arXiv subjects

Qi-Ming Feng

Publications and source records attributed to Qi-Ming Feng.

6 recordsLinked to original sources

arXiv2026

Exclusive Leptonium Electroproduction

Purely leptonic bound states provide precision probes of QED. Positronium $(e^+e^-)$ and muonium $(\mu^+e^-)$ have long been observed, whereas dimuonium $(\mu^+\mu^-)$ and tauonium $(\tau^+\tau^-)$ remain undiscovered. We study exclusive vector-leptonium electroproduction in $ep$ collisions within nonrelativistic QED. We include the Bethe--Heitler and double deeply virtual Compton scattering contributions and their interference, and calculate the NLO QCD hard-scattering kernels entering the dominant Compton form factor $\Hcal$ within collinear GPD factorization. The NLO QCD correction to the DDVCS contribution changes from a strong suppression at low photon virtuality to a sizable enhancement as the lower virtuality cut is raised, with the gluon channel providing the dominant contribution. Bethe--Heitler production dominates the exclusive rate, supporting dedicated dimuonium searches at the EIC and JLab, with larger samples expected at higher-energy electron--proton colliders. The much larger positronium samples provide a high-statistics environment for precision QED studies, whereas tauonium production remains strongly suppressed.

hep-ph↗

arXiv2026

True Leptonium ($l^+ l^-$) Production in UPC Triphoton Interaction

True leptonium states ($l^+ l^-$) are compact pure QED systems, first theoretically predicted eight decades ago. Although considerable efforts have been devoted to their search, only positronium has been experimentally confirmed shortly after its theoretical prediction. By contrast, dimuonium ($\mu^+ \mu^-$) and tauonium ($\tau^+ \tau^-$) remain unobserved to date, partly due to their low production yields. In this work, we find that a significant number of ortho-leptonium states can be generated through the triphoton interaction process in ultraperipheral heavy-ion collisions (UPCs). In this process, two photons are emitted from one beam, while the third photon originates from the other beam. This unique interaction mechanism thus provides a distinctive opportunity to pinpoint dimuonium and tauonium. Moreover, within the three-body interaction mechanism, we find that the experimental data for $J/\psi$ production and dimuon production in ultraperipheral Pb+Pb collisions at the Large Hadron Collider (LHC) can be well reproduced.

hep-ph↗

arXiv2025

NLO Corrections to Dimuonium Production in Photon-Photon Collision

Dimuonium ($\mu^+ \mu^-$) is one of the pure QED bound systems of leptons, together with positronium and ditauonium. The former had been observed in experiment in 1951, while the search for dimuonium and ditauonium ($\tau^+ \tau^-$) are still in vain. The ditauonium is thought to be hard to measure due to its short life time, whereas the dimuonium is very likely to be observed in current running experiments. We calculate in this work the para and ortho dimuonium production in photon-photon collision at the next-to-leading order (NLO) in QED. To handle the Coulomb divergence within the bound system, the non-relativistic QED description is adopted for consistency. The results indicate that the NLO corrections are negative for both para and ortho states, at the normal order of perturbative QED corrections. The measurement of the dimuonium in Belle II experiment, especially at the forthcoming facility of STCF, is tenable.

hep-ph↗

arXiv2025

$J/\psi$ Polarization and $p_T$ distribution in $c\ \!\bar{c}$ associated hadroproduction at $\mathcal{O}(\alpha_s^5)$

The quarkonium production in association with a heavy-quark pair of the same flavor was found plays an important role in various production schemes, let alone it provides a distinctive signature that could be studied in experiment. Within the NRQCD framework, we perform the first complete calculation of the hadroproduction process $gg\to J/\psi+c\bar{c}$ at the next-to-leading order (NLO) in the expansion of strong coupling constant $\alpha_s$. The result tells that the NLO corrections substantially enhance the color-singlet yield and alter the predicted polarization patterns, and hence lead to a better agreement with experimental data across the $p_T$ spectrum. In contrast to charm-quark fragmentation, the $J/\psi$ and $c\bar{c}$ associated production channel displays a markedly different kinematic behavior, underscoring its distinct role in the production mechanism. While the inclusion of this process greatly reduces the discrepancy between color-singlet theoretical prediction and experimental measurement, a residual gap of approximately one order of magnitude still remains.

hep-ph↗

arXiv2025

Higgs boson decays to a fermion pair and a polarized $Z$ boson at NLO accuracy

In this paper, we investigate the Higgs boson decay process $H\to f\bar{f}Z\to f\bar{f}μ^-μ^+$, where $f$ denotes any light fermions, at the next-to-leading order (NLO) accuracy. The calculation is performed within the framework of single-pole approximation, in which the contributions of different polarization states of the $Z$ boson are considered separately. Numerical results show that, by taking appropriate cut, the non-resonant background is negligible, and the NLO corrections are $1\%$--$4\%$ of the LO contributions. We also find that the inclusion of NLO corrections can greatly reduce the dependence on the electroweak coupling scheme, and enhance the prediction reliability. We formulate a method for the extraction of the pseudo-observable $Γ^{H\to ffZ}$ from the $f\bar{f}μ^-μ^+$ signal.

hep-ph↗

arXiv2024

NLO corrections to $J/ψ+c+\bar{c}$ photoproduction

Based on the factorization framework of nonrelativistic quantum chromodynamics, we study the associated $J/ψ+c+\bar{c}$ photoproduction process at next-to-leading order in $α_s$ and leading order in the velocity expansion. The total cross section and differential cross section in $p_T^2$, $W$ and $z$ are presented. The results indicate that the next-to-leading order corrections are substantial, and testable in experiment.

hep-ph↗