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Yunyun Zhang

Publications and source records attributed to Yunyun Zhang.

4 recordsLinked to original sources
arXiv2026

Optimizing Neural Network Architecture for Medical Image Segmentation Using Monte Carlo Tree Search

This paper proposes a novel medical image segmentation framework, MNAS-Unet, which combines Monte Carlo Tree Search (MCTS) and Neural Architecture Search (NAS). MNAS-Unet dynamically explores promising network architectures through MCTS, significantly enhancing the efficiency and accuracy of architecture search. It also optimizes the DownSC and UpSC unit structures, enabling fast and precise model adjustments. Experimental results demonstrate that MNAS-Unet outperforms NAS-Unet and other state-of-the-art models in segmentation accuracy on several medical image datasets, including PROMISE12, Ultrasound Nerve, and CHAOS. Furthermore, compared with NAS-Unet, MNAS-Unet reduces the architecture search budget by 54% (early stopping at 139 epochs versus 300 epochs under the same search setting), while achieving a lightweight model with only 0.6M parameters and lower GPU memory consumption, which further improves its practical applicability. These results suggest that MNAS-Unet can improve search efficiency while maintaining competitive segmentation accuracy under practical resource constraints.

cs.CV↗
arXiv2021

Study of $ B_{u,d,s} \to K_0^*(1430) P $ and $K_0^*(1430) V$ decays within QCD factorization

We study the nonleptonic charmless $B_{u,d,s} \to K_0^*(1430)P$ $(P=K\,, π)$ and $ K_0^*(1430)V$ $ (V=K^*\,, ρ\,, ω\,, ϕ)$ decays. The amplitudes are calculated within the QCD factorization, and the non-perturbative quantities are evaluated by using a covariant light-front approach. The branching fractions and CP asymmetries of theses decay modes are calculated, some decay modes are first predicted, and some useful relations based on $SU(3)$ flavor symmetry are discussed. Comparing the theoretical results with the current available experimental data, it is found that $K_0^*(1430)$ can be described as the lowest-lying p-wave $(s,u/d)$ state rather than the first excited one.

hep-ph↗
arXiv2019

Contributions from $Φ_{B2}$ to the $B$ ${\to}$ $PP$ decays within the QCD factorization

With the potential for the improvements of measurement precision,the refinement of theoretical calculation on hadronic $B$ weak decays is necessary. In this paper, we study the contributions of $B$ mesonic distribution amplitude $Φ_{B2}$ within the QCD factorization approach, and find that $Φ_{B2}$ contributes to only the nonfactorizable annihilation amplitudes for the $B$ ${\to}$ $PP$ decays ($P$ denotes the ground $SU(3)$ pseudoscalar mesons). Although small, the $Φ_{B2}$ contributions might be helpful for improving the performance of the QCD factorization approach, especially for the pure annihilation $B_{d}$ ${\to}$ $K^{+}K^{-}$ and $B_{s}$ ${\to}$ $π^{+}π^{-}$ decays.

hep-ph↗
arXiv2019

Study of $\bar{B}_{u,d,s}^* \to D_{u,d,s}^* V\,(V=D_{d,s}^{*-}\,,K^{*-}\,,ρ^-)$ weak decays

Motivated by the rapid development of heavy flavor physics experiment, we study the tree-dominated nonleptonic $\bar{B}_{u,d,s}^* \to D_{u,d,s}^*V$~($V=D^{*-},D_s^{*-},K^{*-},ρ^-$) decays within the factorization approach. The relevant transition form factors are calculated by employing the covariant light-front quark model. The helicity amplitudes are calculated and analyzed in detail, and a very clear hierarchy structure $ |H_{-0}| \approx 2|H_{00}| > |H_{0-}|\approx|H_{--}|>|H_{0+}|\approx|H_{++}|$ is presented. The branching fractions are computed and discussed. Numerically, the CKM-favored $\bar{B}^*_q\to D^*_q ρ^{-}$ and $D^*_q D_s^{*-}$ decays have relatively large branching fractions, $\gtrsim {\cal O}(10^{-8})$, and are hopeful to be observed by LHC and Belle-II experiments in the future.

hep-ph↗