Due to their large mass, beauty quarks are produced in hard-scattering processes with large transferred momentum, allowing their production to be computed via perturbative quantum chromodynamics (pQCD) calculations. Measurements of beauty-hadron production cross sections in proton--proton (pp) collisions provide a sensitive test of these calculations. Theoretical calculations based on factorisation approach compute the transverse-momentum ($p_{\rm{T}}$)- and rapidity-differential hadron production cross sections as the convolution of three components: the parton distribution functions (PDFs) of the colliding protons; the partonic scattering cross section, expressed as a perturbative series expansion in the strong coupling constant; and the fragmentation function (FF), which describes the non-perturbative transition of the beauty quark into a given hadron. The FF is typically parameterised using measurements from $e^{+}e^{-}$ or ep collisions, under the assumption that the hadronisation process is universal, i.e., independent of the collision system. Measurements down to low $p_{\rm{T}}$ are fundamental for the estimation of the total $b\bar{b}$ production cross section. Insights into the beauty-quark hadronisation mechanisms are given by measurements of the relative abundances of different beauty-hadron species. Finally, measurements of beauty-hadron production cross sections in pp collisions provide a reference for Pb--Pb collisions, where effects due to the formation of a quark-gluon plasma are expected.

In this contribution, the recent measurement of the $\rm{B}^{0}$ production cross section in pp collisions at $\sqrt{s} = 13.6$ TeV performed by the ALICE Collaboration using data collected during LHC Run 3 is presented. The $\rm{B}^{0}$ mesons are fully reconstructed down to very low $p_{\rm{T}}$ in the decay channel $\rm{B}^0 \rightarrow \rm{D}^{-}\pi^{+}$. The measured production cross section is compared with state-of-the-art pQCD calculations, including recent calculations with next-to-next-to-leading order accuracy plus all-order resummation of next-to-next-to-leading logarithms.

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