ALICE mission

ALICE is optimized to study the collisions of nuclei at the ultra-relativistic energies provided by the LHC. The aim is to study the physics of strongly interacting matter at the highest energy densities reached so far in the laboratory. In such conditions, an extreme phase of matter - called the quark-gluon plasma - is formed. Our universe is thought to have been in such a primordial state for the first few millionths of a second after the Big Bang, before quarks and gluons were bound together to form protons and neutrons. Recreating this primordial state of matter in the laboratory and understanding how it evolves will allow us to shed light on questions about how matter is organized and the mechanisms that confine quarks and gluons. For this purpose, we are carrying out a comprehensive study of the hadrons, electrons, muons, and photons produced in the collisions of heavy nuclei (208Pb). ALICE is also studying proton-proton and proton-nucleus collisions both as a comparison with nucleus-nucleus collisions and in their own right. In 2021, ALICE completed a significant upgrade of its detectors to further enhance its capabilities and continue its scientific journey at the LHC in Run 3 and 4, until the end of 2032. At the same time,  upgrade plans are being made for ALICE 3, the next-generation experiment for LHC Runs 5 and 6.

Recent highlights

 

Recent highlights

Machine learning is being integrated to efficiently process and simulate large amounts of ALICE data, improving performance while reducing computing cost.... Read more
The ALICE Collaboration presents a wide range of new physics results at the International Conference on Strangeness in Quark Matter (SQM 2026)... Read more
Published in Nature Communications: ALICE takes a step further in addressing the question of whether a quark–gluon plasma can be formed in pp and p–Pb collisions.... Read more

