Energy dependence of coherent photonuclear production of J/$\psi$ mesons in ultra-peripheral Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$=5.02 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
JHEP 10 (2023) 119, 2023.
Inspire Record 2666011 DOI 10.17182/hepdata.144758

The cross section for coherent photonuclear production of J/$\psi$ is presented as a function of the electromagnetic dissociation (EMD) of Pb. The measurement is performed with the ALICE detector in ultra-peripheral Pb-Pb collisions at a centre-of-mass energy per nucleon pair of $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV. Cross sections are presented in five different J/$\psi$ rapidity ranges within $|y|<4$, with the J/$\psi$ reconstructed via its dilepton decay channels. In some events the J/$\psi$ is not accompanied by EMD, while other events do produce neutrons from EMD at beam rapidities either in one or the other beam direction, or in both. The cross sections in a given rapidity range and for different configurations of neutrons from EMD allow for the extraction of the energy dependence of this process in the range $17 < W_{\gamma\, \mathrm{Pb, n}} <920$ GeV, where $W_{\gamma\, \mathrm{Pb, n}}$ is the centre-of-mass energy per nucleon of the $\gamma\,\mathrm{Pb}$ system. This range corresponds to a Bjorken-$x$ interval spanning about three orders of magnitude: $ 1.1\times10^{-5}<x<3.3\times 10^{-2}$. In addition to the ultra-peripheral and photonuclear cross sections, the nuclear suppression factor is obtained. These measurements point to a strong depletion of the gluon distribution in Pb nuclei over a broad, previously unexplored, energy range. These results, together with previous ALICE measurements, provide unprecedented information to probe quantum chromodynamics at high energies.

6 data tables

Measured coherent J/psi cross section for the 0N0N class. Note that for each rapidity range the 0n0n uncertainty related to migrations is preceded by a ∓, while the other neutron classes have a ±; this means that these uncertainties are anti-correlated.

Measured coherent J/psi cross section for the 0NXN+XN0N class. Note that for each rapidity range the 0n0n uncertainty related to migrations is preceded by a ∓, while the other neutron classes have a ±; this means that these uncertainties are anti-correlated.

Measured coherent J/psi cross section for the XN0N forward class. Note that for each rapidity range the 0n0n uncertainty related to migrations is preceded by a ∓, while the other neutron classes have a ±; this means that these uncertainties are anti-correlated.

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Azimuthal correlations of heavy-flavor hadron decay electrons with charged particles in pp and p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Eur.Phys.J.C 83 (2023) 741, 2023.
Inspire Record 2637679 DOI 10.17182/hepdata.141857

The azimuthal ($\Delta\varphi$) correlation distributions between heavy-flavor decay electrons and associated charged particles are measured in pp and p$-$Pb collisions at $\sqrt{s_{\rm{NN}}} = 5.02$ TeV. Results are reported for electrons with transverse momentum $4<p_{\rm T}<16$ GeV/$c$ and pseudorapidity $|\eta|<0.6$. The associated charged particles are selected with transverse momentum $1<p_{\rm T}<7$ GeV/$c$, and relative pseudorapidity separation with the leading electron $|\Delta\eta| < 1$. The correlation measurements are performed to study and characterize the fragmentation and hadronization of heavy quarks. The correlation structures are fitted with a constant and two von Mises functions to obtain the baseline and the near- and away-side peaks, respectively. The results from p$-$Pb collisions are compared with those from pp collisions to study the effects of cold nuclear matter. In the measured trigger electron and associated particle kinematic regions, the two collision systems give consistent results. The $\Delta\varphi$ distribution and the peak observables in pp and p$-$Pb collisions are compared with calculations from various Monte Carlo event generators.

21 data tables

$\Delta\varphi$ distribution between heavy-flavor decay electrons and associated charged particles for $4 < p_{\rm T}^{\rm e} < 12$ ${\rm GeV}/c$ and $1 < p_{\rm T}^{\rm assoc} < 7$ ${\rm GeV}/c$ in pp collisions at $\sqrt{s_{\rm{NN}}} = 5.02$ TeV. The publication shows $\Delta\varphi$ distribution only for the ranges $1 < p_{\rm T}^{\rm assoc} < 2$, $2 < p_{\rm T}^{\rm assoc} < 3$, and $5 < p_{\rm T}^{\rm assoc} < 7$ ${\rm GeV}/c$.

