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A<sc>bstract</sc> Thep_T-differential cross section ofωmeson production in pp collisions at$$ \sqrt{s} $$ $\sqrt{s}$= 13 TeV at midrapidity (|y| <0.5) was measured with the ALICE detector at the LHC, covering an unprecedented transverse-momentum range of 1.6< p_T<50 GeV/c. The meson is reconstructed via theω→π⁺π⁻π⁰decay channel. The results are compared with various theoretical calculations: PYTHIA8.2 with the Monash 2013 tune overestimates the data by up to 50%, whereas good agreement is observed with Next-to-Leading Order (NLO) calculations incorporatingωfragmentation using a broken SU(3) model. Theω/π⁰ratio is presented and compared with theoretical calculations and the available measurements at lower collision energies. The presented data triples thep_Tranges of previously available measurements. A constant ratio ofC^ω/π0= 0.578 ± 0.006 (stat.) ± 0.013 (syst.) is found above a transverse momentum of 4 GeV/c, which is in agreement with previous findings at lower collision energies within the systematic and statistical uncertainties. 

In this Letter, the first evidence of the ${}_{\overline{\mathrm{\Lambda }}}{}^4\overline{\mathrm{He}}$antihypernucleus is presented, along with the first measurement at the LHC of the production of (anti)hypernuclei with mass number $A=4$, specifically $\left(\mathrm{anti}\right){}_{\mathrm{\Lambda }}{}^4\mathrm{H}$and $\left(\mathrm{anti}\right){}_{\mathrm{\Lambda }}{}^4\mathrm{He}$. In addition, the antiparticle-to-particle ratios for both hypernuclei ( ${}_{\overline{\mathrm{\Lambda }}}{}^4\overline{\mathrm{H}}/{}_{\mathrm{\Lambda }}{}^4\mathrm{H}$and ${}_{\overline{\mathrm{\Lambda }}}{}^4\overline{\mathrm{He}}/{}_{\mathrm{\Lambda }}{}^4\mathrm{He}$) are shown, which are sensitive to the baryochemical potential of the strongly interacting matter created in heavy-ion collisions. The results are obtained from a data sample of central Pb-Pb collisions, collected during the 2018 LHC data taking at a center-of-mass energy per nucleon pair of $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$. The yields measured for the average of the charge-conjugated states are found to be $[0.78\pm 0.19\left(\mathrm{stat}\right)\pm 0.17\left(\mathrm{syst}\right)]\times {10}^{-6}$for the $\left(\mathrm{anti}\right){}_{\mathrm{\Lambda }}{}^4\mathrm{H}$and $[1.08\pm 0.34\left(\mathrm{stat}\right)\pm 0.20\left(\mathrm{syst}\right)]\times {10}^{-6}$for the $\left(\mathrm{anti}\right){}_{\mathrm{\Lambda }}{}^4\mathrm{He}$, and the measured antiparticle-to-particle ratios are in agreement with unity. The presence of $\left(\mathrm{anti}\right){}_{\mathrm{\Lambda }}{}^4\mathrm{H}$and $\left(\mathrm{anti}\right){}_{\mathrm{\Lambda }}{}^4\mathrm{He}$excited states is expected to strongly enhance the production yield of these hypernuclei. The yield values exhibit a combined deviation of $3.3\sigma$from the theoretical ground-state-only expectation, while the inclusion of the excited states in the calculations leads to an agreement within $0.6\sigma$with the present measurements. Additionally, the measured $\left(\mathrm{anti}\right){}_{\mathrm{\Lambda }}{}^4\mathrm{H}$and $\left(\mathrm{anti}\right){}_{\mathrm{\Lambda }}{}^4\mathrm{He}$masses are compatible with the world-average values within the uncertainties. © 2025 CERN, for the ALICE Collaboration2025CERN 

A<sc>bstract</sc> Short-range correlations between charged particles are studied via two-particle angular correlations in pp collisions at$$ \sqrt{s} $$ $\sqrt{s}$= 13 TeV. The correlation functions are measured as a function of the relative azimuthal angle ∆φand the pseudorapidity separation ∆ηfor pairs of primary charged particles within the pseudorapidity interval |η|<0.9 and the transverse-momentum range 1< p_T<8 GeV/c. Near-side (|∆φ|<1.3) peak widths are extracted from a generalised Gaussian fitted over the correlations in full pseudorapidity separation (|∆η|<1.8), while the per-trigger associated near-side yields are extracted for the short-range correlations (|∆η|<1.3). Both are evaluated as a function of charged-particle multiplicity obtained by two different event activity estimators. The width of the near-side peak decreases with increasing multiplicity, and this trend is reproduced qualitatively by the Monte Carlo event generators PYTHIA 8, AMPT, and EPOS. However, the models overestimate the width in the low transverse-momentum region (p_T<3 GeV/c). The per-trigger associated near-side yield increases with increasing multiplicity. Although this trend is also captured qualitatively by the considered event generators, the yield is mostly overestimated by the models in the considered kinematic range. The measurement of the shape and yield of the short-range correlation peak can help us understand the interplay between jet fragmentation and event activity, quantify the narrowing trend of the near-side peak as a function of transverse momentum and multiplicity selections in pp collisions, and search for final-state jet modification in small collision systems. 

