Production of light (anti)nuclei in pp collisions at $\sqrt{s} = 13$TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
CERN-EP-2021-194, 2021.
Inspire Record 1928822 DOI 10.17182/hepdata.115571

Understanding the production mechanism of light (anti)nuclei is one of the key challenges of nuclear physics and has important consequences for astrophysics, since it provides an input for indirect dark-matter searches in space. In this paper, the latest results about the production of light (anti)nuclei in pp collisions at $\sqrt{s} = 13$ TeV are presented, focusing on the comparison with the predictions of coalescence and thermal models. For the first time, the coalescence parameters $B_2$ for deuterons and $B_3$ for helions are compared with parameter-free theoretical predictions that are directly constrained by the femtoscopic measurement of the source radius in the same event class. A fair description of the data with a Gaussian wave function is observed for both deuteron and helion, supporting the coalescence mechanism for the production of light (anti)nuclei in pp collisions. This method paves the way for future investigations of the internal structure of more complex nuclear clusters, including the hypertriton.

24 data tables

(Anti)proton spectrum in HM V0M multiplicity class

(Anti)proton spectrum in HM I V0M multiplicity class

(Anti)proton spectrum in HM II V0M multiplicity class

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Inclusive J/$\psi$ production at midrapidity in pp collisions at $\sqrt{s}~=~13$ TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
CERN-EP-2021-160, 2021.
Inspire Record 1898832 DOI 10.17182/hepdata.115422

We report on the inclusive J/$\psi$ production cross section measured at the CERN Large Hadron Collider in proton-proton collisions at a centre-of-mass energy $\sqrt{s}~=~13$ TeV. The J/$\psi$ mesons are reconstructed in the $\rm e^{+} e^{-}$ decay channel and the measurements are performed at midrapidity ($|y|<0.9$) in the transverse-momentum interval $0< p_{\rm T} <40$ GeV/$c$, using a minimum bias data sample corresponding to an integrated luminosity $L_{\text{int}} = 32.2~\text{nb}^{-1}$ and an Electromagnetic Calorimeter triggered data sample with $L_{\text{int}} = 8.3~\mathrm{pb}^{-1}$. The $p_{\rm T}$-integrated J/$\psi$ production cross section at midrapidity, computed using the minimum bias data sample, is $\text{d}\sigma/\text{d}y|_{y=0} = 8.97\pm0.24~(\text{stat})\pm0.48~(\text{syst})\pm0.15~(\text{lumi})~\mu\text{b}$. An approximate logarithmic dependence with the collision energy is suggested by these results and available world data, in agreement with model predictions. The integrated and $p_{\rm T}$-differential measurements are compared with measurements in pp collisions at lower energies and with several recent phenomenological calculations based on the non-relativistic QCD and Color Evaporation models.

3 data tables

Inclusive J/psi cross section. The first systematic uncertainty is the combined systematic uncertainties excluding luminosity, the second is the luminosity

Inclusive J/psi cross section. The first systematic uncertainty is the combined systematic uncertainties excluding luminosity, the second is the luminosity

Inclusive J/psi cross section. The first systematic uncertainty is the combined systematic uncertainties excluding luminosity, the second is the luminosity


$\mathrm {K_S}^{0}$- and (anti-)$\Lambda $-hadron correlations in pp collisions at ${\sqrt{s}} = 13$ TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Eur.Phys.J.C 81 (2021) 945, 2021.
Inspire Record 1891391 DOI 10.17182/hepdata.114015

Two-particle azimuthal correlations are measured with the ALICE apparatus in pp collisions at $\sqrt{s} = 13$ TeV to explore strangeness- and multiplicity-related effects in the fragmentation of jets and the transition regime between bulk and hard production, probed with the condition that a strange meson (K$^{0}_{\rm S}$) or a baryon ($\Lambda$) with transverse momentum $p_{\rm T} > 3$ GeV/c is produced. Azimuthal correlations between kaons or $\Lambda$ hyperons with other hadrons are presented at midrapidity for a broad range of the trigger ($3 < p_{\rm T}^{\rm trigg} < 20$ GeV/$c$) and associated particle $p_{\rm T}$ (1 GeV/$c$$< p_{\rm T}^{\rm assoc} < p_{\rm T}^{\rm trigg}$), for minimum-bias events and as a function of the event multiplicity. The near- and away-side peak yields are compared for the case of either K$^{0}_{\rm S}$ or $\Lambda$($\overline{\Lambda}$) being the trigger particle with that of inclusive hadrons (a sample dominated by pions). In addition, the measurements are compared with predictions from PYTHIA 8 and EPOS LHC event generators.

81 data tables

Two-dimensional $K_S^0$-h correlation function with $3<p_{\mathrm{T}}^{\mathrm{trigg}}< 4 \mathrm{GeV}/c$ and $1 \mathrm{GeV}/c<p_{\mathrm{T}}^{\mathrm{assoc}}< p_{\mathrm{T}}^{\mathrm{trigg}} $

$\Delta\varphi$ projection of h-h correlation function with $3<p_{\mathrm{T}}^{\mathrm{trigg}}< 4 \mathrm{GeV}/c$ and $1 \mathrm{GeV}/c<p_{\mathrm{T}}^{\mathrm{assoc}}< p_{\mathrm{T}}^{\mathrm{trigg}} $

$\Delta\varphi$ projection of $K_S^0$-h correlation function with $3<p_{\mathrm{T}}^{\mathrm{trigg}}< 4 \mathrm{GeV}/c$ and $1 \mathrm{GeV}/c<p_{\mathrm{T}}^{\mathrm{assoc}}< p_{\mathrm{T}}^{\mathrm{trigg}} $

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Anisotropic flow of identified hadrons in Xe-Xe collisions at $ \sqrt{s_{\mathrm{NN}}} $ = 5.44 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
JHEP 10 (2021) 152, 2021.
Inspire Record 1889989 DOI 10.17182/hepdata.114014

Measurements of elliptic ($v_2$) and triangular ($v_3$) flow coefficients of $\pi^{\pm}$, K$^{\pm}$, p+$\rm \overline{p}$, K$^0_{\rm S}$, and $\Lambda + \overline{\Lambda}$ obtained with the scalar product method in Xe-Xe collisions at $\sqrt{s_{\rm NN}}$ = 5.44 TeV are presented. The results are obtained in the rapidity range $\left | y \right |<0.5$ and reported as a function of transverse momentum, $p_{\rm T}$, for several collision centrality classes. The flow coefficients exhibit a particle mass dependence for $p_{\rm T}<3$ GeV/$c$, while a grouping according to particle type (i.e., meson and baryon) is found at intermediate transverse momenta (3< $p_{\rm T}$ <8 GeV/$c$). The magnitude of the baryon $v_{2}$ is larger than that of mesons up to $p_{\rm T}$ = 6 GeV/$c$. The centrality dependence of the shape evolution of the $p_{\rm T}$-differential $v_2$ is studied for the various hadron species. The $v_2$ coefficients of $\pi^{\pm}$, K$^{\pm}$, and p+$\rm \overline{p}$ are reproduced by MUSIC hydrodynamic calculations coupled to a hadronic cascade model (UrQMD) for $p_{\rm T} <1$ GeV/$c$. A comparison with $v_{\rm n}$ measurements in the corresponding centrality intervals in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV yields an enhanced $v_2$ in central collisions and diminished value in semicentral collisions.

46 data tables

$v_2\{2, |\Delta\eta| > 2.0\}$ of $\pi^{\pm}$ as a function of $p_{\rm T}$ for the 0-5% centrality interval.

$v_2\{2, |\Delta\eta| > 2.0\}$ of $\pi^{\pm}$ as a function of $p_{\rm T}$ for the 5-10% centrality interval.

$v_2\{2, |\Delta\eta| > 2.0\}$ of $\pi^{\pm}$ as a function of $p_{\rm T}$ for the 10-20% centrality interval.

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Kaon–proton strong interaction at low relative momentum via femtoscopy in Pb–Pb collisions at the LHC

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Lett.B 822 (2021) 136708, 2021.
Inspire Record 1863041 DOI 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

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Measurement of the production cross section of prompt $ {\Xi}_{\mathrm{c}}^0 $ baryons at midrapidity in pp collisions at $ \sqrt{s} $ = 5.02 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
JHEP 10 (2021) 159, 2021.
Inspire Record 1863039 DOI 10.17182/hepdata.114189

The transverse momentum ($p_{\rm T}$) differential cross section of the charm-strange baryon $\Xi^0_{\rm c}$ is measured at midrapidity ($|y|<$ 0.5) via its semileptonic decay into ${\rm e^{+}}\Xi^{-}\nu_{\rm e}$ in pp collisions at $\sqrt{s}$ = 5.02 TeV with the ALICE detector at the LHC. The ratio of the $p_{\rm T}$-differential $\Xi^0_{\rm c}$-baryon and ${\rm D^0}$-meson production cross sections is also reported. The measurements are compared with simulations with different tunes of the PYTHIA 8 event generator, with predictions from a statistical hadronisation model (SHM) with a largely augmented set of charm-baryon states beyond the current lists of the Particle Data Group, and with models including hadronisation via quark coalescence. The $p_{\rm T}$-integrated cross section of prompt $\Xi^0_{\rm c}$-baryon production at midrapidity is also reported, which is used to calculate the baryon-to-meson ratio $\Xi^0_{\rm c}/{\rm D^0} = 0.20 \pm 0.04~{\rm (stat.)} ^{+0.08}_{-0.07}~{\rm (syst.)}$. These results provide an additional indication of a modification of the charm fragmentation from $\rm e^+e^-$ and $\rm e^{-}p$ collisions to pp collisions.

