Associated ${\rm Y}+b+\overline{b}$ production at the Fermilab Tevatron and CERN LHC

In the framework of perturbative QCD and nonrelativistic bound state formalism, we calculate the production of ${\rm Y}$ mesons associated with open-beauty particles at the Tevatron and LHC conditions. We show that the contribution from the ${\rm Y}+b+\overline{b}$ channel becomes comparable with that of ${\rm Y}$ sole production at the LHC at high enough transverse momenta, but is small at the Tevatron. We investigate the ${\rm Y}$ polarization effects and kinematic correlations between ${\rm Y}$ mesons and the accompanying open-beauty mesons. We show that the correlations are sensitive to the initial $k_t$ of the colliding partons, and so, can be considered as an additional test discriminating the collinear parton model and the $k_t$-factorization approach.

Figure 1

Feynman diagrams representing the subprocess $g+g\to {\rm Y}+b+\overline{b}$.

Figure 2

${\rm Y}+b+\overline{b}$ production at the Tevatron. Upper panel, ${\rm Y}$ transverse momentum distribution; middle panel, bottom meson transverse momentum distribution; lower panel, the ratio of the ${\rm Y}+b+\overline{b}$ production cross section to the nonassociated ${\rm Y}$ production. Solid histograms, predictions of the collinear parton model; dashed and dash-dotted histograms, $k_t$-factorization approach with JB [12] and dGRV [4] gluon densities, respectively.

Figure 3

Same as Fig. 2, for the LHC conditions.

Figure 4

${\rm Y}+b+\overline{b}$ production at the Tevatron. ${\rm Y}$ and bottom meson rapidity distributions. Notation of the curves is as in Fig. 2.

Figure 5

Same as Fig. 4, for the LHC conditions.

Figure 6

${\rm Y}+b+\overline{b}$ production at the Tevatron. Kinematic correlations between the ${\rm Y}$ and accompanying bottom mesons. Upper panel, azimuthal angle difference; middle panel, pseudorapidity difference; lower panel, combined variable $\Delta R=\sqrt{(\Delta \phi {)}^2+(\Delta \eta {)}^2}$. Notation of the curves is as in Fig. 2.

Figure 7

Same as Fig. 6, for the LHC conditions.

Figure 8

${\rm Y}+b+\overline{b}$ production at the Tevatron. The fraction of longitudinally polarized ${\rm Y}$ mesons as a function of ${\rm Y}$ transverse momentum, ${\rm Y}$ rapidity, ${\rm Y}-B$ azimuthal angle difference, and ${\rm Y}-B$ pseudorapidity difference, from top to bottom, respectively. Notation of the curves is as in Fig. 2.