Universality in physics describes the emergence of common features in vastly different systems. One fascinating example is the Efimov phenomenon where three-body resonantly interacting systems display universal properties. Efimov states have been observed in ultra-cold-atom systems, but their manifestation in nuclei remains elusive due to the long-range repulsive Coulomb interaction and the stringent requirement for at least two s-wave resonances in its subsystems. Recent theories propose another universality in three-body halos with only one s-wave resonance. Here, we report the identification of a precursor of this phenomenon in a neutron-rich 10He nucleus. With higher statistics and better sensitivities than previous experiments, we identify two low-lying 0+ states of 10He at  ~ 1 MeV and  ~ 2 MeV above its two-neutron decay threshold, and determine an s-wave scattering length of  ~ - 3.5 fm between 8He and neutron. It is revealed that the lower energy state, the ground state of 10He, is a three-body state with only s-wave interactions among its subsystems. This state manifests as a resonance structure, which is a direct consequence of a universal long-range three-body repulsion. Our work sheds new light on quantum halos with finite lifetimes, providing a path toward their unified understanding across various scales and fields.

The weak binding and spatially extended neutron densities characteristic of drip-line nuclei give rise to a distinctive low-energy dipole response. The drip-line nucleus ^{8}He is the most neutron-rich bound nucleus with a mass-to-charge ratio of A/Z=4. We measure the dipole response of ^{8}He, including for the first time the four-neutron decay channel. A total dipole strength of ∑B(E1)(E^{*}<15  MeV)=0.95(16)e^{2} fm^{2} and a dipole polarizability of α_{D}=0.61(1)  fm^{3} are extracted from the differential Coulomb-excitation cross section and compared to state-of-the-art theoretical calculations employing coupled cluster and three-body approaches. We find that the dipole continuum is dominated, even at high excitation energies well above the 4n decay threshold, by two-neutron emission, pointing to a ^{6}He+2n structure of the excited dipole mode. No indication was found for a 4n final-state correlation, while pronounced nn and ^{6}He-n final-state correlations are apparent.

Abstract The probability to observe a specific number of strange and multi-strange hadrons (n S), denoted as P(n S), is measured by ALICE at midrapidity (|y| < 0.5) in $$\sqrt{s}=5.02$$ TeV proton-proton (pp) collisions, dividing events into several multiplicity-density classes. Exploiting, for the first time, a technique based on counting the number of strange-particle candidates event-by-event, this measurement allows one to extend the study of strangeness production beyond the mean of the distribution. This constitutes a new test bench for production mechanisms, probing events with a large imbalance between strange and non-strange content. The analysis of a large-statistics data sample makes it possible to extract P(n S) up to a maximum n S of 7 for $${\text{K}}_{\text{S}}^{0}$$ , 5 for Λ and $$\overline{\Lambda }$$ , 4 for Ξ − and $${\overline{\Xi } }^{+}$$ , and 2 for Ω − and $${\overline{\Omega } }^{+}$$ . From this, the probability of producing strange hadron multiplets per event is calculated, thereby enabling the extension of the study of strangeness enhancement to extreme situations where several strange quarks hadronize in a single event at midrapidity. Moreover, comparing hadron combinations with different u and d quark compositions and equal overall s quark content, the contribution to the enhancement pattern coming from non-strangeness related mechanisms is isolated. The results are compared with state-of-the-art phenomenological models implemented in commonly used Monte Carlo event generators, including PYTHIA 8 Monash 2013, PYTHIA 8 with QCD-based Color Reconnection and Rope Hadronization (QCD-CR + Ropes), and EPOS LHC, which incorporates both partonic interactions and hydrodynamic evolution. These comparisons show that the new approach dramatically enhances the sensitivity to the different underlying physics mechanisms modeled by each generator.