6 data tables

$p_{\rm T}-$differential production cross section of prompt $\Xi^{0}_{\rm c}$ baryons in pp collisions at $\sqrt{s} =$ 5.02 TeV for $|y| < 0.5$.

$p_{\rm T}-$differential production cross section of inclusive $\Xi^{0}_{\rm c}$ baryons in pp collisions at $\sqrt{s} =$ 7 TeV for $|y| < 0.5$. The cross section result now is divided by the BR, which was not applied in the previous paper and HEPData.

$\Xi^0_{\rm c}$/${\rm D^0}$ ratio measured in pp collisions at $\sqrt{s}$ = 5.02 TeV for $|y| < 0.5$. The uncertainty of the BR of ${\rm D^0}$ and $\Xi^0_{\rm c}$ are written separately

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Experimental Evidence for an Attractive p-$\phi$ Interaction

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Rev.Lett. 127 (2021) 172301, 2021.
Inspire Record 1863040 DOI 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.


First measurements of $N$-subjettiness in central Pb$-$Pb collisions at ${\sqrt{\it{s}_{\rm {NN}}}} = 2.76$ TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
CERN-EP-2021-082, 2021.
Inspire Record 1862792 DOI 10.17182/hepdata.111055

The ALICE Collaboration reports the first fully-corrected measurements of the $N$-subjettiness observable for track-based jets in heavy-ion collisions. This study is performed using data recorded in pp and Pb$-$Pb collisions at centre-of-mass energies of $\sqrt{s} = 7$ TeV and $\sqrt{s_{\rm NN}} = 2.76$ TeV, respectively. In particular the ratio of 2-subjettiness to 1-subjettiness, $\tau_{2}/\tau_{1}$, which is sensitive to the rate of two-pronged jet substructure, is presented. Energy loss of jets traversing the strongly interacting medium in heavy-ion collisions is expected to change the rate of two-pronged substructure relative to vacuum. The results are presented for jets with a resolution parameter of $R = 0.4$ and charged jet transverse momentum of $40 \leq p_{\rm T,\rm jet} \leq 60$ GeV/$c$, which constitute a larger jet resolution and lower jet transverse momentum interval than previous measurements in heavy-ion collisions. This has been achieved by utilising a semi-inclusive hadron-jet coincidence technique to suppress the larger jet combinatorial background in this kinematic region. No significant modification of the $\tau_{2}/\tau_{1}$ observable for track-based jets in Pb$-$Pb collisions is observed relative to vacuum PYTHIA6 and PYTHIA8 references at the same collision energy. The measurements of $\tau_{2}/\tau_{1}$, together with the splitting aperture angle $\Delta R$, are also performed in pp collisions at $\sqrt{s}=7$ TeV for inclusive jets. These results are compared with PYTHIA calculations at $\sqrt{s}=7$ TeV, in order to validate the model as a vacuum reference for the Pb$-$Pb centre-of-mass energy. The PYTHIA references for $\tau_{2}/\tau_{1}$ are shifted to larger values compared to the measurement in pp collisions. This hints at a reduction in the rate of two-pronged jets in Pb$-$Pb collisions compared to pp collisions.

9 data tables

The $\Delta R$ (with $k_{T}$) fully corrected data distributions for jetsin the jet transverse momentum range 40-60 GeV/c in pp collisions

The $\Delta R$ (with C/A) fully corrected data distributions for jetsin the jet transverse momentum range 40-60 GeV/c in pp collisions

The $\Delta R$ (with Soft Drop) fully corrected data distributions for jetsin the jet transverse momentum range 40-60 GeV/c in pp collisions

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Measurement of the Cross Sections of $\Xi^0_{c}$ and $\Xi^+_{c}$ Baryons and of the Branching-Fraction Ratio BR($\Xi^0_{c} \rightarrow \Xi^-{e}^+\nu_{ e}$)/BR($\Xi^0_{c} \rightarrow \Xi^-\pi^+$) in pp collisions at 13 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Rev.Lett. 127 (2021) 272001, 2021.
Inspire Record 1862793 DOI 10.17182/hepdata.115272

The $p_{\rm T}$-differential cross sections of prompt charm-strange baryons $\Xi^0_{\rm c}$ and $\Xi^+_{\rm c}$ were measured at midrapidity ($|y| < 0.5$) in proton$-$proton (pp) collisions at a centre-of-mass energy $\sqrt{s}=13$ TeV with the ALICE detector at the LHC. The $\Xi^0_{\rm c}$ baryon was reconstructed via both the semileptonic decay ($\Xi^{-}{\rm e^{+}}\nu_{\rm e}$) and the hadronic decay ($\Xi^{-}{\rm \pi^{+}}$) channels. The $\Xi^+_{\rm c}$ baryon was reconstructed via the hadronic decay ($\Xi^{-}\pi^{+}\pi^{+}$) channel. The branching-fraction ratio $\rm {\rm BR}(\Xi_c^0\rightarrow \Xi^-e^+\nu_e)/\rm {\rm BR}(\Xi_c^0\rightarrow \Xi^{-}\pi^+)=$ 1.38 $\pm$ 0.14 (stat) $\pm$ 0.22 (syst) was measured with a total uncertainty reduced by a factor of about 3 with respect to the current world average reported by the Particle Data Group. The transverse momentum ($p_{\rm T}$) dependence of the $\Xi^0_{\rm c}$- and $\Xi^+_{\rm c}$-baryon production relative to the ${\rm D^0}$-meson and to the $\Sigma^{0,+,++}_{\rm c}$- and $\Lambda^+_{\rm c}$-baryon production are reported. The baryon-to-meson ratio increases towards low $p_{\rm T}$ up to a value of approximately 0.3. The measurements are compared with various models that take different hadronisation mechanisms into consideration. The results provide stringent constraints to these theoretical calculations and additional evidence that different processes are involved in charm hadronisation in electron$-$positron ($\rm e^+e^-$) and hadronic collisions.

9 data tables

Cross section of prompt $\rm \Xi_c^0$ baryon as a function of $p_{\rm T}$ in pp collisions at $\sqrt{s}=13$ TeV for $|y|<0.5$.

Cross section of prompt $\rm \Xi_c^+$ baryon as a function of $p_{\rm T}$ in pp collisions at $\sqrt{s}=13$ TeV for $|y|<0.5$.

$\rm \Xi_c^0/D^0$ ratio as a function of $p_{\rm T}$ in pp collisions at $\sqrt{s}=13$ TeV for $|y|<0.5$.

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Energy dependence of $\phi $ meson production at forward rapidity in pp collisions at the LHC

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Eur.Phys.J.C 81 (2021) 772, 2021.
Inspire Record 1861688 DOI 10.17182/hepdata.110876

The production of $\phi$ mesons has been studied in pp collisions at LHC energies with the ALICE detector via the dimuon decay channel in the rapidity region $2.5 < y < 4$. Measurements of the differential cross section ${\rm d}^2\sigma/{\rm d}y {\rm d}p_{\rm T}$ are presented as a function of the transverse momentum ($p_{\rm T}$) at the center-of-mass energies $\sqrt{s}=5.02$, 8 and 13 TeV and compared with the ALICE results at midrapidity. The differential cross sections at $\sqrt{s}=5.02$ and 13 TeV are also studied in several rapidity intervals as a function of $p_{\rm T}$, and as a function of rapidity in three $p_{\rm T}$ intervals. A hardening of the $p_{\rm T}$-differential cross section with the collision energy is observed, while, for a given energy, $p_{\rm T}$ spectra soften with increasing rapidity and, conversely, rapidity distributions get slightly narrower at increasing $p_{\rm T}$. The new results, complementing the published measurements at $\sqrt{s}=2.76$ and 7 TeV, allow one to establish the energy dependence of $\phi$ meson production and to compare the measured cross sections with phenomenological models.

19 data tables

$\phi$ meson production cross section $\mathrm{d}^2\sigma/(\mathrm{d}y\mathrm{d}p_\mathrm{T})$ as a function of $p_\mathrm{T}$ at $\sqrt{s}=5.02$ TeV at forward rapidity in pp collisions.

$\phi$ meson production cross section $\mathrm{d}^2\sigma/(\mathrm{d}y\mathrm{d}p_\mathrm{T})$ as a function of $p_\mathrm{T}$ at $\sqrt{s}=8$ TeV at forward rapidity in pp collisions.

$\phi$ meson production cross section $\mathrm{d}^2\sigma/(\mathrm{d}y\mathrm{d}p_\mathrm{T})$ as a function of $p_\mathrm{T}$ at $\sqrt{s}=13$ TeV at forward rapidity in pp collisions.

