Exploring differential two-particle correlations in $γp$ and low-multiplicity pp collisions using PYTHIA8

Abstract

A study of two-particle differential number ($B$) and transverse momentum ($P_{2}^\mathrm{CD}$) balance functions in photon-proton ($γp$) and proton-proton (pp) collisions at $\sqrt{s}=$ 5.36 TeV is presented. The analysis focuses on inclusive charged hadrons within the pseudorapidity coverage $|η|<2.4$ and the transverse momentum interval $0.3 < p_\mathrm{T} < 3.0$ GeV and examines their correlations in terms of relative pseudorapidity ($Δη$) and relative azimuthal angle ($Δφ$). The correlation functions are evaluated for same- and opposite-sign pairs, and their combinations are used to extract charge-dependent (CD) and charge-independent (CI) components. The evolution of the near-side peak of the CD correlations is investigated in terms of $Δη$ and $Δφ$ as a function of charged-particle multiplicity ($N_\mathrm{ch}$) for $γp$ collisions and compared to pp collisions at a similar multiplicity range. A clear multiplicity dependence of the balance function width is obtained. The width is found systematically lower in $γp$ events than in pp collisions. This study provides valuable information on particle correlations and production mechanisms in low-$N_\mathrm{ch}$ regimes for upcoming measurements in small systems.

Figures (9)

• Figure 1: Comparison of multiplicity ($N_\text{ch}$) and pseudorapidity ($\eta$) distributions of charged hadrons in MB pp, mb-like tune $\gamma\text{p}$ and $\gamma\text{p}$ collisions at $\sqrt{s}$ = 5.36 TeV.
• Figure 2: Comparison of average transverse momentum ($\langle p_{\mathrm{T}} \rangle$) as function of $N_\text{ch}$ for charged hadrons in MB pp, mb-like tune $\gamma\text{p}$ and $\gamma p$ collision at $\sqrt{s}$ = 5.36 TeV. Results are calculated for $|\eta|< 2.4$ and $0.3 < p_{\mathrm{T}} < 3.0$ GeV.
• Figure 3: Two-dimensional number balance functions ($B$) for $0 < N_{\mathrm{ch}} < 5$ (upper panel) and $40 < N_{\mathrm{ch}} < 50$ (lower panel) of charged-hadrons in mb-like tune pp (left), mb-like tune $\gamma\text{p}$ (middle), and $\gamma\text{p}$ (right) collisions at $\sqrt{s}=5.36$ TeV from pythia8. The results are obtained in the kinematic region $|\eta| < 2.4$ and $0.3 < p_{\mathrm{T}} < 3.0$ GeV.
• Figure 4: Two-dimensional momentum balance functions ($P_{2}^\mathrm{CD}$) for $0 < N_{\mathrm{ch}} < 5$ (upper panel) and $40 < N_{\mathrm{ch}} < 50$ (lower panel) of charged-hadrons in mb-like tune pp (left), mb-like tune $\gamma\text{p}$ (middle), and $\gamma\text{p}$ (right) collisions at $\sqrt{s}=5.36$ TeV from pythia8. The results are obtained in the kinematic region $|\eta| < 2.4$ and $0.3 < p_{\mathrm{T}} < 3.0$ GeV.
• Figure 5: One-dimensional near-side projection of the number balance functions ($B$) for $0 < N_{\mathrm{ch}} < 5$ (upper panel) and $40 < N_{\mathrm{ch}} < 50$ (lower panel) in mb-like tune pp (left), mb-like tune $\gamma\text{p}$ (middle), and $\gamma\text{p}$ (right) collisions at $\sqrt{s}=5.36$ TeV from pythia8. The results are obtained in the kinematic region $|\eta| < 2.4$ and $0.3 < p_{\mathrm{T}} < 3.0$ GeV for charged-hadrons.