The transverse momentum spectra and integrated yields of anti-Sigma hyperons ((Sigma) over bar (+/-)) have been measured in pp and p-Pb collisions at root s(NN) = 5.02 TeV with the ALICE experiment. Measurements are performed via the newly accessed decay channel (Sigma) over bar (+/-) -> (n) over bar pi(+/-). A new method of antineutron reconstruction with the PHOS electromagnetic spectrometer is developed and applied to this analysis. The p(T) spectra of (Sigma) over bar (+/-) are measured in the range 0.5 < p(T) < 3 GeV/c and compared to predictions of the PYTHIA 8, DPMJET, PHOJET, EPOS LHC and EPOS4 models. The EPOS LHC and EPOS4 models provide the best descriptions of the measured spectra both in pp and p-Pb collisions, while models which do not account for multiparton interactions provide a considerably worse description at high p(T). The total yields of (Sigma) over bar (+/-) in both pp and p-Pb collisions are compared to predictions of the Thermal-FIST model and dynamical models PYTHIA 8, DPMJET, PHOJET, EPOS LHC and EPOS4. All models reproduce the total yields in both colliding systems within uncertainties. The nuclear modification factors R-pPb for both (Sigma) over bar (+) and (Sigma) over bar (-) are evaluated and compared to those of protons, Lambda and Xi hyperons, and predictions of EPOS LHC and EPOS4 models. No deviations of R-pPb for (Sigma) over bar (+/-) from the model predictions or measurements for other hadrons are found within uncertainties.

We have measured the interaction cross sections (aI) and charge-changing cross sections (acc) for neutron-rich copper isotopes with mass numbers A = 63 - 80 using the transmission method at the RIBF facility, RIKEN. From these values, we aim to derive the proton distribution radius (Rp) and the neutron distribution radius (Rn) for each isotope through subsequent analysis. Then, we plan to determine the neutron skin thickness (Delta Rnp = Rn - Rp) for each isotope. These results will provide a new constraint on the symmetry energy parameter L of the equation of state (EoS) of nuclear matter and contribute to a deeper understanding of the nuclear structure of exotic nuclei.

The first results of K*(892)(+/-) production at midrapidity (|y| < 0.5) in pp collisions at root s = 13 TeV as a function of the event multiplicity are presented. The K*(892)+/- has been reconstructed via its hadronic decay channel K*(892)(+/-) -> pi +/- + K-S(0) using the ALICE detector at the LHC. For each multiplicity class, the differential transverse momentum (p(T)) spectrum, the mean transverse momentum < p(T)>, the p(T)-integrated yield (dN/dy), and the ratio of the K*(892)(+/-) to K-S(0) yields are reported. These are consistent with previous K*(892)0 resonance results with a higher level of precision. Comparisons with phenomenological models such as PYTHIA6, PYTHIA8, EPOS-LHC, and DIPSY are also discussed. For the first time, a significant K*(892)(+/-)/K-S(0) suppression in pp collisions is observed at a 7.. level passing from low to high multiplicity events. The ratios of the p(T)-differential yields of K*(892)(+/-) and K-S(0) in high and low multiplicity events are also presented along with their double ratio. For p(T) less than or similar to 2 GeV/c this double ratio persists below unity by more than 3 sigma suggesting that the suppression affects mainly low p(T) resonances. The measured decreasing trend of the K*(892)(+/-)/K-S(0) ratio with increasing multiplicity, which in heavy-ion collisions is typically attributed to the rescattering of decay particles of the short-lived resonances, is reproduced by the EPOS-LHC model without the use of hadronic afterburners

We report proton-proton correlation function measurements in central ^132Sn+^124Sn and ^108Sn+^112Sn collisions at 270 MeV/nucleon. The proton emitting source sizes are extracted for the systems by using femtoscopic imaging technique. The fast dynamic core radius for the neutron-rich system is found to be 2.22 ± 0.13 (stat.)± 0.07 (syst.) fm, which is approximately 24% larger than that for the neutron-deficient system, 1.74 ± 0.08 (stat.)± 0.05 (syst.) fm. This difference is an order of magnitude larger than the ∼3% difference in the ground-state charge radii of the projectile nuclei. Transport model simulations based on mean-field dynamics cannot reproduce this amplification. The observation reveals a beyond-mean-field mechanism associated to short-range neutron-proton correlations, which dynamically enhance the proton emitting source in the neutron-rich environment. Our results demonstrate that heavy-ion collisions induced by radioactive beam, combined with femtoscopic precision, provide a new hadronic probe of short-range correlation, and that careful treatment of the beyond-mean-field interactions are required in modeling such processes.