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Measurement of beauty and charm production in pp collisions at $ \sqrt{s} $ = 5.02 TeV via non-prompt and prompt D mesons

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
JHEP 05 (2021) 220, 2021.
Inspire Record 1848990 DOI 10.17182/hepdata.105047

The $p_\mathrm{T}$-differential production cross sections of prompt and non-prompt (produced in beauty-hadron decays) D mesons were measured by the ALICE experiment at midrapidity ($|y|<0.5$) in proton--proton collisions at $\sqrt{s}=5.02~\mathrm{TeV}$. The data sample used in the analysis corresponds to an integrated luminosity of $(19.3\pm0.4)~\mathrm{nb^{-1}}$. D mesons were reconstructed from their decays $\mathrm{D^0 \to K^-\pi^+}$, $\mathrm{D^+\to K^-\pi^+\pi^+}$, and $\mathrm{D_s^+\to \phi\pi^+\to K^-K^+\pi^+}$ and their charge conjugates. Compared to previous measurements in the same rapidity region, the cross sections of prompt $\mathrm{D^+}$ and $\mathrm{D_s^+}$ mesons have an extended $p_\mathrm{T}$ coverage and total uncertainties reduced by a factor ranging from 1.05 to 1.6, depending on $p_\mathrm{T}$, allowing for a more precise determination of their $p_\mathrm{T}$-integrated cross sections. The results are well described by perturbative QCD calculations. The fragmentation fraction of heavy quarks to strange mesons divided by the one to non-strange mesons, $f_\mathrm{s}/(f_\mathrm{u}+f_\mathrm{d})$, is compatible for charm and beauty quarks and with previous measurements at different centre-of-mass energies and collision systems. The $\mathrm{b\overline{b}}$ production cross section per rapidity unit at midrapidity, estimated from non-prompt D-meson measurements, is $\mathrm{d}\sigma_\mathrm{b\overline{b}}/\mathrm{d} y|_\mathrm{|y|<0.5} = 34.5 \pm 2.4 (\mathrm{stat.}) ^{+4.7}_{-2.9} (\mathrm{tot. syst.})~\mu\mathrm{b}$. It is compatible with previous measurements at the same centre-of-mass energy and with the cross section predicted by perturbative QCD calculations.

17 data tables

$p_\mathrm{T}$-differential production cross section of non-prompt $\mathrm{D^0}$ mesons in pp collision at $\sqrt{s}=5.02~\mathrm{TeV}$ in the rapidity interval $|y|<0.5$. Branching ratio of $\mathrm{D^0 \to K^-\pi^+}$: 0.0395

$p_\mathrm{T}$-differential production cross section of non-prompt $\mathrm{D^+}$ mesons in pp collision at $\sqrt{s}=5.02~\mathrm{TeV}$ in the rapidity interval $|y|<0.5$. Branching ratio of $\mathrm{D^+\to K^-\pi^+\pi^+}$: 0.0938

$p_\mathrm{T}$-differential production cross section of non-prompt $\mathrm{D_{s}^{+}}$ mesons in pp collision at $\sqrt{s}=5.02~\mathrm{TeV}$ in the rapidity interval $|y|<0.5$. Branching ratio of $\mathrm{D_s^+\to \phi\pi^+\to K^-K^+\pi^+}$: 0.0224

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Measurements of mixed harmonic cumulants in Pb–Pb collisions at $\sqrt {s_{NN}}$ = 5.02 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Lett.B 818 (2021) 136354, 2021.
Inspire Record 1848215 DOI 10.17182/hepdata.105046

Correlations between moments of different flow coefficients are measured in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV recorded with the ALICE detector. These new measurements are based on multiparticle mixed harmonic cumulants calculated using charged particles in the pseudorapidity region $|\eta|<0.8$ with the transverse momentum range $0.2 < p_{\rm T} < 5.0$ GeV/$c$. The centrality dependence of correlations between two flow coefficients as well as the correlations between three flow coefficients, both in terms of their second moments, are shown. In addition, a collection of mixed harmonic cumulants involving higher moments of $v_2$ and $v_3$ is measured for the first time, where the characteristic signature of negative, positive and negative signs of four-, six- and eight-particle cumulants are observed, respectively. The measurements are compared to the hydrodynamic calculations using iEBE-VISHNU with AMPT and TRENTo initial conditions. It is shown that the measurements carried out using the LHC Run 2 data in 2015 have the precision to explore the details of initial-state fluctuations and probe the nonlinear hydrodynamic response of $v_2$ and $v_3$ to their corresponding initial anisotropy coefficients $\varepsilon_2$ and $\varepsilon_3$. These new studies on correlations between three flow coefficients as well as correlations between higher moments of two different flow coefficients will pave the way to tighten constraints on initial-state models and help to extract precise information on the dynamic evolution of the hot and dense matter created in heavy-ion collisions at the LHC.

9 data tables

Centrality dependence of $nMHC(v_2^2,v_3^2)$ in Pb-Pb collisions at 5.02 TeV.

Centrality dependence of $nMHC(v_2^2,v_4^2)$ in Pb-Pb collisions at 5.02 TeV.

Centrality dependence of $nMHC(v_3^2,v_4^2)$ in Pb-Pb collisions at 5.02 TeV.

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First measurement of the |$t$|-dependence of coherent $J/\psi$ photonuclear production

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Lett.B 817 (2021) 136280, 2021.
Inspire Record 1840600 DOI 10.17182/hepdata.104459

The first measurement of the cross section for coherent J/$\psi$ photoproduction as a function of $|t|$, the square of the momentum transferred between the incoming and outgoing target nucleus, is presented. The data were measured with the ALICE detector in ultra-peripheral Pb-Pb collisions at a centre-of-mass energy per nucleon pair $\sqrt{s_{\rm NN}} = 5.02$ TeV with the J/$\psi$ produced in the central rapidity region $|y|<0.8$, which corresponds to the small Bjorken-$x$ range $(0.3-1.4) \times 10^{-3}$. The measured $|t|$-dependence is not described by computations based only on the Pb nuclear form factor, while the photonuclear cross section is better reproduced by models including shadowing according to the leading-twist approximation, or gluon-saturation effects from the impact-parameter dependent Balitsky-Kovchegov equation. These new results are therefore a valid tool to constrain the relevant model parameters and to investigate the transverse gluonic structure at very low Bjorken-$x$.

2 data tables

t-dependence of coherent J/psi photonuclear production cross section in Pb-Pb UPC.

pT**2-dependence of coherent J/psi photoproduction cross section in Pb-Pb UPC.


Coherent $J/ \psi$ and $\phi$' photoproduction at midrapidity in ultra-peripheral Pb–Pb  collisions at $\sqrt {s_{NN}}$ = 5.02 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Eur.Phys.J.C 81 (2021) 712, 2021.
Inspire Record 1840601 DOI 10.17182/hepdata.110176

The coherent photoproduction of $\rm{J/\psi}$ and $\rm{\psi'}$ mesons was measured in ultra-peripheral Pb-Pb collisions at a center-of-mass energy $\sqrt{s_{\mathrm{NN}}}~=~5.02$ TeV with the ALICE detector. Charmonia are detected in the central rapidity region for events where the hadronic interactions are strongly suppressed. The $\rm{J/\psi}$ is reconstructed using the dilepton ($l^{+} l^{-}$) and proton-antiproton decay channels, while for the $\rm{\psi'}$, the dilepton and the $l^{+} l^{-} \pi^{+} \pi^{-}$ decay channels are studied. The analysis is based on an event sample corresponding to an integrated luminosity of about 233 ${\mu b}^{-1}$. The results are compared with theoretical models for coherent $\rm{J/\psi}$ and $\rm{\psi'}$ photoproduction. The coherent cross section is found to be in a good agreement with models incorporating moderate nuclear gluon shadowing of about 0.65 at a Bjorken-$x$ of around $6\times 10^{-4}$, such as the EPS09 parametrization, however none of the models is able to fully describe the rapidity dependence of the coherent $\rm{J/\psi}$ cross section including ALICE measurements at forward rapidity. The ratio of $\rm{\psi'}$ to $\rm{J/\psi}$ coherent photoproduction cross sections was also measured and found to be consistent with the one for photoproduction off protons.

4 data tables

Measured differential cross section of coherent J/Psi photoproduction in Pb–Pb UPCs in |y|<0.8. The points show the measurements for different decay channels.

Measured differential cross section of coherent Psi(2S) photoproduction in Pb–Pb UPCs in |y|<0.8. The points show the measurements for different decay channels.

Measured rapidity differential cross section of coherent J/Psi photoproduction in Pb–Pb UPCs events.

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Production of pions, kaons, (anti-)protons and $\phi $ mesons in Xe–Xe collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.44 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Eur.Phys.J.C 81 (2021) 584, 2021.
Inspire Record 1840099 DOI 10.17182/hepdata.110161

The first measurement of the production of pions, kaons, (anti-)protons and $\phi$ mesons at midrapidity in Xe-Xe collisions at $\sqrt{s_{\rm NN}} = 5.44$ TeV is presented. Transverse momentum ($p_{\rm T}$) spectra and $p_{\rm T}$-integrated yields are extracted in several centrality intervals bridging from p-Pb to mid-central Pb-Pb collisions in terms of final-state multiplicity. The study of Xe-Xe and Pb-Pb collisions allows systems at similar charged-particle multiplicities but with different initial geometrical eccentricities to be investigated. A detailed comparison of the spectral shapes in the two systems reveals an opposite behaviour for radial and elliptic flow. In particular, this study shows that the radial flow does not depend on the colliding system when compared at similar charged-particle multiplicity. In terms of hadron chemistry, the previously observed smooth evolution of particle ratios with multiplicity from small to large collision systems is also found to hold in Xe-Xe. In addition, our results confirm that two remarkable features of particle production at LHC energies are also valid in the collision of medium-sized nuclei: the lower proton-to-pion ratio with respect to the thermal model expectations and the increase of the $\phi$-to-pion ratio with increasing final-state multiplicity.

