constraints on anomalous quartic gauge couplings via $Wγjj$ production at the LHC

The vector boson scattering at the Large Hadron Collider (LHC) is sensitive to anomalous quartic gauge couplings (aQGCs). In this paper, we investigate the aQGC contribution to $ W γjj$ production at the LHC with $\sqrt{s}=13$ TeV in the context of an effective field theory (EFT). The unitarity bound is applied as a cut on the energy scale of this production process, which is found to have significant suppressive effects on the signals. To enhance the statistical significance, we analyse the kinematic and polarization features of the aQGC signals in detail. We find that the polarization effects induced by the aQGCs are unique and can discriminate the signals from the SM backgrounds well. With the proposed event selection strategy, we obtain the constraints on the coefficients of dimension-8 operators with current luminosity. The results indicate that the process $pp \to W γjj$ is powerful for searching for the $O_{M_{2,3,4,5}}$ and $O_{T_{5,6,7}}$ operators.

hep-ph↗

arXiv2023

Constraints on anomalous quartic gauge couplings via $Zγjj$ production at the LHC

In this paper, we investigate the contributions of anomalous quartic gauge couplings (aQGCs) to $Zγjj$ production at the Large Hadron Collider (LHC) in the context of Standard Model effective theory (SMEFT). When energy scale is large, the validity of SMEFT becomes an important issue. To ensure the validity, the unitarity bound is applied in a model independent approach, which is found to have significant suppressive effects on the signals of $O_{M_i}$ operators. The kinematic and polarization features of the aQGC signals are also studied. The polarization effect is useful to highlight the signals of $O_{T_i}$ operators. The sensitivity estimates on dimension-8 operators with unitarity bounds at $\sqrt{s}=14$ TeV are obtained.

hep-ph↗