Search for a common baryon source in high-multiplicity pp collisions at the LHC

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Physics

Letters

B

www.elsevier.com/locate/physletb

Search

for

a common

baryon

source

in

high-multiplicity

pp

collisions

at

the

LHC

.

ALICE

Collaboration



a

r

t

i

c

l

e

i

n

f

o

a

b

s

t

r

a

c

t

Articlehistory: Received21April2020

Receivedinrevisedform16September 2020

Accepted5October2020 Availableonline8October2020 Editor: M.Doser

Wereportonthemeasurementofthesizeoftheparticle-emittingsourcefromtwo-baryoncorrelations with ALICE inhigh-multiplicity ppcollisions at√s=13 TeV. The source radiusis studied with low relative momentum p–p, p–p, p–, and p– pairs as a function of the pair transverse mass mT consideringforthefirsttimeinaquantitativewaytheeffectofstrongresonancedecays.Aftercorrecting forthiseffect,theradiiextractedforpairsofdifferentparticlespeciesagree.Thisindicatesthatprotons, antiprotons,s,andsoriginatefromthesamesource.WithinthemeasuredmTrange(1.1–2.2) GeV/c2 the invariant radius of this common source varies between 1.3 and 0.85 fm. These results provide aprecise reference for studies of the strong hadron–hadron interactions and for the investigation of collectivepropertiesinsmallcollidingsystems.

©2020CERNforthebenefitoftheALICECollaboration.PublishedbyElsevierB.V.Thisisanopen accessarticleundertheCCBYlicense(http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3.

1. Introduction

Correlationtechniqueshavebeenusedinparticlephysicssince the 1960s [1]. Significant theoretical progress has been made to relate two-particle correlationsat small relative momenta to the study ofthespace-timepropertiesoftheparticle-emittingsource and the final state interactions between the two particles [2,3]. Eventually,thesemethodswereusedtostudythesourcesize,also referred to as Hanbury Brown and Twiss (HBT) radius, created in heavy-ion collisions [4–14]. Collective effects such as hydro-dynamic flow introduce position-momentum correlations to the particleemission,andhencemodifythesourceradiiinheavy-ion collisions at LHC energies [5]. In these systems, the decrease of themeasuredsourceradiiwithincreasingpairtransverse momen-tumkT

=| 

pT,1

+ 

pT,2

| /

2,wherepTisthetransversemomentum

ofeach oftheparticles, andthe transversemassmT

=



k2_T

+

m2_,

where m is the average mass of the particle pair, is attributed to the collective expansion of the system created in the colli-sion [5,15].Inthiscontext,therearepredictionsofacommonmT

scalingoftheradiusfordifferentparticlepairs,whicharebasedon the assumption ofthe same flow velocities andfreeze-out times forallparticlespecies [16,17].Therealsoisexperimentalevidence thatacommonmT scalingofthesourceradiusispresentfor

pro-tons and kaons in heavy-ion collisions [18]. On the other hand, forpionsthescalingseemstobeonlyapproximate [18,19],which could be explained by the larger effect of the Lorentz boost for lighter particles [16,18] but could also be influenced by the

ef- _{E-mailaddress:alice-publications@cern.ch.}

fect of feed-down from short-lived resonance decays. The radii obtainedforPb–Pb collisionsatthe LHCcan becompared tothe freeze-out volume obtained from statistical hadronization mod-els [20] and are also essential ingredients for coalescence mod-els [21–23].

Recent studies of high-multiplicity pp collisions reveal unex-pected similarities to heavy-ionreactions whenconsidering vari-ablesnormallylinkedtocollectiveeffects,angularcorrelations,and strangenessproduction[24–27].Thehadronizationinppcollisions isexpectedto occur ona similar time scaleforall particles, and ifacommonradialvelocityforallparticlesshouldbepresent,this wouldleadtoasimilarmT scalingofthesourcesizeasmeasured

forheavy-ion collisions. Unfortunately, the informationregarding themT dependenceof the source size measured inpp collisions

islimitedto low valuesofmT,asthe existingdata are basedon

analysescarriedout with

π

–

π

andK–K pairs.Thesestudiespoint toavariationoftheradiusasafunctionoftheeventmultiplicity andof thepair mT [28–32]. However, aside a qualitative

consid-eration ofa

β

T scaling [33], no quantitative description could be

determinedsofar.

Itisknownthatstronglydecayingresonancesmayleadto sig-nificantexponentialtailsofthesourcedistribution,whichcan in-fluence inparticular the measured

π

–

π

correlations inheavy-ion collisions [34–37]. This effect is even more pronounced insmall collision systemssuch aspp andp–Pb [38,39], andcan substan-tiallymodifythemeasured sourceradii,not onlyformesons,but forbaryonsaswell.Sofarasolidmodelingofthestrongresonance contributiontothesourcefunctionisstillmissing.

