First Detection of Transverse Vertical Oscillation during the Expansion of Coronal Loops

In this Letter, we perform a detailed analysis of the M5.5-class eruptive flare occurring in active region 12929 on 2022 January 20. The eruption hot channel generates fast coronal mass ejection (CME) and dome-shaped extreme-ultraviolet (EUV) wave at speeds 740$-$860 km s$^{-1}$. CME is associated with type II radio burst, implying that EUV fast-mode shock wave. During impulsive phase, shows quasi-periodic pulsations (QPPs) EUV, hard X-ray, wavelengths. periods QPPs range from 18 s to 113 s, indicating energy released nonthermal electrons are accelerated intermittently multiple time scales. interaction between low-lying adjacent loops (ACLs) results contraction, expansion, transverse vertical oscillation ACLs. speed contraction 171, 193, 211 {\AA} higher than 304 {\AA}. 253 275 171 {\AA}, respectively. A new scenario proposed explain interaction. equation interprets overlying above core can also interpret expansion ACLs, suggesting two phenomena same essence.