A Large Ion Collider Experiment

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ALICE INDICO

update on - 16:50:55

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

6th ALICE Upgrade Week, Burghausen

Charming energy–energy correlators

Shape-shifting collisions probe secrets of early Universe

Latest ALICE Submissions

Measurement of the p$-Σ^+$ correlation function in pp collisions at $\sqrt{\textit{s}}=13$ TeV In this letter, the first measurement of the femtoscopic correlation of protons and $\Sigma^+$ hyperons is presented and used to study the p$-\Sigma^+$ interaction. The measurement is performed with the ALICE detector in high-multiplicity triggered pp collisions at $\sqrt{s} = 13$ TeV. The $\Sigma^+$ hyperons are reconstructed using a missing-mass approach in the decay channel to $\textrm{p} + \pi^0$ with $\pi^0\rightarrow\gamma\gamma$, while both $\Sigma^+$ and protons are identified using a machine learning approach. These techniques result in a high reconstruction efficiency and purity, which allows the measurement of the p$-\Sigma^+$ correlation function for the first time. Thanks to the high significance achieved in the p$-\Sigma^+$ correlation signal, it is possible to discriminate between the predictions of different models of the N$-\Sigma$ interaction and to accomplish a first determination of the p$-\Sigma^+$ scattering parameters.	2510.14448
Study of the interaction between $Ξ$ baryons and light mesons via femtoscopy at the LHC Meson-baryon systems with strangeness content provide a unique laboratory for investigating the strong interaction and testing theoretical models of hadron structure and dynamics. In this work, the measured correlation functions for oppositely charged $\Xi-{\rm K}$ and $\Xi-\pi$ pairs obtained in high-multiplicity pp collisions at $\sqrt{s} = 13$ TeV at the LHC are presented. For the first time, high-precision data on the $\Xi-{\rm K}$ interaction are delivered at small relative momenta. The scattering lengths, extracted via the Lednick\'y-Lyuboshits expression of the pair wavefunction, indicate a repulsive and a shallow attractive strong interaction for the $\Xi-{\rm K}$ and $\Xi-\pi$ systems, respectively. The $\Xi(1620)$ and $\Xi(1690)$ states are observed in the $\Xi-\pi$ correlation function and their properties, mass and width, are determined. These measurements are in agreement with other available results. Such high-precision data can help refine the understanding of these resonant states, provide stronger constraints for chirally motivated potentials, and address the key challenge of describing the coupled-channel dynamics that may give rise to molecular configurations.	2509.24519
$Σ^{+}$ 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

See all submissions...

Upcoming Conferences (Next Week)

The 2025 International Workshop on the High Energy Circular Electron Positron Collider

The 22nd International Joint Conference on Computer Science and Software Engineering (JCSSE 2025)

See all conferences...

Jobs info

Job - Wilson Fellowship | Fermilab, USA (20-10-2025 )

Job - Doctoral Student - CMS | Austrian Academy of Sciences (15-10-2025 )

Job - Postdoctoral Fellowship | University of Washington, Seattle (14-10-2025 )

Job - Postdoc & PhD Positions - SHiP Experiment | University of Mainz & PRISMA++ Cluster of Excellence (08-10-2025 )

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

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.