arXiv subjects

Hongxin Dong

Publications and source records attributed to Hongxin Dong.

6 recordsLinked to original sources

arXiv2025

Total Gluon Helicity Contribution to the Proton Spin from Lattice QCD

We report a state-of-the-art lattice QCD calculation of the total gluon helicity contribution to the proton spin, $\Delta G$. The calculation is done on ensembles with three different lattice spacings $a=\{0.08, 0.09, 0.11\}$ fm. By employing distillation and momentum smearing for proton external states, we extract the bare matrix elements of the topological current $K^\mu$ using 5-HYP smeared Coulomb gauge fixing configurations. Furthermore, we apply a non-perturbative $\mathrm{RI/MOM}$ renormalization scheme augmented by the Cluster Decomposition Error Reduction (CDER) technique to determine the renormalization constants of $K^\mu$. The results obtained from different components $K^{t,i}$ (with $i$ being the direction of proton momentum or polarization) are consistent with Lorentz covariance within uncertainties. After extrapolating to the continuum limit, $\Delta G$ is found to be $\Delta G = 0.231(17)^{\mathrm{sta.}}(44)^{\mathrm{sym.}}$ at the $\overline{\mathrm{MS}}$ scale ${\mu}^2=10\ \mathrm{GeV}^2$, which constitutes approximately $46(9)\%$ of the proton spin.

hep-lat↗

arXiv2025

Unpolarized gluon PDF of the nucleon from lattice QCD at physical point in the continuum limit

We report a state-of-the-art lattice QCD calculation of the nucleon unpolarized gluon parton distribution function employing large-momentum effective theory. The calculation is carried out on the 2+1 flavor CLQCD ensembles with five lattice spacings a={0.105,0.0897,0.0775, 0.0688, 0.0519} fm and various pion masses ranging from 136 MeV to 317 MeV, covering nulceon momenta up to 3 GeV. Distillation technique is applied to improve the signal of two-point correlators. We then apply the state-of-the-art hybrid renormalization and one-loop perturbative matching, and extrapolate the result to the continuum limit, infinite momentum limit and physical pion mass.

hep-lat↗

arXiv2024

Global analysis of Sivers and Collins asymmetries within the TMD factorization

We present a global analysis of Sivers functions, transversity distribution functions, and Collins fragmentation functions within the transverse momentum dependent factorization. This analysis encompasses the latest data from semi-inclusive deep inelastic scattering, Drell-Yan, and W/Z-boson production processes as recently reported by the COMPASS and STAR Collaborations. Upon integrating the new data into our fitting, the precision of the extracted d and dbar quark Sivers and transversity distributions, as well as the tensor charge, is notably improved.

hep-ph↗

arXiv2023

Role of sea quarks in the nucleon transverse spin

We present a phenomenological extraction of transversity distribution functions and Collins fragmentation functions by simultaneously fitting to semi-inclusive deep inelastic scattering and electron-positron annihilation data. The analysis is performed within the transverse momentum dependent factorization formalism, and sea quark transversity distributions are taken into account for the first time. We find the $\bar u$ quark favors a negative transversity distribution while that of the $\bar d$ quark is consistent with zero according to the current accuracy. In addition, based on a combined analysis of world data and simulated data, we quantitatively demonstrate the impact of the proposed Electron-ion Collider in China on precise determinations of the transversity distributions, especially for sea quarks, and the Collins fragmentation functions.

hep-ph↗

arXiv2022

Probing the $Hγγ$ coupling via Higgs exclusive decay into quarkonia plus a photon at the HL-LHC

It is well know that the precise measurement of $H\toγγ$ can generate two degenerate parameter spaces of $Hγγ$ anomalous coupling. We propose to utilize the exclusive Higgs rare decays $H\toΥ(ns)+γ$ to break above mentioned degeneracy and further to constrain the $Hγγ$ anomalous coupling at the HL-LHC. We demonstrate that the branching ratios of $H\toΥ(ns)+γ$ can be significantly enhanced in the non-SM-like parameter space from $H\toγγ$ measurement, due to the destructive interference between the direct and indirect production of $Υ(ns)$ in the SM. By applying the NRQCD factorization formalism, we calculate the partial decay widths of $H\toΥ(ns)+γ$ at the NLO accuracy of $α_s$. We show that it is hopeful to break such degenerate parameter space at the HL-LHC if we can further highly suppress the background and enhance the signal efficiency compared to the ATLAS preliminary simulation.

hep-ph↗

arXiv2022

Probing the $Zb\bar{b}$ anomalous couplings via exclusive $Z$ boson decay

We propose to utilize the exclusive $Z$-boson rare decays $Z\to Υ(ns)+γ$ to constrain the $Zb\bar{b}$ couplings at the HL-LHC and 100 TeV proton-proton collider. We demonstrate that the event yield of the proposed processes is sensitive to the axial-vector component of the $Zb\bar{b}$ coupling and can provide complementary information to the jet-charge weighted single-spin asymmetry measurement at the EIC and the $gg\to Zh$ production rate measurement at the LHC. By applying the NRQCD factorization formalism, we calculate the partial decay width of $Z\to Υ(ns)+γ$ to the NLO accuracy in strong interaction, which is found to agree with those obtained from the light-cone distribution amplitude approach. We show that the HL-LHC can break the degeneracy of the $Zb\bar{b}$ couplings, as implied by the precision electroweak data at LEP and SLC, if the signal efficiency can be improved by a factor of 1.7 from the present ATLAS analysis at the 13 TeV LHC with an integrated luminosity of $36.1~{\rm fb}^{-1}$.

hep-ph↗