$\Delta\varphi$ distribution between heavy-flavor decay electrons and associated charged particles for $4 < p_{\rm T}^{\rm e} < 12$ ${\rm GeV}/c$ and $1 < p_{\rm T}^{\rm assoc} < 7$ ${\rm GeV}/c$ in p$\textendash$Pb collisions at $\sqrt{s_{\rm{NN}}} = 5.02$ TeV. The publication shows $\Delta\varphi$ distribution only for the ranges $1 < p_{\rm T}^{\rm assoc} < 2$, $2 < p_{\rm T}^{\rm assoc} < 3$, and $5 < p_{\rm T}^{\rm assoc} < 7$ ${\rm GeV}/c$.

Baseline of $\Delta\varphi$ distribution between heavy-flavor decay electrons and associated charged particles for $4 < p_{\rm T}^{\rm e} < 12$ ${\rm GeV}/c$ in pp and p$\textendash$Pb collisions at $\sqrt{s_{\rm{NN}}} = 5.02$ TeV. The publication shows $\Delta\varphi$ distribution only for the ranges $1 < p_{\rm T}^{\rm assoc} < 2$, $2 < p_{\rm T}^{\rm assoc} < 3$, and $5 < p_{\rm T}^{\rm assoc} < 7$ ${\rm GeV}/c$.

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Inclusive photon production at forward rapidities in pp and p$-$Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Eur.Phys.J.C 83 (2023) 661, 2023.
Inspire Record 2637678 DOI 10.17182/hepdata.141495

A study of multiplicity and pseudorapidity distributions of inclusive photons measured in pp and p$-$Pb collisions at a center-of-mass energy per nucleon$-$nucleon collision of $\sqrt{s_{\rm NN}} = 5.02$ TeV using the ALICE detector in the forward pseudorapidity region $2.3 < \eta_{\rm lab} < 3.9$ is presented. Measurements in p$-$Pb collisions are reported for two beam configurations in which the directions of the proton and lead ion beam were reversed. The pseudorapidity distributions in p$-$Pb collisions are obtained for seven centrality classes which are defined based on different event activity estimators, i.e., the charged-particle multiplicity measured at midrapidity as well as the energy deposited in a calorimeter at beam rapidity. The inclusive photon multiplicity distributions for both pp and p$-$Pb collisions are described by double negative binomial distributions. The pseudorapidity distributions of inclusive photons are compared to those of charged particles at midrapidity in \pp collisions and for different centrality classes in p$-$Pb collisions. The results are compared to predictions from various Monte Carlo event generators. None of the generators considered in this paper reproduces the inclusive photon multiplicity distributions in the reported multiplicity range. The pseudorapidity distributions are, however, better described by the same generators.

19 data tables

Inclusive photon multiplicity distribution measured within $2.3<\eta_{\rm lab}<3.9$ in pp collisions at $\sqrt{s} = 5020~\mathrm{GeV}$.

Inclusive photon multiplicity distribution measured within $2.3<\eta_{\rm lab}<3.9$ in p-Pb collisions at $\sqrt{s_\mathrm{NN}} = 5020~\mathrm{GeV}$.

Inclusive photon multiplicity distribution measured within $2.3<\eta_{\rm lab}<3.9$ in Pb-p collisions at $\sqrt{s_\mathrm{NN}} = 5020~\mathrm{GeV}$.

