arXiv subjects

Hui-Xin Yu

Publications and source records attributed to Hui-Xin Yu.

3 recordsLinked to original sources

arXiv2026

Next-to-Leading-Order QCD Predictions for the $\Sigma$ Dirac Form Factors

In this work, we compute the next-to-leading-order QCD corrections to the Dirac electromagnetic form factors of the $\Sigma$ hyperons within the hard-collinear factorization framework at leading power. The corresponding short-distance coefficient functions are extracted from the relevant seven-point partonic correlation functions. We find that the one-loop radiative corrections to the leading-twist hard-scattering contributions are numerically significant over a broad range of momentum transfer. Combining the perturbatively calculated hard kernels with nonperturbative $\Sigma$ distribution amplitudes determined from lattice QCD, we present state-of-the-art theoretical predictions for the $\Sigma$ hyperon electromagnetic form factors.

hep-ph↗

arXiv2025

Next-to-Next-to-Leading-Order Corrections to the $B \to \pi $ Form Factors from Light-Cone Sum Rules

By incorporating the available leading-power results at $\mathcal{O}(\alpha_s)$ and next-to-leading-power corrections at tree level, we improve the precision of the theoretical predictions for $B\to\pi$ form factors to the $\mathcal{O}(\alpha_s^2\beta_0)$ level in the large-recoil region using the light-cone sum rule approach with $B$-meson light-cone distribution amplitudes. We find that the QCD corrections at $\mathcal{O}(\alpha_s^2\beta_0)$ contribute approximately $+6.1\%$ compared to the tree-level result. Combining the light-cone sum rule predictions in the large-recoil region, lattice QCD results in the small-recoil region, we perform a combined fit for the $B\to\pi$ form factors across the full kinematic range. Utilizing these form factors, we calculate the branching ratios, lepton-flavor-universality ratio $R_\pi$, forward-backward asymmetry $\mathcal{A}_{\rm FB}$, flat term $\mathcal{F}_{\rm H}$ and polarization asymmetry $\mathcal{A}_{\rm \lambda_\ell}$ of $B\to\pi\mu\bar{\nu}_{\mu}$ and $B\to\pi\tau\bar{\nu}_{\tau}$ decays. Using the experimentally measured $q^2$-binned differential branching ratios of $B\to\pi\mu\bar{\nu}_{\mu}$ decay as input, employing the Bourrely-Caprini-Lellouch parametrization, we extract the Cabibbo-Kobayashi-Maskawa matrix element $|V_{ub}| = 3.73(14) \times 10^{-3}$.

hep-ph↗

arXiv2024

Next-to-Next-to-Leading-Order QCD Prediction for the Pion Form Factor

We accomplish for the first time the two-loop computation of the leading-twist contribution to the pion electromagnetic form factor by employing the effective field theory formalism rigorously. The next-to-next-to-leading-order short-distance matching coefficient is determined by evaluating the appropriate $5$-point QCD amplitude with the modern multi-loop technique and subsequently by implementing the ultraviolet renormalization and infrared subtractions with the inclusion of evanescent operators. The renormalization/factorization scale independence of the obtained form factor is then validated explicitly at ${\cal O}(\alpha_s^3)$. The yielding two-loop QCD correction to this fundamental quantity turns out to be numerically significant at experimentally accessible momentum transfers. We further demonstrate that the newly computed two-loop radiative correction is highly beneficial for an improved determination of the leading-twist pion distribution amplitude.

hep-ph↗