Orbital-Selective Quasiparticle Depletion across the Density Wave Transition in Trilayer Nickelate La_{4}Ni_{3}O_{10}

We investigate the evolution of polarized electronic response in trilayer nickelate La_{4}Ni_{3}O_{10}, reporting a systematic reduction of the incoherent electron continuum across the density wave transition in the A_{1g} and B_{1g} representations. Analysis based on the Fermi surface band curvatures points to quasiparticle coherence in momentum positions with dominant d_{x^{2}-y^{2}} orbital character. Our findings establish the symmetry channels and the active role of d_{x^{2}-y^{2}} orbitals involved in the density wave formation, offering important insight into the electronic and magnetic correlations in the nickelate.