58 data tables

$p_{T}$-distributions of pions ($\pi^{+}+\pi^{-}$) measured in Xe-Xe collisions at $\sqrt{s_{NN}}$ = 5.44 TeV. Centrality class 0-5%.

$p_{T}$-distributions of kaons ($K^{+}+K^{-}$) measured in Xe-Xe collisions at $\sqrt{s_{NN}}$ = 5.44 TeV. Centrality class 0-5%.

$p_{T}$-distributions of protons ($p+pbar$) measured in Xe-Xe collisions at $\sqrt{s_{NN}}$ = 5.44 TeV. Centrality class 0-5%.

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Long- and short-range correlations and their event-scale dependence in high-multiplicity pp collisions at $\boldsymbol{\sqrt{{\textit s}}}=13$ TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
JHEP 05 (2021) 290, 2021.
Inspire Record 1840098 DOI 10.17182/hepdata.105588

Two-particle angular correlations are measured in high-multiplicity proton-proton collisions at $\sqrt{s} =13$ TeV by the ALICE Collaboration. The yields of particle pairs at short-($\Delta\eta$$\sim$ 0) and long-range ($1.6 < |\Delta\eta| < 1.8$) in pseudorapidity are extracted on the near-side ($\Delta\varphi$$\sim$ 0). They are reported as a function of transverse momentum ($p_{\mathrm T}$) in the range $1 <p_{\mathrm T}< 4$ GeV/$c$. Furthermore, the event-scale dependence is studied for the first time by requiring the presence of high-$p_{\rm T}$ leading particles and jets for varying $p_{\rm T}$ thresholds. The results demonstrate that the long-range "ridge" yield, possibly related to the collective behavior of the system, is present in events with high-$p_{\mathrm T}$ processes. The magnitudes of the short- and long-range yields are found to grow with the event scale. The results are compared to EPOS LHC and PYTHIA 8 calculations, with and without string-shoving interactions. It is found that while both models describe the qualitative trends in the data, calculations from EPOS LHC show a better quantitative agreement, in particular for the $p_{\rm T}$ and event-scale dependencies.

8 data tables

Long-range $\Delta\varphi$ projections in minimum bias and high-multiplicity events for various $p_\mathrm{T,trig(assoc)}$ ranges.

Ridge yield as a function of $p_\mathrm{T,trig(assoc)}$ in high-multiplicity events.

Long-range $\Delta\varphi$ projections in high-multiplicity events with event-scale selections, requiring minimum $p_\mathrm{T,jet}$

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First measurement of coherent ρ0 photoproduction in ultra-peripheral Xe–Xe collisions at sNN=5.44 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Lett.B 820 (2021) 136481, 2021.
Inspire Record 1839719 DOI 10.17182/hepdata.110661

The first measurement of the coherent photoproduction of $\rho^{0}$ vector mesons in ultra-peripheral Xe-Xe collisions at $\sqrt{s_{\mathrm{\rm NN}}}= 5.44$ TeV is presented. This result, together with previous HERA $\gamma$p data and $\gamma$-Pb measurements from ALICE, describes the atomic number ($A$) dependence of this process, which is particularly sensitive to nuclear shadowing effects and to the approach to the black-disc limit of QCD at a semi-hard scale. The cross section of the ${\rm Xe}+{\rm Xe} \to \rho^{0} + {\rm Xe}+{\rm Xe}$ process, measured at midrapidity through the decay channel $\rho^{0}\to\pi^+\pi^-$, is found to be ${\rm d}\sigma/{\rm d}y=131.5\pm 5.6 {\rm (stat.)} ^{+17.5}_{-16.9} {\rm (syst.)}$ mb. The ratio of the continuum to resonant contributions for the production of pion pairs is also measured. In addition, the fraction of events accompanied by electromagnetic dissociation of either one or both colliding nuclei is reported. The dependence on $A$ of cross section for the coherent $\rho^{0}$ photoproduction at a centre-of-mass energy per nucleon of the $\gamma A$ system of $W_{\gamma A,n}= 65$ GeV is found to be consistent with a power-law behaviour $\sigma (\gamma A\rightarrow \rho^{0} A) \propto A^{\alpha}$ with a slope $\alpha = 0.96 \pm 0.02 {\rm (syst.)}$. This slope signals important shadowing effects, but it is still far from the behaviour expected in the black-disc limit.

1 data table

Differential cross section as a function of rapidity for coherent RHO0 photoproduction in ultra-peripheral Xe-Xe collisions at ALICE.


Multiharmonic Correlations of Different Flow Amplitudes in Pb-Pb Collisions at $\sqrt{s_{_{NN}}}=2.76$  TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Rev.Lett. 127 (2021) 092302, 2021.
Inspire Record 1839720 DOI 10.17182/hepdata.110113

The event-by-event correlations between three flow amplitudes are measured for the first time in Pb--Pb collisions, using higher-order Symmetric Cumulants. We find that different three-harmonic correlations develop during the collective evolution of the medium, when compared with correlations that exist in the initial state. These new results cannot be interpreted in terms of previous lower-order flow measurements, since contributions from two-harmonic correlations are explicitly removed in the new observables. Comparison with Monte Carlo simulations provides new and independent constraints for the initial conditions and system properties of nuclear matter created in heavy-ion collisions.

6 data tables

Centrality dependence of ${\rm SC}(2,3,4)$ in Pb--Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$~TeV.

Centrality dependence of ${\rm SC}(2,3,5)$ in Pb--Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$~TeV.

Centrality dependence of ${\rm SC}(2,4,6)$ in Pb--Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$~TeV.

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Inclusive heavy-flavour production at central and forward rapidity in Xe–Xe collisions at sNN=5.44 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Lett.B 819 (2021) 136437, 2021.
Inspire Record 1830186 DOI 10.17182/hepdata.105962

The first measurements of the production of muons and electrons from heavy-flavour hadron decays in Xe-Xe collisions at $\sqrt{s_{\rm NN}}$ = 5.44 TeV, using the ALICE detector at the LHC, are reported. The measurement of the nuclear modification factor $R_{\rm AA}$ is performed as a function of transverse momentum $p_{\rm T}$ in several centrality classes at forward rapidity ($2.5 < y <4$) and midrapidity ($\vert y \vert < 0.8$) for muons and electrons from heavy-flavour hadron decays, respectively. A suppression by a factor up to about 2.5 compared to the binary-scaled pp reference is observed in central collisions at both central and forward rapidities. The $R_{\rm AA}$ of muons from heavy-flavour hadron decays is compared to previous measurements in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV. When the nuclear modification factors are compared in the centrality classes 0-10% for Xe-Xe collisions and 10-20% for Pb-Pb collisions, which have similar charged-particle multiplicity density, a similar suppression, with $R_{\rm AA} \sim 0.4$ in the $p_{\rm T}$ interval $4 < p_{\rm T} < 8$ GeV/$c$, is observed. The comparison of the measured $R_{\rm AA}$ values in the two collision systems brings new insights on the properties of the quark-gluon plasma by investigating the system-size and path-length dependence of medium-induced parton energy loss. The results of muons and electrons from heavy-flavour hadron decays provide new constraints to model calculations.

12 data tables

Transverse momentum differential production of muons from heavy-flavour hadron decays at forward rapidity in Xe-Xe collisions at 5.44 TeV.

Transverse momentum differential production of muons from heavy-flavour hadron decays at forward rapidity in Xe-Xe collisions at 5.44 TeV.

Transverse momentum differential production of muons from heavy-flavour hadron decays at forward rapidity in Xe-Xe collisions at 5.44 TeV.

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Jet-associated deuteron production in pp collisions at s=13 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Lett.B 819 (2021) 136440, 2021.
Inspire Record 1829410 DOI 10.17182/hepdata.105975

Deuteron production in high-energy collisions is sensitive to the space-time evolution of the collision system, and is typically described by a coalescence mechanism. For the first time, we present results on jet-associated deuteron production in \pp collisions at $\sqrt{s}=13$ TeV, providing an opportunity to test the established picture for deuteron production in events with a hard scattering. Using a trigger particle with high transverse-momentum ($p_{\rm T}>5$ GeV/$c$) as a proxy for the presence of a jet at midrapidity, we observe a measurable population of deuterons being produced around the jet proxy. The associated deuteron yield measured in a narrow angular range around the trigger particle differs by 2.4-4.8 standard deviations from the uncorrelated background. The data are described by PYTHIA model calculations featuring baryon coalescence.

6 data tables

The per-trigger associated yield versus $\Delta\varphi$ for charged particles with $p_{\rm T}>5.0$ GeV/$c$ and associate deuterons and anti-deuterons for 1.0-1.35 GeV/$c$.

The per-trigger associated yield versus $\Delta\varphi$ for charged particles with $p_{\rm T}>5.0$ GeV/$c$ and associate deuterons and anti-deuterons for 1.35-1.8 GeV/$c$.

The per-trigger associated yield versus $\Delta\varphi$ for charged particles with $p_{\rm T}>5.0$ GeV/$c$ and associate deuterons and anti-deuterons for 1.8-2.4 GeV/$c$.

