A Large Ion Collider Experiment

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ALICE INDICO

update on - 21:22:58

ALICE Calendar

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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

Shape-shifting collisions probe secrets of early Universe

Physics with small ions: jet quenching in Oxygen collisions at the LHC

Geometry-driven flow in collisions of Oxygen and Neon ions at the LHC

Latest ALICE Submissions

$Σ^{+}$ production in pp collisions at $\sqrt{s} = 13$ TeV The measurement of $\Sigma^{+}$ production in pp collisions at $\sqrt{s} = 13$ TeV is presented. The measurement is performed at midrapidity in both minimum-bias and high-multiplicity pp collisions at $\sqrt{s} = 13$ TeV. The $\Sigma^{+}$ is reconstructed via its weak-decay topology in the decay channel $\Sigma^{+} \rightarrow {\rm p} + \pi^{0}$ with $\pi^{0} \rightarrow \gamma + \gamma$. In a novel approach, the neutral pion is reconstructed by combining photons that convert in the detector material with photons measured in the calorimeters. The transverse-momentum ($p_{\rm T}$) distributions of the $\Sigma^{+}$ and its rapidity densities ${\rm d}N$/${\rm d}y$ in both event classes are reported. The $p_{\rm T}$ spectrum in minimum-bias collisions is compared to QCD-inspired event generators. The ratio of $\Sigma^{+}$ to previously measured $\Lambda$ baryons is in good agreement with calculations from the Statistical Hadronization Model. The high efficiency and purity of the novel reconstruction method for $\Sigma^{+}$ presented here will enable future studies of the interaction of $\Sigma^{+}$ with protons in the context of femtoscopic measurements, which could be crucial for understanding the equation of state of neutron stars.	2508.20808
Multiplicity dependence of $Ξ_c^+$ and $Ξ_c^0$ production in pp collisions at $\sqrt{s} = 13$ TeV The first measurement at midrapidity ($\|y\| < ~ 0.5$) of the production yield of the strange-charm baryons $\Xi_c^+$ and $\Xi_c^0$ as a function of charged-particle multiplicity in proton-proton collisions at $\sqrt{s} = 13$ TeV with the ALICE experiment at the LHC is reported. The $\Xi_c^+$ baryon is reconstructed via the $\Xi_c^+ \rightarrow \Xi^-\pi^+\pi^+$ decay channel in the range $4 < ~ p_{\rm T} < ~ 12$ GeV/$c$, while the $\Xi_c^0$ baryon is reconstructed via both the $\Xi_c^0 \rightarrow \Xi^-\pi^+$ and $\Xi_c^0 \rightarrow \Xi^-e^+\nu_e$ decay channels in the range $2 < ~ p_{\rm T} < ~ 12$ GeV/$c$. The baryon-to-meson ($\Xi_c^{0,+}/D^0$) and the baryon-to-baryon ($\Xi_c^{0,+}/\Lambda_c^+$) production yield ratios show no significant dependence on multiplicity. In addition, the observed yield ratios are not described by theoretical predictions that model charm-quark fragmentation based on measurements at $e^+e^-$ and $e^-$p colliders, indicating differences in the charm-baryon production mechanism in pp collisions. A comparison with different event generators and tunings, including different modelling of the hadronisation process, is also discussed. Moreover, the branching-fraction ratio of BR($\Xi_c^0 \rightarrow \Xi^-e^+\nu_e$)/BR($\Xi_c^0 \rightarrow \Xi^-\pi^+$) is measured as 0.825 $\pm$ 0.094 (stat.) $\pm$ 0.081 (syst.). This value supersedes the previous ALICE measurement, improving the statistical precision by a factor of 1.6.	2508.09955
First direct access to the $ρ^0$p interaction via correlation studies at the LHC Direct measurements of the $\rho^0$p interaction have remained so far elusive, with most insights derived indirectly from photoproduction or low-energy partial wave analyses. This letter presents the first direct observation of the $\rho^0$p interaction, obtained through two-particle correlations measured in high-multiplicity, ultrarelativistic proton-proton collisions at $\sqrt{s} = 13$ TeV by the ALICE Collaboration at the LHC. Two-particle correlation data, analyzed within chiral effective field theory ($\chi$EFT) using a coupled-channel approach and incorporating recent $\phi$-p data, yield a scattering length of $a_{\rho^0p} = (-0.46 \pm 0.04) + i(0.20 \pm 0.04)$ fm and constrain coupling strengths of two states identified with the N(1958) and N(1700). These findings emphasize the importance of coupled-channel dynamics and dynamically generated states in understanding the $\rho^0$p interaction. The results establish a vacuum baseline for extrapolation studies to high densities, contributing to the foundation for chiral symmetry restoration searches, and offer collider-based insights into the QCD spectrum, complementing traditional low-energy approaches. This work marks a significant advance in correlation studies, extending the exploration of interactions to the most short-lived QCD states.	2508.09867
Multiplicity dependence of K$^(892)^{\pm}$ production in pp collisions at $\sqrt{s}$ = 13 TeVThe first results of K$^$(892)$^{\pm}$ production at midrapidity ($\|y\| < ~ 0.5$) in pp collisions at $\sqrt{s} = 13$ TeV as a function of the event multiplicity are presented. The K$^$(892)$^{\pm}$ has been reconstructed via its hadronic decay channel K$^$(892)$^{\pm} \rightarrow \pi^{\pm} + K_{\rm S}^0$ using the ALICE detector at the LHC. For each multiplicity class the differential transverse momentum ($p_{\rm T}$) spectrum, the mean transverse momentum $\langle p_{\rm T} \rangle$, the $p_{\rm T}$-integrated yield (d$N$/d$y$), and the ratio of the K$^$(892)$^{\pm}$ to $K_{\rm S}^0$ 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. A first evidence of a significant K$^$(892)$^{\pm}$/$K_{\rm S}^0$ suppression in pp collisions is observed at a 7$\sigma$ level passing from low to high multiplicity events. The ratios of the $p_{\rm T}$-differential yields of K$^$(892)$^{\pm}$ and $K_{\rm S}^0$ in high and low multiplicity events are also presented along with their double ratio. For $p_{\rm T} \lesssim 2$ GeV/$c$ this double ratio persists below unity by more than $3\sigma$ suggesting that the suppression affects mainly low $p_{\rm T}$ resonances. The measured decreasing trend of the K$^*$(892)$^{\pm}$/$K_{\rm S}^0$ 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.	2507.19332
Multiplicity dependence of f$_0$(980) production in pp collisions at $\sqrt{s} = 13$ TeV The dependence of f$_0$(980) production on the final-state charged-particle multiplicity is reported for proton-proton (pp) collisions at the centre-of-mass energy, $\sqrt{s}= 13$ TeV. The production of f$_0$(980) is measured with the ALICE detector via the f$_0(980) \rightarrow \pi^{+}\pi^{-}$ decay channel in a midrapidity region of $\|y\| < ~ 0.5$. The evolution of the integrated yields and mean transverse momentum of f$_{0}$(980) as a function of charged-particle multiplicity measured in pp at $\sqrt{s} = 13$ TeV follows the trends observed in pp at $\sqrt{s} = 5.02$ TeV and in proton-lead (p-Pb) collisions at $\sqrt{s_{\rm{NN}}} = 5.02$ TeV. Particle yield ratios of f$_{0}$(980) to $\pi^{\pm}$ and K$^{*}$(892)$^{0}$ are found to decrease with increasing charged-particle multiplicity. These particle ratios are compared with calculations from the canonical statistical thermal model as a function of charged-particle multiplicity. The thermal model calculations provide a better description of the decreasing trend of particle ratios when no strange or antistrange quark composition for f$_{0}$(980) is assumed, which suggests that the tetraquark interpretation of the f$_{0}$(980) is disfavored.	2507.19347

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Upcoming Conferences (Next Week)

FATA2025: FAst Timing Applications for nuclear physics and medical imaging

TWEPP 2025

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Jobs info

ALICE Job - 2 ALICE post-doc positions at the IFJ PAN (26-09-2025 )

Job - Tenure Track Assistant Professor | Stony Brook University, USA (19-09-2025 )

Job - Multiple Lecturer Positions, Wits School of Physics | University of Witwatersrand, Johannesburg (10-09-2025 )

Job - PhD Position - LHCb | University of Groningen (01-09-2025 )

ALICE Job - PhD Research Fellow in Experimental Subatomic Physics | University of Bergen (08-07-2025 )

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.