Rise and Fall of the Bottom Quark Production Excess

TL;DR

The paper challenges the longstanding claim that bottom-quark production is systematically larger than NLO QCD predictions. It advocates a paradigm where comparisons are made to physical, observable cross sections with at least NLO accuracy, supplemented by minimal, data-driven non-perturbative input via LEP-derived fragmentation within the FONLL framework. A survey of gamma-gamma, gamma-p/ep, and p-pbar data shows that, once uncertainties and potential deconvolution biases are properly accounted for, the measurements are compatible with QCD predictions. The work concludes that no new physics is required to explain bottom production and emphasizes publishing observable-level results to enable robust future tests.

Abstract

We review the history of comparisons between bottom production measurements and QCD predictions. We challenge the existence of a `significant discrepancy', and argue that standard approaches to QCD calculations do a good job in describing the experimental findings.

Figures (5)

• Figure 1: Total cross sections for $\gamma\gamma\to c\bar{c}$ and $b\bar{b}$.
• Figure 2: One of the plots published in Chekanov:2003si of the observable cross sections measured by ZEUS and their comparisons to theoretical predictions.
• Figure 3: A collection of bottom quark production measurements and comparisons with theory. From top to bottom, left to right: a) the UA1 results Albajar:1990zu, b) a collection of CDF and D0 data, c) the CDF Run I $B^+$ cross section Acosta:2001rz, and d) the D0 $b$-jets cross section Abbott:2000iv.
• Figure 4: On the left (a), $B^+$ mesons production at the Tevatron and the new theoretical prediction. On the right (b), description of moments of $B$ fragmentation data at LEP with different non-perturbative fragmentation functions. Both plots from Cacciari:2002pa.
• Figure 5: CDF $J/\psi$ spectrum from $H_b$ decays, compared to theoretical predictions Cacciari:2003uh.