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ALICE Collaboration

Publications and source records attributed to ALICE Collaboration.

At least 19 recordsLinked to original sources
arXiv2026

Three-baryon femtoscopy as an effective 3$\rightarrow$3 scattering experiment

Scattering experiments have long been the gold standard for constraining hadron$-$hadron interactions, providing direct information on the angular momentum and spin dependence over a wide range of kinematic configurations. However, experimental constraints on three-body dynamics remain limited, specifically for unbound systems and systems involving short-lived hadrons. In this work, the three-proton correlation function is measured in pp collisions at $\sqrt{s}=13.6$ TeV with ALICE at the LHC and presented as a novel approach to access hadronic interactions in three-body systems. A new analysis strategy is employed to isolate the p$-$p$-$p contribution to the correlation function by correcting for background channels and experimental effects, and enabling a direct comparison with state-of-the-art three-body continuum calculations. The extracted correlation function provides the first direct access to the isospin $3/2$ three-body system. The measured observable is found to be sensitive to the partial-wave structure of the nucleon$-$nucleon interaction and indicates that the nuclear interaction acts even at high angular momentum and parity states of the three-body system, revealing an effective long-range attractive component, observed experimentally for the first time in a three-proton continuum system. Hence, three-hadron femtoscopy emerges as an effective 3$\rightarrow$3 scattering experiment with three unbound hadrons in initial and final states. The copious production of hyperons at the modern high-energy colliders ensures the possibility of extending such measurements beyond nucleons, opening a new avenue for future precision studies of three-body dynamics in the strangeness sector.

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arXiv2026

First measurement of $\mathbf{\rm \Xi_{\rm c}^{0}}$ production in $\mathbf{Pb}-\mathbf{Pb}$ collisions at $\mathbf{\sqrt{\textit{s}_{\rm NN}}}$ = 5.02 TeV

The ALICE Collaboration reports the first measurement of the production of prompt $\Xi_{\mathrm c}^{0}$ baryons in nucleus$-$nucleus collisions by analyzing data from $\mathrm{Pb}-\mathrm{Pb}$ collisions at $\sqrt{s_{\mathrm{NN}}}~=5.02~\mathrm{TeV}$. The production and transverse-momentum ($p_{\mathrm T}$) differential spectra of $\Xi_{\mathrm c}^{0}$ are particularly sensitive to the hadronization process and to strangeness production in the quark--gluon plasma formed in high-energy heavy-ion collisions. The $\Xi_{\mathrm c}^{0}$ baryons are reconstructed at midrapidity ($|y|<0.5$) in the transverse-momentum intervals $3<p_{\mathrm T}~<12~\mathrm{GeV}/c$ and $4<p_{\mathrm T}~<12~\mathrm{GeV}/c$ in the 0$-$10\% and 30$-$50\% centrality intervals, respectively. The nuclear modification factor ($R_{\mathrm{AA}}$) reaches values up to 3 in the interval $3<p_{\mathrm T}~<4~\mathrm{GeV}/c$, which is the largest value measured so far for charm hadrons. Model predictions are compatible with the measured $R_{\mathrm{AA}}$, while, in the measured $p_{\mathrm T}$ intervals, they underestimate the production yield as well as the measured $\Xi_{\mathrm c}^{0}/\mathrm{D}^{0}$, $\Xi_{\mathrm c}^{0}/\Lambda_{\mathrm c}^{+}$, and $\Xi_{\mathrm c}^{0}/\mathrm{D}^{+}_{\mathrm s}$ yield ratios.

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arXiv2026

Multiplicity dependence of the size of the common hadron emission source in pp collisions at the LHC

Femtoscopic analysis can shed light on hadron production in pp collisions. In this paper, proton-proton correlations measured in collisions at $\sqrt{s}=13.6$ TeV recorded with the ALICE detector at the LHC are presented. The analysis is based on the minimum bias dataset collected in 2022 following the upgrade of the ALICE detector and corresponds to an integrated luminosity of $19.3$ pb$^{-1}$. The increased integrated luminosity allows us, for the first time, to simultaneously measure the multiplicity and transverse-mass ($m_{\rm T}$) dependence of the size of the hadron-emitting source. Precise knowledge of the femtoscopic source size in pp collisions is a crucial ingredient for using femtoscopy to study the residual strong interaction among stable and unstable hadrons at the LHC. In this light, the source radius was determined from the measured correlation functions by assuming several state-of-the-art models of the nucleon$-$nucleon interactions. The consistency among the extracted radii demonstrates the robustness of the measurement with respect to interaction model assumptions. A comparison to femtoscopic radii measured in Pb$-$Pb collisions at $\sqrt{s}=5.02$ TeV reveals a markedly different multiplicity dependence in similar $m_{\rm T}$ intervals, providing new insight into the system-size dependence of particle emission dynamics.

