Multi-strange Particle Production Research Articles

Production of {textrm{K}}_{textrm{S}}^0 , Λ ( overline{Lambda} ), Ξ±, and Ω± in jets and in the underlying event in pp and p–Pb collisions

The production of strange hadrons ( {textrm{K}}_{textrm{S}}^0 , Λ, Ξ±, and Ω±), baryon-to-meson ratios (Λ/ {textrm{K}}_{textrm{S}}^0 , Ξ/ {textrm{K}}_{textrm{S}}^0 , and Ω/ {textrm{K}}_{textrm{S}}^0 ), and baryon-to-baryon ratios (Ξ/Λ, Ω/Λ, and Ω/Ξ) associated with jets and the underlying event were measured as a function of transverse momentum (pT) in pp collisions at sqrt{s} = 13 TeV and p Pb collisions at sqrt{s_{textrm{NN}}} = 5.02 TeV with the ALICE detector at the LHC. The inclusive production of the same particle species and the corresponding ratios are also reported. The production of multi-strange hadrons, Ξ± and Ω±, and their associated particle ratios in jets and in the underlying event are measured for the first time. In both pp and p–Pb collisions, the baryon-to-meson and baryon-to-baryon yield ratios measured in jets differ from the inclusive particle production for low and intermediate hadron pT (0.6–6 GeV/c). Ratios measured in the underlying event are in turn similar to those measured for inclusive particle production. In pp collisions, the particle production in jets is compared with Pythia 8 predictions with three colour-reconnection implementation modes. None of them fully reproduces the data in the measured hadron pT region. The maximum deviation is observed for Ξ± and Ω± which reaches a factor of about six. The event multiplicity dependence is further investigated in p−Pb collisions. In contrast to what is observed in the underlying event, there is no significant event-multiplicity dependence for particle production in jets. The presented measurements provide novel constraints on hadronisation and its Monte Carlo description. In particular, they demonstrate that the fragmentation of jets alone is insufficient to describe the strange and multi-strange particle production in hadronic collisions at LHC energies.

Dynamics of particle production in Pb-Pb collisions at sNN=2.76 TeV using the PYTHIA8 Angantyr model

We study the dynamics of identified, strange, and multistrange particle production in Pb-Pb collisions at $\sqrt{{s}_{NN}}$ = 2.76 TeV using the recently developed Angantyr model, incorporated within pythia8. We show the interplay between multiparton interactions (MPIs) and color reconnection (CR) on the experimentally measured quantities. We also investigate the role of string shoving within the rope hadronization framework and its impact in particle production. The charged-particle multiplicity (${N}_{\mathrm{ch}}$) and mean transverse momentum ($\ensuremath{\langle}{p}_{\mathrm{T}}\ensuremath{\rangle}$) distributions are well explained by pythia8 Angantyr with proper tuning, as presented in this paper. Predictions of ${p}_{\mathrm{T}}$ spectra, $\ensuremath{\langle}{p}_{\mathrm{T}}\ensuremath{\rangle}$, and ${p}_{\mathrm{T}}$ integrated yields of the identified, strange, and multistrange particles are studied. To provide insight into the collective nature of the produced particles, we look into the ratio of particle yields to pions and kaons. pythia8 Angantyr with MPI$+$CR and hadronization via string shoving is seen to mimic signs of collectivity due to different implementations in string interactions.

Production of strange particles in jets and underlying events in pp collisions at √S = 13 TeV with ALICE

The production of strange KS0, Λ and multi-strange (Ξ± and Ω±) particles in jets and the underlying event in pp collisions at √S = 13 TeV has been studied with ALICE at the LHC. The pT-differential density of the particles produced in a jet is compared to the inclusive distribution. The corresponding (Λ + Λ¯)/2KS0 and (Ξ− + Ξ¯+)/(Λ + Λ¯) ratios in jets as a function of pT are also reported in this work. The pT-differential density distribution of hadrons associated with jets decreases slower than the one reported for inclusive particle production. The ratios measured in jets show a clear difference when compared to the inclusive ones at the intermediate pT range. The results provide an opportunity to test the strange and multi-strange particle production mechanisms with hard scattering.

Hadronic resonances, strange and multi-strange particle production in Xe-Xe and Pb-Pb collisions with ALICE at the LHC

We present measurements of hadronic resonance, strange and multi-strange particle production in collisions of Xe-Xe and Pb-Pb at the center-of-mass energies of sNN=5.44and5.02TeV, respectively, by the ALICE collaboration at the LHC. Particle ratios are presented as a function of multiplicity for Ks0, Λ, Ξ−, Ξ‾+, Ω−, Ω‾+, ρ(770)0, K*(892)0, ϕ(1020) and Λ(1520). Our results are discussed and compared with predictions of QCD-inspired event generators. Additionally, comparisons with lower energy measurements and smaller systems are also presented.

Strange and multi-strange particle production in Pb-Pb collisions at $\sqrt{s_{{\rm NN}}} = 2.76~{\rm TeV}$ with ALICE

We present ALICE results on strange and multi-strange hadron production as a function of centrality in Pb-Pb collisions at [Formula: see text] at the LHC. Their transverse momentum spectra, yields and particle ratios are compared to the corresponding measurements in pp collisions to address strangeness enhancement and high p T particle suppression. The results are also compared to measurements at RHIC and SPS energies.

