EEUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH
CERN-EP-2020-02503 March 2020© 2020 CERN for the benefit of the ALICE Collaboration.Reproduction of this article or parts of it is allowed as specified in the CC-BY-4.0 license. (Anti-)Deuteron production in pp collisions at √ s = TeV
ALICE Collaboration * Abstract
The study of (anti-)deuteron production in pp collisions has proven to be a powerful tool to investigatethe formation mechanism of loosely bound states in high energy hadronic collisions. In this paperthe production of (anti-)deuterons is studied as a function of the charged particle multiplicity ininelastic pp collisions at √ s =
13 TeV using the ALICE experiment. Thanks to the large numberof accumulated minimum bias events, it has been possible to measure (anti-)deuteron productionin pp collisions up to the same charged particle multiplicity (d N ch / d η ∼
26) as measured in p–Pb collisions at similar centre-of-mass energies. Within the uncertainties, the deuteron yield in ppcollisions resembles the one in p–Pb interactions, suggesting a common formation mechanism behindthe production of light nuclei in hadronic interactions. In this context the measurements are comparedwith the expectations of coalescence and Statistical Hadronisation Models (SHM). * See Appendix A for the list of collaboration members a r X i v : . [ nu c l - e x ] F e b Anti-)Deuteron production in pp collisions at √ s =
13 TeV ALICE Collaboration
High energy collisions at the Large Hadron Collider (LHC) create a suitable environment for the pro-duction of light (anti-)nuclei. In ultra-relativistic heavy-ion collisions light (anti-)nuclei are abundantlyproduced [1–3], but in elementary pp collisions their production is lower [1, 4–6]. As a consequence,there are only few detailed measurements of (anti-)nuclei production rate in pp collisions. However, withthe recently collected large data sample it is now possible to perform more differential measurements oflight (anti-)nuclei production as a function of multiplicity and transverse momentum. In this paper, wepresent the detailed study of the multiplicity dependence of (anti-)deuteron production in pp collisionsat √ s =
13 TeV, the highest collision energy so far delivered at the LHC.The production mechanism of light (anti-)nuclei in high energy hadronic collisions is not completelyunderstood. However, two groups of models have turned out to be particularly useful, namely StatisticalHadronisation Models (SHM) and coalescence models. The SHMs, which assume particle production ac-cording to the thermal equilibrium expectation, have been very successful in explaining the yields of light(anti-)nuclei along with other hadrons in Pb–Pb collisions [7], suggesting a common chemical freeze-outtemperature for light (anti-)nuclei and other hadron species. The ratio between the p T -integrated yieldsof deuterons and protons (d/p ratio) in Pb–Pb collisions remains constant as a function of centrality, butrises in pp and p–Pb collisions with increasing multiplicity, finally reaching the value observed in Pb–Pb[1, 8, 9]. The constant d/p ratio in Pb–Pb collisions as a function of centrality is consistent with ther-mal production, suggesting that the chemical freeze-out temperature in Pb–Pb collisions does not varywith centrality [10]. Assuming thermal production in pp collisions as well, the lower d/p ratio wouldindicate a lower freeze-out temperature [10]. On the other hand, the ratio between the p T -integratedyields of protons and pions (p/ π ratio) does not show a significant difference between pp and Pb–Pbcollisions [11, 12]. Also, for p–Pb collisions the freeze-out temperature obtained with SHMs using onlylight-flavoured particles is constant with multiplicity and its value is similar to that obtained in Pb–Pbcollisions [13]. Thus, the increase of the d/p ratio with multiplicity for smaller systems cannot be ex-plained within the scope of the grand-canonical SHM as is done in case of Pb–Pb. It is also not consistentwith a simple SHM that the d/p and p/ π ratios behave differently as a function of multiplicity even thoughnumerator and denominator differ in both cases by one unit of baryon number. Nonetheless, a processsimilar to the canonical suppression of strange particles might be worth considering also for baryons. Arecent calculation within the SHM approach with exact conservation of baryon number, electric charge,and strangeness focuses on this aspect [14].In coalescence models (anti-)nuclei are formed by nucleons close in phase-space [15]. In this approach,the coalescence parameter B quantitatively describes the production of (anti-)deuterons. B is definedas B (cid:0) p p T (cid:1) = E d d N d d p d (cid:30) (cid:32) E p d N p d p p (cid:33) = π p d T d N d d y d p d T (cid:30) (cid:18) π p p T d N p d y d p p T (cid:19) , (1)where E is the energy, p is the momentum, p T is the transverse momentum and y is the rapidity. Thelabels p and d are used to denote properties related to protons and deuterons, respectively. The invariantspectra of the (anti-)protons are evaluated at half of the transverse momentum of the deuterons, so that p p T = p d T /
2. Neutron spectra are assumed to be equivalent to proton spectra, since neutrons and protonsbelong to the same isospin doublet. Since the coalescence process is expected to occur at the late stage ofthe collision, the parameter B is related to the emission volume. In a simple coalescence approach, whichdescribes the uncorrelated particle emission from a point-like source, B is expected to be independentof p T and multiplicity. However, it has been observed that B at a given transverse momentum decreasesas a function of multiplicity, suggesting that the nuclear emission volume increases with multiplicity[2, 9, 16]. In Pb–Pb collisions the B parameter as a function of p T shows an increasing trend, whichis usually attributed to the position-momentum correlations caused by radial flow or hard scatterings[17, 18]. Such an increase of B as a function of p T has in fact also been observed in pp collisions2Anti-)Deuteron production in pp collisions at √ s =
13 TeV ALICE Collaborationat √ s = B isfound to be almost constant as a function of p T [8]. Similarly, B does not depend on p T in multiplicityselected p–Pb collisions [9]. Moreover, the highest multiplicities reached in pp collisions are comparablewith those obtained in p–Pb collisions and not too far from peripheral Pb–Pb collisions. Therefore, themeasure of B as a function of p T for finer multiplicity intervals in pp collisions at √ s =
13 TeV gives theopportunity to compare different collision systems and to evaluate the dependence on the system size.The paper is organized as follows. Section 2 discusses the details of the ALICE detector. Section 3describes the data sample used for the analysis and the corresponding event and track selection criteria.Section 4 presents the data analysis steps in detail, such as raw yield extraction and various corrections,as well as the systematic uncertainty estimation. In Section 5, the results are presented and discussed.Finally, conclusions are given in Section 6.
