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A<sc>bstract</sc> A study of strange hadron production associated with hard scattering processes and with the underlying event is conducted to investigate the origin of the enhanced production of strange hadrons in small collision systems characterised by large charged-particle multiplicities. For this purpose, the production of the single-strange meson$$ {\textrm{K}}_{\textrm{S}}^0 $$ and the double-strange baryon Ξ±is measured, in each event, in the azimuthal direction of the highest-pTparticle (“trigger” particle), related to hard scattering processes, and in the direction transverse to it in azimuth, associated with the underlying event, in pp collisions at$$ \sqrt{s} $$ = 5.02 TeV and$$ \sqrt{s} $$ = 13 TeV using the ALICE detector at the LHC. The per-trigger yields of$$ {\textrm{K}}_{\textrm{S}}^0 $$ and Ξ±are dominated by the transverse-to-leading production (i.e., in the direction transverse to the trigger particle), whose contribution relative to the toward-leading production is observed to increase with the event charged-particle multiplicity. The transverse-to-leading and the toward-leading Ξ±/$$ {\textrm{K}}_{\textrm{S}}^0 $$ yield ratios increase with the multiplicity of charged particles, suggesting that strangeness enhancement with multiplicity is associated with both hard scattering processes and the underlying event. The relative production of Ξ±with respect to$$ {\textrm{K}}_{\textrm{S}}^0 $$ is higher in transverse-to-leading processes over the whole multiplicity interval covered by the measurement. The$$ {\textrm{K}}_{\textrm{S}}^0 $$ and Ξ±per-trigger yields and yield ratios are compared with predictions of three different phenomenological models, namely Pythia8.2 with the Monash tune, Pythia8.2 with ropes and EPOS LHC. The comparison shows that none of them can quantitatively describe either the transverse-to-leading or the toward-leading yields of$$ {\textrm{K}}_{\textrm{S}}^0 $$ and Ξ±.
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Multiplicity-dependent production of Σ(1385)± and Ξ(1530)0 in pp collisions at $$ \sqrt{s} $$ = 13 TeV
A<sc>bstract</sc> The production yields of the Σ(1385)±and Ξ(1530)0resonances are measured in pp collisions at$$ \sqrt{s} $$ = 13 TeV with ALICE. The measurements are performed as a function of the charged-particle multiplicity ⟨dNch/dη⟩, which is related to the energy density produced in the collision. The results include transverse momentum (pT) distributions,pT-integrated yields, mean transverse momenta of Σ(1385)±and Ξ(1530)0, as well as ratios of thepT-integrated resonance yields relative to yields of other hadron species. The Σ(1385)±/π±and Ξ(1530)0/π±yield ratios are consistent with the trend of the enhancement of strangeness production from low to high multiplicity pp collisions, which was previously observed for strange and multi-strange baryons. The yield ratio between the measured resonances and the long-lived baryons with the same strangeness content exhibits a hint of a mild increasing trend at low multiplicity, despite too large uncertainties to exclude the flat behaviour. The results are compared with predictions from models such as EPOS-LHC and PYTHIA 8 with Rope shoving. The latter provides the best description of the multiplicity dependence of the Σ(1385)±and Ξ(1530)0production in pp collisions at$$ \sqrt{s} $$ = 13 TeV.
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- PAR ID:
- 10514231
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- link.springer.com
- Date Published:
- Journal Name:
- Journal of High Energy Physics
- Volume:
- 2024
- Issue:
- 5
- ISSN:
- 1029-8479
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1007/JHEP05(2024)317
