Exploring the limit of partonic collectivity in small collision systems at the LHC
Abstract
The existence of a partonic phase in small collision systems has been investigated previously through measurements of the elliptic flow (v2) of mesons (π±, K±, and KS0) and baryons (p(p̅), Λ(Λ̅)) in high-multiplicity p-Pb collisions at √(sNN) = 5.02 TeV and pp collisions at √s = 13 TeV recorded by ALICE. The results have revealed a grouping and splitting behavior of v2 for baryons and mesons at intermediate transverse momentum (pT), establishing that partonic collectivity, as observed in heavy-ion collisions, is also present in these systems. In this Letter, the pT-differential v2 of various hadronic species is investigated in p-Pb collisions for the multiplicity intervals Nch ≥ 50, 25 ≤ Nch < 50, and 15 ≤ Nch < 25, as well as in pp collisions for 25 ≤ Nch < 50 and 15 ≤ Nch < 25. Here, Nch is the efficiency-corrected number of charged particles produced in the kinematic region of |η|< 0.8 and 0.2 < pT < 3.0 GeV/c. The characteristic mass dependence of v2, as well as the grouping and splitting patterns among identified particles, are examined. The results in both p-Pb and pp collisions with Nch ≥ 25 are consistent with the development of partonic collectivity. In the low-multiplicity region, 15 ≤ Nch < 25, the baryon-to-meson v2 splitting, as quantified by the baryon-to-meson v2 ratios, remains broadly consistent with that at higher multiplicities. However, its significance decreases to ∼2σ in p-Pb collisions and to less than 1σ in pp collisions owing to the sizable experimental uncertainties. These measurements constitute the first steps towards identifying the limits of partonic flow in small collision systems at the LHC.
Related
- Evidence of partonic collectivity in OO collisions through the measurement of ϕ, K0S, and Λ elliptic flow
- Exploring Collective Effects in Small Collision Systems via Light-Flavour Particle Production in High-Multiplicity pp Collisions at √s= 13 TeV in ALICE
- Exact flavor conservation at the quark level in causal clusters: strange particles, protons and light nuclei in small collision systems
- Heavy Quark Recombination Across Collision Systems: Meson and Baryon production
- Strange-quark-number-dependent response to partonic dynamics in baryon-rich Au+Au collisions
BibTeX
@misc{collaboration2026exploring,
title = {{Exploring the limit of partonic collectivity in small collision systems at the LHC}},
author = {ALICE Collaboration},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.08327},
eprint = {2611.08327},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.08327},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Exploring the limit of partonic collectivity in small collision systems at the LHC
AU - ALICE Collaboration
PY - 2026
DA - 2026/11/05
PB - arXiv
DO - 10.48550/arxiv.2611.08327
UR - https://arxiv.org/abs/2611.08327
AB - The existence of a partonic phase in small collision systems has been investigated previously through measurements of the elliptic flow (v_2) of mesons (π^±, K^±, and K_S^0) and baryons (p(p̅), Λ(Λ̅)) in high-multiplicity p-Pb collisions at √(s_NN) = 5.02 TeV and pp collisions at √s = 13 TeV recorded by ALICE. The results have revealed a grouping and splitting behavior of v_2 for baryons and mesons at intermediate transverse momentum (p_T), establishing that partonic collectivity, as observed in heavy-ion collisions, is also present in these systems. In this Letter, the p_T-differential v_2 of various hadronic species is investigated in p-Pb collisions for the multiplicity intervals N_ch ≥ 50, 25 ≤ N_ch < 50, and 15 ≤ N_ch < 25, as well as in pp collisions for 25 ≤ N_ch < 50 and 15 ≤ N_ch < 25. Here, N_ch is the efficiency-corrected number of charged particles produced in the kinematic region of |η|< 0.8 and 0.2 < p_T < 3.0 GeV/c. The characteristic mass dependence of v_2, as well as the grouping and splitting patterns among identified particles, are examined. The results in both p-Pb and pp collisions with N_ch ≥ 25 are consistent with the development of partonic collectivity. In the low-multiplicity region, 15 ≤ N_ch < 25, the baryon-to-meson v_2 splitting, as quantified by the baryon-to-meson v_2 ratios, remains broadly consistent with that at higher multiplicities. However, its significance decreases to ∼2σ in p-Pb collisions and to less than 1σ in pp collisions owing to the sizable experimental uncertainties. These measurements constitute the first steps towards identifying the limits of partonic flow in small collision systems at the LHC.
ER -