A detailed description of the ALICE detectors can be found in [19] and references therein. For the presentanalysis the main sub-detectors used are the V0, the Inner Tracking System (ITS), the Time ProjectionChamber (TPC) and the Time-of-Flight (TOF), which are all located inside a 0.5 T solenoidal magneticfield.The V0 detector [20] is formed by two arrays of scintillation counters placed around the beampipe oneither side of the interaction point: one covering the pseudorapidity range 2 . < η < . − . < η < − . | η | < . /N gas mixture (Ar/CO /N in 2016), at atmospheric pressure, has an inner radius of about85 cm, an outer radius of about 250 cm, and an overall length along the beam direction of 500 cm. Thegas is ionised by charged particles traversing the detector and the ionisation electrons drift, under the in-fluence of a constant electric field of ∼
400 V/cm, towards the endplates, where their position and arrivaltime are measured. The trajectory of a charged particle is estimated using up to 159 combined measure-ments (clusters) of drift times and radial positions of the ionisation electrons. The charged-particle tracksare then formed by combining the hits in the ITS and the reconstructed clusters in the TPC. The TPC isused for particle identification by measuring the specific energy loss (d E / d x ) in the TPC gas.The TOF system [23] covers the full azimuth for the pseudorapidity interval | η | < .
9. The detector isbased on the Multi-gap Resistive Plate Chambers (MRPCs) technology and it is located, with a cylindri-cal symmetry, at an average distance of 380 cm from the beam axis. The particle identification is basedon the difference between the measured time-of-flight and its expected value, computed for each masshypothesis from track momentum and length. The overall resolution on the time-of-flight of particles isabout 80 ps.A precise starting signal for the TOF system can be also provided by the T0 detector, consisting of two3Anti-)Deuteron production in pp collisions at √ s =
13 TeV ALICE Collaborationarrays of Cherenkov counters, T0A and T0C, which cover the pseudorapidity regions 4 . < η < . . < η < .
97, respectively [24]. Alternatively, the start time can be provided by the TOF itself orthe bunch-crossing time can be used, as described in [24].
The data samples used in this work consist of approximately 950 million minimum bias pp events col-lected during the LHC proton runs in 2016 and 2017. The data were collected using a minimum-biastrigger requiring at least one hit in both the V0 detectors. Moreover, the timing information of the V0scintillators is used for the offline rejection of events triggered by interactions of the beam with the resid-ual gas in the LHC vacuum pipe. To ensure the best possible performance of the detector, events withmore than one reconstructed primary interaction vertex (pile-up events) were rejected.The production of primary (anti-)deuterons is measured around mid-rapidity. In particular, the spectra areprovided within a rapidity window of | y | < .
5. To ensure that all tracks have the maximal length, onlythose in the pseudorapidity interval | η | < . E / d x resolution in the relevant p T ranges, the selected tracks are required to have at least 70reconstructed points in the TPC and two points in the ITS. In addition, at least one of the ITS points hasto be measured by the SPD in order to assure for the selected tracks a resolution better than 300 µ m onthe distance of closest approach to the primary vertex in the plane perpendicular (DCA xy ) and parallel(DCA z ) to the beam axis [19]. Furthermore, it is required that the χ per TPC reconstructed point is lessthan 4 and tracks originating from kink topologies of weak decays are rejected.Data are divided into ten multiplicity classes, identified by a roman number from I to X, going from thehighest to the lowest multiplicity. However, in this analysis classes IV and V are merged into a singleclass to achieve a better statistical precision. The multiplicity classes are determined from the sum ofthe V0 signal amplitudes and defined in terms of percentiles of the INEL > > | η | < (cid:104) d N ch / d η (cid:105) for each class is reported in Table 2. The identification of (anti-)deuterons is performed with two different methods, depending on their trans-verse momentum. For p T < c , the identification is done using a measurement of the d E / d x inthe TPC only. In particular, for each p T interval the number of (anti-)deuterons is extracted through a fitwith a Gaussian with two exponential tails to the n σ distribution. Here, n σ is the difference between themeasured TPC d E / d x and the expected one for (anti-)deuterons divided by the TPC d E / d x resolution.However, for p T ≥ c it is more difficult to separate (anti-)deuterons from other charged particleswith this technique. Therefore, the particle identification in this kinematic region is performed using theTOF detector. The squared mass of the particle is computed as m = p (cid:0) t / L − / c (cid:1) , where t TOF isthe measured time-of-flight, L is the length of the track and p is the momentum of the particle. In orderto reduce the background, only the candidates with a d E /d x measured in the TPC compatible within3 σ with the expected value for a (anti-)deuteron are selected. The squared-mass-distributions are fittedwith a Gaussian function with an exponential tail for the signal. A significant background is present for p T ≥ c and is modelled with two exponential functions. In the range where the background isnegligible, the raw yield is extracted by directly counting the candidates. Otherwise, the squared-massdistribution is fitted with the described model, using an extended-maximum-likelihood approach. The(anti-)deuteron yield is then obtained by a fit parameter.4Anti-)Deuteron production in pp collisions at √ s =
13 TeV ALICE Collaboration
A correction for the tracking efficiency and the detector acceptance must be applied to obtain the realyield. The correction is evaluated from Monte Carlo (MC) simulated events. The events are generatedusing the standard generator PYTHIA8 (Monash 2013)[26]. However, PYTHIA8 does not handle theproduction of nuclei. Therefore, in each event it is necessary to inject (anti-)deuterons. In each pp col-lision one deuteron or one anti-deuteron is injected, randomly chosen from a flat rapidity distribution inthe range | y | < p T distribution in the range p T ∈ [ , ] GeV/ c . The correction is definedas the ratio between the number of reconstructed (anti-)deuterons in the rapidity range | y | < . | η | < . | y | < .
