Production Of Multi-strange Hadrons Research Articles

Theoretical prediction of cosmic rays models for strange particles production at RHIC energy

This study conducts a comprehensive assessment of Monte Carlo models, including Sibyll, EPOS-LHC, and EPOS4, in the context of simulating strange and multi-strange hadron production within high-multiplicity proton–proton collisions at 200 GeV. The analysis reveals common trends across various particle types: models tend to overestimate low transverse momentum (pT) distributions and approach experimental data as pT increases. EPOS-LHC produce better predictions in the intermediate pT range. However, none of the models adequately reproduce pT distributions for Λ and Λ̄ particles, typically underpredicting the data. EPOS4_Hydro performs relatively better due to its ability to account for reduced particle multiplicity at high pT and energy redirection into flow. For Ξ and Ξ̄ particles, models underpredict distributions at high pT, except for EPOS4_Hydro, which consistently overpredicts. Additionally, the study delves into particle ratios, such as Λ̄/Λ and Ξ+/Ξ−, highlighting varying model performance. The mean transverse momentum increases with particle mass, and specific models demonstrate good fits for certain mass ranges. EPOS-LHC and EPOS4 with hydrodynamics were notably accurate for particles below 0.6 GeV. Within the mass range of 0.6 to 1.4 GeV, EPOS-LHC displayed the closest fit. However, particles surpassing 1.2 GeV showed higher accuracy with EPOS4 without hydrodynamics. These insights underscore the significance of selecting appropriate Monte Carlo models based on specific research requirements in high-energy physics.

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.

Highlights from the NA61/SHINE Experiment

The NA61/SHINE experiment is a fixed-target, broad acceptance facility at the CERN SPS. This contribution summarizes the most recent results from the strong interactions NA61/SHINE programme and presents news on the detector upgrade in preparation for the future data taking. The strong interactions programme consists in a two-dimensional scan in beam momentum (from 13A to 150A/158A GeV/c, \sqrt{s_{NN}} from 5.1 to 17.3 GeV) and system size (p + p, Be + Be, Ar + Sc, Xe + La reactions). The experiment searches for the second-order critical end-point in the temperature versus baryo-chemical potential phase diagram and studies the properties of the onset of deconfinement discovered by its predecessor, NA49 at the CERN SPS. The presented results include K/{\pi} multiplicity ratios as a function of energy and system size, singly and multi-strange hadron production in p + p reactions, multiplicity and net-charge fluctuations measured by higher order moments in p + p, Be + Be and Ar + Sc collisions, proton and charged hadron intermittency in Ar + Sc and Pb + Pb reactions, HBT measurements in Ar + Sc and collective electromagnetic effects in Ar + Sc collisions.

Production of strange hadrons in jets and underlying events in pp and p–Pb collisions with ALICE

The production of strange (, Λ) and multi-strange (Ξ± and Ω±) hadrons in jets and underlying events in pp and p–Pb collisions is studied with ALICE at the LHC. Transverse momentum (p T) differential density distribution of particles produced in a jet is compared to that of inclusive particle production and that in underlying events. The particle yield ratios of and as a function of p T are also investigated in jets and underlying events. The production of the multi-strange hadrons, Ξ± and Ω±, and the corresponding ratio in jets and underlying events are measured for the first time. The p T-differential density distribution of hadrons associated with hard scattering decreases slower than that for inclusive production. The baryon-to-meson and baryon-to-baryon ratios measured in jets exhibit clear differences from values obtained from the inclusive spectra in the intermediate p T range. The p T distribution of strange hadrons produced in jets is also studied in pp collisions at and and in p–Pb collisions at . The p T spectra of particle produced in jets are independent of collision systems and collision energies. No apparent collision energy and collision system dependence is observed for the particle yield ratios of and associated with energetic jets. These new results are compared to PYTHIA 8 event generator. The ratio are generally reproduced by the model, but large discrepancies between data and PYTHIA simulations are observed for .

Multi-strange hadron production in p+p interactions at √SNN= 17.3 GeV

The production of multi-strange hadrons in proton-proton interactions is currently studied with the NA61/SHINE experiment at the SPS. These particles are reconstructed via their weak decay typologies, exploiting the tracking and particle identification capabilities of NA61/SHINE. New measurements of rapidity and transverse momentum spectra of Ξ−and Ξ resonances and their antiparticles are shown. The results are compared to those observed in A+A collisions as well as to model predictions.

Light-flavour hadron production vs. multiplicity in pp and in p–Pb collisions with ALICE

The study of light-flavour hadron production plays an important role in understanding the dynamics of the strongly-interacting system created in high-multiplicity pp and p–Pb collisions at the LHC energies. Historically, it has been assumed that no QGP is formed in small collision systems, but this paradigm is challenged by the observation of collective-like behaviour and strangeness enhancement in high-multiplicity pp and p–Pb collisions. Exploiting its optimal particle identification capabilities, the ALICE experiment is able to measure pion, kaon, (anti-)proton, strange and multi-strange hadron production in a wide transverse momentum range. We report on the study of light-flavour hadron production as a function of multiplicity and center-of-mass energy in pp and p–Pb collisions using the ALICE apparatus. In addition, new multi-differential measurements are presented, comparing identified particle production in the underlying event to the one in jets.

