The
ALICE
collaboration
Acharya, Shreyasi
;
Adamova, Dagmar
;
Adler, Alexander
;
*et al. *

Phys.Rev.C 107 (2023) 054617, 2023.

https://inspirehep.net/literature/2182733
Inspire Record
2182733
DOI
10.17182/hepdata.137819
https://doi.org/10.17182/hepdata.137819
Two-particle transverse momentum differential correlators, recently measured in Pb--Pb collisions at energies available at the CERN Large Hadron Collider (LHC), provide an additional tool to gain insights into particle production mechanisms and infer transport properties, such as the ratio of shear viscosity to entropy density, of the medium created in Pb-Pb collisions. The longitudinal long-range correlations and the large azimuthal anisotropy measured at low transverse momenta in small collision systems, namely pp and p-Pb, at LHC energies resemble manifestations of collective behaviour. This suggests that locally equilibrated matter may be produced in these small collision systems, similar to what is observed in Pb-Pb collisions. In this work, the same two-particle transverse momentum differential correlators are exploited in pp and p-Pb collisions at $\sqrt{s} = 7$ TeV and $\sqrt{s_{\rm NN}} = 5.02$ TeV, respectively, to seek evidence for viscous effects. Specifically, the strength and shape of the correlators are studied as a function of the produced particle multiplicity to identify evidence for longitudinal broadening that might reveal the presence of viscous effects in these smaller systems. The measured correlators and their evolution from pp and p--Pb to Pb--Pb collisions are additionally compared to predictions from Monte Carlo event generators, and the potential presence of viscous effects is discussed.

24
data tables

The
ALICE
collaboration

CERN-EP-2022-110, 2022.

https://inspirehep.net/literature/2092560
Inspire Record
2092560
DOI
10.17182/hepdata.134041
https://doi.org/10.17182/hepdata.134041
Three-body nuclear forces play an important role in the structure of nuclei and hypernuclei and are also incorporated in models to describe the dynamics of dense baryonic matter, such as in neutron stars. So far, only indirect measurements anchored to the binding energies of nuclei can be used to constrain the three-nucleon force, and if hyperons are considered, the scarce data on hypernuclei impose only weak constraints on the three-body forces. In this work, we present the first direct measurement of the p$-$p$-$p and p$-$p$-\Lambda$ systems in terms of three-particle mixed moments carried out for pp collisions at $\sqrt{s}$ = 13 TeV. Three-particle cumulants are extracted from the normalised mixed moments by applying the Kubo formalism, where the three-particle interaction contribution to these moments can be isolated after subtracting the known two-body interaction terms. A negative cumulant is found for the p$-$p$-$p system, hinting to the presence of a residual three-body effect while for p$-$p$-\Lambda$ the cumulant is consistent with zero. This measurement demonstrates the accessibility of three-baryon correlations at the LHC.

11
data tables

The (p-p)-p correlation function obtained using the data-driven approach

The (p-p)-$\Lambda$ correlation function obtained using the data-driven approach

The p-(p-$\Lambda$) correlation function obtained using the data-driven approach

The
ALICE
collaboration
Acharya, Shreyasi
;
Adamova, Dagmar
;
Adler, Alexander
;
*et al. *

Eur.Phys.J.C 83 (2023) 340, 2023.

https://inspirehep.net/literature/2088954
Inspire Record
2088954
DOI
10.17182/hepdata.132766
https://doi.org/10.17182/hepdata.132766
The interaction of $\rm{K}^{-}$ with protons is characterised by the presence of several coupled channels, systems like ${\rm \overline{K}^0}$n and $\pi\Sigma$ with a similar mass and the same quantum numbers as the $\rm{K}^{-}$p state. The strengths of these couplings to the $\rm{K}^{-}$p system are of crucial importance for the understanding of the nature of the $\Lambda(1405)$ resonance and of the attractive $\rm{K}^{-}$p strong interaction. In this article, we present measurements of the $\rm{K}^{-}$p correlation functions in relative momentum space obtained in pp collisions at $\sqrt{s}~=~13$ TeV, in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}~=~5.02$ TeV, and (semi)peripheral Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}~=~5.02$ TeV. The emitting source size, composed of a core radius anchored to the $\rm{K}^{+}$p correlation and of a resonance halo specific to each particle pair, varies between 1 and 2 fm in these collision systems. The strength and the effects of the ${\rm \overline{K}^0}$n and $\pi\Sigma$ inelastic channels on the measured $\rm{K}^{-}$p correlation function are investigated in the different colliding systems by comparing the data with state-of-the-art models of chiral potentials. A novel approach to determine the conversion weights $\omega$, necessary to quantify the amount of produced inelastic channels in the correlation function, is presented. In this method, particle yields are estimated from thermal model predictions, and their kinematic distribution from blast-wave fits to measured data. The comparison of chiral potentials to the measured $\rm{K}^{-}$p interaction indicates that, while the $\pi\Sigma-\rm{K}^{-}$p dynamics is well reproduced by the model, the coupling to the ${\rm \overline{K}^0}$n channel in the model is currently underestimated.