5. The correction iscomputed separately for deuterons and anti-deuterons and for the TPC and TOF analyses.Another correction is related to the trigger efficiency. All the selected events are required to have at leastone charged particle in the acceptance, i.e. in the pseudo-rapidity region | η | < >
0) [25]. Due tothe imperfection of the trigger, some INEL > ∼
12% for multiplicity class X and < p T regionwhere both the techniques can be used. Secondary deuterons are produced in the interaction of particles with the detector material and theircontribution must be subtracted from the total measured deuteron yield. However, the production ofsecondary anti-deuterons is extremely rare due to baryon number conservation. Hence, the correctionis applied only to the deuteron spectra. The fraction of primary deuterons is evaluated via a fit to theDCA xy distribution of the data, as described in [1]. The template for primary deuterons is obtainedfrom the measured DCA xy of anti-deuterons. The template from secondary deuterons is instead obtainedfrom MC simulations. The production of secondary deuterons is more relevant at low p T (at p T = c the fraction of secondary deuterons is ∼ <
5% for p T = c ). The only other possible contribution to secondary deuteronsthat is known is the decay Λ H → d + p + π . However, Λ H production has not yet been observed in ppcollisions and its production yield is therefore lower than that of He, which is less than a thousandth ofthe deuteron production rate [6]. 5Anti-)Deuteron production in pp collisions at √ s =
13 TeV ALICE Collaboration
A list of all the sources of systematic uncertainty is shown in Table 1. The values are reported for themultiplicity classes I and X, for the lowest and highest p T values.The track selection criteria are a source of systematic uncertainty. In this category we include all thecontributions related to the single-track selection: DCA, number of clusters in the TPC and, for theTOF analysis, the width of the d E / d x selection applied in the TPC. These uncertainties are evaluatedby varying the relevant selections, as done in [8]. At low p T ( p T < c ) the contribution is 2%for deuterons due to the DCA z and DCA xy selections, which influence the estimation of the fraction ofprimary deuterons, while for anti-deuterons this systematic uncertainty is around 1%. It increases with p T and the growth is more pronounced for low multiplicity. The systematic uncertainty on the signalextraction is evaluated by directly counting the (anti-)deuteron candidates. It is obtained by varying theinterval in which the direct counting is performed. Its contribution is ∼
1% at low p T and increases with p T . Another source of systematic uncertainty is given by the incomplete knowledge of the material bud-get of the detector in the Monte Carlo simulations. The effect is evaluated by comparing different MCsimulations in which the material budget was increased and decreased by 4.5%. This value correspondsto the uncertainty on the determination of the material budget by measuring photon conversions. Thisparticular systematic uncertainty is below 1%. The imperfect knowledge of the hadronic interaction crosssection of (anti-)deuterons with the material contributes to the systematic uncertainty as well. Its effectis evaluated with the same data-driven approach used to investigate the TOF-matching efficiency, as de-scribed in section 4.2. Half of the correction, corresponding to the 1 σ confidence interval, is taken asits uncertainty contributing 4% to the systematic uncertainty for deuterons and 7.5% for anti-deuterons.Similarly, an uncertainty related to the ITS-TPC matching is considered. It is evaluated from the differ-ence between the ITS-TPC matching efficiencies in data and MC and its contribution is less than 2.5%.Finally, a source of systematic uncertainties results from the signal loss correction. It is assumed to behalf of the difference between the signal-loss correction (described in section 4.2) and 1. It is stronglydependent on the event multiplicity: it is negligible at high multiplicity (multiplicity classes from I toVII) and contributes up to 6% in the lowest multiplicity class (class X). Where present, it decreases with p T . Table 1:
Summary of the main contributions to the systematic uncertainties for the extreme multiplicity classesI and X. Values in brackets are referred to anti-deuterons. If they are not present, the systematic uncertainty iscommon for deuterons and anti-deuterons. More details about the sources of the uncertainties can be found in thetext.
Source d (¯d)Multiplicity Class I Class X p T (GeV/ c ) 0.7 3.8 0.7 2.6Track selection 2% (1%) 2% (3%) 2% (1%) 5% (6%)Signal extraction 1% 7% (7%) 1% 5% (5%)Material budget < < < < √ s =
13 TeV ALICE Collaboration ) c (GeV/ T p - - - - - -
10 1 - ) c ( G e V / y d T p d N d e v N = 13 TeV s deuterons, pp, = 26.02 æh / d ch N d Æ = 2.55 æh / d ch N d Æ V0M Multiplicity Classes) · I ( ) · II () · III ( ) · IV + V () · VI ( ) · VII () · VIII ( ) · IX () · X ( ) · INEL > 0 (Individual fit ) c (GeV/ T p - - - - - -
10 1 - ) c ( G e V / y d T p d N d e v N = 13 TeV s anti-deuterons, pp, = 26.02 æh / d ch N d Æ = 2.55 æh / d ch N d Æ V0M Multiplicity Classes) · I ( ) · II () · III ( ) · IV + V () · VI ( ) · VII () · VIII ( ) · IX () · X ( ) · INEL > 0 (Individual fit
Figure 1:
Transverse-momentum spectra of deuterons (top) and anti-deuterons (bottom) measured in pp collisionsat √ s =
13 TeV in different multiplicity classes (circles) and in INEL > The transverse momentum spectra of deuterons and anti-deuterons in different multiplicity classes aswell as INEL > (cid:104) d N ch / d η (cid:105) for each class is reported in Table 2. The spectra exhibit a slight hardening with increasingmultiplicity: the slope of the spectra becomes less steep and the mean transverse momentum (cid:104) p T (cid:105) movestowards higher values. This effect is similar to that observed in Pb–Pb collisions, where it is explainedwith the presence of increasing radial flow with centrality [1, 28]. However, in pp collisions the intensity7Anti-)Deuteron production in pp collisions at √ s =
13 TeV ALICE Collaboration
Table 2:
Summary of the relevant information about the multiplicity classes and the fits to the measured trans-verse momentum spectra of anti-deuterons. (cid:104) d N ch / d η (cid:105) is the mean pseudorapidity density of the primary chargedparticles [25]. n and C are the parameters of the Lévy-Tsallis fit function [27]. d N / d y is the integrated yield, withstatistical uncertainties, multiplicity-uncorrelated and multiplicity-correlated systematic uncertainties (see the textfor details). (cid:104) p T (cid:105) is the mean transverse momentum. Multiplicity (cid:104) d N ch / d η (cid:105) n C (GeV) d N / d y (cid:0) × − (cid:1) (cid:104) p T (cid:105) (GeV/ c )classI 26.02 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
0. 3 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