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arXiv2026

Evidence for parton energy loss in oxygen$-$oxygen collisions at $\mathbf{\sqrt{s_{\rm NN}}=5.36}$ TeV

Ultra-relativistic heavy-ion collisions create a hot and dense medium of deconfined quarks and gluons, the quark$-$gluon plasma (QGP), in which parton energy loss ("jet quenching") is a key probe of hot medium properties. While parton energy loss has been firmly established in large systems such as Pb$-$Pb and Au$-$Au collisions, no unambiguous direct evidence exists in smaller systems such as high-multiplicity p$-$Pb and pp collisions. To probe the onset of parton energy loss at intermediate system size, measurements of neutral-pion production are presented in this Letter for oxygen$-$oxygen (OO) and proton$-$oxygen (pO) collisions recorded with the ALICE detector in July 2025, relative to a pp baseline. The nuclear modification factor $R_{\rm OO}$ is suppressed relative to unity with a transverse-momentum dependence similar to that observed in Pb$-$Pb collisions, consistent with a previous CMS measurement in OO collisions with charged particles. As $R_{\rm OO}$ contains contributions from both cold and hot nuclear matter effects, $R_{\rm pO}$ is also presented in order to constrain cold nuclear matter (CNM) contributions. $R_{\rm pO}$ is found to be compatible with unity, indicating that CNM effects alone cannot account for the suppression observed in $R_{\rm OO}$. Final-state effects are isolated using the measured double ratio $R_{\rm OO} \left/ R_{\rm pO}^2 \right.$, which largely cancels CNM contributions and exhibits a significant suppression relative to expectations without energy loss at a 4.9$\sigma$ level. Theoretical models incorporating parton energy loss via different mechanisms predict a significant suppression of the $R_{\rm OO} \left/ R_{\rm pO}^2 \right.$ relative to unity, consistent with the data. These findings establish parton energy loss in OO collisions, extending experimental evidence for jet quenching to the smallest nuclear system studied to date.

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arXiv2026

Probing flavor effects in the QCD parton shower using $\mathbf{{\rm D}^0}$-tagged jet angularities in proton$-$proton collisions at $\mathbf{ \sqrt{s} = 5.02}$ TeV

The ALICE Collaboration presents the first measurements of ${\rm D}^0$-tagged jet angularities in proton$-$proton (pp) collisions at $\sqrt{s} = 5.02$ TeV. Jet angularities are powerful substructure observables that characterize the angular and momentum distributions of particles within jets via tunable weighting parameters. Varying the angular parameter in jet angularities allows for a systematic probe of the sensitivity to collinear and soft radiation, enabling the study of flavor-dependent fragmentation and hadronization through comparisons of jets initiated by different partons. This paper reports ${\rm D}^0$-tagged and inclusive (gluon-dominated) charged-particle jet angularities with a resolution parameter $R=0.4$ in the low jet transverse momentum range ($10 < p_{\rm T}^{\rm ch. \, jet} < 20$ GeV/$c$), where charm-quark mass effects are most significant. At low angular weight, which emphasizes collinear radiation, ${\rm D}^0$-tagged jets exhibit smaller angularity values than inclusive jets. This provides evidence for the radiation suppression from massive quarks -- a phenomenon known as the QCD dead-cone effect. As the angular weight increases, giving more emphasis to wide-angle radiation, the difference between ${\rm D}^0$-tagged and inclusive jet distributions decreases. This indicates that the modification is concentrated within the jet core rather than its edge. PYTHIA 8 simulations qualitatively reproduce both the angularity of ${\rm D}^0$-tagged and inclusive charged-particle jets, but reproduce the ${\rm D}^0$-tagged jet distributions better than those of inclusive jets, offering a powerful new constraint for models. These results provide insight into flavor-dependent fragmentation and establish an essential baseline for future studies of jet modifications in the quark-gluon plasma produced in heavy-ion collisions.

