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Jinmian Li

Publications and source records attributed to Jinmian Li.

At least 19 recordsLinked to original sources

Disentangling Dark Gauge Symmetries with Deep Learning on the Lund Jet Plane

While dark sectors with new confining gauge symmetries are compelling candidates for resolving the dark matter mystery, discerning the underlying dark gauge group structure remains a significant phenomenological challenge. In this work, we systematically investigate the distinct radiation patterns of dark quarks and gluons by developing a novel Monte Carlo parton shower simulation framework applicable to arbitrary gauge groups. To handle generalized color topologies and the momentum recoil scheme, our algorithm constructs color dipoles using a group-theoretic tagging procedure. Furthermore, our simulation framework employs an exact three-body phase-space parameterization by analytically solving the cubic kinematic equation for each branching. This enables capturing full mass effects for both dark quarks and dark gluons, naturally yielding precise boundaries including mass-induced gaps and dead-cone thresholds. To decode these complex emission topologies, we utilize the Lund Jet Plane representation alongside a dedicated Neural Sorter Mamba Network. We demonstrate that our framework can successfully disentangle the perturbative footprints of different gauge symmetries. Finally, we show that our discrimination power remains robust against the unknown non-perturbative details of dark hadronization by maintaining high classification efficiencies even under stringent infrared $k_T$ cutoffs, and we explicitly quantify the impact of massive dark gauge bosons on the classification sensitivity.

hep-ph

Search for Cosmic-Ray Produced Dark Meson via the $U(1)_\text{D}$ Portal at JUNO

We investigate the atmospheric production and subsequent detection of sub-GeV dark mesons within the framework of a confining dark sector coupled to the Standard Model (SM) via a $U(1)_{\text{D}}$ vector portal. High-energy cosmic ray interactions in the atmosphere produce dark quarks through proton bremsstrahlung, rare decays of Standard Model mesons, and Drell-Yan processes, which subsequently hadronize into dark mesons. We adopt a modified Quark Combination Model to describe the non-perturbative dark hadronization process, allowing for a detailed event-level characterization of the dark meson flux. We simulate the flux and the interactions of these relativistic dark mesons in the Jiangmen Underground Neutrino Observatory (JUNO) using the GENIE generator, considering both elastic scattering off nuclei and deep inelastic scattering channels. Adopting a LES-inspired conservative signal definition with $15~\mathrm{MeV}<E_{\rm vis}<100~\mathrm{MeV}$ and vetoing events containing final-state neutrons, we derive projected $90\%$ C.L. sensitivities to the coupling strength between the dark gauge boson and the SM sector for a $20~\mathrm{kton}\!\cdot\!\mathrm{year}$ exposure. For the representative benchmark masses $m_{Z^\prime}=0.001$, $0.01$, and $0.1~\mathrm{GeV}$, the projected JUNO reach corresponds to $g_{\rm SM}^{90}=6.48\times10^{-5}$, $7.75\times10^{-5}$, and $2.37\times10^{-4}$, respectively. This reach is found to be only mildly sensitive to order-one variations of the hadronization parameter, as illustrated by the choices $κ_β=1/3,\,1,$ and $3$.

hep-ph

Dark photon dark matter constraints at the Taiwan axion search experiment with haloscope

The dark photon is a well motivated candidate for the dark matter which comprises most of the mass of our visible Universe, leading to worldwide experimental and observational efforts towards its discovery. A primary tool in this search is the cavity haloscope, which facilitates resonantly enhanced conversion to photons from both dark photons and axions. In this context, limits from axion search experiments are often directly converted into dark photon constraints, without re-analyzing the original data. However, this rescaling may not fully capture all of the relevant physics due to various reasons. By re-examining data taken by the Taiwan Axion Search Experiment with Haloscope (TASEH) experiment, we derive a world-leading constraint on the dark photon parameter space, excluding $|ε|\gtrsim2\times10^{-14}$ in the $19.46 - 19.84\,μ$eV mass range, which exceeds the na{ï}ve `rescaling limit' by roughly a factor of two. We emphasize that accounting for the scanning timing information is crucial for deriving limits for the polarized dark photon case. In the data, we also analyze a tentative signal excess with a local significance of 4.7$σ$ ($m_X \simeq 19.5\,μ$eV) that persists in the absence of a magnetic field. While this excess mimics the behavior of a dark photon signal, it has been excluded by recent results from the HAYSTAC and ORGAN-Q experiments. This case study, nevertheless, highlights the risk of discarding valid dark photon signals when relying on axion-specific magnetic field vetoes.