Abstract The measurement of three-dimensional femtoscopic correlations between identical charged kaons (K ± K ± ) produced in p–Pb collisions at center-of-mass energy per nucleon pair $$\sqrt{{s}_{\text{NN}}}=5.02$$ TeV with ALICE at the LHC is presented for the first time. This measurement, supplementary to those in pp and Pb–Pb collisions, allows understanding the particle-production mechanisms at different charged-particle multiplicities and provides information on the dynamics of the source of particles created in p–Pb collisions, for which a general consensus does not yet exist. It is shown that the measured source sizes increase with charged-particle multiplicity and decrease with increasing pair transverse momentum. These trends for K ± K ± are similar to the ones observed earlier in identical charged-pion and $${\text{K}}_{\text{s}}^{0}{\text{K}}_{\text{s}}^{0}$$ correlations in Pb–Pb collisions at various energies and in π ± π ± correlations in p–Pb collisions at $$\sqrt{{s}_{\text{NN}}}=5.02$$ TeV. At comparable multiplicity, the source sizes measured in p–Pb collisions agree within uncertainties with those observed in pp collisions, and there is an indication that they are smaller than those observed in Pb–Pb collisions. The obtained results are also compared with predictions from the hadronic interaction model EPOS 3, which tends to underestimate the source size for the most central collisions and agrees with the data for semicentral and peripheral events. Furthermore, the time of maximal emission for kaons is extracted. It turns out to be comparable with the value obtained in highly peripheral Pb–Pb collisions at the same energy, indicating that the kaon emission evolution is similar to that in p–Pb collisions.

Despite its nucleon numbers not coinciding with the traditional nuclear magic numbers, the structure of Ca 54 shows signatures of a doubly closed shell nucleus. This article details the structures of neutron-excited states up to beyond the two-neutron emission threshold populated by the Ca 55 ( p , p n ) reaction at ∼ 200 MeV/nucleon. Level energies and population cross sections were determined through γ -ray spectroscopy and invariant-mass spectroscopy of Ca 54 . Large-scale shell model calculations with protons and neutrons allowed to occupy the s d − p f − s d g orbitals were performed to predict energy levels and spectroscopic factors. Distorted wave impulse approximation calculations provided single-particle knockout cross sections and momentum distributions of the reaction products. The theoretical calculations reproduce the data well. Both theory and experiment are suggestive of a well-preserved shell structure at high excitation energy. Also, inelastic scattering of Ca 54 , carried out within the same experiment, validates previously proposed level schemes.

Abstract Proton-rich new isotopes in the regions of atomic numbers Z = 57 and 72 were produced through the projectile fragmentation of a 345-MeV/nucleon 208Pb79 + beam at the RI Beam Factory, RIKEN. In addition to $^{118}_{\;\: 58}$Ce, $^{120}_{\;\: 59}$Pr, $^{152,153}_{\qquad \! 72}$Hf, and $^{154}_{\;\: 73}$Ta, which are new isotopes reported in our previous letter, $^{113}_{\;\: 56}$Ba, $^{117}_{\;\: 58}$Ce, and $^{122}_{\;\: 60}$Nd were newly confirmed. These highly proton-rich radioactive isotopes (RIs) were separated and identified using BigRIPS, the large-acceptance two-stage separator in RIKEN. Cross sections of the neighboring proton-rich RIs were measured and compared with predicted values of the semi-empirical formulas: FRACS1.1 and EPAX3.1a reproduced them fairly well. The cross sections of proton-rich RIs around Z = 58 produced from the 208Pb beam were approximately three times those produced from a 238U beam.

This letter reports the results from the first experimental study utilizing a 345-MeV/nucleon Pb-208 beam at the RI Beam Factory at RIKEN Nishina Center. This experiment aimed at searching for new proton- and neutron-rich isotopes beyond Z=50. The BigRIPS in-flight separator and state-of-the-art radiation detectors were used to efficiently separate and reliably identify the produced isotopes. We confirmed a total of 22 new exotic isotopes: Ce-118, Pr-120, Ho-179, Er-181,Er-182, Tm184-186, Yb-188,Yb-189, Lu-191, Hf-152,Hf-153,Hf-193,Hf-194, Ta-154,Ta-195,Ta-196, W-198,W-199, and Re-200,Re-201. This discovery significantly extends the known boundaries of the nuclear chart, paving the way for investigating the properties of unstable nuclei far from the beta-stability line in the Z=58-75 region. This region is of particular importance for exploring phenomena such as exotic decay modes appearing on the proton-rich side and r-process nucleosynthesis associated with neutron-rich nuclei.