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arXiv2026

Modification of jet-energy flow in heavy-ion collisions

The ALICE Collaboration presents the first measurements of the jet-energy flow ($\Delta p_{\rm T}$) observable in proton-proton and heavy-ion collisions. Jets are excellent probes for the quark$-$gluon plasma, a deconfined state of matter produced in heavy-ion collisions. The jet-energy flow observable characterizes the radial distribution of energy from the jet axis in an infrared and collinear-safe way and is sensitive to medium-induced parton-shower modifications. Inclusive charged jets are measured in Pb$-$Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV for the transverse-momentum interval 60$-$80 GeV/$c$. For pp collisions at $\sqrt{s}=13$ TeV, measurements include the 40$-$60 and 60$-$80 GeV/$c$ intervals, where the latter serves as the reference for investigating medium-induced modifications. Results show that most parton energy is concentrated in the jet core, with a clear suppression of energy flow in heavy-ion collisions at larger radii (significance 3.5$-$4.5$\sigma$) indicating a narrowing of the energy flow. While all models -- PYTHIA 8, HERWIG, JEWEL, and JETSCAPE -- reproduce the pp results with only small deviations in the tails, the relative modification in Pb$-$Pb collisions is well described by JEWEL without recoil. Conversely, JEWEL with recoil (medium response) and JETSCAPE show significant deviations, exhibiting increasing or more constant trends with radius that are disfavored by the data.

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arXiv2026

Precision mass measurements of multistrange baryons and their antiparticles

The $\Omega^-$ baryon, composed of three strange quarks (sss), was predicted by the quark model and discovered in 1964, playing a pivotal role in establishing quarks as fundamental constituents of matter. Despite its importance, experimental knowledge of its mass remains limited, with the current world average relying on measurements performed more than four decades ago and lacking robust estimates of systematic uncertainties. This is notable given the central role of the $\Omega^-$ mass, and alternatively that of the $\Xi^-$(dss), in lattice QCD calculations, where it is widely used to set the overall physical scale. Precise scale setting is essential for first-principles studies of quark confinement, chiral symmetry breaking, and stringent tests of the Standard Model. Here we report high-precision measurements of the masses of the $\Omega^-$ and $\Xi^-$ baryons and their antiparticles, determined from invariant-mass reconstruction of their decay products in proton$-$proton collisions at the LHC. The analysis exploits the excellent tracking and particle-identification capabilities of the ALICE experiment, enabling accurate reconstruction of the displaced decay vertices characteristic of these short-lived particles. Each mass is measured with a fractional uncertainty of about 60 parts per million, for example $M_{\bar{\Omega}^+}=1672.558\,\pm\,0.034\,({\rm stat.})\,\pm\,0.102\,({\rm syst.})$ MeV/$c^2$. The precisely known K$^0_{\rm S}$ and $\Lambda$ masses are used for calibration. These results establish new precision benchmarks in strange-baryon spectroscopy and enable stringent tests of Charge-Parity-Time invariance in the multistrange-hadron sector. Our measurement reduces the scale uncertainty in lattice QCD calculations, enabling for instance sub per mille precision for the hadronic vacuum-polarization contribution to the muon anomalous magnetic moment.

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arXiv2026

Hyperon ($\Lambda$) polarization along the beam axis in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 5.36$ TeV

The measurement of hyperon ($\Lambda$ and $\overline{\Lambda}$) polarization along the beam axis in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 5.36$ TeV using the ALICE detector is presented. The polarization, arising from vorticity components induced by anisotropic flow, is studied relative to the second- and third-order event planes. The measured polarization exhibits clear azimuthal sine modulations, providing the first observation of polarization along the beam direction measured relative to the third-order event plane at the Large Hadron Collider. The values of the polarization measured with respect to the second-order event plane relative to the second harmonic event plane are consistent with previous measurements at $\sqrt{s_{\rm NN}} = 5.02$ TeV and show improved statistical precision owing to the larger data sample. Comparisons with hydrodynamic calculations indicate that the measured polarization is sensitive to the bulk viscosity and the vortical structure of the quark-gluon plasma, offering new constraints on its transport properties. In particular, the polarization measured relative to the third-order event plane is expected to provide an additional and independent input to constrain both bulk and shear viscosities of the quark-gluon plasma.

