Light-flavor particle production in high-multiplicity pp collisions at $\mathbf{\sqrt{\textit{s}} = 13}$ TeV as a function of transverse spherocity

The ALICE collaboration
JHEP 05 (2024) 184, 2024.

Abstract
Results on the transverse spherocity dependence of light-flavor particle production ($\pi$, K, p, $\phi$, ${\rm K^{*0}}$, ${\rm K}^{0}_{\rm{S}}$, $\Lambda$, $\Xi$) at midrapidity in high-multiplicity pp collisions at $\sqrt{s} = 13$ TeV were obtained with the ALICE apparatus. The transverse spherocity estimator ($S_{{\rm O}}^{{\it p}_{\rm T}=1}$) categorizes events by their azimuthal topology. Utilizing narrow selections on $S_{\text{O}}^{{\it p}_{\rm T}=1}$, it is possible to contrast particle production in collisions dominated by many soft initial interactions with that observed in collisions dominated by one or more hard scatterings. Results are reported for two multiplicity estimators covering different pseudorapidity regions. The $S_{{\rm O}}^{{\it p}_{\rm T}=1}$ estimator is found to effectively constrain the hardness of the events when the midrapidity ($\left | \eta \right |< 0.8$) estimator is used. The production rates of strange particles are found to be slightly higher for soft isotropic topologies, and severely suppressed in hard jet-like topologies. These effects are more pronounced for hadrons with larger mass and strangeness content, and observed when the topological selection is done within a narrow multiplicity interval. This demonstrates that an important aspect of the universal scaling of strangeness enhancement with final-state multiplicity is that high-multiplicity collisions are dominated by soft, isotropic processes. On the contrary, strangeness production in events with jet-like processes is significantly reduced. The results presented in this article are compared with several QCD-inspired Monte Carlo event generators. Models that incorporate a two-component phenomenology, either through mechanisms accounting for string density, or thermal production, are able to describe the observed strangeness enhancement as a function of $S_{{\rm O}}^{{\it p}_{\rm T}=1}$.

  • Table 1

    Figure 1

    10.17182/hepdata.153642.v1/t1

    Spherocity distributions with respect to different multiplicity selections.

  • Table 2

    Figure 2

    10.17182/hepdata.153642.v1/t2

    vs for different multiplicity and spherocity classes.

  • Table 3

    Figures 3(4)_Phi-pT spectra

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    pT differential Phi spectra as a function of spherocity within 0-1% nTracklets.

  • Table 4

    Figures 3(4)_Proton-pT spectra

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    pT differential Proton spectra as a function of spherocity within 0-1% nTracklets.

  • Table 5

    Figures 3(4)_Lambda-pT spectra

    10.17182/hepdata.153642.v1/t5

    pT differential Lambda spectra as a function of spherocity within 0-1% nTracklets.

  • Table 6

    Figures 3(4)_Xi-pT spectra

    10.17182/hepdata.153642.v1/t6

    pT differential Xi spectra as a function of spherocity within 0-1% nTracklets.

  • Table 7

    Figures 3(4)_Pion-pT spectra

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    pT differential Pion spectra as a function of spherocity within 0-1% nTracklets.

  • Table 8

    Figures 3(4)_Kaon-pT spectra

    10.17182/hepdata.153642.v1/t8

    pT differential Kaon spectra as a function of spherocity within 0-1% nTracklets.

  • Table 9

    Figures 3(4)_K0-pT spectra

    10.17182/hepdata.153642.v1/t9

    pT differential K0 spectra as a function of spherocity within 0-1% nTracklets.

  • Table 10

    Figures 3(4)_Kstar-pT spectra

    10.17182/hepdata.153642.v1/t10

    pT differential Kstar spectra as a function of spherocity within 0-1% nTracklets.

  • Table 11

    Figure 6

    10.17182/hepdata.153642.v1/t11

    Mean distributions as a function of Spherocity for nTracklets:0-1%.

  • Table 12

    Figures 7(8)_Phi over Pi

    10.17182/hepdata.153642.v1/t12

    pT differential Phito-pion ratios as a function of spherocity within 0-1% nTracklets.

  • Table 13

    Figures 7(8)_Proton over Pi

    10.17182/hepdata.153642.v1/t13

    pT differential Protonto-pion ratios as a function of spherocity within 0-1% nTracklets.

  • Table 14

    Figures 7(8)_Lambda over Pi

    10.17182/hepdata.153642.v1/t14

    pT differential Lambdato-pion ratios as a function of spherocity within 0-1% nTracklets.

  • Table 15

    Figures 7(8)_Xi over Pi

    10.17182/hepdata.153642.v1/t15

    pT differential Xito-pion ratios as a function of spherocity within 0-1% nTracklets.

  • Table 16

    Figures 7(8)_Kaon over Pi

    10.17182/hepdata.153642.v1/t16

    pT differential Kaonto-pion ratios as a function of spherocity within 0-1% nTracklets.

  • Table 17

    Figures 7(8)_K0 over Pi

    10.17182/hepdata.153642.v1/t17

    pT differential K0to-pion ratios as a function of spherocity within 0-1% nTracklets.

  • Table 18

    Figures 7(8)_Kstar over Pi

    10.17182/hepdata.153642.v1/t18

    pT differential Kstarto-pion ratios as a function of spherocity within 0-1% nTracklets.