13 0.23 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± of the hardening is not as dramatic. The ratio between the spectra of anti-deuterons and deuterons for allthe multiplicity classes under study is reported in Figure 2. The ratio is compatible within uncertaintieswith unity in all multiplicity classes.To calculate the integrated yield (d N / d y ) and the mean p T the spectra have been fitted with the Lévy-Tsallis function [27, 29, 30]:d N d y d p T = d N d y p T ( n − ) ( n − ) nC [ nC + m ( n − )] (cid:18) + m T − mnC (cid:19) − n , (2)where m is the particle rest mass (i.e. the mass of the deuteron), m T = (cid:113) m + p is the transverse mass,while n , d N / d y and C are free fit parameters. The Lévy-Tsallis function is used to extrapolate the spectrain the unmeasured regions of p T . One contribution to the systematic uncertainty is obtained by shiftingthe data points to the upper border of their systematic uncertainty and to the corresponding lower border.The difference between these values and the reference one is taken as an uncertainty which amounts to ∼ p T and m T , as well as a Boltzmann function, and is found tobe ∼ p T range is measured, and increases up to35% in the lowest multiplicity class.The statistical uncertainty on the integrated yield is obtained by moving the data points randomly withintheir statistical uncertainties, using a Gaussian probability distribution centered at the measured datapoint, with a standard deviation corresponding to the statistical uncertainty. In the unmeasured regionsat low and high p T , the value of the fit function at a given p T is considered. In this case the statisticaluncertainty is estimated using a Monte Carlo method to propagate the uncertainties on the fit parameters.Following the same procedure, the (cid:104) p T (cid:105) and its statistical and systematic uncertainties are computed.The resulting mean p T and d N / d y , as well as the parameters of the individual Lévy-Tsallis fits, are listedin Table 2.The coalescence parameter as a function of the transverse momentum is shown in Figure 3. The trans-verse momentum spectra needed for the B computation are taken from Ref. [31]. The B values forINEL > √ s =
13 TeV ALICE Collaboration / dd I r { d } / d = 13 TeV s pp, IV + V r { d } / d V0M Multiplicity ClassesVIII / dd II r { d } / d VI r { d } / d IX / dd III ) c (GeV/ T p r { d } / d VII r { d } / d X Figure 2:
Ratio between the transverse momentum spectra of anti-deuterons and deuterons in different multi-plicity classes. The statistical uncertainties are represented by vertical bars while the systematic uncertainties arerepresented by boxes. shown [8] that the the multiplicity-integrated coalescence parameter is distorted because deuterons arebiased more towards higher multiplicity than protons, and consequently have harder p T spectra thanexpected from inclusive protons. The coalescence parameter evaluated in fine multiplicity classes isconsistent with a flat behaviour, in agreement with the expectation of the simple coalescence model.The evolution of the coalescence parameter as a function of the charged particle multiplicity is sensitiveto the production mechanism of deuterons. Recent formulations of the coalescence model [32, 33] im-plement an interplay between the size of the collision system and the size of the light nuclei producedvia coalescence.Figure 4 shows how the B , for a fixed transverse momentum interval, evolves in different systems as afunction of the charged particle multiplicity. B is shown at p T = .
75 GeV / c , which was measured inall the analyses. However, the trend is the same for other p T values. The measurements are comparedwith the model descriptions detailed in [33]. The two descriptions use different parameterisations forthe size of the source. Parameterisation A uses the ALICE measurements of system radii R from HBTstudies as a function of multiplicity[34]. These values are fitted with the function: R = a (cid:104) d N / d η (cid:105) / + b , (3)where a and b are free parameters. In Parameterisation B the free parameters a and b in Eq. 3 are fixedto reproduce the B of deuterons in Pb–Pb collisions at √ s NN = .
76 TeV in the centrality class 0–10%.The first parameterisation (dashed red line) describes well the measured B in pp and p–Pb collisions,while it overestimates the measurements in Pb–Pb collisions. However, as outlined by the authors in[33], a more refined parameterisation of the HBT radius evolution through different systems might re-duce the observed discrepancy. The parameterisation of the source size fixed to the B measurement incentral Pb–Pb collisions already departs from the measurements in peripheral Pb–Pb collisions and itunderestimates the coalescence parameter for small colliding systems.Figure 5 shows the ratio of the p T -integrated yields of deuterons and protons for different multiplic-9Anti-)Deuteron production in pp collisions at √ s =
13 TeV ALICE Collaboration ) c (GeV/ A / T p - - -
10 110 ) c / ( G e V B = 13 TeV s anti-deuterons, pp, = 26.02 æh / d ch N d Æ = 2.55 æh / d ch N d Æ V0M Multiplicity Classes 1) · I ( 2) · II ( 4) · III ( 8) · IV + V ( 16) · VI ( 32) · VII ( 64) · VIII ( 128) · IX ( 256) · X ( 512) · INEL > 0 (
Figure 3:
Coalescence parameter B for anti-deuterons for different multiplicity classes (circles) and for INEL > B is shown as a function of p T / A , being A = ities in different collisions systems and at different energies. The ratio increases monotonically withmultiplicity for pp and p–Pb collisions and eventually saturates for Pb–Pb collisions. The experimentaldata are compared with a SHM prediction. In this implementation of the model, called the CanonicalStatistical Model (CSM), exact conservation of baryon number ( B ), charge ( Q ), and strangeness ( S ) isenforced using the recently developed THERMAL-FIST package [14]. The calculations with the CSMare performed using 155 MeV for the chemical freeze-out temperature, B = Q = S = 0 and two differentvalues of the correlation volume, which is expressed in terms of rapidity units d V / d y , correspondingto one and three units of rapidity, respectively. The model qualitatively reproduces the trend observedin data. This might suggest that for small collision systems the light (anti-) nuclei production couldbe canonically suppressed and that a canonical correlation volume might exist. The correlation volumerequired to describe the measurements is larger than one unit of rapidity. However, such a canonicalsuppression should also affect the p/ π ratio in a similar way and this is not observed in the experimentalmeasurements [11, 35].A full coalescence calculation, taking into account the interplay between the system size and the widthof the wave function of the produced (anti-)deuterons, is also able to describe the measured trend of thed/p ratio [36] and it describes the data consistently better than CSM for all system sizes. The results on (anti-)deuteron production presented in this paper display a smooth evolution with mul-tiplicity across different reaction systems, in agreement with the measurements of other light-flavouredhadrons. This suggests that a common physics process might be able to describe the nuclei productionin all hadronic collision systems. Coalescence and statistical hadronisation models are able to describequalitatively the observed trend in the d/p ratio and B as a function of the charged particle multiplicity.However, with the precision of the current measurements it is not possible to distinguish which mecha-10Anti-)Deuteron production in pp collisions at √ s =
13 TeV ALICE Collaboration | < 0.5 lab h | æ lab h / d ch N d Æ - - - ) c / ( G e V B ALICE = 13 TeV s pp, = 7 TeV s pp, = 5.02 TeV NN s p-Pb, = 2.76 TeV NN s Pb-Pb, (d) = 3.2 fm (PRC 99 (2019) 054905) r coalesc. B Param. A (fit to HBT radii) ) B Param. B (constrained to ALICE Pb--Pb c = 0.75 GeV/ A / T p Figure 4:
Coalescence parameter B at p T / A = c as a function of multiplicity in pp collisions at √ s =
