Production ofχbmesons at the LHC

Abstract

In the present paper we discuss the P-wave bottomonium production within both color octet and color singlet models in next-to-leading order at LHC energies. We calculate the cross section and the transverse momentum distributions for the 1;2b states. We obtain that the ratios of bottomonium and charmonium spin state production are fundamentally complementary at different p T scales. We give predictions for the ratio of the n ¼ 2 and n ¼ 1 radial excitations production cross sections.

Measurement of the χ b (3P) mass and of the relative rate of χ b1(1P) and χ b2(1P) production

“…The ratio of efficiencies is given in table 5. This ratio differs from unity because the p Υ T spectrum is different for χ b1 and χ b2 in Pythia 8, as expected [8]. The ratio of efficiencies is also calculated assuming equal p T spectra.…”

“…According to ref. [8] the ratio of production cross-sections is expected to be the same for the χ b (3P ) and χ b (1P ) mesons and thus, using the measurement detailed in section 6, we obtain σ(χ b2 (nP ))/σ(χ b1 (nP )) = 0.9 ± 0.2. To summarise, the value r 12 = 0.47 × 0.9 = 0.42 is used in the fits to the mass distributions associated with the transitions of the χ b (3P ) meson to Υ (1S) and Υ (2S) mesons.…”

“…Measurements of the relative rate of J = 1 and J = 2 states provide information on the colour octet contribution. This relative rate is also predicted to have the same dependence on the meson transverse momentum (p T ) in χ b and χ c states, once the p T of the χ b meson is scaled by the ratio of χ c and χ b masses [8].…”

“…The common systematic uncertainty (9.0%) due to the branching fraction of χ b → Υ (1S)γ is not shown. Theory predicts the χ c and χ b ratio of production cross-section to be the same when the χ c p T value is scaled by the ratio of the χ b and χ c masses [8]. As the χ b (χ c ) and Υ (J/ψ ) p T are strongly correlated, this is assumed to be valid when replacing the χ b (χ c ) by the Υ (J/ψ ) p T .…”

“…Figure 4 (a) shows a comparison of the measured values with LO NRQCD predictions from ref. [8]. The common systematic uncertainty (9.0%) due to the branching fraction of χ b → Υ (1S)γ is not shown.…”