Measurement of the $B^+$ Total Cross Section and $B^+$ Differential Cross Section $dσ/dp_T$ in $p \bar p $ Collisions at $\sqrt{s}=1.8$ TeV

TL;DR

This study measures the B^+ production cross section and its differential distribution dσ/dp_T in p p̄ collisions at √s = 1.8 TeV using B^± → J/ψ K^± with J/ψ → μ^+μ^- decays in Run 1 data from CDF. The analysis employs a full reconstruction approach, combining a detailed trigger and detector efficiency study with unbinned likelihood fits across four p_T bins to extract signal yields, acceptance, and luminosity corrections. The results show a total cross section σ_B(p_T>6.0 GeV/ c, |y|<1.0) = 3.6 ± 0.6 μb and a differential cross section that is about 2.9 times larger than NLO QCD predictions, though the observed shape agrees with theory. This work supersedes earlier Run 1A results and provides important constraints on heavy-flavor production and fragmentation at hadron colliders.

Abstract

We present measurements of the B+ meson total cross section and differential cross section $dσ/ dp_T$. The measurements use a $98\pm 4$ pb^{-1} sample of $p \bar p$ collisions at $\sqrt{s}=1.8$ TeV collected by the CDF detector. Charged $B$ meson candidates are reconstructed through the decay $B^{\pm} \to J/ψK^{\pm}$ with $J/ψ\to μ^+ μ^-$. The total cross section, measured in the central rapidity region $|y|<1.0$ for $p_T(B)>6.0$ GeV/$c$, is $3.6 \pm 0.6 ({\rm stat} \oplus {\rm syst)} μ$b. The measured differential cross section is substantially larger than typical QCD predictions calculated to next-to-leading order.

Figures (5)

• Figure 1: $B^{\pm}$ invariant mass distribution reconstructed from the decay $B^{\pm} \to J/\psi \, K^{\pm}$ . The curve is a binned fit to a Gaussian distribution plus linear background and is for illustration only.
• Figure 2: $B^{\pm}$ candidate mass distribution for the four $p_T$ ranges. The curve is a binned fit to a Gaussian distribution plus linear background and is for illustration only.
• Figure 3: $B^+$ meson differential cross measurements compared to the theoretical prediction. The solid curve is the theoretical prediction for $m_b = 4.75$ GeV/$c^2$, $\mu_0 =\sqrt{m_b^2 + p_T^2}$, $\epsilon_P = 0.006$ and $f_u = 0.375$. The dashed lines illustrate the changes in the theory once these parameters are varied as explained in the text.
• Figure 4: Plot of data/theory as a shape comparison with the NLO QCD differential cross section calculations.
• Figure 5: $B^{\pm}$ candidate mass distribution for $p_T(B)$$>$ 15 GeV/$c$. The curve is a binned fit to a Gaussian distribution plus linear background and is for illustration only.