13 TeV (anti-deuterons) and in √ s = √ s NN = .
02 TeV [9] (deuterons) and in Pb–Pb collisions at √ s NN = .
76 TeV [1] (deuterons).The statistical uncertainties are represented by vertical bars while the systematic uncertainties are represented byboxes. The two lines are theoretical predictions based on two different parameterisations of the HBT radius, seetext for details. nism drives the (anti-)deuteron production. On the other hand, it is not clear whether the CSM would beable to describe simultaneously the d/p and the p/ π ratios with the same chemical freeze-out conditions.No substantial differences are seen in the dependence of nuclei production on the charged multiplicityin pp and p–Pb collisions and with the Pb–Pb data sample collected in Run 2 it will be also possible toperform a direct comparison with peripheral Pb–Pb collisions. With the enhanced luminosity in Run 3,it will be possible to measure pp collisions with multiplicities similar to those observed in mid-centralPb–Pb collisions. It will be interesting to see whether ALICE can confirm this dependence when mea-suring nuclei production in pp and Pb–Pb collisions at the same multiplicity. Acknowledgements
The ALICE Collaboration would like to thank all its engineers and technicians for their invaluable con-tributions to the construction of the experiment and the CERN accelerator teams for the outstandingperformance of the LHC complex. The ALICE Collaboration gratefully acknowledges the resources andsupport provided by all Grid centres and the Worldwide LHC Computing Grid (WLCG) collaboration.The ALICE Collaboration acknowledges the following funding agencies for their support in buildingand running the ALICE detector: A. I. Alikhanyan National Science Laboratory (Yerevan Physics In-stitute) Foundation (ANSL), State Committee of Science and World Federation of Scientists (WFS),Armenia; Austrian Academy of Sciences, Austrian Science Fund (FWF): [M 2467-N36] and National-stiftung für Forschung, Technologie und Entwicklung, Austria; Ministry of Communications and HighTechnologies, National Nuclear Research Center, Azerbaijan; Conselho Nacional de DesenvolvimentoCientífico e Tecnológico (CNPq), Financiadora de Estudos e Projetos (Finep), Fundação de Amparo àPesquisa do Estado de São Paulo (FAPESP) and Universidade Federal do Rio Grande do Sul (UFRGS),11Anti-)Deuteron production in pp collisions at √ s =
13 TeV ALICE Collaboration |<0.5 lab h | æ lab h / d ch N d Æ ) p / ( p + ALICE = 5.02 TeV NN s p-Pb, V0A Multiplicity Classes (Pb-side) = 2.76 TeV NN s Pb-Pb, = 7 TeV s pp, = 13 TeV s pp, V0M Multiplicity Classes Thermal-FIST CSM (PLB 785 (2018) 171-174) y /d V = 3 d c V = 155 MeV, ch T y /d V = d c V = 155 MeV, ch TCoalescence (PLB 792 (2019) 132-137)
Figure 5:
Ratio between the p T -integrated yields of deuterons and protons (sum of protons and anti-protons) fordifferent multiplicities in pp collisions at √ s =
13 TeV (anti-deuterons) and in √ s = √ s NN = .
02 TeV [9] (deuterons) and in Pb–Pb collisions at √ s NN = .
76 TeV [1] (deuterons).The statistical uncertainties are represented by vertical bars while the systematic uncertainties are represented byboxes. The two black lines are the theoretical predictions of the Thermal-FIST statistical model [14] for two sizesof the correlation volume V C , while the magenta line represents the expectation from a coalescence model [36]. Brazil; Ministry of Education of China (MOEC) , Ministry of Science & Technology of China (MSTC)and National Natural Science Foundation of China (NSFC), China; Ministry of Science and Educationand Croatian Science Foundation, Croatia; Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear(CEADEN), Cubaenergía, Cuba; Ministry of Education, Youth and Sports of the Czech Republic, CzechRepublic; The Danish Council for Independent Research | Natural Sciences, the VILLUM FONDEN andDanish National Research Foundation (DNRF), Denmark; Helsinki Institute of Physics (HIP), Finland;Commissariat à l’Energie Atomique (CEA), Institut National de Physique Nucléaire et de Physique desParticules (IN2P3) and Centre National de la Recherche Scientifique (CNRS) and Région des Pays dela Loire, France; Bundesministerium für Bildung und Forschung (BMBF) and GSI Helmholtzzentrumfür Schwerionenforschung GmbH, Germany; General Secretariat for Research and Technology, Ministryof Education, Research and Religions, Greece; National Research, Development and Innovation Office,Hungary; Department of Atomic Energy Government of India (DAE), Department of Science and Tech-nology, Government of India (DST), University Grants Commission, Government of India (UGC) andCouncil of Scientific and Industrial Research (CSIR), India; Indonesian Institute of Science, Indonesia;Centro Fermi - Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi and Istituto Nazionaledi Fisica Nucleare (INFN), Italy; Institute for Innovative Science and Technology , Nagasaki Instituteof Applied Science (IIST), Japanese Ministry of Education, Culture, Sports, Science and Technology(MEXT) and Japan Society for the Promotion of Science (JSPS) KAKENHI, Japan; Consejo Nacionalde Ciencia (CONACYT) y Tecnología, through Fondo de Cooperación Internacional en Ciencia y Tec-nología (FONCICYT) and Dirección General de Asuntos del Personal Academico (DGAPA), Mexico;Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO), Netherlands; The Research Coun-cil of Norway, Norway; Commission on Science and Technology for Sustainable Development in theSouth (COMSATS), Pakistan; Pontificia Universidad Católica del Perú, Peru; Ministry of Science and12Anti-)Deuteron production in pp collisions at √ s =
13 TeV ALICE CollaborationHigher Education and National Science Centre, Poland; Korea Institute of Science and Technology In-formation and National Research Foundation of Korea (NRF), Republic of Korea; Ministry of Educationand Scientific Research, Institute of Atomic Physics and Ministry of Research and Innovation and Insti-tute of Atomic Physics, Romania; Joint Institute for Nuclear Research (JINR), Ministry of Education andScience of the Russian Federation, National Research Centre Kurchatov Institute, Russian Science Foun-dation and Russian Foundation for Basic Research, Russia; Ministry of Education, Science, Research andSport of the Slovak Republic, Slovakia; National Research Foundation of South Africa, South Africa;Swedish Research Council (VR) and Knut & Alice Wallenberg Foundation (KAW), Sweden; EuropeanOrganization for Nuclear Research, Switzerland; Suranaree University of Technology (SUT), NationalScience and Technology Development Agency (NSDTA) and Office of the Higher Education Commis-sion under NRU project of Thailand, Thailand; Turkish Atomic Energy Agency (TAEK), Turkey; Na-tional Academy of Sciences of Ukraine, Ukraine; Science and Technology Facilities Council (STFC),United Kingdom; National Science Foundation of the United States of America (NSF) and United StatesDepartment of Energy, Office of Nuclear Physics (DOE NP), United States of America.
