Heavy-Quark production in proton-nucleus collision at the LHC

TL;DR

The paper examines heavy-quark production in proton-nucleus collisions at the LHC as a probe of multiparton interactions. It develops a formalism for double parton scattering, separating contributions where two partons interact within one nucleon from those involving two different nucleons, and shows that the latter yields an anomalous, A-dependent enhancement not captured by simple shadowing. Using LO diagrams with rescaled higher-order effects, and incorporating $k_t$-factorization insights and realistic kinematics, the study finds large cross sections for multiple heavy-quark pairs and highlights the potential to measure longitudinal-transverse parton correlations via the $\sigma_A^D|_2$ term. The results underscore the significance of pA collisions as a laboratory for multiparton QCD dynamics, with practical predictions for charm and bottom quark production at the LHC and a fewfold theoretical uncertainty.

Abstract

A sizable rate of events, with several pairs of heavy-quarks produced contemporarily by multiple parton interactions, may be expected at very high energies as a consequence of the large parton luminosities. The production rates are enhanced in hadron-nucleus reactions, which may represent a convenient tool to study the phenomenon. We compare the different contributions to ccbar bbar pairs production due to single and double parton scatterings, in collisions of protons with nuclei at the CERN-LHC.

Figures (6)

• Figure 1: Relative weights of the terms with "anomalous" and "usual" $A$-dependence in the double scattering cross section for $b\bar{b} b \bar{b},\,c\bar{c} c \bar{c},\,b\bar{b} c \bar{c}$ production.
• Figure 2: Pseudorapidity distribution in a forward calorimeter of a heavy quark produced in events with $b\bar{b} b \bar{b}$, $c\bar{c} c \bar{c}$ and $b\bar{b} c \bar{c}$: one-nucleon (dashed lines) and two-nucleon contributions (continuous lines) in the case of a heavy (higher curves) and of a light nucleus (lower curves).
• Figure 3: Different contributions to the cross section of $b\bar{b} b \bar{b}$ production in a central and in a forward calorimeter as a function of $A$. Cross sections without any cut in $p_t$ (left figures) and after applying a cut of $10$ GeV in the transverse momenta of each produced heavy-quark (right figure): one-nucleon (dashed lines), two nucleons contribution (dotted lines) and total cross section (continuous lines).
• Figure 4: Different contributions to the cross section of $c\bar{c} c \bar{c}$ production in a central and in a forward calorimeter as a function of $A$. Cross sections without any cut in $p_t$ (left figures) and after applying a cut of $10$ GeV in the transverse momenta of each produced heavy-quark (right figure): one-nucleon (dashed lines), two nucleons contribution (dotted lines) and total cross section (continuous lines).
• Figure 5: Different contributions to the cross section of $b\bar{b} c \bar{c}$ production in a central and in a forward calorimeter as a function of $A$. Cross sections without any cut in $p_t$ (left figures) and after applying a cut of $10$ GeV in the transverse momenta of each produced heavy-quark (right figure): one-nucleon (dashed lines), two nucleons contribution (dotted lines) and total cross section (continuous lines).