Latest ALICE Submissions

$\mathbf{\textbf{K}^{0}_{\textbf{S}}}-\mathbf{\textbf{K}^{0}_{\textbf{S}}}$ femtoscopy in Pb$-$Pb collisions at $\mathbf{\sqrt{\textit{s}_{\rm NN}} = 5.02}$ TeV at the LHCResults from a one-dimensional femtoscopic analysis of ${\rm K}^{0}_{\rm S}-{\rm K}^{0}_{\rm S}$ correlations in Pb$-$Pb collisions at the center-of-mass energy $\sqrt{s_{\mathrm{NN}}}~=~5.02$ TeV using data collected by the ALICE experiment at the LHC are presented. The source radius $R$ and correlation strength $λ$ are studied as a function of centrality and pair-transverse momentum ($k_{\rm T}$) to provide insight into the space-time structure and composition of the particle-emitting source. The observed trends of radii as a function of $k_{\rm T}$ and centrality are consistent with the collective expansion of the system. Comparisons with measurements at $\sqrt{s_{\mathrm{NN}}}~=~2.76$ TeV by the ALICE Collaboration show agreement across multiplicities and $k_{\rm T}$. Hydrokinetic model predictions match the most central collision results but deviate in peripheral events, potentially reflecting limitations in the model's description of peripheral collisions. A comparison with recent measurements at the same energy by the CMS Collaboration shows compatibility in both $R$ and $λ$ within 1.3$σ$. These results extend previous ${\rm K}^{0}_{\rm{S}}-{\rm K}^{0}_{\rm{S}}$ femtoscopy to a higher energy, providing a consistent baseline for future comparisons.
2605.02321
Measurement of isolated-prompt photon$-$hadron correlations in Pb$-$Pb collisions at $\mathbf{\sqrt{\textit{s}_{\rm NN}} = 5.02}$ TeVThe ALICE Collaboration has measured the azimuthal correlation between trigger isolated-prompt photons and associated charged hadrons in Pb$-$Pb collisions at the CERN LHC, at a centre-of-mass energy per nucleon pair of \snnfive. The trigger isolated-prompt photons are measured in the transverse-momentum range $18 < ~ p_{\rm T}^γ < ~ 40$ GeV/$c$ and pseudorapidity range $|η^γ| < ~0.67$. The isolation selection is based on a charged particle isolation momentum threshold $p_{\rm T}^{\rm iso, ch} = 1.5$ GeV/$c$ within a cone of radius $R=0.2$. The associated charged particles are measured in the transverse-momentum ranges $p_{\rm T}^{\rm h} > 1.8$ GeV/$c$ and pseudorapidity $|η^{\rm h}| < ~0.9$. The yield D$(z_{\rm T})$ of associated hadrons per trigger, with $z_{\rm T} = p_{\rm T}^{\rm h}/p_{\rm T}^γ$, is measured in three Pb$-$Pb collision centrality classes: central (0$-$30%), semicentral (30$-$50%), and peripheral (50$-$90%). An approximation to the standard $I_{\rm AA}$ is computed from the D$(z_{\rm T})$ conditional yields, using NLO pQCD predictions as pp reference. A strong suppression of this ratio is observed in central collisions compared to peripheral collisions. The result extends to a lower $p_{\rm T}^γ$ relative to those reported in previously published Pb$-$Pb collisions measurements at $\sqrt{s_{\rm NN}}=5.02$ TeV. The measurement is compared to NLO pQCD calculations that include energy loss, and to the CoLBT-hydro model. The results from central collisions are also compared with measurements of jets correlated with isolated-prompt photons and of hadrons correlated with Z$^0$ bosons, both reported by the CMS Collaboration at the LHC, as well as with direct photon$-$hadron correlation measurements reported by the PHENIX and STAR Collaborations at RHIC.
2605.02342
Dijet invariant mass of charged-particle jets in pp and p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeVThe ALICE collaboration presents the first measurement of the dijet invariant mass spectra of charged-particle jets in pp and p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV. Charged particles in the mid-pseudorapidity region, $|η| < ~ 0.9$, are clustered into jets using the anti-$k_{\rm T}$ algorithm with a resolution parameter $R = 0.4$. The leading and subleading jets are required to have a transverse momentum $p_{\rm T} > 20$ GeV$/c$ and to be contained within $\left|η_{\rm jet}\right| < ~ 0.5$. The dijet invariant mass spectrum and the nuclear modification factor $R_{\rm pA}$ are presented in the low-mass region of 75 to 150 GeV/$c^2$. The nuclear modification factor for charged-particle dijet invariant mass is consistent with unity. This is in line with previous small-system jet studies. Comparisons with Monte Carlo simulations suggest that the low-mass region is sensitive to anti-shadowing effects on parton densities in the nucleus, however, the expected signal is subtle and below the present experimental sensitivity.
2604.07961
Multiplicity dependence of prompt and non-prompt J/$ψ$ production at midrapidity in pp collisions at $\sqrt{s} = 13$ TeVThe yields of prompt and non-prompt J/$ψ$ and the fraction of non-prompt J/$ψ$ are measured at midrapidity ($|y| < ~ 0.9$) via the dielectron decay channel as a function of the midrapidity charged-particle multiplicity ($|η| < ~ 0.9$) in pp collisions at $\sqrt{s} = 13$ TeV. The J/$ψ$ yields and the multiplicity are normalized by their average value in inelastic collisions. The multiplicity-dependent yield ratio between prompt J/$ψ$ and D$^0$ is reported. The multiplicity is further divided into three azimuthal regions with respect to the J/$ψ$ momentum: toward the J/$ψ$ emission direction, transverse, or opposite to it. A stronger-than-linear increase of the self-normalized yields is observed for both prompt and non-prompt J/$ψ$ production, with similar trends. This behaviour is also observed in the toward region, while a weaker increase is observed in the transverse and away regions.
2604.07968
Wave-Function Femtometry: Hypertriton - The Ultimate Halo NucleusThe interaction between nucleons and hyperons - baryons containing a strange quark - is key to understanding the properties of dense nuclear matter, such as that expected in the interior of neutron stars. Direct scattering experiments are hindered by the short lifetime of hyperons, prompting the study of hypernuclei - bound states of nucleons and hyperons - as an alternative approach. The lightest known hypernucleus, the hypertriton ($^3_Λ$H), is a weakly bound state composed of a proton, a neutron and a $Λ$ hyperon, and is believed to exhibit a halo-like structure with the $Λ$ being loosely bound to a deuteron core. Based on the first measurement of hypertriton production in proton-proton collisions at the CERN Large Hadron Collider (LHC), its halo structure is confirmed. A successful description of the hypertriton production yield within the nuclear coalescence framework enables an estimation of the $Λ$ separation from the deuteron core as $9.54^{+2.67}_{-1.11}$ fm.
2604.07949
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Diversity and Inclusivity in ALICE

The ALICE Collaboration embraces and values the diversity of its team members and colleagues. We are committed to fostering an inclusive environment for all people regardless of their nationality/culture, profession, age/generation, family situation and gender, as well as individual differences such as but not limited to ethnic origin, sexual orientation, belief, disability, or opinions provided that they are consistent with the Organization’s values.