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33 ,53 , L. Pinsky , C. Pinto ,S. Pisano
10 ,51 , D. Pistone , M. Płosko´n , M. Planinic , F. Pliquett , J. Pluta , S. Pochybova
145 ,i ,M.G. Poghosyan , B. Polichtchouk , N. Poljak , A. Pop , H. Poppenborg , S. Porteboeuf-Houssais ,V. Pozdniakov , S.K. Prasad , R. Preghenella , F. Prino , C.A. Pruneau , I. Pshenichnov ,M. Puccio
25 ,33 , J. Putschke , R.E. Quishpe , S. Ragoni , S. Raha , S. Rajput , J. Rak ,A. Rakotozafindrabe , L. Ramello , F. Rami , R. Raniwala , S. Raniwala , S.S. Räsänen , R. Rath ,V. Ratza , I. Ravasenga
30 ,89 , K.F. Read
95 ,130 , K. Redlich
84 ,v , A. Rehman , P. Reichelt , F. Reidt ,X. Ren , R. Renfordt , Z. Rescakova , J.-P. Revol , K. Reygers , V. Riabov , T. Richert
80 ,88 ,M. Richter , P. Riedler , W. Riegler , F. Riggi , C. Ristea , S.P. Rode , M. Rodríguez Cahuantzi ,K. Røed , R. Rogalev , E. Rogochaya , D. Rohr , D. Röhrich , P.S. Rokita , F. Ronchetti ,E.D. Rosas , K. Roslon , A. Rossi
28 ,56 , A. Rotondi , A. Roy , P. Roy , O.V. Rueda , R. Rui , √ s =
13 TeV ALICE Collaboration
B. Rumyantsev , A. Rustamov , E. Ryabinkin , Y. Ryabov , A. Rybicki , H. Rytkonen ,O.A.M. Saarimaki , S. Sadhu , S. Sadovsky , K. Šafaˇrík , S.K. Saha , B. Sahoo , P. Sahoo
48 ,49 ,R. Sahoo , S. Sahoo , P.K. Sahu , J. Saini , S. Sakai , S. Sambyal , V. Samsonov
92 ,97 , D. Sarkar ,N. Sarkar , P. Sarma , V.M. Sarti , M.H.P. Sas , E. Scapparone , B. Schaefer , J. Schambach ,H.S. Scheid , C. Schiaua , R. Schicker , A. Schmah , C. Schmidt , H.R. Schmidt ,M.O. Schmidt , M. Schmidt , N.V. Schmidt
68 ,95 , A.R. Schmier , J. Schukraft , Y. Schutz
33 ,136 ,K. Schwarz , K. Schweda , G. Scioli , E. Scomparin , M. Šefˇcík , J.E. Seger , Y. Sekiguchi ,D. Sekihata , I. Selyuzhenkov
92 ,106 , S. Senyukov , D. Serebryakov , E. Serradilla , A. Sevcenco ,A. Shabanov , A. Shabetai , R. Shahoyan , W. Shaikh , A. Shangaraev , A. Sharma , A. Sharma ,H. Sharma , M. Sharma , N. Sharma , A.I. Sheikh , K. Shigaki , M. Shimomura , S. Shirinkin ,Q. Shou , Y. Sibiriak , S. Siddhanta , T. Siemiarczuk , D. Silvermyr , G. Simatovic ,G. Simonetti
33 ,104 , R. Singh , R. Singh , R. Singh , V.K. Singh , V. Singhal , T. Sinha , B. Sitar ,M. Sitta , T.B. Skaali , M. Slupecki , N. Smirnov , R.J.M. Snellings , T.W. Snellman
43 ,126 ,C. Soncco , J. Song
60 ,125 , A. Songmoolnak , F. Soramel , S. Sorensen , I. Sputowska , J. Stachel ,I. Stan , P. Stankus , P.J. Steffanic , E. Stenlund , D. Stocco , M.M. Storetvedt , L.D. Stritto ,A.A.P. Suaide , T. Sugitate , C. Suire , M. Suleymanov , M. Suljic , R. Sultanov , M. Šumbera ,S. Sumowidagdo , S. Swain , A. Szabo , I. Szarka , U. Tabassam , G. Taillepied , J. Takahashi ,G.J. Tambave , S. Tang , M. Tarhini , M.G. Tarzila , A. Tauro , G. Tejeda Muñoz , A. Telesca ,C. Terrevoli , D. Thakur , S. Thakur , D. Thomas , F. Thoresen , R. Tieulent , A. Tikhonov ,A.R. Timmins , A. Toia , N. Topilskaya , M. Toppi , F. Torales-Acosta , S.R. Torres , A. Trifiro ,S. Tripathy , T. Tripathy , S. Trogolo , G. Trombetta , L. Tropp , V. Trubnikov , W.H. Trzaska ,T.P. Trzcinski , B.A. Trzeciak , T. Tsuji , A. Tumkin , R. Turrisi , T.S. Tveter , K. Ullaland ,E.N. Umaka , A. Uras , G.L. Usai , A. Utrobicic , M. Vala , N. Valle , S. Vallero , N. van derKolk , L.V.R. van Doremalen , M. van Leeuwen , P. Vande Vyvre , D. Varga , Z. Varga ,M. Varga-Kofarago , A. Vargas , M. Vasileiou , A. Vasiliev , O. Vázquez Doce
104 ,117 , V. Vechernin ,A.M. Veen , E. Vercellin , S. Vergara Limón , L. Vermunt , R. Vernet , R. Vértesi , L. Vickovic ,Z. Vilakazi , O. Villalobos Baillie , A. Villatoro Tello , G. Vino , A. Vinogradov , T. Virgili ,V. Vislavicius , A. Vodopyanov , B. Volkel , M.A. Völkl , K. Voloshin , S.A. Voloshin , G. Volpe ,B. von Haller , I. Vorobyev , D. Voscek , J. Vrláková , B. Wagner , M. Weber , S.G. Weber ,A. Wegrzynek , D.F. Weiser , S.C. Wenzel , J.P. Wessels , J. Wiechula , J. Wikne , G. Wilk ,J. Wilkinson
10 ,53 , G.A. Willems , E. Willsher , B. Windelband , M. Winn , W.E. Witt , Y. Wu ,R. Xu , S. Yalcin , K. Yamakawa , S. Yang , S. Yano , Z. Yin , H. Yokoyama , I.-K. Yoo ,J.H. Yoon , S. Yuan , A. Yuncu , V. Yurchenko , V. Zaccolo , A. Zaman , C. Zampolli ,H.J.C. Zanoli , N. Zardoshti , A. Zarochentsev , P. Závada , N. Zaviyalov , H. Zbroszczyk ,M. Zhalov , S. Zhang , X. Zhang , Z. Zhang , V. Zherebchevskii , D. Zhou , Y. Zhou , Z. Zhou ,J. Zhu , Y. Zhu , A. Zichichi
10 ,26 , M.B. Zimmermann , G. Zinovjev , N. Zurlo , Affiliation notes i Deceased ii Dipartimento DET del Politecnico di Torino, Turin, Italy iii
M.V. Lomonosov Moscow State University, D.V. Skobeltsyn Institute of Nuclear, Physics, Moscow, Russia iv Department of Applied Physics, Aligarh Muslim University, Aligarh, India v Institute of Theoretical Physics, University of Wroclaw, Poland
