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arXiv · 2011.13401

Bottomonium production and polarization in the NRQCD with $k_T$-factorization. III: $Υ(1S)$ and $χ_b(1P)$ mesons

N. A. Abdulov·A. V. Lipatov
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Abstract

The $Υ(1S)$ meson production and polarization at high energies is studied in the framework of the $k_T$-factorization approach. Our consideration is based on the non-relativistic QCD formalism for a bound states formation and off-shell production amplitudes for hard partonic subprocesses. The direct production mechanism, feed-down contributions from radiative $χ_b(mP)$ decays and contributions from $Υ(3S)$ and $Υ(2S)$ decays are taken into account. The transverse momentum dependent (TMD) gluon densities in a proton were derived from the Ciafaloni-Catani-Fiorani-Marchesini evolution equation and the Kimber-Martin-Ryskin prescription. Treating the non-perturbative color octet transitions in terms of multipole radiation theory, we extract the corresponding non-perturbative matrix elements for $Υ(1S)$ and $χ_b(1P)$ mesons from a combined fit to transverse momenta distributions measured at various LHC experiments. Then we apply the extracted values to investigate the polarization parameters $λ_θ$, $λ_ϕ$ and $λ_{θϕ}$, which determine the $Υ(1S)$ spin density matrix. Our predictions have a reasonably good agreement with the currently available Tevatron and LHC data within the theoretical and experimental uncertainties.

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N. A. Abdulov, A. V. Lipatov. 2021-10-18. Bottomonium production and polarization in the NRQCD with $k_T$-factorization. III: $Υ(1S)$ and $χ_b(1P)$ mesons. https://doi.org/10.1140/epjc%2Fs10052-021-09880-5

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