hep-ex

Letter of Intent: The Forward Physics Facility

The Forward Physics Facility (FPF) is a proposed extension of the HL-LHC program designed to exploit the unique scientific opportunities offered by the intense flux of high energy neutrinos, and possibly new particles, in the far-forward direction. Located in a well-shielded cavern 627 m downstream of one of the LHC interaction points, the facility will support a broad and ambitious physics program that significantly expands the discovery potential of the HL-LHC. Equipped with four complementary detectors -- FLArE, FASER$ν$2, FASER2, and FORMOSA -- the FPF will enable breakthrough measurements that will advance our understanding of neutrino physics, quantum chromodynamics, and astroparticle physics, and will search for dark matter and other new particles. With this Letter of Intent, we propose the construction of the FPF cavern and the construction, integration, and installation of its experiments. We summarize the physics case, the facility design, the layout and components of the detectors, as well as the envisioned collaboration structure, cost estimate, and implementation timeline.

hep-ex

New Physics Search at the CEPC: a General Perspective

The Circular Electron-Positron Collider (CEPC), a proposed next-generation Higgs factory, provides new opportunities to explore physics beyond the Standard Model (SM). With its clean electron-positron collision environment and the ability to collect large samples of Higgs, W, and Z bosons, the CEPC enables precision measurements and searches for new physics. This white paper outlines the CEPC's discovery potential, including studies of exotic decays of the Higgs, Z, and top quarks, dark matter and dark sector phenomena, long-lived particles, supersymmetry, and neutrino-related signatures. Advanced detector technologies and reconstruction techniques, such as one-to-one correspondence reconstruction and jet origin identification, significantly improve sensitivity to rare and weakly interacting processes. The CEPC is particularly well suited to probe the electroweak phase transition and test models of electroweak baryogenesis and dark sector interactions. In addition, global fit analyses highlight the CEPC's complementary role in constraining a wide range of new physics scenarios. These features position the CEPC as a powerful tool for exploring the next frontier in fundamental particle physics in the post-Higgs discovery era.

hep-ex

Jet Reconstruction with Mamba Networks in Collider Events

We introduce a novel end-to-end framework for jet reconstruction in high-energy collider events, leveraging the efficiency and long-range modeling capabilities of the Mamba architecture. Our model unifies instance segmentation, classification, and kinematic regression into a single multi-task learning system, enabling a sophisticated multi-level reconstruction that simultaneously identifies primary heavy jets ($t$, $H$, $W/Z$) and their constituent sub-jets. To facilitate supervised learning for this complex task, we develop a novel method for assigning final-state hadrons to their ancestor colored partons using a Mixed-Integer Linear Programming solver, which generates high-fidelity ground-truth labels. The model achieves high classification accuracy, with an Average Precision score of 0.569 for $W/Z$-jets and 0.568 for $b$-jets, and shows exceptional precision in kinematic reconstruction. Furthermore, we show that the model not only maintains stable performance in high-pileup environments but also successfully reconstructs the mass peaks of beyond the standard model particles. This work presents a powerful and versatile new tool for comprehensive event reconstruction at the LHC.

hep-ph

Dark Parton Shower Effects for Cosmic Ray Boosted Dark Matter

We investigate the dark parton shower effects in the direct detection of cosmic-ray boosted dark matter (CRDM), focusing on a dark photon-mediated model with fermionic dark matter-electron interactions. Utilizing a Monte Carlo framework to incorporate the Sudakov form factors and kinematic dipole recoil schemes, we simulate the CRDM energy spectrum evolution under the dark sector splitting. Our results reveal a significant energy-dependent modification of the CRDM flux. For a 1 keV dark matter (DM) mass and a coupling of $g_D=3$, the CRDM flux can be enhanced by a factor up to 1.12 in the $\mathcal{O}(10^{-2} \sim 1)$ MeV energy range for $2m_χ\lesssim m_{A^\prime} \lesssim 10^{-2}$ MeV, while it is suppressed by more than $50\%$ at energy around 100 MeV for $m_{A^\prime} \lesssim 10^{-3}$ MeV. We then translate these effects into the experimental sensitivities for PandaX-4T, Super-Kamiokande, and JUNO. At $m_{A^\prime} = 10^{-3}$ MeV and $g_D=3$, the bounds on the kinetic mixing parameter $ε^2$ are relaxed by factors of 1.02, 1.6 and 1.4, respectively. Finally, we demonstrate that the parameter space considered is consistent with those astrophysical constraints on dark matter self-interactions from observations of the Bullet Cluster.

