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Abstract

We use the forward modeling approach to galaxy clustering combined with the likelihood from the effective-field theory of large-scale structure to measure assembly bias, i.e. the dependence of halo bias on properties beyond the total mass, in the linear (b₁) and second order bias parameters (b₂ and b_K²) of dark matter halos in N-body simulations. This is the first time that assembly bias in the tidal bias parameter b_K² is measured. We focus on three standard halo properties: the concentration c, spin λ, and sphericity s, for which we find an assembly bias signal in b_K² that is opposite to that in b₁. Specifically, at fixed mass, halos that get more (less) positively biased in b₁, get less (more) negatively biased in b_K². We also investigate the impact of assembly bias on the b₂(b₁) and b_K²(b₁) relations, and find that while the b₂(b₁) relation stays roughly unchanged, assembly bias strongly impacts the b_K²(b₁) relation. This impact likely extends also to the corresponding relation for galaxies, which motivates future studies to design better priors on b_K²(b₁) for use in cosmological constraints from galaxy clustering data.