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Measurement of the non-prompt D-meson fraction as a function of multiplicity in proton$-$proton collisions at $\sqrt{s} = 13$ TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
JHEP 10 (2023) 092, 2023.
Inspire Record 2632796 DOI 10.17182/hepdata.141166

The fractions of non-prompt (i.e. originating from beauty-hadron decays) D$^0$ and D$^+$ mesons with respect to the inclusive yield are measured as a function of the charged-particle multiplicity in proton$-$proton collisions at a centre-of-mass energy of $\sqrt{s} = 13$ TeV with the ALICE detector at the LHC. The results are reported in intervals of transverse momentum ($p_{\rm T}$) and integrated in the range $1 < p_{\rm T} < 24$ GeV/$c$. The fraction of non-prompt D$^0$ and D$^+$ mesons is found to increase slightly as a function of $p_{\rm T}$ in all the measured multiplicity intervals, while no significant dependence on the charged-particle multiplicity is observed. In order to investigate the production and hadronisation mechanisms of charm and beauty quarks, the results are compared to PYTHIA 8 as well as EPOS 3 and EPOS 4 Monte Carlo simulations, and to calculations based on the colour glass condensate including three-pomeron fusion.

4 data tables
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Symmetry plane correlations in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$TeV

The ALICE collaboration Acharya, S. ; Adamová, D. ; Adler, A. ; et al.
Eur.Phys.J.C 83 (2023) 576, 2023.
Inspire Record 2628969 DOI 10.17182/hepdata.141027

A newly developed observable for correlations between symmetry planes, which characterize the direction of the anisotropic emission of produced particles, is measured in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV with ALICE. This so-called Gaussian Estimator allows for the first time the study of these quantities without the influence of correlations between different flow amplitudes. The centrality dependence of various correlations between two, three and four symmetry planes is presented. The ordering of magnitude between these symmetry plane correlations is discussed and the results of the Gaussian Estimator are compared with measurements of previously used estimators. The results utilizing the new estimator lead to significantly smaller correlations than reported by studies using the Scalar Product method. Furthermore, the obtained symmetry plane correlations are compared to state-of-the-art hydrodynamic model calculations for the evolution of heavy-ion collisions. While the model predictions provide a qualitative description of the data, quantitative agreement is not always observed, particularly for correlators with significant non-linear response of the medium to initial state anisotropies of the collision system. As these results provide unique and independent information, their usage in future Bayesian analysis can further constrain our knowledge on the properties of the QCD matter produced in ultrarelativistic heavy-ion collisions.

9 data tables

Centrality dependence of $\langle \cos[4(\Psi_{4}-\Psi_{2})]\rangle_{\mathrm{GE}}$ in Pb--Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV.

Centrality dependence of $\langle \cos[6(\Psi_{6}-\Psi_{3})]\rangle_{\mathrm{GE}}$ in Pb--Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV.

Centrality dependence of $\langle \cos[6(\Psi_{2}-\Psi_{3})]\rangle_{\mathrm{GE}}$ in Pb--Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV.

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Production of pions, kaons and protons as a function of the transverse event activity in pp collisions at $\sqrt{s}=13$ TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
JHEP 06 (2023) 027, 2023.
Inspire Record 2626034 DOI 10.17182/hepdata.140124

The production of $\pi^\pm$, ${\rm K}^\pm$, and $(\overline{\rm p})$p is measured in pp collisions at $\sqrt{s}=13$ TeV in different topological regions. Particle transverse momentum ($p_{\rm T}$) spectra are measured in the ``toward'', ``transverse'', and ``away'' angular regions defined with respect to the direction of the leading particle in the event. While the toward and away regions contain the fragmentation products of the near-side and away-side jets, respectively, the transverse region is dominated by particles from the Underlying Event (UE). The relative transverse activity classifier, $R_{\rm T}=N_{\rm T}/\langle N_{\rm T}\rangle$, is used to group events according to their UE activity, where $N_{\rm T}$ is the measured charged-particle multiplicity per event in the transverse region and $\langle N_{\rm T}\rangle$ is the mean value over all the analysed events. The first measurements of identified particle $p_{\rm T}$ spectra as a function of $R_{\rm T}$ in the three topological regions are reported. The yield of high transverse momentum particles relative to the $R_{\rm T}$-integrated measurement decreases with increasing $R_{\rm T}$ in both the toward and away regions, indicating that the softer UE dominates particle production as $R_{\rm T}$ increases and validating that $R_{\rm T}$ can be used to control the magnitude of the UE. Conversely, the spectral shapes in the transverse region harden significantly with increasing $R_{\rm T}$. This hardening follows a mass ordering, being more significant for heavier particles. The $p_{\rm T}$-differential particle ratios $({\rm p+\overline{p}})/(\pi^+ +\pi^-)$ and $({\rm K^+ +K^-})/(\pi^+ +\pi^-)$ in the low UE limit $(R_{\rm T}\rightarrow 0)$ approach expectations from Monte Carlo generators such as PYTHIA 8 with Monash 2013 tune and EPOS LHC, where the jet-fragmentation models have been tuned to reproduce ${\rm e^+ e^-}$ results.

