IV Hot QCD Matter Conference 2026

Probing the role of color reconnection in the radial-flow observable $v_{0}(p_{\rm T})$ in pp collisions at $\sqrt{s} = 13.6$ TeV with PYTHIA8

Not scheduled

20m

Indian institute of Science Education and Research (IISER), Tirupati

Poster Presentation Collectivity and Bulk Dynamics from Small to Large Collision Systems

Speaker

Mr Rohit Agarwala (Department of Physics, Bodoland University)

Description

Color reconnection (CR) in PYTHIA8 is known to generate flow-like effects in small collision systems [1], yet its impact on the $p_{\rm T}$-differential radial-flow observable $v_{0}(p_{\rm T})$ has remained unexplored. Using the PYTHIA8 model, we study the effect of CR mechanism on the $v_{0}(p_{\rm T})$ observable in pp collisions at $\sqrt{s} = 13.6$ TeV. The inclusive $v_{0}(p_{\rm T})$ exhibits the characteristic sign change, negative at low-$p_{\rm T}$ and positive at intermediate-to-high-$p_{\rm T}$, qualitatively resembling recent heavy-ion measurements [2,3]. A pseudorapidity-gap ($\eta_{\rm gap}$) scan reveals a substantial short-range (non-flow) contribution that is progressively suppressed with increasing $\eta_{\rm gap}$. At $\eta_{\rm gap} = 0.8$, $v_{0}(p_{\rm T})$ is approximately independent of the reference-$p_{\rm T}$ interval (factorization) up to $p_{\rm T} \approx$ $1.5$ GeV/$c$, with deviations appearing at higher $p_{\rm T}$. Switching off CR leaves the $v_{0}(p_{\rm T})$ magnitude and factorization pattern nearly unchanged, suggesting a negligible role played by the CR mechanism on the estimated $v_{0}(p_{\rm T})$ observable.

References:

[1] A. Ortiz et al., Phys. Rev. Lett. 111, 042001 (2013).
[2] G. Aad et al. (ATLAS Collaboration), Phys. Rev. Lett. 136, 032301 (2026).
[3] S. Acharya et al. (ALICE Collaboration), Phys. Rev. Lett. 136, 032302 (2026).