Collaboration Institutes A.I. Alikhanyan National Science Laboratory (Yerevan Physics Institute) Foundation, Yerevan, Armenia Bogolyubov Institute for Theoretical Physics, National Academy of Sciences of Ukraine, Kiev, Ukraine Bose Institute, Department of Physics and Centre for Astroparticle Physics and Space Science (CAPSS),Kolkata, India Budker Institute for Nuclear Physics, Novosibirsk, Russia California Polytechnic State University, San Luis Obispo, California, United States Central China Normal University, Wuhan, China Centre de Calcul de l’IN2P3, Villeurbanne, Lyon, France Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN), Havana, Cuba Centro de Investigación y de Estudios Avanzados (CINVESTAV), Mexico City and Mérida, Mexico √ s =
13 TeV ALICE Collaboration Centro Fermi - Museo Storico della Fisica e Centro Studi e Ricerche “Enrico Fermi’, Rome, Italy Chicago State University, Chicago, Illinois, United States China Institute of Atomic Energy, Beijing, China Comenius University Bratislava, Faculty of Mathematics, Physics and Informatics, Bratislava, Slovakia COMSATS University Islamabad, Islamabad, Pakistan Creighton University, Omaha, Nebraska, United States Department of Physics, Aligarh Muslim University, Aligarh, India Department of Physics, Pusan National University, Pusan, Republic of Korea Department of Physics, Sejong University, Seoul, Republic of Korea Department of Physics, University of California, Berkeley, California, United States Department of Physics, University of Oslo, Oslo, Norway Department of Physics and Technology, University of Bergen, Bergen, Norway Dipartimento di Fisica dell’Università ’La Sapienza’ and Sezione INFN, Rome, Italy Dipartimento di Fisica dell’Università and Sezione INFN, Cagliari, Italy Dipartimento di Fisica dell’Università and Sezione INFN, Trieste, Italy Dipartimento di Fisica dell’Università and Sezione INFN, Turin, Italy Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN, Bologna, Italy Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN, Catania, Italy Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN, Padova, Italy Dipartimento di Fisica ‘E.R. Caianiello’ dell’Università and Gruppo Collegato INFN, Salerno, Italy Dipartimento DISAT del Politecnico and Sezione INFN, Turin, Italy Dipartimento di Scienze e Innovazione Tecnologica dell’Università del Piemonte Orientale and INFNSezione di Torino, Alessandria, Italy Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy European Organization for Nuclear Research (CERN), Geneva, Switzerland Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, University of Split,Split, Croatia Faculty of Engineering and Science, Western Norway University of Applied Sciences, Bergen, Norway Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague,Czech Republic Faculty of Science, P.J. Šafárik University, Košice, Slovakia Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt,Germany Fudan University, Shanghai, China Gangneung-Wonju National University, Gangneung, Republic of Korea Gauhati University, Department of Physics, Guwahati, India Helmholtz-Institut für Strahlen- und Kernphysik, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn,Germany Helsinki Institute of Physics (HIP), Helsinki, Finland High Energy Physics Group, Universidad Autónoma de Puebla, Puebla, Mexico Hiroshima University, Hiroshima, Japan Hochschule Worms, Zentrum für Technologietransfer und Telekommunikation (ZTT), Worms, Germany Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest, Romania Indian Institute of Technology Bombay (IIT), Mumbai, India Indian Institute of Technology Indore, Indore, India Indonesian Institute of Sciences, Jakarta, Indonesia INFN, Laboratori Nazionali di Frascati, Frascati, Italy INFN, Sezione di Bari, Bari, Italy INFN, Sezione di Bologna, Bologna, Italy INFN, Sezione di Cagliari, Cagliari, Italy INFN, Sezione di Catania, Catania, Italy INFN, Sezione di Padova, Padova, Italy INFN, Sezione di Roma, Rome, Italy INFN, Sezione di Torino, Turin, Italy INFN, Sezione di Trieste, Trieste, Italy Inha University, Incheon, Republic of Korea √ s =
13 TeV ALICE Collaboration Institut de Physique Nucléaire d’Orsay (IPNO), Institut National de Physique Nucléaire et de Physique desParticules (IN2P3/CNRS), Université de Paris-Sud, Université Paris-Saclay, Orsay, France Institute for Nuclear Research, Academy of Sciences, Moscow, Russia Institute for Subatomic Physics, Utrecht University/Nikhef, Utrecht, Netherlands Institute of Experimental Physics, Slovak Academy of Sciences, Košice, Slovakia Institute of Physics, Homi Bhabha National Institute, Bhubaneswar, India Institute of Physics of the Czech Academy of Sciences, Prague, Czech Republic Institute of Space Science (ISS), Bucharest, Romania Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico City, Mexico Instituto de Física, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil Instituto de Física, Universidad Nacional Autónoma