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Free, publiclyaccessible full text available August 1, 2024

Free, publiclyaccessible full text available July 1, 2024

A<sc>bstract</sc> The production of strange hadrons (
, Λ, Ξ^{±}, and Ω^{±}), baryontomeson ratios (Λ$$ {\textrm{K}}_{\textrm{S}}^0 $$ ${K}_{S}^{0}$/ , Ξ$$ {\textrm{K}}_{\textrm{S}}^0 $$ ${K}_{S}^{0}$/ , and Ω$$ {\textrm{K}}_{\textrm{S}}^0 $$ ${K}_{S}^{0}$/ ), and baryontobaryon ratios (Ξ$$ {\textrm{K}}_{\textrm{S}}^0 $$ ${K}_{S}^{0}$/ Λ, Ω/ Λ, and Ω/ Ξ) associated with jets and the underlying event were measured as a function of transverse momentum (p _{T}) in pp collisions at = 13 TeV and p Pb collisions at$$ \sqrt{s} $$ $\sqrt{s}$ = 5$$ \sqrt{s_{\textrm{NN}}} $$ $\sqrt{{s}_{\mathrm{NN}}}$. 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 multistrange 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 baryontomeson and baryontobaryon yield ratios measured in jets differ from the inclusive particle production for low and intermediate hadronp _{T}(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 colourreconnection implementation modes. None of them fully reproduces the data in the measured hadronp _{T}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 eventmultiplicity 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 multistrange particle production in hadronic collisions at LHC energies.Free, publiclyaccessible full text available July 1, 2024 
Abstract A newly developed observable for correlations between symmetry planes, which characterize the direction of the anisotropic emission of produced particles, is measured in Pb–Pb collisions at $$\sqrt{s_\text {NN}}$$ s NN = 2.76 TeV with ALICE. This socalled Gaussian Estimator allows for the first time the study of these quantities without the influence of correlations between different flow amplitudes. The centrality dependence of various correlations between two, three and four symmetry planes is presented. The ordering of magnitude between these symmetry plane correlations is discussed and the results of the Gaussian Estimator are compared with measurements of previously used estimators. The results utilizing the new estimator lead to significantly smaller correlations than reported by studies using the Scalar Product method. Furthermore, the obtained symmetry plane correlations are compared to stateoftheart hydrodynamic model calculations for the evolution of heavyion collisions. While the model predictions provide a qualitative description of the data, quantitative agreement is not always observed, particularly for correlators with significant nonlinear response of the medium to initial state anisotropies of the collision system. As these results provide unique and independent information, their usage in future Bayesian analysis can further constrain our knowledge on the properties of the QCD matter produced in ultrarelativistic heavyion collisions.more » « lessFree, publiclyaccessible full text available July 1, 2024