17
data tables

The
ALICE
collaboration
Acharya, Shreyasi
;
Adamova, Dagmar
;
Adler, Alexander
;
*et al. *

Eur.Phys.J.C 82 (2022) 335, 2022.

https://inspirehep.net/literature/1946828
Inspire Record
1946828
DOI
10.17182/hepdata.128823
https://doi.org/10.17182/hepdata.128823
Angular correlations of heavy-flavour and charged particles in high-energy proton-proton collisions are sensitive to the production mechanisms of heavy quarks and to their fragmentation as well as hadronisation processes. The measurement of the azimuthal-correlation function of prompt D mesons with charged particles in proton-proton collisions at a centre-of-mass energy of $\sqrt{s} = 13$ TeV with the ALICE detector is reported, considering D$^{0}$, D$^{+}$, and D$^{*+}$ mesons in the transverse-momentum interval $3 < p_{\rm T} < 36$ GeV/$c$ at midrapidity ($|y| < 0.5$), and charged particles with $p_{\rm T} > 0.3$ GeV/$c$ and pseudorapidity $|\eta| < 0.8$. This measurement has an improved precision and provides an extended transverse-momentum coverage compared to previous ALICE measurements at lower energies. The study is also performed as a function of the charged-particle multiplicity, showing no modifications of the correlation function with multiplicity within uncertainties. The properties and the transverse-momentum evolution of the near- and away-side correlation peaks are studied and compared with predictions from various Monte Carlo event generators. Among those considered, PYTHIA8 and POWHEG+PYTHIA8 provide the best description of the measured observables. The obtained results can provide guidance on tuning the generators.

56
data tables

The
ALICE
collaboration
Acharya, Shreyasi
;
Adamova, Dagmar
;
Adler, Alexander
;
*et al. *

Phys.Lett.B 833 (2022) 137338, 2022.

https://inspirehep.net/literature/1943964
Inspire Record
1943964
DOI
10.17182/hepdata.132486
https://doi.org/10.17182/hepdata.132486
First measurements of balance functions (BFs) of all combinations of identified charged hadron $(\pi,\rm K,\rm p)$ pairs in Pb$-$Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV recorded by the ALICE detector are presented. The BF measurements are carried out as two-dimensional differential correlators versus the relative rapidity ($\Delta y$) and azimuthal angle ($\Delta\varphi$) of hadron pairs, and studied as a function of collision centrality. The $\Delta\varphi$ dependence of BFs is expected to be sensitive to the light quark diffusivity in the quark$-$gluon plasma. While the BF azimuthal widths of all pairs substantially decrease from peripheral to central collisions, the longitudinal widths exhibit mixed behaviors: BFs of $\pi\pi$ and cross-species pairs narrow significantly in more central collisions, whereas those of $\rm KK$ and $\rm pp$ are found to be independent of collision centrality. This dichotomy is qualitatively consistent with the presence of strong radial flow effects and the existence of two stages of quark production in relativistic heavy-ion collisions. Finally, the first measurements of the collision centrality evolution of BF integrals are presented, with the observation that charge balancing fractions are nearly independent of collision centrality in Pb$-$Pb collisions. Overall, the results presented provide new and challenging constraints for theoretical models of hadron production and transport in relativistic heavy-ion collisions.

24
data tables

The
ALICE
collaboration
Acharya, Shreyasi
;
Adamova, Dagmar
;
Adler, Alexander
;
*et al. *

Phys.Rev.Lett. 127 (2021) 172301, 2021.

https://inspirehep.net/literature/1863040
Inspire Record
1863040
DOI
10.17182/hepdata.113758
https://doi.org/10.17182/hepdata.113758
This Letter presents the first experimental evidence of the attractive strong interaction between a proton and a $\phi$ meson. The result is obtained from two-particle correlations of combined p-$\phi \oplus \overline{\rm {p}}$-$\phi$ pairs measured in high-multiplicity pp collisions at $\sqrt{s}~=~13$ TeV by the ALICE collaboration. The spin-averaged scattering length and effective range of the p-$\phi$ interaction are extracted from the fully corrected correlation function employing the Lednický-Lyuboshits approach. In particular, the imaginary part of the scattering length vanishes within uncertainties, indicating that inelastic processes do not play a prominent role for the p-$\phi$ interaction. These data demonstrate that the interaction is dominated by elastic p-$\phi$ scattering. Furthermore, an analysis employing phenomenological Gaussian- and Yukawa-type potentials is conducted. Under the assumption of the latter, the N-$\phi$ coupling constant is found to be $g_{\rm{N}-\phi} = 0.14\pm 0.03\,(\mathrm{stat.})\pm 0.02\,(\mathrm{syst.})$. This work provides valuable experimental input to accomplish a self-consistent description of the N-$\phi$ interaction, which is particularly relevant for the more fundamental studies on partial restoration of chiral symmetry in nuclear medium.