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ϒ production and nuclear modification at forward rapidity in Pb–Pb collisions at sNN=5.02TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Lett.B 822 (2021) 136579, 2021.
Inspire Record 1829413 DOI 10.17182/hepdata.114190

The production of $\Upsilon$ mesons in Pb-Pb collisions at a centre-of-mass energy per nucleon pair $\sqrt{s_{\rm NN}}$ = 5 TeV is measured with the muon spectrometer of the ALICE detector at the LHC. The yields as well as the nuclear modification factors are determined in the forward rapidity region $2.5<y<4.0$, as a function of rapidity, transverse momentum and collision centrality. The results show that the production of the $\Upsilon$(1S) meson is suppressed by a factor of about three with respect to the production in proton-proton collisions. For the first time, a significant signal for the $\Upsilon$(2S) meson is observed at forward rapidity, indicating a suppression stronger by about a factor 2-3 with respect to the ground state. The measurements are compared with transport, hydrodynamic, comover and statistical hadronisation model calculations.

14 data tables

Rapidity-differential yield of $\Upsilon(1\mathrm{S}) \rightarrow \mu^{+}\mu^{-}$ divided by the average nuclear overlap function $\langle T_{\mathrm{AA}} \rangle$ for the 0–90% centrality interval ($\langle T_{\mathrm{AA}} \rangle$ = 6.28 $\pm$ 0.06 mb$^{-1}$).

Rapidity-differential yield of $\Upsilon(2\mathrm{S}) \rightarrow \mu^{+}\mu^{-}$ divided by the average nuclear overlap function $\langle T_{\mathrm{AA}} \rangle$ for the 0–90% centrality interval ($\langle T_{\mathrm{AA}} \rangle$ = 6.28 $\pm$ 0.06 mb$^{-1}$).

$p_{\mathrm{T}}$-differential yield of $\Upsilon(1\mathrm{S}) \rightarrow \mu^{+}\mu^{-}$ divided by the average nuclear overlap function $\langle T_{\mathrm{AA}} \rangle$ for the 0–90% centrality interval ($\langle T_{\mathrm{AA}} \rangle$ = 6.28 $\pm$ 0.06 mb$^{-1}$).

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$\Lambda^+_c$ Production and Baryon-to-Meson Ratios in pp and p-Pb Collisions at $\sqrt {s_{NN}}$=5.02  TeV at the LHC

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Rev.Lett. 127 (2021) 202301, 2021.
Inspire Record 1829739 DOI 10.17182/hepdata.114213

The prompt production of the charm baryon $\rm \Lambda_{c}^{+}$ and the $\rm \Lambda_{c}^{+}/\mathrm {D^0}$ production ratios were measured at midrapidity with the ALICE detector in pp and p-Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$TeV. These new measurements show a clear decrease of the $\rm \Lambda_{c}^{+}/\mathrm {D^0}$ ratio with increasing transverse momentum ($p_{\rm T}$) in both collision systems in the range $2<p_{\rm T}<12$ GeV/$c$, exhibiting similarities with the light-flavour baryon-to-meson ratios ${\rm p}/\pi$ and $\Lambda/\mathrm {K^0_S}$. At low $p_{\rm T}$, predictions that include additional colour-reconnection mechanisms beyond the leading-colour approximation; assume the existence of additional higher-mass charm-baryon states; or include hadronisation via coalescence can describe the data, while predictions driven by charm-quark fragmentation processes measured in $\mathrm {e^+e^-}$ and $\mathrm {e^-p}$ collisions significantly underestimate the data. The results presented in this letter provide significant evidence that the established assumption of universality (colliding-system independence) of parton-to-hadron fragmentation is not sufficient to describe charm-baryon production in hadronic collisions at LHC energies.

8 data tables

Prompt $\Lambda_{\rm {c}}^{+}$ baryon $p_{\rm {T}}$-differential cross section in pp collisions at $\sqrt{s} = 5.02$ TeV in the rapidity interval $|y|<0.5$.

Prompt $\Lambda_{\rm {c}}^{+}$ baryon $p_{\rm {T}}$-differential cross section in p-Pb collisions at $\sqrt{s_{\rm {NN}}} = 5.02$ TeV in the rapidity interval $-0.96 \lt y \lt 0.04$.

The nuclear modification factor $R_\mathrm{pPb}$ of prompt $\Lambda_{\rm {c}}^{+}$ baryons in p-Pb collisions at $\sqrt{s_{\rm {NN}}} = 5.02$ TeV in the rapidity interval $ -0.96\lt y \lt 0.04$.

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Production of muons from heavy-flavour hadron decays at high transverse momentum in Pb–Pb collisions at sNN=5.02 and 2.76 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Lett.B 820 (2021) 136558, 2021.
Inspire Record 1829412 DOI 10.17182/hepdata.110833

Measurements of the production of muons from heavy-flavour hadron decays in Pb$-$Pb collisions at $\sqrt{s_{\rm NN}}$ = $5.02$ and $2.76$ TeV using the ALICE detector at the LHC are reported. The nuclear modification factor $R_{\rm AA}$ at $\sqrt{s_{\rm NN}}$ = 5.02 TeV is measured at forward rapidity ($2.5 < y <4$) as a function of transverse momentum $p_{\rm T}$ in central, semi-central, and peripheral collisions over a wide $p_{\rm T}$ interval, $3 < p_{\rm T} < 20$ GeV/$c$, in which muons from beauty-hadron decays are expected to take over from charm as the dominant source at high $p_{\rm T}$ ($p_{\rm T} > 7$ GeV/$c$). The $R_{\rm AA}$ shows an increase of the suppression of the yields of muons from heavy-flavour hadron decays with increasing centrality. A suppression by a factor of about three is observed in the $10\%$ most central collisions. The $R_{\rm AA}$ at $\sqrt{s_{\rm NN}}$ = 5.02 is similar to that at 2.76 TeV. The precise $R_{\rm AA}$ measurements have the potential to distinguish between model predictions implementing different mechanisms of parton energy loss in the high-density medium formed in heavy-ion collisions. They place important constraints for the understanding of the heavy-quark interaction with the hot and dense QCD medium.

7 data tables

$p_{\rm T}$-differential yield of muons from heavy-flavour hadron decays at forward rapidity ($2.5 < y < 4$) for central (0--10%) and semi-central (20--40%) Pb--Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV.

$p_{\rm T}$-differential yield of muons from heavy-flavour hadron decays at forward rapidity ($2.5 < y < 4$) for peripheral (60--80%) Pb--Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV.

$p_{\rm T}$-differential yield of muons from heavy-flavour hadron decays at forward rapidity ($2.5 < y < 4$) for central (0--10%) Pb--Pb collisions at $\sqrt{s_{\rm NN}}=2.76$ TeV.

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Pseudorapidity distributions of charged particles as a function of mid- and forward rapidity multiplicities in pp collisions at $\sqrt{s}$ = 5.02, 7 and 13 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Eur.Phys.J.C 81 (2021) 630, 2021.
Inspire Record 1818157 DOI 10.17182/hepdata.106205

The multiplicity dependence of the pseudorapidity density of charged particles in proton-proton (pp) collisions at centre-of-mass energies $\sqrt{s}$ = 5.02, 7 and 13 TeV measured by ALICE is reported. The analysis relies on track segments measured in the midrapidity range ($|\eta| < 1.5$). Results are presented for inelastic events having at least one charged particle produced in the pseudorapidity interval $|\eta|<1$ ($\mathrm{INEL}_{>0}$). The multiplicity dependence of the pseudorapidy density of charged particles is measured with mid and forward rapidity multiplicity estimators, the latter being less affected by autocorrelations. A detailed comparison with predictions from the PYTHIA 8 and EPOS LHC event generators is also presented. Both generators provide a good description of the data.

6 data tables

Charged-particle pseudorapidity density for forward multiplicity classes as a function of $\eta$ in pp collisions at $\sqrt{s} = 5.02\,\mathrm{TeV}$. Statistical errors are generally insignificant.

Charged-particle pseudorapidity density for forward multiplicity classes as a function of $\eta$ in pp collisions at $\sqrt{s} = 7\,\mathrm{TeV}$. Statistical errors are generally insignificant.

Charged-particle pseudorapidity density for forward multiplicity classes as a function of $\eta$ in pp collisions at $\sqrt{s} = 13\,\mathrm{TeV}$. Statistical errors are generally insignificant.

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Centrality dependence of J/$\psi$ and $\psi$(2S) production and nuclear modification in p-Pb collisions at $\sqrt{s_{\rm NN}} =$ 8.16 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
JHEP 02 (2021) 002, 2021.
Inspire Record 1811102 DOI 10.17182/hepdata.100166

The inclusive production of the J/$\psi$ and $\psi$(2S) charmonium states is studied as a function of centrality in p-Pb collisions at a centre-of-mass energy per nucleon pair $\sqrt{s_{\rm NN}} = 8.16$ TeV at the LHC. The measurement is performed in the dimuon decay channel with the ALICE apparatus in the centre-of-mass rapidity intervals $-4.46 < y_{\rm cms} < -2.96$ (Pb-going direction) and $2.03 < y_{\rm cms} < 3.53$ (p-going direction), down to zero transverse momentum ($p_{\rm T}$). The J/$\psi$ and $\psi$(2S) production cross sections are evaluated as a function of the collision centrality, estimated through the energy deposited in the zero degree calorimeter located in the Pb-going direction. The $p_{\rm T}$-differential J/$\psi$ production cross section is measured at backward and forward rapidity for several centrality classes, together with the corresponding average $\langle p_{\rm T} \rangle$ and $\langle p^{2}_{\rm T} \rangle$ values. The nuclear effects affecting the production of both charmonium states are studied using the nuclear modification factor. In the p-going direction, a suppression of the production of both charmonium states is observed, which seems to increase from peripheral to central collisions. In the Pb-going direction, however, the centrality dependence is different for the two states: the nuclear modification factor of the J/$\psi$ increases from below unity in peripheral collisions to above unity in central collisions, while for the $\psi$(2S) it stays below or consistent with unity for all centralities with no significant centrality dependence. The results are compared with measurements in p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV and no significant dependence on the energy of the collision is observed. Finally, the results are compared with theoretical models implementing various nuclear matter effects.