128 data tables

$N_{\mathrm{T}}$ probability distribution in the transverse region using events with leading particles $(p_{\mathrm{T}}^{\mathrm{leading}} \geq 5~\mathrm{GeV}/c)$ in the pseudorapidity interval $|\eta|<0.8$ in pp collisions at $\sqrt{s} = 13~\mathrm{TeV}$.

$R_{\mathrm{T}}$ probability distribution in the transverse region using events with leading particles $(p_{\mathrm{T}}^{\mathrm{leading}} \geq 5~\mathrm{GeV}/c)$ in the pseudorapidity interval $|\eta|<0.8$ in pp collisions at $\sqrt{s} = 13~\mathrm{TeV}$.

$\pi^{+}+\pi^{-}$ transverse momentum spectrum for events with $0 \leq R_{\mathrm{T}} < 5$ in the Toward region in pp collisions at $\sqrt{s} = 13~\mathrm{TeV}$.

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Version 2
Enhanced deuteron coalescence probability in jets

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Rev.Lett. 131 (2023) 042301, 2023.
Inspire Record 2601274 DOI 10.17182/hepdata.141173

The transverse-momentum ($p_{\rm T}$) spectra and coalescence parameters $B_2$ of (anti)deuterons are measured in pp collisions at $\sqrt{s} = 13$ TeV for the first time in and out of jets. In this measurement, the direction of the leading particle with the highest $p_{\rm T}$ in the event ($p_{\rm T}^{\rm{ lead}} > 5$ GeV/$c$) is used as an approximation for the jet axis. The event is consequently divided into three azimuthal regions and the jet signal is obtained as the difference between the Toward region, that contains jet fragmentation products in addition to the underlying event (UE), and the Transverse region, which is dominated by the UE. The coalescence parameter in the jet is found to be approximately a factor of 10 larger than that in the underlying event. This experimental observation is consistent with the coalescence picture and can be attributed to the smaller average phase-space distance between nucleons inside the jet cone as compared to the underlying event. The results presented in this Letter are compared to predictions from a simple nucleon coalescence model, where the phase space distributions of nucleons are generated using PYTHIA 8 with the Monash 2013 tuning, and to predictions from a deuteron production model based on ordinary nuclear reactions with parametrized energy-dependent cross sections tuned on data. The latter model is implemented in PYTHIA 8.3. Both models reproduce the observed large difference between in-jet and out-of-jet coalescence parameters, although the almost flat trend of the $B^{\rm Jet}_2$ is not reproduced by the models, which instead give a decreasing trend.

6 data tables

Transverse momentum spectra for the transverse azimuthal regions. Events with a leading track with PT>5 GEV at midrapidity are selected. The spectrum is shown in Figure 1 (left panel).

Transverse momentum spectra for the toward azimuthal regions. Events with a leading track with PT>5 GEV at midrapidity are selected. The spectrum is shown in Figure 1 (left panel).

Transverse momentum spectra for the away azimuthal regions. Events with a leading track with PT>5 GEV at midrapidity are selected. The spectrum is shown in Figure 1 (left panel).