2
data tables

Measured $\mathrm{p}-\phi$ $\oplus$ $\overline{\mathrm{p}}-\phi$ correlation function.

Genuine $\mathrm{p}-\phi$ $\oplus$ $\overline{\mathrm{p}}-\phi$ correlation function.

The
ALICE
collaboration
Acharya, Shreyasi
;
Adamova, Dagmar
;
Adler, Alexander
;
*et al. *

Phys.Lett.B 822 (2021) 136708, 2021.

https://inspirehep.net/literature/1863041
Inspire Record
1863041
DOI
10.17182/hepdata.114016
https://doi.org/10.17182/hepdata.114016
In quantum scattering processes between two particles, aspects characterizing the strong and Coulomb forces can be observed in kinematic distributions of the particle pairs. The sensitivity to the interaction potential reaches a maximum at low relative momentum and vanishing distance between the two particles. Ultrarelativistic heavy-ion collisions at the LHC provide an abundant source of many hadron species and can be employed as a measurement method of scattering parameters that is complementary to scattering experiments. This study confirms that momentum correlations of particles produced in Pb-Pb collisions at the LHC provide an accurate measurement of kaon-proton scattering parameters at low relative momentum, allowing precise access to the $ {K}^{-} p\rightarrow {K}^{-} p$ process. This work also validates the femtoscopic measurement in ultrarelativistic heavy-ion collisions as an alternative to scattering experiments and a complementary tool to the study of exotic atoms with comparable precision. In this work, the first femtoscopic measurement of momentum correlations of ${K}^{-} p\ ({K}^{+}\overline{p})$ and ${K}^{+}p ({K}^{-}\overline{p})$ pairs in Pb-Pb collisions at centre-of-mass energy per nucleon pair of $\sqrt{s_{\rm NN}} = 5.02$ TeV registered by the ALICE experiment is reported. The components of the ${K}^{-} p$ complex scattering length are extracted and found to be $\Re f_0=-0.91\pm~{0.03}$(stat)$^{+0.17}_{-0.03}$(syst) and $\Im f_0 = 0.92\pm~{0.05}$(stat)$^{+0.12}_{-0.33}$(syst). The results are compared with chiral effective field theory predictions as well as with existing data from dedicated scattering and exotic kaonic atom experiments.

12
data tables

K p (opposite charge) correlation function for centrality 0-5% from Pb-Pb collisions at 5020 GeV

K p (same charge) correlation function for centrality 0-5% from Pb-Pb collisions at 5020 GeV

K p (opposite charge) correlation function for centrality 5-10% from Pb-Pb collisions at 5020 GeV

The
ALICE
collaboration
Acharya, Shreyasi
;
Adamova, Dagmar
;
Adler, Alexander
;
*et al. *

Phys.Lett.B 833 (2022) 137272, 2022.

https://inspirehep.net/literature/1857549
Inspire Record
1857549
DOI
10.17182/hepdata.131625
https://doi.org/10.17182/hepdata.131625
The interaction of $\Lambda$ and $\Sigma$ hyperons (Y) with nucleons (N) is strongly influenced by the coupled-channel dynamics. Due to the small mass difference of the $\rm N \Lambda$ and $\rm N \Sigma$ systems, the sizeable coupling strength of the $\rm N \Sigma\leftrightarrow N \Lambda$ processes constitutes a crucial element in the determination of the N$\Lambda$ interaction. In this letter we present the most precise measurements on the interaction of p$\Lambda$ pairs, from zero relative momentum up to the opening of the $\rm N \Sigma$ channel. The correlation function in the relative momentum space for $\mathrm{p}\Lambda\oplus\overline{\mathrm{p}}\overline{\Lambda}$ pairs measured in high-multiplicity triggered pp collisions at $\sqrt{s}~=~13$ TeV at the LHC is reported. The opening of the inelastic N$\Sigma$ channels is visible in the extracted correlation function as a cusp-like structure occurring at relative momentum $k^{*}$ = 289 MeV/$c$. This represents the first direct experimental observation of the $\rm N \Sigma\rightarrow N \Lambda$ coupled channel in the p$\Lambda$ system. The correlation function is compared with recent chiral effective field theory calculations, based on different strengths of the $\rm N \Sigma\leftrightarrow N \Lambda$ transition potential. A weaker coupling, as possibly supported by the present measurement, would require a more repulsive three-body NN$\Lambda$ interaction for a proper description of the $\Lambda$ in-medium properties, which has implications on the nuclear equation of state and for the presence of hyperons inside neutron stars.