22 data tables

The $p_{\rm T}$-differential inclusive J/$\psi$ cross sections for six centrality classes at backward ($-4.46 < y_{\rm cms} < -2.96$) centre-of-mass rapidity. The first uncertainty is statistical, the second one and the third ones are the uncorrelated and correlated systematic uncertainties, respectively. The third uncertainty is fully correlated over $p_{\rm T}$.

The $p_{\rm T}$-differential inclusive J/$\psi$ cross sections for six centrality classes at forward ($2.03 < y_{\rm cms} < 3.53$) centre-of-mass rapidity. The first uncertainty is statistical, the second one and the third ones are the uncorrelated and correlated systematic uncertainties, respectively. The third uncertainty is fully correlated over $p_{\rm T}$.

The values of $\langle p_{\rm T} \rangle$ and $\langle p^{2}_{\rm T} \rangle$ for six centrality classes at backward ($-4.46 < y_{\rm cms} < -2.96$) and forward ($2.03 < y_{\rm cms} < 3.53$) centre-of-mass rapidity. The first uncertainty is statistical, the second one is the systematic uncertainty.

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Production of $\omega $ mesons in pp collisions at $\mathbf {\sqrt{s}=7\,\text {TeV}}$

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Eur.Phys.J.C 80 (2020) 1130, 2020.
Inspire Record 1805263 DOI 10.17182/hepdata.99031

The invariant differential cross section of inclusive $\omega(782)$ meson production at midrapidity ($|y|<0.5$) in pp collisions at $\sqrt{s}$ = 7 TeV was measured with the ALICE detector at the LHC over a transverse momentum range of 2 < $p_{\rm{T}}$ < 17 GeV/$c$. The $\omega$ meson was reconstructed via its $\omega\rightarrow\pi^+\pi^-\pi^0$ decay channel. The measured $\omega$ production cross section is compared to various calculations: PYTHIA 8.2 Monash 2013 describes the data, while PYTHIA 8.2 Tune 4C overestimates the data by about 50%. A recent NLO calculation, which includes a model describing the fragmentation of the whole vector-meson nonet, describes the data within uncertainties below 6 GeV/$c$, while it overestimates the data by up to 50% for higher $p_{\rm{T}}$. The $\omega/\pi^0$ ratio is in agreement with previous measurements at lower collision energies and the PYTHIA calculations. In addition, the measurement is compatible with transverse mass scaling within the measured $p_{\rm{T}}$ range and the ratio is constant with $C^{\omega/\pi^{0}}$ = 0.67 $\pm$ 0.03 (stat) $\pm$ 0.04 (sys) above a transverse momentum of 2.5 GeV/$c$.

2 data tables

Invariant differential cross section of OMEGA mesons produced in inelastic pp collisions at center-of-mass energy 7 TeV, the uncertainty of sigma_{MB} of 3.5% is not included in the systematic error.

The measured ratio of cross sections for inclusive OMEGA to PI0 production at a centre-of-mass energy of 7 TeV.


J/$\psi$ elliptic and triangular flow in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
JHEP 10 (2020) 141, 2020.
Inspire Record 1798507 DOI 10.17182/hepdata.99234

The inclusive J/$\psi$ elliptic ($v_2$) and triangular ($v_3$) flow coefficients measured at forward rapidity (2.5 $<y<$ 4) and the $v_2$ measured at midrapidity ($|y|<$ 0.9) in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV using the ALICE detector at the LHC are reported. The entire Pb-Pb data sample collected during Run 2 is employed, amounting to an integrated luminosity of 750 $\mu$b$^{-1}$ at forward rapidity and 93 $\mu$b$^{-1}$ at midrapidity. The results are obtained using the scalar product method and are reported as a function of transverse momentum $p_{\rm T}$ and collision centrality. At midrapidity, the J/$\psi$ $v_2$ is in agreement with the forward rapidity measurement. The centrality averaged results indicate a positive J/$\psi$ $v_3$ with a significance of more than 5$\sigma$ at forward rapidity in the $p_{\rm T}$ range $2<p_{\rm T}<5$ GeV/$c$. The forward rapidity $v_2$, $v_3$, and $v_3$/$v_2$ results at low and intermediate $p_{\rm T}$ ($p_{\rm T} \lesssim 8$ GeV/$c$) exhibit a mass hierarchy when compared to pions and D mesons, while converging into a species-independent curve at higher $p_{\rm T}$. At low and intermediate $p_{\rm T}$, the results could be interpreted in terms of a later thermalization of charm quarks compared to light quarks, while at high $p_{\rm T}$, path-length dependent effects seem to dominate. The J/$\psi$ $v_2$ measurements are further compared to a microscopic transport model calculation. Using a simplified extension of the quark scaling approach involving both light and charm quark flow components, it is shown that the D-meson $v_{\rm n}$ measurements can be described based on those for charged pions and J/$\psi$ flow.

19 data tables

Inclusive J/$\psi$ $v_2$ as a function of $p_{T}$ in the centrality interval 0$-$10.0 %

Inclusive J/$\psi$ $v_2$ as a function of $p_{T}$ in the centrality interval 10$-$30 %

Inclusive J/$\psi$ $v_2$ as a function of $p_{T}$ in the centrality interval 30$-$50 %

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Elliptic and triangular flow of (anti)deuterons in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Rev.C 102 (2020) 055203, 2020.
Inspire Record 1798556 DOI 10.17182/hepdata.99901

The measurements of the (anti)deuterons elliptic flow ($v_2$) and the first measurements of triangular flow ($v_3$) in Pb-Pb collisions at a center-of-mass energy per nucleon-nucleon collisions $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV are presented. A mass ordering at low transverse momentum ($p_{\rm T}$) is observed when comparing these measurements with those of other identified hadrons, as expected from relativistic hydrodynamics. The measured (anti)deuterons $v_2$ lies between the predictions from the simple coalescence and blast-wave models, which provide a good description of the data only for more peripheral and for more central collisions, respectively. The mass number scaling, which is violated for $v_2$, is approximately valid for the (anti)deuterons $v_3$. The measured $v_2$ and $v_3$ are also compared with the predictions from a coalescence approach with phase-space distributions of nucleons generated by iEBE-VISHNU with AMPT initial conditions coupled with UrQMD, and from a dynamical model based on relativistic hydrodynamics coupled to the hadronic afterburner SMASH. The model predictions are consistent with the data within the uncertainties in mid-central collisions, while a deviation is observed in central centrality intervals.

11 data tables

v2 as a function of pT for Pb-Pb collisions at \sqrt{s_NN} = 5.02 TeV and centrality 0-5%.

v2 as a function of pT for Pb-Pb collisions at \sqrt{s_NN} = 5.02 TeV and centrality 5-10%.

v2 as a function of pT for Pb-Pb collisions at \sqrt{s_NN} = 5.02 TeV and centrality 10-20%.

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Constraining the Chiral Magnetic Effect with charge-dependent azimuthal correlations in Pb-Pb collisions at $ \sqrt{s_{\mathrm{NN}}} $ = 2.76 and 5.02 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
JHEP 09 (2020) 160, 2020.
Inspire Record 1798528 DOI 10.17182/hepdata.97127

Systematic studies of charge-dependent two- and three-particle correlations in Pb-Pb collisions at $\sqrt{\it{s}_\mathrm{{NN}}} = $ 2.76 and 5.02 TeV used to probe the Chiral Magnetic Effect (CME) are presented. These measurements are performed for charged particles in the pseudorapidity ($\eta$) and transverse momentum ($p_{\rm{T}}$) ranges $\left|\eta \right| < 0.8$ and $0.2 < p_{\mathrm{T}} < 5$ GeV/$c$. A significant charge-dependent signal that becomes more pronounced for peripheral collisions is reported for the CME-sensitive correlators $\gamma_{1,1} = \langle \cos (\varphi_{\alpha} +\varphi_{\beta} - 2\Psi_{2}) \rangle$ and $\gamma_{1,-3} = \langle \cos (\varphi_{\alpha} -3\varphi_{\beta} + 2\Psi_{2}) \rangle$. The results are used to estimate the contribution of background effects, associated with local charge conservation coupled to anisotropic flow modulations, to measurements of the CME. A blast-wave parametrisation that incorporates local charge conservation tuned to reproduce the centrality dependent background effects is not able to fully describe the measured $\gamma_{1,1}$. Finally, the charge and centrality dependence of mixed-harmonics three-particle correlations, of the form $\gamma_{1,2} = \langle \cos (\varphi_{\alpha} +2\varphi_{\beta} - 3\Psi_{3}) \rangle$, which are insensitive to the CME signal, verify again that background contributions dominate the measurement of $\gamma_{1,1}$.