  • Table 19

    Figures 9(10)_Proton over Pi

    10.17182/hepdata.153642.v1/t19

    pT differential Protonto-pion ratios as a function of spherocity within 0-1% nTracklets.

  • Table 20

    Figures 9(10)_Lambda over Pi

    10.17182/hepdata.153642.v1/t20

    pT differential Lambdato-pion ratios as a function of spherocity within 0-1% nTracklets.

  • Table 21

    Figures 9(10)_Xi over Pi

    10.17182/hepdata.153642.v1/t21

    pT differential Xito-pion ratios as a function of spherocity within 0-1% nTracklets.

  • Table 22

    Figures 9(10)_Kaon over Pi

    10.17182/hepdata.153642.v1/t22

    pT differential Kaonto-pion ratios as a function of spherocity within 0-1% nTracklets.

  • Table 23

    Figures 9(10)_K0 over Pi

    10.17182/hepdata.153642.v1/t23

    pT differential K0to-pion ratios as a function of spherocity within 0-1% nTracklets.

  • Table 24

    Figure 11_hPoverPi_ pT ratios

    10.17182/hepdata.153642.v1/t24

    pT differential hPoverPi_ratios as a function of spherocity within 0-1% nTracklets.

  • Table 25

    Figure 11_hLoverK0s_ pT ratios

    10.17182/hepdata.153642.v1/t25

    pT differential hLoverK0s_ratios as a function of spherocity within 0-1% nTracklets.

  • Table 26

    Figure 11_hXioverPhi_ pT ratios

    10.17182/hepdata.153642.v1/t26

    pT differential hXioverPhi_ratios as a function of spherocity within 0-1% nTracklets.

  • Table 27

    Figure 12_hK0soverK_ pT ratios

    10.17182/hepdata.153642.v1/t27

    pT differential hK0soverK_ratios as a function of spherocity within 0-1% nTracklets and V0M.

  • Table 28

    Figure 13

    10.17182/hepdata.153642.v1/t28

    Integrated double-ratios as a function of spherocity within 0-1% nTracklets, extrapolated over the full pT range.

  • Table 29

    Figure 14

    10.17182/hepdata.153642.v1/t29

    Integrated double-ratios as a function of spherocity within 0-1% nTracklets, only utilizing the measured pT range.

  • Table 30

    Figures 16_Phi over Pi

    10.17182/hepdata.153642.v1/t30

    pT differential Phito-pion ratios as a function of spherocity within 0-10% nTracklets.

  • Table 31

    Figures 16_Proton over Pi

    10.17182/hepdata.153642.v1/t31

    pT differential Protonto-pion ratios as a function of spherocity within 0-10% nTracklets.

  • Table 32

    Figures 16_Lambda over Pi

    10.17182/hepdata.153642.v1/t32

    pT differential Lambdato-pion ratios as a function of spherocity within 0-10% nTracklets.

  • Table 33

    Figures 16_Xi over Pi

    10.17182/hepdata.153642.v1/t33

    pT differential Xito-pion ratios as a function of spherocity within 0-10% nTracklets.

  • Table 34

    Figures 16_Kaon over Pi

    10.17182/hepdata.153642.v1/t34

    pT differential Kaonto-pion ratios as a function of spherocity within 0-10% nTracklets.

  • Table 35

    Figures 16_K0 over Pi

    10.17182/hepdata.153642.v1/t35

    pT differential K0to-pion ratios as a function of spherocity within 0-10% nTracklets.

  • Table 36

    Figures 16_Kstar over Pi

    10.17182/hepdata.153642.v1/t36

    pT differential Kstarto-pion ratios as a function of spherocity within 0-10% nTracklets.

  • Table 37

    Figures 17_Phi over Pi

    10.17182/hepdata.153642.v1/t37

    pT differential Phito-pion ratios as a function of spherocity within 0-1% V0M.

  • Table 38

    Figures 17_Proton over Pi

    10.17182/hepdata.153642.v1/t38

    pT differential Protonto-pion ratios as a function of spherocity within 0-1% V0M.

  • Table 39

    Figures 17_Lambda over Pi

    10.17182/hepdata.153642.v1/t39

    pT differential Lambdato-pion ratios as a function of spherocity within 0-1% V0M.

  • Table 40

    Figures 17_Xi over Pi

    10.17182/hepdata.153642.v1/t40

    pT differential Xito-pion ratios as a function of spherocity within 0-1% V0M.

  • Table 41

    Figures 17_Kaon over Pi

    10.17182/hepdata.153642.v1/t41

    pT differential Kaonto-pion ratios as a function of spherocity within 0-1% V0M.

  • Table 42

    Figures 17_K0 over Pi

    10.17182/hepdata.153642.v1/t42

    pT differential K0to-pion ratios as a function of spherocity within 0-1% V0M.

  • Table 43

    Figures 17_Kstar over Pi

    10.17182/hepdata.153642.v1/t43

    pT differential Kstarto-pion ratios as a function of spherocity within 0-1% V0M.

  • Table 44

    Figure 18 and Figure 19 (for Phi/Pi ratio)

    10.17182/hepdata.153642.v1/t44

    Integrated double-ratios as a function of spherocity within 0-10% nTracklets, only utilizing the measured pT range.

  • Table 45

    Figure 18

    10.17182/hepdata.153642.v1/t45

    Integrated double-ratios as a function of spherocity within 0-1% V0M, only utilizing the measured pT range.

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