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Free, publiclyaccessible full text available August 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.Free, publiclyaccessible full text available July 1, 2024

Abstract This article presents measurements of the groomed jet radius and momentum splitting fraction in pp collisions at $$ \sqrt{s} $$ s = 5 . 02 TeV with the ALICE detector at the Large Hadron Collider. Inclusive chargedparticle jets are reconstructed at midrapidity using the anti k T algorithm for transverse momentum $$ 60<{p}_{\textrm{T}}^{\textrm{ch}\;\textrm{jet}}<80 $$ 60 < p T ch jet < 80 GeV/ c . We report results using two different grooming algorithms: soft drop and, for the first time, dynamical grooming. For each grooming algorithm, a variety of grooming settings are used in order to explore the impact of collinear radiation on these jet substructure observables. These results are compared to perturbative calculations that include resummation of large logarithms at all orders in the strong coupling constant. We find good agreement of the theoretical predictions with the data for all grooming settings considered.Free, publiclyaccessible full text available June 1, 2024

Free, publiclyaccessible full text available June 1, 2024

Abstract This article presents new measurements of the fragmentation properties of jets in both proton–proton (pp) and heavyion collisions with the ALICE experiment at the Large Hadron Collider (LHC). We report distributions of the fraction z r of transverse momentum carried by subjets of radius r within jets of radius R . Chargedparticle jets are reconstructed at midrapidity using the anti k T algorithm with jet radius R = 0 . 4, and subjets are reconstructed by reclustering the jet constituents using the anti k T algorithm with radii r = 0 . 1 and r = 0 . 2. In proton–proton collisions, we measure both the inclusive and leading subjet distributions. We compare these measurements to perturbative calculations at nexttoleading logarithmic accuracy, which suggest a large impact of threshold resummation and hadronization effects on the z r distribution. In heavyion collisions, we measure the leading subjet distributions, which allow access to a region of harder jet frag mentation than has been probed by previous measurements of jet quenching via hadron fragmentation distributions. The z r distributions enable extraction of the partontosubjet fragmentation function and allow for tests of the universality of jet fragmentation functions in the quark–gluon plasma (QGP).more »Free, publiclyaccessible full text available June 1, 2024

A bstract Production of inclusive charmonia in pp collisions at centerofmass energy of $$ \sqrt{s} $$ s = 13 TeV and p–Pb collisions at centerofmass energy per nucleon pair of $$ \sqrt{s_{\textrm{NN}}} $$ s NN = 8 . 16 TeV is studied as a function of chargedparticle pseudorapidity density with ALICE. Ground and excited charmonium states ( J/ψ , ψ (2S)) are measured from their dimuon decays in the interval of rapidity in the centerofmass frame 2 . 5 < y cms < 4 . 0 for pp collisions, and 2 . 03 < y cms < 3 . 53 and −4 . 46 < y cms < −2 . 96 for p–Pb collisions. The chargedparticle pseudorapidity density is measured around midrapidity ( η  < 1 . 0). In pp collisions, the measured chargedparticle multiplicity extends to about six times the average value, while in pPb collisions at forward (backward) rapidity a multiplicity corresponding to about three (four) times the average is reached. The ψ (2S) yield increases with the chargedparticle pseudorapidity density. The ratio of ψ (2S) over J/ψ yield does not show a significant multiplicity dependence in either colliding system, suggesting a similar behavior of J/ψ andmore »Free, publiclyaccessible full text available June 1, 2024

A bstract The first measurements of elliptic flow of π ± , K ± , $$ \textrm{p}+\overline{\textrm{p}} $$ p + p ¯ , $$ {\textrm{K}}_{\textrm{S}}^0 $$ K S 0 , $$ \Lambda +\overline{\Lambda} $$ Λ + Λ ¯ , ϕ , $$ {\Xi}^{}+{\overline{\Xi}}^{+} $$ Ξ − + Ξ ¯ + , and $$ {\varOmega}^{}+{\overline{\varOmega}}^{+} $$ Ω − + Ω ¯ + using multiparticle cumulants in Pb–Pb collisions at $$ \sqrt{s_{\textrm{NN}}} $$ s NN = 5 . 02 TeV are resented. Results obtained with two ( v 2 {2}) and fourparticle cumulants ( v 2 {4}) are shown as a function of transverse momentum, p T , for various collision centrality intervals. Combining the data for both v 2 {2} and v 2 {4} also allows us to report the first measurements of the mean elliptic flow, elliptic flow fluctuations, and relative elliptic flow fluctuations for various hadron species. These observables probe the eventbyevent eccentricity fluctuations in the initial state and the contributions from the dynamic evolution of the expanding quark–gluon plasma. The characteristic features observed in previous p T differential anisotropic flow measurements for identified hadrons with twoparticle correlations, namely the mass ordering at low p T and the approximatemore »Free, publiclyaccessible full text available June 1, 2024