hep-ph

Testing tree level TeV scale seesaw scenarios in $μ$TRISTAN

We investigate TeV scale seesaw scenarios at $μ^+ e^-$ and $μ^+ μ^+$ colliders in the $μ$TRISTAN experiment. In minimal type-I seesaw scenario we consider two generations of Standard Model (SM) singlet heavy Majorana type Right Handed Neutrinos (RHNs) which couples with SM gauge bosons through light-heavy neutrino mixing. We discuss the prospects of probing heavy neutrinos via the processes such as $μ^+e^-\to νN_i\to e^+ j jν$ or $μ^- j jν$ for $\sqrt{s}=346$~GeV and $1\text{ ab}^{-1}$ luminosity. Studying these process, we estimate limits on the light-heavy neutrino mixing angles as a function of heavy neutrino mass, which could be two orders of magnitude stronger than electroweak precision data. Further, we study the effect of doubly charged scalar boson $(H^{++})$ from the type-II seesaw scenario in $μ^+ μ^+$ collision at $\sqrt{s}=2$ TeV. In this case we consider $μ^+ μ^+ \to \ell_i^+ \ell_j^+$ and $μ^+ μ^+ \to H^{++} Z/ γ$ processes followed by the same sign dilepton decay of $H^{++}$. We find that events involving $e^+ e^+$ among these final states can probe the neutrino mass ordering in $μ$TRISTAN experiment at 5$σ$ significance. In addition to that we study the production of positively charged triplet fermion in $μ$TRISTAN following $μ^+ μ^+ \to μ^+ Σ^+$ process where $Σ^+$ decays into $μ^+ jj$ mode through $Z$ boson exchange. Considering a triplet at 1 TeV and studying SM backgrounds we estimate the discovery potential of $μ^+ μ^+ jj$ signal at $μ$TRISTAN with respect to projected luminosity.

hep-ph

Multi-Lepton Jets from Quadruple $Z'$ via the Higgs Decay at LHC

We investigate multi-lepton jet events from the decay of the 125 GeV Higgs boson ($h$) into quadruple new gauge bosons $(Z')$ at the LHC. Such an exotic decay is realized via the process of $h \to ϕϕ\to Z'Z'Z'Z'$ with new scalar boson $ϕ$ in models with an additional $U(1)$ gauge symmetry. Charged leptons coming from the $Z'$ decay tend to be observed as lepton-jets rather than isolated leptons when the masses of $Z'$ and $ϕ$ are smaller than ${\cal O}$(10) GeV, because of the highly-boosted effects. Performing the signal and background analyses, we find that the branching ratio of $h \to 4Z'$ is maximally constrained to be smaller than of order $10^{-6}$ ($10^{-7}$) by using the muonic-lepton jets assuming the integrated luminosity of 140 fb$^{-1}$ (3000 fb$^{-1}$) at LHC. For lighter $Z'$ ($< 2m_μ$), we can use the electronic-lepton jets instead of the muon-jets, by which the upper limit on the branching ratio is obtained to be of order $10^{-6}$-$10^{-5}$. These bounds can be converted into the constraint on model parameters such as a mixing angle between $h$ and $ϕ$. It is shown that stronger bounds on the mixing angle are obtained in the dark photon case as compared with the previous constraints given by flavor experiments and the Higgs decay $h \to Z'Z'$ in the mass range of $m_{Z'}\lesssim 10$ GeV.

hep-ph

FPF@FCC: Neutrino, QCD, and BSM Physics Opportunities with Far-Forward Experiments at a 100 TeV Proton Collider

