The Second LHAASO Collaboration Conference in 2026 & The Academic Symposium for the 10th Anniversary of the LHAASO collaboration

Quasi-periodic oscillations (QPOs) in blazar gamma-ray emission offer valuable clues to jet dynamics and central-engine activity. With its wide field of view and long-term monitoring capability, LHAASO-WCDA provides an opportunity to search for such variability at TeV energies. We investigate the long-term WCDA light curves of Mrk 421 and Mrk 501 and compare them with Fermi-LAT observations over the corresponding periods. Wavelet-based time-frequency analysis is used to examine the persistence and evolution of candidate periodic features, with comparisons across different time binning schemes. Particular attention is given to the effects of red noise, the treatment of low-significance time bins, and multiple trials on the interpretation of candidate signals. We also use the Crab Nebula as a control source to investigate annual modulation and potential instrumental systematics. This poster presents the search procedure, preliminary results, and GeV–TeV comparisons, and discusses the robustness of candidate features and the next steps for their validation.