A bstract The first measurement of the e + e − pair production at low lepton pair transverse momentum ( p T , ee ) and low invariant mass ( m ee ) in noncentral Pb–Pb collisions at $$ {\sqrt{s}}_{\textrm{NN}} $$ s NN = 5 . 02 TeV at the LHC is presented. The dielectron production is studied with the ALICE detector at midrapidity ( η e  < 0 . 8) as a function of invariant mass (0.4 ≤ m ee < 2 . 7 GeV/ c 2 ) in the 50–70% and 70–90% centrality classes for p T , ee < 0.1 GeV/ c , and as a function of p T , ee in three m ee intervals in the most peripheral Pb–Pb collisions. Below a p T , ee of 0.1 GeV/ c , a clear excess of e + e − pairs is found compared to the expectations from known hadronic sources and predictions of thermal radiation from the medium. The m ee excess spectra are reproduced, within uncertainties, by different predictions of the photon–photon production of dielectrons, where the photons originate from the extremely strong electromagnetic fields generated by the highly Lorentzcontracted Pb nuclei.more »Free, publiclyaccessible full text available June 1, 2024

A bstract We report about the properties of the underlying event measured with ALICE at the LHC in pp and p–Pb collisions at $$ \sqrt{s_{\textrm{NN}}} $$ s NN = 5 . 02 TeV. The event activity, quantified by chargedparticle number and summed p T densities, is measured as a function of the leadingparticle transverse momentum $$ \left({p}_{\textrm{T}}^{\textrm{trig}}\right) $$ p T trig . These quantities are studied in three azimuthalangle regions relative to the leading particle in the event: toward, away, and transverse. Results are presented for three different p T thresholds (0.15, 0.5 and 1 GeV/ c ) at midpseudorapidity ( η  < 0 . 8). The event activity in the transverse region, which is the most sensitive to the underlying event, exhibits similar behaviour in both pp and p–Pb collisions, namely, a steep increase with $$ {p}_{\textrm{T}}^{\textrm{trig}} $$ p T trig for low $$ {p}_{\textrm{T}}^{\textrm{trig}} $$ p T trig , followed by a saturation at $$ {p}_{\textrm{T}}^{\textrm{trig}}\approx 5 $$ p T trig ≈ 5 GeV/ c . The results from pp collisions are compared with existing measurements at other centreofmass energies. The quantities in the toward and away regions are also analyzed after the subtraction of the contributionmore »Free, publiclyaccessible full text available June 1, 2024

Abstract The transversemomentum $$(p_{\textrm{T}})$$ ( p T ) spectra of K $$^{*}(892)^{0}~$$ ∗ ( 892 ) 0 and $$\mathrm {\phi (1020)}~$$ ϕ ( 1020 ) measured with the ALICE detector up to $$p_{\textrm{T}} $$ p T = 16 GeV/ c in the rapidity range $$1.2< y < 0.3,$$  1.2 < y < 0.3 , in p–Pb collisions at the centerofmass energy per nucleon–nucleon collision $$\sqrt{s_{\textrm{NN}}} = 5.02$$ s NN = 5.02 TeV are presented as a function of charged particle multiplicity and rapidity. The measured $$p_{\textrm{T}} $$ p T distributions show a dependence on both multiplicity and rapidity at low $$p_{\textrm{T}} $$ p T whereas no significant dependence is observed at high $$p_{\textrm{T}} $$ p T . A rapidity dependence is observed in the $$p_{\textrm{T}} $$ p T integrated yield (d N /d y ), whereas the mean transverse momentum $$\left( \langle p_{\textrm{T}} \rangle \right) $$ ⟨ p T ⟩ shows a flat behavior as a function of rapidity. The rapidity asymmetry ( $$Y_{\textrm{asym}}$$ Y asym ) at low $$p_{\textrm{T}} $$ p T (< 5 GeV/ c ) is more significant for higher multiplicity classes. At high $$p_{\textrm{T}} $$ p T , no significant rapidity asymmetry is observed in any of the multiplicitymore »Free, publiclyaccessible full text available June 1, 2024