Proton-proton collisions at energy-frontier facilities produce an intense flux of high-energy light particles, including neutrinos, in the forward direction. At the LHC, these particles are currently being studied with the far-forward experiments FASER/FASER$ν$ and SND@LHC, while new dedicated experiments have been proposed in the context of a Forward Physics Facility (FPF) operating at the HL-LHC. Here we present a first quantitative exploration of the reach for neutrino, QCD, and BSM physics of far-forward experiments integrated within the proposed Future Circular Collider (FCC) project as part of its proton-proton collision program (FCC-hh) at $\sqrt{s} \simeq 100$ TeV. We find that $10^9$ electron/muon neutrinos and $10^7$ tau neutrinos could be detected, an increase of several orders of magnitude compared to (HL-)LHC yields. We study the impact of neutrino DIS measurements at the FPF@FCC to constrain the unpolarised and spin partonic structure of the nucleon and assess their sensitivity to nuclear dynamics down to $x \sim 10^{-9}$ with neutrinos produced in proton-lead collisions. We demonstrate that the FPF@FCC could measure the neutrino charge radius for $ν_{e}$ and $ν_μ$ and reach down to five times the SM value for $ν_τ$. We fingerprint the BSM sensitivity of the FPF@FCC for a variety of models, including dark Higgs bosons, relaxion-type scenarios, quirks, and millicharged particles, finding that these experiments would be able to discover LLPs with masses as large as 50 GeV and couplings as small as $10^{-8}$, and quirks with masses up to 10 TeV. Our study highlights the remarkable opportunities made possible by integrating far-forward experiments into the FCC project, and it provides new motivation for the FPF at the HL-LHC as an essential precedent to optimize the forward physics experiments that will enable the FCC to achieve its full physics potential.

hep-ph

Dark photon constraints from a 7.139 GHz cavity haloscope experiment

The dark photon is a promising candidate for the dark matter which comprises most of the matter in our visible Universe. Via kinetic mixing with the Standard Model it can also be resonantly converted to photons in an electromagnetic cavity, offering novel experimental possibilities for the discovery and study of dark matter. We report the results of a pathfinder dark photon dark matter cavity search experiment performed at Hunan Normal University and the Institute of Physics, Chinese Academy of Sciences, representing the first stage of the APEX (Axion and dark Photon EXperiment) program. Finding no statistically significant excess, we place an upper limit on the kinetic mixing parameter $|χ|<3.7\times 10^{-13}$ around $m_A\simeq 29.5$ $μ$eV at 90% confidence level. This result exceeds other constraints on dark photon dark matter in this frequency range by roughly an order of magnitude.

hep-ex

Discovering Quirks through Timing at FASER and Future Forward Experiments at the LHC

Quirks are generic predictions of strongly-coupled dark sectors. For weak-scale masses and a broad range of confining scales in the dark sector, quirks can be discovered only at the energy frontier, but quirk--anti-quirk pairs are produced with unusual signatures at low $p_T$, making them difficult to detect at the large LHC detectors. We determine the prospects for discovering quirks using timing information at FASER, FASER2, and an "ultimate detector" in the far-forward region at the LHC. NLO QCD corrections are incorporated in the simulation of quirk production, which can significantly increase the production rate. To accurately propagate quirk pairs from the ATLAS interaction point to the forward detectors, the ionization energy loss of charged quirks traveling through matter, the radiation of infracolor glueballs and QCD hadrons during quirk pair oscillations, and the annihilation of quirkonium are properly considered. The quirk signal is separated from the large muon background using timing information from scintillator detectors by requiring either two coincident delayed tracks, based on arrival times at the detector, or two coincident slow tracks, based on time differences between hits in the front and back scintillators. We find that simple cuts preserve much of the signal, but reduce the muon background to negligible levels. With the data already collected, FASER can discover quirks in currently unconstrained parameter space. FASER2, running at the Forward Physics Facility during the HL-LHC era, will greatly extend this reach, probing the TeV-scale quirk masses motivated by the gauge hierarchy problem for the broad range of dark-sector confining scales between 100 eV and 100 keV.

hep-ph

Detection prospects of long-lived quirk pairs at the LHC far detectors

We examine the sensitivity reaches of several LHC far detectors, such as FASER2, MATHUSLA, ANUBIS, SND@LHC, and FACET, to five simplified quirk scenarios. We include the next-to-leading order QCD corrections in our simulation of quirk events, which enhance the total production rate and increase the fraction of events in the forward direction for most cases. We calculate the time scales for the quirk pair to lose energy through radiations and for the quirk pair annihilation. Our results show that these far detectors can offer promising probes to the quirk scenario, complementing the searches at the main detectors. Especially, FACET and FASER2 detectors can surpass the majority of searches conducted at the LHC main detector, with the exception of the HSCP search, for the color-neutral quirk $\mathcal{E}$.