11 data tables

2-particle integrated correlators

2-particle differential correlator versus pT difference

2-particle differential correlator versus average pT

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Measurement of isolated photon-hadron correlations in $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV $pp$ and $p$-Pb collisions

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Rev.C 102 (2020) 044908, 2020.
Inspire Record 1798523 DOI 10.17182/hepdata.98564

This paper presents isolated photon-hadron correlations using pp and p-Pb data collected by the ALICE detector at the LHC. For photons with |$\eta$| < 0.67 and 12 < $p_{\rm{T}}$ < 40 GeV/$c$, the associated yield of charged particles in the range |$\eta$| < 0.80 and 0.5 < $p_{\rm{T}}$ < 10 GeV/$c$ is presented. These momenta are much lower than previous measurements at the LHC. No significant difference between pp and p-Pb is observed, with PYTHIA 8.2 describing both data sets within uncertainties. This measurement constrains nuclear effects on the parton fragmentation in p-Pb collisions, and provides a benchmark for future studies of Pb-Pb collisions.

5 data tables

$\gamma^\mathrm{iso}$-hadron correlation functions for pp (red) and p$-$Pb (blue) data at $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV as measured by the ALICE detector. The different panels represent three different $z_\mathrm{T}$ bins. The correlation functions are projected over the range $|\Delta\eta| < 1.2$. The darker bands at zero represents the uncertainty from the underlying event estimation in pp and p$-$Pb. The underlying event was estimated over the range $|0.4 <\Delta\varphi < 1.6|$. The vertical bars represent statistical uncertainties only. The boxes indicate the systematic uncertainties. The dashed green line represents the $\gamma^\mathrm{iso}$-hadron correlation function obtained with PYTHIA 8.2 Monash Tune. '$p$' is the p-value for the hypothesis that the pp and p$-$Pb data follow the same true correlation function.

$\gamma^\mathrm{iso}$-hadron correlation functions for pp (red) and p$-$Pb (blue) data at $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV as measured by the ALICE detector. The different panels represent three different $z_\mathrm{T}$ bins. The correlation functions are projected over the range $|\Delta\eta| < 1.2$. The darker bands at zero represents the uncertainty from the underlying event estimation in pp and p$-$Pb. The underlying event was estimated over the range $|0.4 <\Delta\varphi < 1.6|$. The vertical bars represent statistical uncertainties only. The boxes indicate the systematic uncertainties. The dashed green line represents the $\gamma^\mathrm{iso}$-hadron correlation function obtained with PYTHIA 8.2 Monash Tune. '$p$' is the p-value for the hypothesis that the pp and p$-$Pb data follow the same true correlation function.

$\gamma^\mathrm{iso}$-hadron correlation functions for pp (red) and p$-$Pb (blue) data at $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV as measured by the ALICE detector. The different panels represent three different $z_\mathrm{T}$ bins. The correlation functions are projected over the range $|\Delta\eta| < 1.2$. The darker bands at zero represents the uncertainty from the underlying event estimation in pp and p$-$Pb. The underlying event was estimated over the range $|0.4 <\Delta\varphi < 1.6|$. The vertical bars represent statistical uncertainties only. The boxes indicate the systematic uncertainties. The dashed green line represents the $\gamma^\mathrm{iso}$-hadron correlation function obtained with PYTHIA 8.2 Monash Tune. '$p$' is the p-value for the hypothesis that the pp and p$-$Pb data follow the same true correlation function.

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Dielectron production in proton-proton and proton-lead collisions at $\sqrt{s_{NN}}=$ 5.02 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Rev.C 102 (2020) 055204, 2020.
Inspire Record 1797621 DOI 10.17182/hepdata.98625

The first measurements of dielectron production at midrapidity ($|\eta_{c}|<0.8$) in proton-proton and proton-lead collisions at $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV at the LHC are presented. The dielectron cross section is measured with the ALICE detector as a function of the invariant mass $m_{\rm{ee}}$ and the pair transverse momentum $p_{\rm{T,ee}}$ in the ranges $m_{\rm{ee}}$ < 3.5 GeV/$c^{2}$ and $p_{\rm{T,ee}}$ < 8.0 GeV/$c^{2}$, in both collision systems. In proton-proton collisions, the charm and beauty cross sections are determined at midrapidity from a fit to the data with two different event generators. This complements the existing dielectron measurements performed at $\sqrt{s}$ = 7 and 13 TeV. The slope of the $\sqrt{s}$ dependence of the three measurements is described by FONLL calculations. The dielectron cross section measured in proton-lead collisions is in agreement, within the current precision, with the expected dielectron production without any nuclear matter effects for $\rm{e}^{+}\rm{e}^{-}$ pairs from open heavy-flavor hadron decays. For the first time at LHC energies, the dielectron production in proton-lead and proton-proton collisions are directly compared at the same $\sqrt{s_{\rm{NN}}}$ via the dielectron nuclear modification factor $R_{\rm{pPb}}$. The measurements are compared to model calculations including cold nuclear matter effects, or additional sources of dielectrons from thermal radiation.

9 data tables

Inclusive $e^+e^-$ cross section in pp collisions at $\sqrt{s}$ = 5.02 TeV as a function of $m_{\rm ee}$. Electrons are measured within $|\eta_{\rm e}| < 0.8$ and $p_{\rm T,e} > 0.2$ GeV/$c$.

Inclusive $e^+e^-$ cross section in p-Pb collisions at $\sqrt{s}$ = 5.02 TeV as a function of $m_{\rm ee}$. Electrons are measured within $|\eta_{\rm e}| < 0.8$ and $p_{\rm T,e} > 0.2$ GeV/$c$.

Inclusive $e^+e^-$ cross section in pp collisions at $\sqrt{s}$ = 5.02 TeV as a function of $p_{\rm T,ee}$ for $0.5 < m_{\rm ee} < 1.1$ GeV/$c$. Electrons are measured within $|\eta_{\rm e}| < 0.8$ and $p_{\rm T,e} > 0.2$ GeV/$c$.

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Unveiling the strong interaction among hadrons at the LHC

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Nature 588 (2020) 232-238, 2020.
Inspire Record 1797617 DOI 10.17182/hepdata.100195

One of the big challenges for nuclear physics today is to understand, starting from first principles, the effective interaction between hadrons with different quark content. First successes have been achieved utilizing techniques to 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 hence, high quality measurements exist only for hadrons containing up and down quarks. In this work, we demonstrate that measuring correlations in the momentum space between hadron pairs produced in ultrarelativistic proton-proton collisions at the CERN LHC provides a precise method 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 for the first time how, using precision measurements of p-$\Omega^{-}$ correlations, the effect of the strong interaction for this hadron-hadron pair can be studied and compared with predictions from lattice calculations.

2 data tables

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

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


Transverse-momentum and event-shape dependence of D-meson flow harmonics in Pb–Pb collisions at $\sqrt {s_{NN}}$ = 5.02 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Lett.B 813 (2021) 136054, 2021.
Inspire Record 1797463 DOI 10.17182/hepdata.105256

The elliptic and triangular flow coefficients $v_2$ and $v_3$ of prompt D$^{0}$, D$^{+}$, and D$^{*+}$ mesons were measured at midrapidity ($|y|<0.8$) in Pb-Pb collisions at the centre-of-mass energy per nucleon pair of $\sqrt{s_{NN}} = 5.02$ TeV with the ALICE detector at the LHC. The D mesons were reconstructed via their hadronic decays in the transverse momentum interval $1< p_{\rm T}<36$ GeV/$c$ in central (0-10%) and semi-central (30-50%) collisions. Compared to pions, protons, and J/$\psi$ mesons, the average D-meson $v_{n}$ harmonics are compatible within uncertainties with a mass hierarchy for $p_{\rm T} \lesssim 3$ GeV/$c$, and are similar to those of charged pions for higher $p_{\rm T}$. The coupling of the charm quark to the light quarks in the underlying medium is further investigated with the application of the event-shape engineering (ESE) technique to the D-meson $v_2$ and $p_{\rm T}$-differential yields. The D-meson $v_2$ is correlated with average bulk elliptic flow in both central and semi-central collisions. Within the current precision, the ratios of per-event D-meson yields in the ESE-selected and unbiased samples are found to be compatible with unity. All the measurements are found to be reasonably well described by theoretical calculations including the effects of charm-quark transport and the recombination of charm quarks with light quarks in a hydrodynamically expanding medium.

16 data tables

Average $v_2${SP} vs. $p_\mathrm{T}$ of prompt D$^0$, D$^+$, and D$^{*+}$ mesons in Pb-Pb collisions at $\sqrt{s_\mathrm{NN}}=5.02$ TeV in the centrality class 0-10% in the rapidity interval $|y|<0.8$. The first (sys,data) error is the systematic uncertainty from all the other sources except for the B feed-down. The second (sys,FD) error is the systematic uncertainty from the B feed-down contribution.

Average $v_2${SP} vs. $p_\mathrm{T}$ of prompt D$^0$, D$^+$, and D$^{*+}$ mesons in Pb-Pb collisions at $\sqrt{s_\mathrm{NN}}=5.02$ TeV in the centrality class 30-50% in the rapidity interval $|y|<0.8$. The first (sys,data) error is the systematic uncertainty from all the other sources except for the B feed-down. The second (sys,FD) error is the systematic uncertainty from the B feed-down contribution.

Average $v_3${SP} vs. $p_\mathrm{T}$ of prompt D$^0$, D$^+$, and D$^{*+}$ mesons in Pb-Pb collisions at $\sqrt{s_\mathrm{NN}}=5.02$ TeV in the centrality class 0-10% in the rapidity interval $|y|<0.8$. The first (sys,data) error is the systematic uncertainty from all the other sources except for the B feed-down. The second (sys,FD) error is the systematic uncertainty from the B feed-down contribution.