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arXiv2026

Probing jet evolution with charged energy correlators in small systems

The ALICE Collaboration presents measurements of charged energy-energy correlators (charged EECs) within charged-particle jets at $\sqrt{s_{\rm NN}} = 5.02$ Tev in proton-proton and proton-lead collisions at the LHC. Charged EECs are a class of jet substructure observables that trace the flow of energy and electric charge within a jet, and provide a tool for disentangling the energy scales involved in the jet fragmentation process through the angular separation and charges of particle pairs. The interplay between energy distribution and charge conservation enables charged EECs to provide novel constraints on hadronization mechanisms. Measurements of charged EECs in proton--proton collisions in charged-particle jets with $20 < p_{\rm T,chjet} < 80$ GeV/$c$ are compared to event generators to investigate different hadronization mechanisms and parton shower models. These model comparisons show that the like-sign EECs are sensitive to changes in parton shower modeling, while unlike-sign EECs are sensitive to different hadronization schemes. Measurements in proton-lead collisions indicate that cold nuclear matter effects on charged EECs are consistent with charge-independent behavior.

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arXiv2026

Energy-energy correlators in p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV

This paper presents the first measurement of the two-point energy-energy correlator (EEC) inside charged-particle jets in p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV with the ALICE experiment. The two-point EEC, an infrared- and collinear-safe measure of angular energy flow within jets, is used to probe both perturbative and non-perturbative stages of the jet evolution. The EEC is reported in 20-80 GeV/$c$ jets in p-Pb collisions and compared to a measurement of the EEC in pp events at $\sqrt{s} = 5.02$ TeV. A modification is observed in the 20-40 GeV/$c$ interval, with an enhancement at large opening angles and a suppression at small angles relative to pp collisions. The dependence of this modification on jet transverse momentum, rapidity, and forward activity is investigated. These results provide new constraints on cold nuclear matter effects relevant for disentangling initial- and final-state contributions to jet-structure modifications. An understanding of these cold nuclear matter effects is also relevant for interpreting EEC measurements in heavy-ion collisions.

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arXiv2026

Exclusive dimuon production and coherent charmonium photoproduction at forward rapidity in ultra-peripheral Pb$-$Pb collisions at $\mathbf{\sqrt{s_{\rm NN}}=5.36}$ TeV

This Paper presents rapidity-differential measurements of coherent J/$\psi$ and $\psi({\rm 2S})$ photoproduction, as well as rapidity- and mass-differential measurements of exclusive dimuon production, in the forward rapidity region $-4 < y < -2.5$ in ultra-peripheral Pb$-$Pb collisions at $\sqrt{s_{\rm NN}}=5.36$ TeV using data recorded by the ALICE detector at the LHC in 2023, corresponding to an integrated luminosity of $\mathcal{L} = 1170 \pm 50~\mu{\rm b}^{-1}$. The J/$\psi$ and $\psi({\rm 2S})$ results reveal the significant role of nuclear shadowing effects. The square root of the ratio of the measured quarkonium cross section to the impulse approximation prediction is about 0.76 for J/$\psi$ and 0.71 for $\psi({\rm 2S})$, at $y \approx -3$, corresponding to typical Bjorken-$x$ values of $10^{-2}$. The exclusive dimuon results highlight the sensitivity of such measurements to precise modeling of the photon flux, particularly at impact parameters near the nuclear radius.

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arXiv2026

$\mathbf{{\textbf{K}}^{0}_{\textbf{S}}}-\mathbf{{\textbf{K}}^{0}_{\textbf{S}}}$ femtoscopy in Pb$-$Pb collisions at $\mathbf{\sqrt{\textit{s}_{\rm NN}} = 5.02}$ TeV at the LHC

Results 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 $\lambda$ 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 $\lambda$ within 1.3$\sigma$. 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.

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arXiv2026

Measurement of isolated-prompt photon$-$hadron correlations in Pb$-$Pb collisions at $\mathbf{\sqrt{\textit{s}_{\rm NN}} = 5.02}$ TeV

The 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 $18< p_{\rm T}^{\gamma} < 40$ GeV/$c$ and pseudorapidity range $|\eta^{\gamma}| <0.67$. 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 $|\eta^{\rm h}| <0.9$. The yield D$(z_{\rm T})$ of associated hadrons per trigger, with $z_{\rm T} = p_{\rm T}^{\rm h}/p_{\rm T}^{\gamma}$, 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 $p_{\rm T}^{\gamma}$ 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.

