Two-particle azimuthal correlations in γp interactions using pPb collisions at sNN=8.16TeV

Measurements of elliptic azimuthal anisotropies in 𝜸p interactions in pPb collisions with the CMS experiment

“…The comparison between the pythia8 predictions and the 𝛾p data reveals that 𝑉 2Δ and 𝑉 3Δ from pythia8 are reasonably consistent with the measured values. This consistency suggests that the model captures the observed dependencies of 𝑉 2Δ and 𝑉 3Δ on 𝑝 T [10].…”

“…However, neither distribution displays a "ridge" structure at |Δ𝜙| ≈ 0 for |Δ𝜂| > 2. Figure 2 (right) illustrates the correlation functions for 𝛾p-enhanced and MB events, showing the presence of jet peaks and recoiling jets [10]. These distributions are fitted over the range of Δ𝜙 [0, 𝜋] using a Fourier decomposition series with terms ∝ 1 + Σ n 2𝑉 𝑛Δ cos(𝑛Δ𝜙).…”

“…Notably, neither of these models includes collective effects. Despite the absence of collective effects in the simulations, both the data and the simulations exhibit a slow variation of 𝑣 2 with track multiplicity for the 𝛾p and pPb samples [9,10]. At a given 𝑁 trk , the 𝑣 2 values are larger in the higher 𝑝 T range.…”

“…These selected events are then used for the subsequent analysis of long-range correlations and the measurement of the 𝑉 nΔ coefficients. In the analysis of the 𝛾p-enhanced selection, a rapidity gap is defined as a continuous region with low detector activity [10]. The detector acceptance in terms of pseudorapidity is |𝜂| < 5.0, which covers a wide range of detector coverage.…”

“…Figure 4 presents the elliptic flow (𝑣 2 ) as a function of 𝑁 trk and 𝑝 T for both the 𝛾p and MB events [10]. The figure also includes predictions from the pythia8 generator for 𝛾p interactions and the hijing generator for MB pPb interactions.…”