Jet-like correlations with respect to K$^{0}_{\rm S}$ and $Λ$ ($\barΛ$) in pp and central Pb-Pb collisions at $\mathbf{\it\sqrt{s_\mathrm{NN}}}$ = 5.02 TeV

Two-particle correlations with ${\rm K}^{0}_{\rm{S}}$, $\Lambda$/$\bar{\Lambda}$, and charged hadrons as trigger particles in the transverse momentum range $8 <~ p_\mathrm{T,trig}<~16$ GeV/$c$, and associated charged particles within $1 <~ p_\mathrm{T,assoc}<~8$ GeV/$c$, are studied at mid-rapidity in pp and central Pb-Pb collisions at a centre-of-mass energy per nucleon-nucleon collision $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV with the ALICE detector at the LHC. After subtracting the contributions of the flow background, the per-trigger yields are extracted on both the near and away sides, and the ratio in Pb-Pb collisions with respect to pp collisions ($I_{\mathrm {AA}}$) is computed. The per-trigger yield in Pb-Pb collisions on the away side is strongly suppressed to the level of $I_{\mathrm {AA}} \approx 0.6$ for $p_\mathrm{T,assoc}>3$ GeV/$c$ as expected from strong in-medium energy loss, while an enhancement develops at low $p_\mathrm{T,assoc}$ on both the near and away sides, reaching $I_{\mathrm {AA}} \approx 1.8$ and $2.7$ respectively. These findings are in good agreement with previous ALICE measurements from two-particle correlations triggered by neutral pions ($\pi^{0}$-h) and charged hadrons (h-h) in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 2.76$ TeV. Moreover, the correlations with ${\rm K}^{0}_{\rm{S}}$ mesons and $\Lambda$/$\bar{\Lambda}$ baryons as trigger particles are compared to those of inclusive charged hadrons. The results are compared with the predictions of Monte Carlo models.


Eur. Phys. J. C 83 (2023) 497
HEP Data
e-Print: arXiv:2211.01197 | PDF | inSPIRE
Figure group

Figure 1

Distributions of $C(\Delta\varphi)$ for h$-$h (left), ${\rm K^0_S}-$h (middle) and ($\Lambda$+$\overline{\Lambda})-$h (right) trigger particles with $8 < p_\mathrm{T,trig}<16$ GeV/$c$ and associated particles with $4 < p_\mathrm{T,assoc}<6$ GeV/$c$ in 0$-$10% central Pb$-$Pb (solid points) and pp (open circles) collisions The error bars represent the statistical uncertainties while the boxes represent the systematic uncertainties. The background has been subtracted based on the estimation of ZYAM in \pp collisions and the additional contributions of the anisotropic flow harmonics $v_{2}$ and $v_{3}$ in Pb$-$Pb collisions.

Figure 2

Top panel: per-trigger yield modification, $I_{\rm AA}$, of ${\rm K^0_S}-$h (square points), ($\Lambda$+$\overline{\Lambda})-$h (circle points) and h$-$h (diamond points), on the near side (left) and away side (right). Bottom panel: comparison of $I_{\rm AA}$ of h$-$h (diamond points) from this measurements at $\sqrt{s_{\rm NN}} = 5.02$ TeV, with $I_{\rm AA}$ of h$-$h (square points) and $\pi^{0}-$h (circle points) at $\sqrt{s_{\rm NN}} = 2.76$ TeV, on the near side (left) and away side (right).

Figure 3

Per-trigger yield modification, $I_{\rm AA}$, of ${\rm K^0_S}-$-h (square points), ($\Lambda$+$\overline{\Lambda})-$h (circle points) and h$-$h (diamond points), on the near side (left) and away side (right), compared to model calculations from AMPT and HIJING event generators.

Figure 4

Ratios of $V^0$-triggered yields to charged-hadron triggered (h$-$h) ones, ${{Y}^{\mathrm{K^0_S}-\mathrm{h}}_{\Delta\varphi}}/{{Y}^{\mathrm{h-h}}_{\Delta\varphi}}$ (square points) and ${{Y}^{(\Lambda+\overline{\Lambda})-\mathrm{h}}_{\Delta\varphi}}/{{Y}^{\mathrm{h-h}}_{\Delta\varphi}}$ (circle points), for Pb$-$Pb (top panels) and pp (bottom panels) collisions in near side (left) and away side (right).

Figure A.1

Ratios of $V^0$-triggered yields to charged-hadron (h$-$h) yields, ${{Y}^{\mathrm{K^0_S}-\mathrm{h}}_{\Delta\varphi}}/{{Y}^{\mathrm{h-h}}_{\Delta\varphi}}$ (top panels) and ${{Y}^{(\Lambda+\overline{\Lambda})-\mathrm{h}}_{\Delta\varphi}}/{{Y}^{\mathrm{h-h}}_{\Delta\varphi}}$ (bottom panels), for pp collisions on the near side (left) and away side (right) from this measurement compared with published results at higher collision energy.