Constituent Quark Scaling of Strangeness Enhancement in Heavy-Ion Collisions

In the framework of a nuclear overlap model, we estimate the number of nucleons and quark participants in proton-proton, proton-nucleus, and nucleus-nucleus collisions. We observe the number of nucleon- (NN-part-) normalized enhancement of multistrange particles, which shows a monotonic increase with centrality and turns out to be a centrality-independent scaling behavior when normalized to number of constituent quarks participating in the collision (Nq-part). In addition, we observe that theNq-part-normalized enhancement, when further normalized to the strangeness content, shows a strangeness-independent scaling behavior. This holds good at top RHIC energy. However, the corresponding SPS data show a weakNq-part-scaling. Moreover, the strangeness scaling seems to be violated at top SPS energy. This scaling at RHIC indicates that the partonic degrees of freedom play an important role in the production of multistrange particles. Top SPS energy, in view of the above observations, shows a coexistence of hadronic and partonic phases. Therefore we give a comparison of data with HIJING, AMPT, and UrQMD models to understand the particle production dynamics at different energies.

Strange and multi-strange particle production at the LHC energies with ALICE

Strange quark and particle production is studied at the LHC with unprecedented high beam energies in both heavy-ion and proton-proton collisions: on the one hand, strangeness is used for investigating chemical equilibration and bulk properties; on the other hand, strange particles contribute to probe different kinematical domains, from the one where collective phenomena are at play up to the region dominated by pQCD-calculable processes. We highlight the suitability of the ALICE experiment for this topic, presenting our latest measurements and comparing them to models.

Multi-strange particle measurements in 7 TeV proton–proton and 2.76 TeV Pb–Pb collisions with the ALICE experiment at the LHC

The production of charged multi-strange particles is studied with the ALICE experiment at the CERN LHC. Measurements of the central rapidity yields of Ξ− and Ω− baryons, as well as their antiparticles, are presented as a function of transverse momentum (pt) for inelastic pp collisions at TeV and compared to existing measurements performed at the same and/or at lower energies. The results are also compared to predictions from two different tunes of the PYTHIA event generator. We find that data significantly exceed the production rates from those models. Finally, we present the status of the multi-strange particle production studies in Pb–Pb at TeV performed as a function of collision centrality.

Strange and multistrange particle production in Au + Au collisions atsNN=62.4 GeV

We present results on strange and multi-strange particle production in Au+Au collisions at $\sqrt{s_{NN}}=62.4$ GeV as measured with the STAR detector at RHIC. Mid-rapidity transverse momentum spectra and integrated yields of $K^{0}_{S}$, $\Lambda$, $\Xi$, $\Omega$ and their anti-particles are presented for different centrality classes. The particle yields and ratios follow a smooth energy dependence. Chemical freeze-out parameters, temperature, baryon chemical potential and strangeness saturation factor obtained from the particle yields are presented. Intermediate transverse momentum ($p_T$) phenomena are discussed based on the ratio of the measured baryon-to-meson spectra and nuclear modification factor. The centrality dependence of various measurements presented show a similar behavior as seen in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.

Multi-strange particle production in relativistic heavy ion collisions at GeV

We present preliminary STAR results on measurements of multi-strange particles Ξ, Ω and their anti-particles from Au+Au and Cu+Cu at GeV collisions. In order to better understand the role of strangeness enhancement in nucleus–nucleus collisions and its scaling properties with system size, we compare the results from Au+Au and Cu+Cu reactions for different event centrality classes. Strangeness enhancement is discussed in the context of multi-strange to pion ratios. Finally, the Ω/ϕ ratio is shown for different systems and energies for a systematic study.

Multistrange particle production and the statistical hadronization model

We consider the chemical freeze-out of $\ensuremath{\Xi}$, $\overline{\ensuremath{\Xi}}$, and $\ensuremath{\phi}$ multistrange hadrons within a statistical hadronization model inspired approach. We study particle yields across a wide range of reaction energy and centrality from NA49 at the Super Proton Synchrotron (SPS) and the Solenoidal Tracker at RHIC (STAR) experiments. We constrain the physical conditions present in the fireball source of strange hadrons and anticipate results expected at the Large Hadron Collider (LHC).

NA57 main results

The CERN NA57 experiment was designed to study the production of strange and multi-strange particles in heavy-ion collisions at SPS energies; its physics programme is essentially completed. A review of the main results is presented.

Study of the production of strange and multi-strange particles in lead–lead interactions at the CERN SPS: the NA57 experiment

Study of the production of strange and multi-strange particles in lead–lead interactions at the CERN SPS: the NA57 experiment

Ξ− and -production in Pb + Pb collisions at 158 GeV per nucleon

Preliminary results on multistrange particle production in central Pb + Pb collisions at 158 GeV per nucleon are presented. The NA49 experiment provides the capability of performing measurements of multistrange particles in two independent methods. The complementary acceptance of the methods in the MTPC and the VTPC2 detector cover a wide range of rapidity. Transverse mass spectra and rapidity distributions are presented. Preliminary particle ratios are shown and a first estimation of full phase-space multiplicity is completed.

Hyperon production in proton-lead and lead-lead collisions at 158 GeV/c per nucleon

The WA97 experiment studies the production of strange and multistrange particles in Pb−Pb and p−Pb collisions at 158 GeV/c per nucleon. Recent results on ≡ and ω production ratios and transverse mass distributions are reported and compared with those obtained by WA85 and WA94 experiments. A significant enhancement of the ω/≡ ratio has been observed when going from nucleon-Nucleus to Nucleus-Nucleus reactions.

Production of multi-strange particles in Pb - Pb interactions at 158 A GeV c−1

The first results on fully corrected ratios and production cross sections of Ω−, , Ξ− and detected by the WA97 experiment in Pb - Pb collisions are presented.