arXiv subjects

Wei-Min Song

Publications and source records attributed to Wei-Min Song.

3 recordsLinked to original sources

arXiv2026

CKM determination from $W$ decays with jet flavor tagging at CEPC

This study investigates the sensitivity of the CEPC to CKM matrix elements $|V_{ij}|$ in semileptonic $W$-pair decays using simulated $e^+e^- \to W^+W^- \to \mu\nu \bar{q}q^\prime$ samples corresponding to $21.6\,\mathrm{ab}^{-1}$ at $\sqrt{s}=240\,\mathrm{GeV}$, with $|V_{ub}|$ excluded because of its negligible contribution. The projected statistical precisions reach $0.59\,\%$ for $|V_{cb}|$ and $0.01\,\%$ for $|V_{cs}|$, indicating that the CEPC can provide direct, high-precision, and largely model-independent determinations of CKM matrix elements from hadronic $W$ decays. The main sources of systematic uncertainty are discussed, and further improvements are expected from both experimental and theoretical developments, including dedicated data-driven calibrations of detector response and jet flavor tagging performance, as well as more precise higher-order calculations of the relevant electroweak and QCD corrections. Such measurements would provide stringent consistency tests of the Standard Model charged-current flavor structure and offer sensitivity to possible new physics effects through deviations from the Standard Model expectations.

hep-ex↗

arXiv2026

Precision $YN$ and $\bar{n}N$ measurements with an LH$_2$/LD$_2$ target in the BESIII detector

Located at the BEPCII $e^{+}e^{-}$ collider, the BESIII experiment provides a robust platform for investigating (anti)hyperon-nucleon ($YN$) and antineutron-nucleon ($\bar{n}N$) interactions. This is made possible by the high production cross-sections of $J/\psi$ and $\psi(3686)$ resonances and their substantial decay branches into these baryons. Although previous studies using the beam pipe as a target demonstrated feasibility, statistical precision remains constrained by the limited material budget. To address this, we propose installing a dedicated liquid hydrogen or liquid deuterium target between the beam pipe and the Cylindrical Gas Electron Multiplier Inner Tracker. Monte Carlo simulations confirm that the added material has a negligible effect on charged particle tracking. This upgrade is expected to enhance the effective luminosity for scattering on free protons by a factor of 10--30 for $\Lambda$, $\Sigma^{+}$, $\Xi$, and $\bar{n}$ beams, enabling high-precision measurements of $YN$ and $\bar{n}N$ interactions that will significantly advance our knowledge of non-perturbative strong interactions.

hep-ex↗

arXiv2024

Polarization study of the P-wave charmonium radiative decay into a light vector meson at $e^{+}e^{-}$ collider experiment

In this work, a formalism is presented for the helicity amplitude analysis of the decays $\psi(2S) \to \gamma_1 \chi_{cJ},~ \chi_{cJ} \to \gamma_2 V (V=\rho^0,~\phi,~\omega)$~(the subscript 1,2 is used to distinguish the two radiative photons), and the polarization expressions of the P-wave charmonia $\chi_{cJ}$ and the vector mesons $\rho^0, \phi, \omega$ for experimental measurements at Electron-Positron Collider. In addition, we derive the formulae of the angular distributions of the $\chi_{c1,2} \to \gamma V$ to extract the degree of transverse polarization $P_T$ of $e^+ e^-$ pairs with symmetric beam energy as well as the ratios of two helicity amplitudes $x$ (in $\chi_{c1}$ decays) and $x,~y$ (in $\chi_{c2}$ decays) representing the relative magnitudes of transverse to longitudinal polarization amplitude, and validate it by performing the Monte Carlo simulation. Finally, the statistical sensitivity of $P_T$, $x$ and $y$ are estimated based on the large $\psi(2S)$ data samples collected at the current and proposed future $e^+e^-$ collider experiment.

hep-ph↗