1
data table

p-$\Lambda$ correlation function in high-multiplicity pp collisions at $\sqrt{s}=13$ TeV.

Version 2

A new laboratory to study hadron-hadron interactions
The
ALICE
collaboration
Collaboration, Alice
;
Acharya, Shreyasi
;
Adamova, Dagmar
;
*et al. *

Nature 588 (2020) 232-238, 2020.

https://inspirehep.net/literature/1797617
Inspire Record
1797617
DOI
10.17182/hepdata.100195
https://doi.org/10.17182/hepdata.100195
One of the key challenges for nuclear physics today is to understand from first principles the effective interaction between hadrons with different quark content. First successes have been achieved using techniques that solve the dynamics of quarks and gluons on discrete space-time lattices. Experimentally, the dynamics of the strong interaction have been studied by scattering hadrons off each other. Such scattering experiments are difficult or impossible for unstable hadrons and so high-quality measurements exist only for hadrons containing up and down quarks. Here we demonstrate that measuring correlations in the momentum space between hadron pairs produced in ultrarelativistic proton-proton collisions at the CERN Large Hadron Collider (LHC) provides a precise method with which to obtain the missing information on the interaction dynamics between any pair of unstable hadrons. Specifically, we discuss the case of the interaction of baryons containing strange quarks (hyperons). We demonstrate how, using precision measurements of p-omega baryon correlations, the effect of the strong interaction for this hadron-hadron pair can be studied with precision similar to, and compared with, predictions from lattice calculations. The large number of hyperons identified in proton-proton collisions at the LHC, together with an accurate modelling of the small (approximately one femtometre) inter-particle distance and exact predictions for the correlation functions, enables a detailed determination of the short-range part of the nucleon-hyperon interaction.

4
data tables

The p--$\Xi^{-}$ $\oplus$ $\overline{\mathrm{p}}$--$\overline{\Xi}^{+}$ correlation function.

The p--$\Xi^{-}$ $\oplus$ $\overline{\mathrm{p}}$--$\overline{\Xi}^{+}$ correlation function.

The p--$\Omega^{-}$ $\oplus$ $\overline{\mathrm{p}}$--$\overline{\Omega}^{+}$ correlation function.

The
ALICE
collaboration
Acharya, Shreyasi
;
Adamova, Dagmar
;
Adler, Alexander
;
*et al. *

Phys.Rev.C 103 (2021) 055201, 2021.

https://inspirehep.net/literature/1797451
Inspire Record
1797451
DOI
10.17182/hepdata.104979
https://doi.org/10.17182/hepdata.104979
The first measurements of the scattering parameters of $\Lambda$K pairs in all three charge combinations ($\Lambda$K$^{+}$, $\Lambda$K$^{-}$, and $\Lambda\mathrm{K^{0}_{S}}$) are presented. The results are achieved through a femtoscopic analysis of $\Lambda$K correlations in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV recorded by ALICE at the LHC. The femtoscopic correlations result from strong final-state interactions, and are fit with a parametrization allowing for both the characterization of the pair emission source and the measurement of the scattering parameters for the particle pairs. Extensive studies with the THERMINATOR 2 event generator provide a good description of the non-femtoscopic background, which results mainly from collective effects, with unprecedented precision. Furthermore, together with HIJING simulations, this model is used to account for contributions from residual correlations induced by feed-down from particle decays. The extracted scattering parameters indicate that the strong force is repulsive in the $\Lambda\rm{K}^{+}$ interaction and attractive in the $\Lambda\rm{K}^{-}$ interaction. The data hint that the and $\Lambda\rm{K}^{0}_{S}$ interaction is attractive, however the uncertainty of the result does not permit such a decisive conclusion. The results suggest an effect arising either from different quark-antiquark interactions between the pairs ($\rm s\overline{s}$ in $\Lambda$K$^{+}$ and $\rm u\overline{u}$ in $\Lambda$K$^{-}$) or from different net strangeness for each system (S = 0 for $\Lambda$K$^{+}$, and S = $-2$ for $\Lambda$K$^{-}$). Finally, the $\Lambda$K systems exhibit source radii larger than expected from extrapolation from identical particle femtoscopic studies. This effect is interpreted as resulting from the separation in space-time of the single-particle $\Lambda$ and K source distributions.

71
data tables