Abstract Measurements of transverse momentum (p T) and pseudorapidity (η) dependent flow vector fluctuations in p–Pb collisions at $$\sqrt{{s}_{NN}}=5.02$$ TeV at the CERN Large Hadron Collider are presented. By studying long-range two-particle correlations with a template fit method, potential biases from non-flow effects such as jets and resonance decays are effectively suppressed. Significant p T- and η-dependent fluctuations of the second-harmonic flow vector are observed with more than 5σ confidence in p–Pb collisions, similar to the observations in Pb–Pb collisions. The influence of residual non-flow effects has been evaluated and cannot account for the observed fluctuations, thereby confirming the observation of flow vector fluctuations in small collision systems at the LHC. Comparisons to model calculations from 3DGlauber+MUSIC+UrQMD and the parton transport model from AMPT are also presented. The measurements provide constraints on the theoretical modelling of the three-dimensional initial geometry and its event-by-event fluctuations, offering critical insights into the origin of collective flow in small collision systems at the LHC.

The size of neutron and proton single-particle orbitals of ^52Ca, ^53Ca, ^54Ca, and ^55Sc were investigated via nucleon knockout reactions at ∼ 230 MeV/nucleon. The determination method is based on the measured fragment momentum distributions in (p,pn) and (p,2p) reactions, which are shown to be sensitive to the spatial extension of the wave function of the knocked-out nucleon, interpreted within the distorted wave impulse approximation (DWIA) framework. A systematic sensitivity study is carried out for the (p,pn) recoil-momentum distribution method and is presented in this work. The experimental momentum distributions are compared to state-of-the-art mean field and ab initio in-medium similarity renormalization group and self-consistent Green's function calculations in combination with DWIA reaction theory calculations. Based on this work, the 1p neutron orbitals are consistently found 0.48-0.78 fm larger than the 0f_7/2 neutron orbitals in ^52-54Ca, while the size evolution of the valence proton orbitals remains inconclusive due to the large associated statistical uncertainties.

Three-neutron emission from He-7 has been directly measured for the first time, following neutron knockout from a He-8 beam at 156 MeV/nucleon. A resonancelike structure at 2.08(4) MeV above the He-4+3n threshold [E-x = 2.68(4) MeV] with a width of 3.9(2) MeV was observed and deduced to arise predominately from the predicted J(pi) = 3/2(2)(-) level. The three-neutron invariant-mass spectrum was reconstructed and found to peak at around 1 MeV and could, through complete simulations incorporating neutron-neutron correlations, be very well described by the sequential decay of He-7* via the 2(1)(+) excited state of He-6. No evidence was found for any significant three-neutron correlations beyond those expected from well-established two-body interactions, including a trineutron resonance.

(Multi-)strange particle production rates and transverse momentum distributions are measured at midrapidity ( | y | < 0.5 ) as a function of the charged-particle multiplicity density by the ALICE experiment at the CERN Large Hadron Collider (LHC), using proton-proton collisions at a center-of-mass energy of s = 5.02 TeV. This study extends similar studies performed at s = 7 TeV and s = 13 TeV to a lower-energy regime, improving the statistical precision and extending the measurement to previously unexplored low-multiplicity regions. While K S 0 , Λ , and Ξ yields can be described with a linear multiplicity dependence within uncertainties, the Ω yields follow a significantly faster than linear increasing trend. For all analyzed particles, the overall production rate is consistent with that observed at higher energy and at similar multiplicity densities. Transverse momentum distributions are observed to evolve with multiplicity. Several state-of-the-art QCD-inspired Monte Carlo models have been compared with the data, testing some recently introduced features to address the findings at higher energies. Models can qualitatively describe the transverse momentum spectra and the Λ / K S 0 spectral ratio only if collectivity is introduced in the evolution of the system.

Results of decay studies of nuclei in the vicinity of 54Zn, which is the most neutron-deficient isotope of zinc and undergoes ground-state two-proton radioactivity (2p), are presented. The measurements were performed with a gaseous time-projection chamber with optical readout, which allowed us to record tracks of protons emitted in the decays. A new method of data analysis was used to reconstruct energies and emission angles of low-energy protons that were stopped within the active volume of the chamber. Half-lives and branching ratios for 9-delayed proton emission channels were determined for 56Zn, 55Zn, and 55Cu. The 9-delayed emission of two protons for 55Zn was observed for the first time. Five events of 2p radioactivity of 54Zn were detected and reconstructed. The distribution of the opening angle between momenta of the two protons is consistent with the findings published by Ascher et al. [Phys. Rev. Lett. 107, 102502 (2011)].