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arXiv2026

Wave-Function Femtometry: Hypertriton - The Ultimate Halo Nucleus

The 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 ($^3_{\Lambda}$H), is a weakly bound state composed of a proton, a neutron and a $\Lambda$ hyperon, and is believed to exhibit a halo-like structure with the $\Lambda$ 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 $\Lambda$ separation from the deuteron core as $9.54^{+2.67}_{-1.11}$ fm.

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arXiv2026

Dijet invariant mass of charged-particle jets in pp and p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV

The 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, $|\eta| < 0.9$, 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 $\left|\eta_{\rm jet}\right| < 0.5$. 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.

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arXiv2026

Multiplicity dependence of prompt and non-prompt J/$\psi$ production at midrapidity in pp collisions at $\sqrt{s} = 13$ TeV

The yields of prompt and non-prompt J/$\psi$ and the fraction of non-prompt J/$\psi$ are measured at midrapidity ($|y| < 0.9$) via the dielectron decay channel as a function of the midrapidity charged-particle multiplicity ($|\eta| < 0.9$) in pp collisions at $\sqrt{s} = 13$ TeV. The J/$\psi$ yields and the multiplicity are normalized by their average value in inelastic collisions. The multiplicity-dependent yield ratio between prompt J/$\psi$ and D$^0$ is reported. The multiplicity is further divided into three azimuthal regions with respect to the J/$\psi$ momentum: toward the J/$\psi$ 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/$\psi$ 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.

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arXiv2026

Measurement of the $\mathbf{B^0}$-meson production cross section in proton--proton collisions at $\mathbf{\sqrt{\textit{s}}=13.6}$ TeV

This article reports the measurement of the transverse-momentum ($p_{\rm T}$) differential production cross section of B$^0$ mesons in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=13.6$ TeV with the ALICE detector at the CERN LHC. For the first time, the B$^0$ production cross section is measured at midrapidity ($|y|<0.5$) down to $p_{\rm T}=1~\mathrm{GeV}/c$ at LHC energies. The B$^0$ mesons and their charge conjugates were reconstructed via the B$^{0}\to$D$^{-}\pi^+$ decay channel, followed by the D$^-\to$K$^+\pi^-\pi^-$ decay. The measured $p_{\rm T}$-differential production cross section is described within uncertainties by state-of-the-art models based on perturbative quantum-chromodynamics calculations. Its rapidity dependence is also studied by computing the $p_{\rm T}$-differential ratios between the ALICE measurement and the one of B$^+$ mesons performed by the LHCb Collaboration at forward rapidity. The B$^0$ production cross section per unit of rapidity at midrapidity is ${\rm d}\sigma({\rm B^0})/{\rm d} y|_{|y|<0.5} = 24.2 \pm 1.4~(\text{stat.}) \pm 2.6~(\text{syst.})_{-0.3}^{+0.2}~(\text{extrap.})~\mu{\rm b}$.

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arXiv2026

Evidence of different $\Lambda_{\rm c}$-baryon and D-meson elliptic flow in Pb$-$Pb collisions at $\mathbf{\sqrt{\textit{s}_{\rm NN}}}$ = 5.36 TeV with ALICE at the LHC

The ALICE collaboration reports the azimuthal-anisotropy coefficient $v_2$ of prompt D$^0$, D$^+$, D$^+_{\rm s}$ mesons and the first measurement of $v_2$ of prompt $\Lambda_{\rm c}$ baryons in semicentral Pb$-$Pb collisions at a center-of-mass energy per nucleon pair of $\sqrt{s_{\rm NN}} = 5.36$ TeV. The D mesons and $\Lambda_{\rm c}$ baryons are reconstructed in their hadronic decays at midrapidity ($ |y|<0.8$) in the transverse-momentum interval $0.5< p_{\rm T} < 24$ GeV/$c$. Similar $v_2$ values are measured for D$^0$ and D$^+$, while a hint of a difference ($2.6\sigma$) emerges between D$^0$ and D$^+_{\rm s}$ mesons in the $1 < p_{\rm T} < 5 $ GeV/$c$ interval. A larger $v_2$ for $\Lambda_{\rm c}$ baryons with respect to D$^0$ mesons is observed with $3.7\sigma$ significance for $4 < p_{\rm T} < 12$ GeV/$c$, providing evidence for the partonic origin of charm-hadron $v_2$ and hadron formation via quark coalescence. This interpretation is further supported by comparisons with theoretical calculations of charm-quark transport in a hydrodynamically expanding medium.

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