Abstract A study of multiplicity and pseudorapidity distributions of inclusive photons measured in pp and p–Pb collisions at a centerofmass energy per nucleon–nucleon collision of
TeV using the ALICE detector in the forward pseudorapidity region 2.3$$\sqrt{s_{\textrm{NN}}}~=~5.02$$ $\sqrt{{s}_{\text{NN}}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}5.02$ 3.9 is presented. Measurements in p–Pb collisions are reported for two beam configurations in which the directions of the proton and lead ion beam were reversed. The pseudorapidity distributions in p–Pb collisions are obtained for seven centrality classes which are defined based on different event activity estimators, i.e., the chargedparticle multiplicity measured at midrapidity as well as the energy deposited in a calorimeter at beam rapidity. The inclusive photon multiplicity distributions for both pp and p–Pb collisions are described by double negative binomial distributions. The pseudorapidity distributions of inclusive photons are compared to those of charged particles at midrapidity in pp collisions and for different centrality classes in p–Pb collisions. The results are compared to predictions from various Monte Carlo event generators. None of the generators considered in this paper reproduces the inclusive photon multiplicity distributions in the reported multiplicity range. The pseudorapidity distributions are, however, better described by the same generators.$$<~\eta _\textrm{lab} ~<$$ $<\phantom{\rule{0ex}{0ex}}{\eta}_{\text{lab}}\phantom{\rule{0ex}{0ex}}<$Free, publiclyaccessible full text available July 1, 2024 
A<sc>bstract</sc> This article reports measurements of the angle between differently defined jet axes in pp collisions at
= 5$$ \sqrt{s} $$ $\sqrt{s}$. 02 TeV carried out by the ALICE Collaboration. Charged particles at midrapidity are clustered into jets with resolution parametersR = 0. 2 and 0.4. The jet axis, before and after Soft Drop grooming, is compared to the jet axis from the WinnerTakesAll (WTA) recombination scheme. The angle between these axes, ∆R _{axis}, probes a wide phase space of the jet formation and evolution, ranging from the initial highmomentumtransfer scattering to the hadronization process. The ∆R _{axis}observable is presented for 20< $$ {p}_{\textrm{T}}^{\textrm{ch}\ \textrm{jet}} $$ ${p}_{T}^{\mathrm{ch}\phantom{\rule{0ex}{0ex}}\mathrm{jet}}$< 100 GeV/c , and compared to predictions from the PYTHIA 8 and Herwig 7 event generators. The distributions can also be calculated analytically with a leading hadronization correction related to the nonperturbative component of the CollinsSoperSterman (CSS) evolution kernel. Comparisons to analytical predictions at nexttoleadinglogarithmic accuracy with leading hadronization correction implemented from experimental extractions of the CSS kernel in DrellYan measurements are presented. The analytical predictions describe the measured data within 20% in the perturbative regime, with surprising agreement in the nonperturbative regime as well. These results are compatible with the universality of the CSS kernel in the context of jet substructure.Free, publiclyaccessible full text available July 1, 2024 
Free, publiclyaccessible full text available July 1, 2024

Free, publiclyaccessible full text available July 1, 2024

A<sc>bstract</sc> The production of inclusive, prompt and nonprompt J/
ψ was studied for the first time at midrapidity (−1. 37< y _{cms}< 0. 43) in pPb collisions at = 8$$ \sqrt{s_{\textrm{NN}}} $$ $\sqrt{{s}_{\mathrm{NN}}}$. 16 TeV with the ALICE detector at the LHC. The inclusive J/ψ mesons were reconstructed in the dielectron decay channel in the transverse momentum (p _{T}) interval 0< p _{T}< 14 GeV/c and the prompt and nonprompt contributions were separated on a statistical basis forp _{T}> 2 GeV/c . The study of the J/ψ mesons in the dielectron channel used for the first time in ALICE online singleelectron triggers from the Transition Radiation Detector, providing a data sample corresponding to an integrated luminosity of 689 ± 13μ b^{−1}. The protonproton reference cross section for inclusive J/ψ was obtained based on interpolations of measured data at different centreofmass energies and a universal function describing thep _{T}differential J/ψ production cross sections. Thep _{T}differential nuclear modification factorsR _{pPb}of inclusive, prompt, and nonprompt J/ψ are consistent with unity and described by theoretical models implementing only nuclear shadowing.Free, publiclyaccessible full text available July 1, 2024 
Abstract Threebody nuclear forces play an important role in the structure of nuclei and hypernuclei and are also incorporated in models to describe the dynamics of dense baryonic matter, such as in neutron stars. So far, only indirect measurements anchored to the binding energies of nuclei can be used to constrain the threenucleon force, and if hyperons are considered, the scarce data on hypernuclei impose only weak constraints on the threebody forces. In this work, we present the first direct measurement of the p–p–p and p–p– $$\Lambda $$ Λ systems in terms of threeparticle correlation functions carried out for pp collisions at $$\sqrt{s} = 13$$ s = 13 TeV. Threeparticle cumulants are extracted from the correlation functions by applying the Kubo formalism, where the threeparticle interaction contribution to these correlations can be isolated after subtracting the known twobody interaction terms. A negative cumulant is found for the p–p–p system, hinting to the presence of a residual threebody effect while for p–p– $$\Lambda $$ Λ the cumulant is consistent with zero. This measurement demonstrates the accessibility of threebaryon correlations at the LHC.more » « lessFree, publiclyaccessible full text available July 1, 2024