This Letter presents measurements of long-range transverse-momentum correlations using a new observable, v_{0}(p_{T}), serving as a probe of event-by-event radial-flow fluctuations, the underlying radial expansion, and the medium's properties in heavy-ion collisions. Results are reported for inclusive charged particles, pions, kaons, and protons across various centrality intervals in Pb-Pb collisions at sqrt[s_{NN}]=5.02  TeV, recorded by the ALICE detector. A pseudorapidity-gap technique, similar to that used in anisotropic-flow studies, is employed to suppress short-range correlations. At low p_{T}, a characteristic mass ordering consistent with hydrodynamic collective flow is observed. At higher p_{T} (>3  GeV/c), protons exhibit larger v_{0}(p_{T}) than pions and kaons, in agreement with expectations from quark-recombination models. Comparisons to viscous hydrodynamic calculations with varying bulk viscosity and equation of state demonstrate the sensitivity of the v_{0}(p_{T}) observable to these key medium properties. The findings establish v_{0}(p_{T}) as a valuable addition to the set of observables used in Bayesian analyses for extracting the transport properties and constraining the equation of state of strongly interacting matter, while also helping to systematically explore its sensitivity and impact within such global studies.

The beam composition of a tertiary \(^{130}\)Sn beam that was produced in projectile fragmentation is analyzed. This allows, in a first step, to identify contaminants in the beam and, in a second step, to determine isomeric ratios for different isotopes present in the beam. The results help to understand the process of projectile fragmentation and to plan future experiments that involve similar reactions. Abstract Published by the Jagiellonian University 2026 authors

Per-trigger yields of π 0 − hadron correlations were measured in semicentral Pb-Pb collisions at s NN = 5.02 TeV in ALICE at the CERN Large Hadron Collider. The reconstructed π 0 → γ γ , with a transverse momentum of 11 GeV / c < p T ( π 0 ) < 14 GeV / c , is used as the trigger particle to calculate yields of associated charged particles on the near- and away-side. The photons are reconstructed using the ALICE Electromagnetic Calorimeter, and the charged particles are measured in the ALICE central barrel within a pseudorapidity range of | η | < 0.8 . The yields are reported relative to the orientation of the π 0 with the second-order event plane and are background subtracted using the reaction-plane fit method. The data give an indication of a suppression of the associated charged-particle yields near p T ≈ 2 GeV / c when comparing out-of-plane to in-plane trigger particles. At associated charged-particle p T > 3 GeV/ c , no significant event-plane dependence is observed within uncertainties. The results are compared with predictions from the JEWEL model, which implements jet energy loss in an expanding medium. JEWEL predicts no significant modification of either the near- or away-side associated yields, independent of whether medium recoils are included. The observed behavior may indicate the presence of additional energy-loss mechanisms beyond those governed by path-length dependence.

Particle identification (PID) is a fundamental aspect of the ALICE detector system, central to its heavy-ion and proton–proton physics programs. Among the different PID strategies, ALICE uses the time-of-flight (TOF) detector to identify particles at intermediate momenta ( 0.5< p_T <4 GeV/c ). The ALICE TOF detector performed successfully during the first 10 years of LHC operations. During the Long Shutdown 2, many ALICE sub-detectors, including TOF, were upgraded to fully leverage the targeted 50 kHz interaction rate of Pb–Pb collisions, which required the implementation of a continuous readout scheme. The TOF detector electronics were upgraded and refurbished, while processing algorithms for data quality control, reconstruction, calibration, and analysis were rewritten. This paper presents the upgraded TOF detector operation and calibration procedures and its performance in terms of timing resolution, a key factor for particle separation in ALICE analyses. Using 2022 pp collision data at √(s) = 13.6 TeV from Run 3, the time resolution of the detector was estimated with two independent methods, both yielding consistent results, better than 80 ps. Despite the excellent performance already achieved, further improvements are expected after additional detector commissioning and refined calibration procedures, thus enhancing the ALICE PID capabilities for Run 3 and beyond.