A<sc>bstract</sc> The production of (multi-)strange hadrons is measured at midrapidity in proton-proton collisions at$$ \sqrt{s} $$ $\sqrt{s}$= 13 TeV as a function of the local charged-particle multiplicity in the pseudorapidity interval |η|<0.5 and of the very-forward energy measured by the ALICE Zero-Degree Calorimeters. The latter provides information on the effective energy, i.e. the energy available for particle production in the collision once subtracted from the centre-of-mass energy. The yields of$$ {\textrm{K}}_{\textrm{S}}^0 $$ $K_S^0$,$$ \Lambda +\overline{\Lambda} $$ $\Lambda +\overline{\Lambda }$, and$$ {\Xi}^{-}+{\overline{\Xi}}^{+} $$ ${\Xi }^{-}+{\overline{\Xi }}^{+}$per charged-particle increase with the effective energy. In addition, this work exploits a multi-differential approach to decouple the roles of local multiplicity and effective energy in such an enhancement. The results presented in this article provide new insights into the interplay between global properties of the collision, such as the initial available energy in the event, and the locally produced final hadronic state, connected to the charged-particle multiplicity at midrapidity. Notably, a strong increase of strange baryon production with effective energy is observed for fixed charged-particle multiplicity at midrapidity. These results are discussed within the context of existing phenomenological models of hadronisation implemented in different tunes of the PYTHIA 8 event generator. 

Abstract The femtoscopic study of pairs of identical pions is particularly suited to investigate the effective source function of particle emission, due to the resulting Bose–Einstein correlation signal. In small collision systems at the LHC, pp in particular, the majority of the pions are produced in resonance decays, which significantly affect the profile and size of the source. In this work, we explicitly model this effect in order to extract the primordial source in pp collisions at$$\sqrt{s}~=~13$$ $\sqrt{s}=13$ TeV from charged$$\uppi $$ $\pi$–$$\uppi $$ $\pi$correlations measured by ALICE. We demonstrate that the assumption of a Gaussian primordial source is compatible with the data and that the effective source, resulting from modifications due to resonances, is approximately exponential, as found in previous measurements at the LHC. The universality of hadron emission in pp collisions is further investigated by applying the same methodology to characterize the primordial source of$$\textrm{K}$$ $\text{K}$–$$\textrm{p}$$ $\text{p}$ pairs. The size of the primordial source is evaluated as a function of the transverse mass ($$m_{\textrm{T}}$$ $m_{\text{T}}$) of the pairs, leading to the observation of a common scaling for both$$\uppi $$ $\pi$–$$\uppi $$ $\pi$and$$\textrm{K}$$ $\text{K}$–$$\textrm{p}$$ $\text{p}$ , suggesting a collective effect. Further, the present results are compatible with the$$m_{\textrm{T}}$$ $m_{\text{T}}$scaling of the$$\textrm{p}$$ $\text{p}$–$$\textrm{p}$$ $\text{p}$ and p$$-\Lambda $$ $-\Lambda$primordial source measured by ALICE in high multiplicity pp collisions, providing additional evidence for the presence of a common emission source for all hadrons in small collision systems at the LHC. This will allow the determination of the source function for any hadron–hadron pairs with high precision, granting access to the properties of the possible final-state interaction among pairs of less abundantly produced hadrons, such as strange or charmed particles. 

This paper reports the first measurement of the transverse momentum ( $p_{\mathrm{T}}$) spectra of primary charged pions, kaons, (anti)protons, and unidentified particles as a function of the charged-particle flattenicity in pp collisions at $\sqrt{s}=13\mathrm{TeV}$. Flattenicity is a novel event shape observable that is measured in the pseudorapidity intervals covered by the V0 detector, $2.8<\eta <5.1$and $-3.7<\eta <-1.7$. According to QCD-inspired phenomenological models, it shows sensitivity to multiparton interactions and is less affected by biases toward larger $p_{\mathrm{T}}$due to local multiplicity fluctuations in the V0 acceptance than multiplicity. The analysis is performed in minimum-bias (MB) as well as in high-multiplicity events up to $p_{\mathrm{T}}=20\mathrm{GeV}/c$. The event selection requires at least one charged particle produced in the pseudorapidity interval $\left|\eta \right|<1$. The measured $p_{\mathrm{T}}$distributions, average $p_{\mathrm{T}}$, kaon-to-pion and proton-to-pion particle ratios, presented in this paper, are compared to model calculations using 8 based on color strings and EPOS LHC. The modification of the $p_{\mathrm{T}}$-spectral shapes in low-flattenicity events that have large event activity with respect to those measured in MB events develops a pronounced peak at intermediate $p_{\mathrm{T}}$( $2<p_{\mathrm{T}}<8\mathrm{GeV}/c$), and approaches the vicinity of unity at higher $p_{\mathrm{T}}$. The results are qualitatively described by , and they show different behavior than those measured as a function of charged-particle multiplicity based on the V0M estimator. © 2025 CERN, for the ALICE Collaboration2025CERN