Heavy flavor particle production in p+p collisions at the CERN Large Hadron Collider energies

TL;DR

The paper addresses heavy-flavor production in proton-proton collisions at LHC energies and investigates the role of color-string junctions in hadronization by comparing ALICE and LHCb data for prompts $\Lambda_c^+$, $D^0$, $\Lambda_b^0$, $B^0$, and $\bar{B}^0$ with PYTHIA-8.314 tunes that include string-junction dynamics. It employs multiple tunes (e.g., MON, SJ, SJ_RC, DJ, DJ_MOD, mb4.2) to generate $pp$ events at $\sqrt{s}=7$ and $13$ TeV, computing differential cross-sections via $\frac{d^2\sigma}{dp_T dy}=\frac{1}{L_{int}}\frac{d^2N}{dp_T dy}$ and comparing to data for $p_T$-dependent yields and heavy-flavor baryon/meson ratios. The study finds that no single tuning describes all observables; $\text{PYTHIA_SJ_DJ_MOD}$ best reproduces ALICE charm data, while $\text{PYTHIA_SJ_RC_MOD}$ (and its $m_b$-adjusted variant) best describes LHCb charm and bottom results, highlighting the substantial impact of string-junction dynamics and fragmentation parameters on heavy-flavor hadronization modeling. Overall, the work demonstrates the need for refined QCD hadronization models and provides guidance for future tuning to simultaneously describe ALICE and LHCb measurements at multiple energies.

Abstract

The study of heavy-flavored baryon and meson production in proton-proton (pp) collisions provides crucial insight into the hadronization mechanisms of Quantum Chromodynamics (QCD). In this work an attempt has been made to describe the existing ALICE and LHCb results on the $p_\mathrm{T}$-differential production cross-section of $Λ_c^+$, $D^0$, $Λ_b^0$ and $B^0$ ($\bar{B}^0$), and $p_\mathrm{T}$-dependent $Λ_c^+/D^0$ and $Λ_b^0/B^0(\bar{B}^0)$ ratios, in light of the color-string junction inspired PYTHIA-8.314 model. A comparison of the results obtained with various datasets generated with different tuning parameters and the existing experimental results of ALICE and LHCb at $\sqrt{s} = 7$ and $13$ TeV underlines the relevance of string-junction dynamics in heavy-flavored particle production. The results of the present investigation reveal that while stopping the junction-antijunction reconfiguration in the non-perturbative PYTHIA-8.314 model successfully describes the considered ALICE experimental observables of the charm sector, on the other hand, allowing junction-antijunction reconfiguration, keeping other fragmentation parameters the same, better describes the LHCb experimental observables of both charm and bottom sectors.

Figures (6)

• Figure 1: $p_\mathrm{T}$-dependent differential production cross-section of $\Lambda_c^+$ [(a), (c)] and $D^0$ [(b), (d)] measured by ALICE 2018PhysRevC.94.054908 and LHCb 20131 experiments in p+p collisions at $\sqrt{s}=$ 7 TeV respectively, compared with various model predictions. The error bars associated with the data points represent the statistical uncertainty, whereas the square boxes around the data points represent the systematic uncertainty. The shaded region around the solid and dashed lines represents the uncertainty associated with the models. The lower panel of each plot illustrates the ratio between the model and the experimental data points.
• Figure 2: Comparisons of $p_\mathrm{T}$-dependent $\Lambda_c^+/D^0$ ratio measured by (a) ALICE2018 and (b) LHCb201820131 in p+p collisions at $\sqrt{s}=$ 7 TeV with different model predictions. The error bars associated with the data-points represent the statistical uncertainty, whereas the square boxes around the data points represent the systematic uncertainty.
• Figure 3: Comparison of $p_\mathrm{T}$-dependent $\Lambda_c^+/D^0$ ratio measured by ALICE PhysRevLett.128.012001 in p+p collisions at $\sqrt{s}=$ 13 TeV with different model predictions. The error bars associated with the data-points represent the statistical uncertainty, whereas the square boxes around the data points represent the systematic uncertainty.
• Figure 4: A comparison of model predictions with the experimental $p_\mathrm{T}$-dependent differential production cross-section times branching ratio of (a) $\Lambda_b^0$ and (b) $\bar{B}^0$ measured by LHCb Aaij_2016 in p+p collisions at $\sqrt{s} =$ 7 TeV. The error bars associated with the data-points represent the statistical uncertainty, whereas the square boxes around the data points represent the systematic uncertainty.
• Figure 5: A comparison of model predictions with experimental $p_\mathrm{T}$-dependent (a) $\Lambda_b^0/\bar{B}^0$ and (b) $\Lambda_b^0/B^0$ ratio measured by LHCb Aaij_2016PhysRevLett.132.081901 in p+p collisions at $\sqrt{s}=$ 7 TeV and $\sqrt{s}=$ 13 TeV. The error bars associated with the data-points represent the statistical uncertainty, whereas the square boxes around the data points represent the systematic uncertainty.