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First measurement of quarkonium polarization in nuclear collisions at the LHC

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Lett.B 815 (2021) 136146, 2021.
Inspire Record 1797469 DOI 10.17182/hepdata.102403

The polarization of inclusive J/$\psi$ and $\Upsilon(1{\rm S})$ produced in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}=5.02$ TeV at the LHC is measured with the ALICE detector. The study is carried out by reconstructing the quarkonium through its decay to muon pairs in the rapidity region $2.5<y<4$ and measuring the polar and azimuthal angular distributions of the muons. The polarization parameters $\lambda_{\theta}$, $\lambda_{\phi}$ and $\lambda_{\theta\phi}$ are measured in the helicity and Collins-Soper reference frames, in the transverse momentum interval $2<p_{\rm T}<10$ GeV/$c$ and $p_{\rm T}<15$ GeV/$c$ for the J/$\psi$ and $\Upsilon(1{\rm S})$, respectively. The polarization parameters for the J/$\psi$ are found to be compatible with zero, within a maximum of about two standard deviations at low $p_{\rm T}$, for both reference frames and over the whole $p_{\rm T}$ range. The values are compared with the corresponding results obtained for pp collisions at $\sqrt{s}=7$ and 8 TeV in a similar kinematic region by the ALICE and LHCb experiments. Although with much larger uncertainties, the polarization parameters for $\Upsilon(1{\rm S})$ production in Pb-Pb collisions are also consistent with zero.

12 data tables

J/$\psi$ polarization parameters, measured for Pb--Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV, in the helicity and Collins-Soper reference frames in the rapidity interval $2.5<y<4$.The first uncertainty is statistical and the second systematic.

J/$\psi$ polarization parameters, measured for Pb--Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV, in the helicity and Collins-Soper reference frames in the rapidity interval $2.5<y<4$.The first uncertainty is statistical and the second systematic.

J/$\psi$ polarization parameters, measured for Pb--Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV, in the helicity and Collins-Soper reference frames in the rapidity interval $2.5<y<4$.The first uncertainty is statistical and the second systematic.

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

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Lett.B 810 (2020) 135758, 2020.
Inspire Record 1797445 DOI 10.17182/hepdata.96306

Measurements of the inclusive J/$\psi$ yield as a function of charged-particle pseudorapidity density ${\rm d}N_{\rm ch}/\rm{d}\eta$ in pp collisions at $\sqrt{s}$ = 13 TeV with ALICE at the LHC are reported. The J/$\psi$ meson yield is measured at midrapidity ($|y|<0.9$) in the dielectron channel, for events selected based on the charged-particle multiplicity at midrapidity ($|\eta|<1$) and at forward rapidity ($-3.7<\eta<-1.7$ and $2.8<\eta<5.1$); both observables are normalized to their corresponding averages in minimum bias events. The increase of the normalized J/$\psi$ yield with normalized ${\rm d}N_{\rm ch}/\rm{d}\eta$ is significantly stronger than linear and dependent on the transverse momentum. The data are compared to theoretical predictions, which describe the observed trends well, albeit not always quantitatively.

6 data tables

$N_{J/psi}/<N_{J/\psi}> / N_{ch}/<N_{ch}>$, $|y^{J/\psi}|<0.9$, $p_{T}^{J/\psi}$ integrated, event selection SPD

$N_{J/psi}/<N_{J/\psi}> / N_{ch}/<N_{ch}>$, $|y^{J/\psi}|<0.9$, $p_{T}^{J/\psi}$ integrated, event selection V0

$N_{J/psi}/<N_{J/\psi}> / N_{ch}/<N_{ch}>$, $|y^{J/\psi}|<0.9$, $p_{T}^{J/\psi}$ 0-4 and 4-8 GeV/c, event selection SPD

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Elliptic Flow of Electrons from Beauty-Hadron Decays in Pb-Pb Collisions at $\sqrt {s_{NN}}$ = 5.02 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Rev.Lett. 126 (2021) 162001, 2021.
Inspire Record 1797450 DOI 10.17182/hepdata.102642

The elliptic flow of electrons from beauty hadron decays at midrapidity ($|y|$$<$ 0.8) is measured in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV with the ALICE detector at the LHC. The azimuthal distribution of the particles produced in the collisions can be parameterized with a Fourier expansion, in which the second harmonic coefficient represents the elliptic flow, $v_{\rm 2}$. The $v_{\rm 2}$ coefficient of electrons from beauty-hadron decays is measured for the first time in the transverse momentum ($p_{\rm{T}}$) range 1.3-6 GeV/$c$ in the centrality class 30-50%. The measurement of electrons from beauty-hadron decays exploits their larger mean proper decay length $c\tau \approx$ 500 $\mu$m compared to that of charm hadrons and most of the other background sources. The $v_{\rm 2}$ of electrons from beauty hadron decays at midrapidity is found to be positive with a significance of 3.75$\sigma$. The results provide insights on the degree of thermalization of beauty quarks in the medium. A model assuming full thermalization of beauty quarks is strongly disfavoured by the measurement at high $p_{\rm{T}}$, but is in agreement with the results at low $p_{\rm{T}}$. Transport models including substantial interactions of beauty quarks with an expanding strongly-interacting medium describe the measurement.

1 data table

$v_{2}$ of electrons from beauty hadron decays as a function of $p_{\rm T}$ in the centrality range 30-50% for $\sqrt{s_{\rm NN}}=5.02 {\rm~TeV}$


Z-boson production in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=8.16$ TeV and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
JHEP 09 (2020) 076, 2020.
Inspire Record 1797444 DOI 10.17182/hepdata.97372

Measurement of Z-boson production in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=8.16$ TeV and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV is reported. It is performed in the dimuon decay channel, through the detection of muons with pseudorapidity $-4 < \eta_{\mu} < -2.5$ and transverse momentum $p_{\rm T}^{\mu} > 20$ GeV/$c$ in the laboratory frame. The invariant yield and nuclear modification factor are measured for opposite-sign dimuons with invariant mass $60 < m^{\mu\mu} < 120$ GeV$c^2$ and rapidity $2.5 < y_{cms}^{\mu\mu} < 4$. They are presented as a function of rapidity and, for the Pb-Pb collisions, of centrality as well. The results are compared with theoretical calculations, both with and without nuclear modifications to the Parton Distribution Functions (PDFs). In p-Pb collisions the center-of-mass frame is boosted with respect to the laboratory frame, and the measurements cover the backward ($-4.46< y_{cms}^{\mu\mu}<-2.96$) and forward ($2.03< y_{cms}^{\mu\mu}<3.53$) rapidity regions. For the p-Pb collisions, the results are consistent within experimental and theoretical uncertainties with calculations that include both free-nucleon and nuclear-modified PDFs. For the Pb-Pb collisions, a $3.4\sigma$ deviation is seen in the integrated yield between the data and calculations based on the free-nucleon PDFs, while good agreement is found once nuclear modifications are considered.

5 data tables

Differential fiducial cross section in p-Pb

Integrated fiducial invariant yield in Pb-Pb

Rapidity differential fiducial invariant yield in Pb-Pb

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Measurement of the low-energy antideuteron inelastic cross section

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Rev.Lett. 125 (2020) 162001, 2020.
Inspire Record 1797442 DOI 10.17182/hepdata.96844

In this Letter, we report the first measurement of the inelastic cross section for antideuteron-nucleus interactions at low particle momenta, covering a range of $0.3 \leq p < 4$ GeV/$c$. The measurement is carried out using p-Pb collisions at a center-of-mass energy per nucleon-nucleon pair of $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV, recorded with the ALICE detector at the CERN LHC and utilizing the detector material as an absorber for antideuterons and antiprotons. The extracted raw primary antiparticle-to-particle ratios are compared to the results from detailed ALICE simulations based on the GEANT4 toolkit for the propagation of antiparticles through the detector material. The analysis of the raw primary (anti)proton spectra serves as a benchmark for this study, since their hadronic interaction cross sections are well constrained experimentally. The first measurement of the inelastic cross section for antideuteron-nucleus interactions averaged over the ALICE detector material with atomic mass numbers $\langle A \rangle$ = 17.4 and 31.8 is obtained. The measured inelastic cross section points to a possible excess with respect to the Glauber model parameterization used in GEANT4 in the lowest momentum interval of $0.3 \leq p < 0.47$ GeV/$c$ up to a factor 2.1. This result is relevant for the understanding of antimatter propagation and the contributions to antinuclei production from cosmic ray interactions within the interstellar medium. In addition, the momentum range covered by this measurement is of particular importance to evaluate signal predictions for indirect dark-matter searches.

16 data tables

Raw primary antiproton-to-proton ratio as a function of the momentum p_primary.

Raw primary antiproton-to-proton ratio from Geant4-based MC simulations as a function of the momentum p_primary.

Raw primary antideuteron-to-deuteron ratio as a function of the momentum p_primary.

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$\Lambda\rm{K}$ femtoscopy in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 2.76 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Rev.C 103 (2021) 055201, 2021.
Inspire Record 1797451 DOI 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

Invariant mass distributions in the 0--10\% centrality interval of (a) p$\uppi^{-}$ pairs showing the $\Lambda$ peak for V$^{0}$ candidates.

Invariant mass distributions in the 0--10\% centrality interval of $\uppi^{+}\uppi^{-}$ pairs showing the $\mathrm{K^{0}_{S}}$ peak for V$^{0}$ candidates.

Measured correlation function for the $\Lambda\mathrm{K^{+}}\oplus\overline{\Lambda}\mathrm{K^{-}}$ system in the 0--10\% centrality interval.