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J/$\psi$ production at midrapidity in p$-$Pb collisions at $\sqrt{s_{\rm NN}} = 8.16$ TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
JHEP 07 (2023) 137, 2023.
Inspire Record 2593303 DOI 10.17182/hepdata.138403

The production of inclusive, prompt and non-prompt J/$\psi$ was studied for the first time at midrapidity ($ -1.37 < y_{\rm cms} < 0.43$) in p$-$Pb collisions at $\sqrt{s_{\rm NN}} = 8.16$ TeV with the ALICE detector at the LHC. The inclusive J/$\psi$ mesons were reconstructed in the dielectron decay channel in the transverse momentum ($p_{\rm T}$) interval $0 < p_{\rm T} < 14$ GeV/$c$ and the prompt and non-prompt contributions were separated on a statistical basis for $p_{\rm T} > 2$ GeV/$c$. The study of the J/$\psi$ mesons in the dielectron channel used for the first time in ALICE online single-electron triggers from the Transition Radiation Detector, providing a data sample corresponding to an integrated luminosity of $689 \pm 13 \mu{\rm b}^{-1}$. The proton$-$proton reference cross section for inclusive J/$\psi$ was obtained based on interpolations of measured data at different centre-of-mass energies and a universal function describing the $p_{\rm T}$-differential J/$\psi$ production cross sections. The $p_{\rm T}$-differential nuclear modification factors $R_{\rm pPb}$ of inclusive, prompt, and non-prompt J/$\psi$ are consistent with unity and described by theoretical models implementing only nuclear shadowing.

8 data tables

d$^2\sigma$/d$y$d$p_{\rm T}$ in bins of $p_{\mathrm{T}}^{J/\psi}$ for inclusive J/$\psi$ in p--Pb collisions at $\sqrt{s_{NN}}$ = 8.16 TeV.

Nuclear modification factor ($R_{pPb}$) of inclusive J/$\psi$ in p--Pb collisions at $\sqrt{s_{NN}}$ = 8.16 TeV at midrapidity.

$p_\mathrm{T}$ integrated nuclear modification factor ($R_{pPb}$) of inclusive J/$\psi$ in p--Pb collisions at $\sqrt{s_{NN}}$ = 8.16 TeV at midrapidity.

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Light (anti)nuclei production 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 107 (2023) 064904, 2023.
Inspire Record 2667337 DOI 10.17182/hepdata.141376

The measurement of the production of deuterons, tritons and $^{3}\mathrm{He}$ and their antiparticles in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV is presented in this article. The measurements are carried out at midrapidity ($|y| < $ 0.5) as a function of collision centrality using the ALICE detector. The $p_{\rm T}$-integrated yields, the coalescence parameters and the ratios to protons and antiprotons are reported and compared with nucleosynthesis models. The comparison of these results in different collision systems at different centre-of-mass collision energies reveals a suppression of nucleus production in small systems. In the Statistical Hadronisation Model framework, this can be explained by a small correlation volume where the baryon number is conserved, as already shown in previous fluctuation analyses. However, a different size of the correlation volume is required to describe the proton yields in the same data sets. The coalescence model can describe this suppression by the fact that the wave functions of the nuclei are large and the fireball size starts to become comparable and even much smaller than the actual nucleus at low multiplicities.

75 data tables

Deuteron spectrum in 0-5% V0M centrality class

Antideuteron spectrum in 0-5% V0M centrality class

Deuteron spectrum in 5-10% V0M centrality class

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Two-particle transverse momentum correlations in pp and p-Pb collisions at LHC energies

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Rev.C 107 (2023) 054617, 2023.
Inspire Record 2182733 DOI 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

Two-particle transverse momentum correlation $G_{2}^{\rm CD}$ for 0$-$5% multiplicity class pp collisions at $\sqrt{s}=7\;\text{TeV}$.

Two-particle transverse momentum correlation $G_{2}^{\rm CD}$ for 30$-$40% multiplicity class pp collisions at $\sqrt{s}=7\;\text{TeV}$.

Two-particle transverse momentum correlation $G_{2}^{\rm CD}$ for 70$-$80% multiplicity class pp collisions at $\sqrt{s}=7\;\text{TeV}$.

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