de México, Mexico City, Mexico iThemba LABS, National Research Foundation, Somerset West, South Africa Jeonbuk National University, Jeonju, Republic of Korea Johann-Wolfgang-Goethe Universität Frankfurt Institut für Informatik, Fachbereich Informatik undMathematik, Frankfurt, Germany Joint Institute for Nuclear Research (JINR), Dubna, Russia Korea Institute of Science and Technology Information, Daejeon, Republic of Korea KTO Karatay University, Konya, Turkey Laboratoire de Physique Subatomique et de Cosmologie, Université Grenoble-Alpes, CNRS-IN2P3,Grenoble, France Lawrence Berkeley National Laboratory, Berkeley, California, United States Lund University Department of Physics, Division of Particle Physics, Lund, Sweden Nagasaki Institute of Applied Science, Nagasaki, Japan Nara Women’s University (NWU), Nara, Japan National and Kapodistrian University of Athens, School of Science, Department of Physics , Athens,Greece National Centre for Nuclear Research, Warsaw, Poland National Institute of Science Education and Research, Homi Bhabha National Institute, Jatni, India National Nuclear Research Center, Baku, Azerbaijan National Research Centre Kurchatov Institute, Moscow, Russia Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark Nikhef, National institute for subatomic physics, Amsterdam, Netherlands NRC Kurchatov Institute IHEP, Protvino, Russia NRC «Kurchatov Institute» - ITEP, Moscow, Russia NRNU Moscow Engineering Physics Institute, Moscow, Russia Nuclear Physics Group, STFC Daresbury Laboratory, Daresbury, United Kingdom Nuclear Physics Institute of the Czech Academy of Sciences, ˇRež u Prahy, Czech Republic Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States Ohio State University, Columbus, Ohio, United States Petersburg Nuclear Physics Institute, Gatchina, Russia Physics department, Faculty of science, University of Zagreb, Zagreb, Croatia Physics Department, Panjab University, Chandigarh, India
Physics Department, University of Jammu, Jammu, India
Physics Department, University of Rajasthan, Jaipur, India
Physikalisches Institut, Eberhard-Karls-Universität Tübingen, Tübingen, Germany
Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
Physik Department, Technische Universität München, Munich, Germany
Politecnico di Bari, Bari, Italy
Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum fürSchwerionenforschung GmbH, Darmstadt, Germany
Rudjer Boškovi´c Institute, Zagreb, Croatia
Russian Federal Nuclear Center (VNIIEF), Sarov, Russia
Saha Institute of Nuclear Physics, Homi Bhabha National Institute, Kolkata, India
School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom
Sección Física, Departamento de Ciencias, Pontificia Universidad Católica del Perú, Lima, Peru √ s =
13 TeV ALICE Collaboration
St. Petersburg State University, St. Petersburg, Russia
Stefan Meyer Institut für Subatomare Physik (SMI), Vienna, Austria
SUBATECH, IMT Atlantique, Université de Nantes, CNRS-IN2P3, Nantes, France
Suranaree University of Technology, Nakhon Ratchasima, Thailand
Technical University of Košice, Košice, Slovakia
Technische Universität München, Excellence Cluster ’Universe’, Munich, Germany
The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Cracow, Poland
The University of Texas at Austin, Austin, Texas, United States
Universidad Autónoma de Sinaloa, Culiacán, Mexico
Universidade de São Paulo (USP), São Paulo, Brazil
Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil
Universidade Federal do ABC, Santo Andre, Brazil
University of Cape Town, Cape Town, South Africa
University of Houston, Houston, Texas, United States
University of Jyväskylä, Jyväskylä, Finland
University of Liverpool, Liverpool, United Kingdom
University of Science and Techonology of China, Hefei, China
University of South-Eastern Norway, Tonsberg, Norway
University of Tennessee, Knoxville, Tennessee, United States
University of the Witwatersrand, Johannesburg, South Africa
University of Tokyo, Tokyo, Japan
University of Tsukuba, Tsukuba, Japan
Université Clermont Auvergne, CNRS/IN2P3, LPC, Clermont-Ferrand, France
Université de Lyon, Université Lyon 1, CNRS/IN2P3, IPN-Lyon, Villeurbanne, Lyon, France
Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France, Strasbourg, France
Université Paris-Saclay Centre d’Etudes de Saclay (CEA), IRFU, Départment de Physique Nucléaire(DPhN), Saclay, France
Università degli Studi di Foggia, Foggia, Italy
Università degli Studi di Pavia, Pavia, Italy
Università di Brescia, Brescia, Italy
Variable Energy Cyclotron Centre, Homi Bhabha National Institute, Kolkata, India
Warsaw University of Technology, Warsaw, Poland
Wayne State University, Detroit, Michigan, United States
Westfälische Wilhelms-Universität Münster, Institut für Kernphysik, Münster, Germany
Wigner Research Centre for Physics, Budapest, Hungary
Yale University, New Haven, Connecticut, United States