hep-ph

Calibration of the Cryogenic Measurement System of a Resonant Haloscope Cavity

Possible light bosonic dark matter interactions with the Standard Model photon have been searched by microwave resonant cavities. In this paper, we demonstrate the cryogenic readout system calibration of a 7.138 GHz copper cavity with a loaded quality factor $Q_l=10^4$, operated at 22 mK temperature based on a dilution refrigerator. Our readout system consists of High Electron Mobility Transistors as cryogenic amplifiers at 4 K, plus room-temperature amplifiers and a spectrum analyzer for signal power detection. We test the system with a superconducting two-level system as a single-photon source in the microwave frequency regime and report an overall 95.6 dB system gain and -71.4 dB attenuation in the cavity's input channel. The effective noise temperature of the measurement system is 7.5 K.

hep-ex

Probing for chiral $Z^\prime$ gauge boson through scattering measurement experiments

Motivated by the observation of tiny neutrino mass can not be explained within the framework of Standard Model (SM), we consider extra gauge extended scenarios in which tiny neutrino masses are generated through seesaw mechanism. These scenarios are equipped with beyond the standard model (BSM) neutral gauge boson called $Z^\prime$ in the general $U(1)_X$ symmetry which is a linear combination of $U(1)_Y$ and $U(1)_{B-L}$. In this case, left and right handed fermions interact differently with the $Z^\prime$. The $Z^\prime$ gives rise to different processes involving neutrino-nucleon, neutrino-electron, electron-nucleus and electron-muon scattering processes. By comparing with proton, electron beam-dump experiments data, recast data from searches for the long-lived and dark photon at BaBaR, LHCb and CMS experiments, the electron and muon $g-2$ data, and the data of the dilepton and dijet searches at the LEP experiment, we derive bounds on the gauge coupling and the corresponding gauge boson mass for different $U(1)_X$ charges and evaluate the prospective limits from the future beam-dump scenarios at DUNE, FASER(2) and ILC. We conclude that large parameter regions could be probed by scattering, beam-dump and collider experiments in future.

hep-ph

Automatic detection of boosted Higgs boson and top quark jets in an event image

We build a deep neural network based on the Mask R-CNN framework to detect the Higgs jets and top quark jets in any event image. We propose an algorithm to assign the top quark final states at the ground truth level so that the network can be trained in a supervised manner. A new jet branch is added to the network, which uses constituent information to predict the four-momenta of the original parton, thus intrinsically implementing the pileup mitigation. The network can predict both the shapes and the momenta of target jets. We show that the network surpasses the LorentzNet in top and Higgs tagging and the PELICAN network in momentum regression for certain cases, in terms of reconstruction efficiency and accuracy. We also show that the performance of the network does not degrade much when applied to events of a process different from the trained one and to events with overlapping jets.

hep-ph

Boosting indirect detection of a secluded dark matter sector

Dark Matter (DM) residing in a secluded sector with suppressed portal interaction could evade direct detections and collider searches. The indirect detections provide the most robust probe to this scenario. Depending on the structure of the dark sector, novel DM annihilation spectra are possible. The dark shower is a common phenomenon for particles in the dark sector which take part in strong interactions and are boosted. In terms of simplified two-component DM models with vector portal interaction and pseudoscalar portal interaction, we study the dark showering effects for DM indirect detection. In those models, the heavier DM component which dominates the relic density annihilates into boosted lighter species. Together with the large coupling through which the lighter DM annihilates away in the early universe, the showered spectra provide as the smoking gun for the DM existence. Considering bounds obtained by the AMS-02 positron data and Fermi-LAT measurement of gamma-ray from the dwarf galaxies, we find the dark shower could open a new region of sensitivity that can not be probed before.

hep-ph

Investigating the collinear splitting effects of boosted dark matter at neutrino detectors

We study the probing prospects of cosmic ray boosted dark matter (DM) in the framework of simplified electron-philic dark photon model. Focusing on the dark matter and dark photon masses around keV $\sim $ MeV scale, we consider the bounds obtained from the XENON1T and Super-K experiments. The electron bound state effects are treated carefully in calculating the XENON1T constraint. As for the detection at neutrino detector where the energy threshold is relatively higher, the large logarithmic effects induced by the scale hierarchy between the masses and momentum transfer are considered by introducing the DM parton distribution function (PDF). The logarithmic effects will reduce the electron recoil rate for DM scattering in neutrino detectors. Moreover, we find the DUNE and JUNO experiments provide high sensitivities for probing the dark photon component in the DM PDF through the dark Compton process. We also check the Bullet Cluster constraint on the DM self-scattering cross section.

hep-ph