Evolution of strange and multi-strange hadron production with relative transverse multiplicity activity in underlying event

In this work, the relative Underlying event (UE) transverse multiplicity activity classifier (R_mathrm{{T}}) is used to study the strange and multi-strange hadron production in proton-proton collisions. Our study with R_mathrm{{T}} would allow to disentangle these particles, which are originating from the soft and hard QCD processes. We have used the PYTHIA 8 Monte-Carlo (MC) with a different implementation of color reconnection and rope hadronization models to demonstrate the proton-proton collisions data at sqrt{s}~= 13 TeV. The relative production of strange and multi-strange hadrons are discussed extensively in low and high transverse activity regions. In this contribution, the relative strange hadron production is enhanced with increasing R_mathrm{{T}}. This enhancement is significant for the strange baryons as compared to mesons. In addition, the particle ratios as a function of R_mathrm{{T}}~confirm the baryon enhancement in new Color Reconnection (newCR), whereas the Rope model confirms the baryon enhancement only with strange quark content. Experimental confirmation of such results will provide more insight into the soft physics in the transverse region, which will be useful to investigate various tunes based on hadronization and color reconnection schemes.

Enhanced production of strange baryons in high-energy nuclear collisions from a multiphase transport model

We introduce additional coalescence factors for the production of strange baryons in a multiphase transport (AMPT) model in order to describe the enhanced production of multistrange hadrons observed in Pb-Pb collisions at $\rm \sqrt{s_{NN}}$ = 2.76 TeV at the Large hadron Collider (LHC) and Au+Au collisions at $\rm \sqrt{s_{NN}}$ = 200 GeV at Relativistic Heavy-Ion Collider (RHIC).This extended AMPT model is found to also give a reasonable description of the multiplicity dependence of the strangeness enhancement observed in high multiplicity events in $pp$ collisions at $\rm \sqrt{s}$ = 7 TeV and $p$-Pb collisions at $\rm \sqrt{s_{NN}}$ = 5.02 TeV. We find that the coalescence factors depend on the system size but not much on whether the system is produced from A+A or p+A collisions. The extended AMPT model thus provides a convenient way to model the mechanism underlying the observed strangeness enhancement in collisions of both small and large systems at RHIC and LHC energies.

Monte-Carlo study of long-range correlations of average transverse momentum and multiplicity for strange particles in pp-collisions at the LHC energies

This study is motivated by the puzzling enhanced production of multi-strange hadrons observed for the first time by the ALICE Collaboration in high-multiplicity pp-collisions at at the LHC. We investigate this effect of strangeness enhancement in pp-collisions in the framework of the MC event generator PYTHIA 8 where the collectivity processes are taken into account by the formation of a so-called flavour rope. The latter is hadronized with a larger effective string tension providing the increase of strangeness yield. This concept of the flavour rope, as a source of multi-strange hadrons, extended in rapidity, is being tested by the study of so called long-range correlations (LRC) between the average transverse momentum 〈pT〉 and multiplicity n for charged particles containing strange quarks produced in high energy pp-collisions.The dependencies of correlation coefficients bn−n, bPT−n and bPT−PT on the gap between forward and backward pseudorapidity windows, and on the width of the forward pseudorapidity windows, are studied and the results are discussed.

Multiplicity dependence of strangeness and hadronic resonance production in pp and p-Pb collisions with ALICE at the LHC

One of the key results of the LHC Run 1 was the observation of an enhanced production of strange particles in high multiplicity pp and p–Pb collisions at sNN=7 and 5.02 TeV, respectively. The strangeness enhancement is investigated by measuring the evolution with multiplicity of single-strange and multi-strange baryon production relative to non-strange particles. A smooth increase of strange particle yields relative to the non-strange ones with event multiplicity has been observed in such systems. We report the latest results on multiplicity dependence of strange and multi-strange hadron production in pp collisions at s=13TeV with ALICE. We also presented recent measurements of mesonic and baryonic resonances in small collision systems like pp and p–Pb at sNN=13 and 8.16 TeV, respectively. The multiplicity dependent studies in pp and p-Pb collisions have been used to investigate how the hadronic scattering processes affect measured resonance yields and to better understand the interplay between canonical suppression and strangeness enhancement. The measurement of the ϕ(1020) meson as a function of multiplicity provides crucial constraints in this context.

Enhanced production of multi-strange hadrons in high-multiplicity proton\u2013proton collisions

Quark–gluon plasma is an exotic state of matter that can emerge in heavy nuclei high-energy collisions. The ALICE collaboration reports the first observation of strangeness enhancement in proton–proton collisions, a possible signature of this state.

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.

Near-threshold production of the multistrange Xi- hyperon.

The yield for the multistrange Xi(-) hyperon has been measured in 6A GeV Au+Au collisions via reconstruction of its decay products pi(-) and Lambda, the latter also being reconstructed from its daughter tracks of pi(-) and p. The measurement is rather close to the threshold for Xi(-) production and therefore provides an important test of model predictions. The measured yield for Xi(-) and Lambda are compared for several centralities. In central collisions the Xi(-) yield is found to be in excellent agreement with statistical and transport model predictions, suggesting that multistrange hadron production approaches chemical equilibrium in high baryon density nuclear matter.

Strangeness enhancement and energy dependence in heavy ion collisions

The canonical statistical model analysis of strange and multistrange hadron production in central A-A relative to p-p/p-A collisions is presented over the energy range from $\sqrt s=8.73$ GeV up to $\sqrt s =130$ GeV. It is shown that the relative enhancement of strange particle yields from p-p/p-A to A-A collisions substantially increases with decreasing collision energy. It is largest at $\sqrt s= 8.7$ GeV, where the enhancement of $\Omega,\Xi$ and $\Lambda$ is of the order of 100, 20 and 3, respectively. In terms of the model these results are due to the canonical suppression of particle thermal phase space at lower energies, which increases with the strangeness content of the particle and with decreasing size of the collision fireball. The comparison of the model with existing data on energy dependence of the kaon/pion ratio is also discussed.