Inthiswork, wepresentthefirststudy ofthesourcefunction with a quantitative evaluation of the effect of strong resonance

https://doi.org/10.1016/j.physletb.2020.135849

0370-2693/©2020CERNforthebenefitoftheALICECollaboration.PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYlicense (http://creativecommons.org/licenses/by/4.0/).FundedbySCOAP3_.

decays.The searchforacommonparticle-emitting sourceis con-ductedemployingdatameasuredinhigh-multiplicityppcollisions at

√

s

=

13 TeV. The emission sources of protons and



baryons are studied using p–p andp–



correlationsasa function of the pairmT.After correctingfortheeffectofstrongresonancedecays,

the overall source size decreases significantly by up to 20% and the values extracted from the different pair combinations are in agreement.Thecommonparticle-emittingsourcedescribedinthis work willallow fordirectcomparisonsof thesourcesizes to the ones resulting from theoretical models and the presence of col-lective phenomena in smallcolliding systems to be studied ina complementary wayto analyses carried out so far [28–32,38,39]. Theseanalysesconcentratedon

π

–

π

andK–K correlationstudiesin ppcollisions,probingthekT andmT rangesofupto1–1.5 GeV

/

c2

andobservinga decreaseofthesourceradius athighermT,with

themeasuredradiireachingvaluesevenbelow1 fminthecaseof minimumbiasevents.ThehighermT rangeisonlyaccessiblewith

baryonfemtoscopy.

Additionally, recentALICEstudies revealedthat smallcollision systems, such aspp, area suitable environment to study the in-teraction potential between more exotic pairs, like p–K−, p–



,



–



,p–



0,andp–



−[40–44].Thedataofhigh-multiplicity trig-gered pp collisions at

√

s

=

13 TeV provides a significantly im-proved precision compared to the previously analyzed minimum bias data.Detailed studies ofthe interactions will be enabledby a precise knowledge of the size of the common source for par-ticleemission, once correctedforthe broadeningdueto the res-onance decays, which depends on the pair type. Moreover, the effectivesourcesizeisanimportantinputforthemodelingof co-alescence and hasconsequences forthe prediction of antimatter formation [21–23,45,46].

2. Dataanalysis

Thispaper presentsmeasurements ofthe p–p, p–p,p–



,and p–



correlation functions in high-multiplicity pp collisions at

√

s

=

13 TeVperformedwithALICE [47,48].The high-multiplicity trigger selected events based on the measured amplitude in the V0 detector system [49], comprisingtwo arraysof plastic scintil-lators at 2

.

8

<

η

<

5

.

1 and

−

3

.

7

<

η

<

−

1

.

7. The thresholdwas adjusted such that the selectedevents correspond tothe highest 0.17%fractionofthemultiplicity distributionofall INEL

>

0 colli-sions.Insuchevents,anaverageof30charged-particletracksare foundintherange

|

η

|

<

0

.

5 [50],whichconstitutesanincreaseby afactorofaboutfourwithrespecttotheminimumbiasdata sam-ple[42].The V0 timinginformationwasevaluatedwithrespectto theLHCclocktodistinguishcollisionswiththebeampipematerial orbeam–gasinteractions.

TheInnerTrackingSystem(ITS) [48] andTimeProjection Cham-ber (TPC) [51] arethemaintrackingdevicesinALICE.Theycover thefullazimuthalangleandthepseudorapidityrangeof

|

η

|

<

0

.

9. The solenoidsurrounding thesedetectorscreates ahomogeneous magnetic field of B

=

0

.

5 T directed along the beam axis which defines the z direction. The spatial coordinates of the primary eventvertex(PV)arereconstructedonceusingglobaltracks recon-structedwiththe TPC and ITS andonceusing ITS tracklets [47].If both methods yielda vertex, the longitudinaldifference between thetwo,



z,isrequiredtobe lessthan 5 mm.The z component of the vertex, preferably determined by global tracks, hasto lay within

|

Vz

|

<

10 cmofthenominalinteraction pointtoensure a uniform detectorcoverage. Multiple reactions per bunch crossing areidentified bythepresenceofsecondary collisionvertices [47]. Approximately 109 events fulfill the above requirements andare available forthe analysis. The identification ofprotons andtheir respectiveantiparticlesfollowsthecompletesetofcriterialistedin Refs. [41,42].Primaryprotons areselectedin thetransverse-

mo-mentum rangebetween0.5 GeV

/

c and 4.05 GeV

/

c within

|

η

|<

0

.

8. Particle identification (PID) isperformed by using the infor-mationprovidedbythe TPC andtheTime-Of-Flight(TOF) [52] de-tectors.Theenergylossinthe TPC gasismeasuredforeachtrack, while the timing information of TOF is required for tracks with p

>

0

.

75 GeV

/

c.Particlesareidentifiedbyaselectiononthe devia-tionsfromthesignalhypothesesinunitsoftherespectivedetector resolution

σ

TPCand

σ

TOF,accordingtonσ

=



n2_σ,TPC

+

n2_σ,TOF

<

3. Thedistance ofclosest approach (DCA)to the PVisrestricted to a maximum of 0.1 cm in the transverse plane and 0.2 cm in the z direction, in order to suppress weak decay products or particles created in interactions with the detector material. The compositionofthesample isobtainedfollowingthe methods de-scribed in [41]. For this purpose, events were generated with Pythia8.2 [53] (Monashtune [54]),processedbyGEANT3 [55], fil-teredthroughtheALICEdetectorresponseandsubsequently han-dledbythereconstructionalgorithm [48].Thesesimulationswere usedtoestimate thattheselectedprotonsandantiprotonshavea momentum-averaged purity of 99%. The fraction of primary and secondary contributions was estimated by a fit of templates of their individual DCA distributions from MC to the pT-integrated

measureddistributions.Thiswaythesample wasfoundtoconsist of82% primaryparticles.Theremainder isduetoweak decaysof



(



+)baryonscontributingwith13%(5%).

The



(



) candidates are selected following the procedures discussed in[41,42] by reconstructing the weak decay



→

p

π

− (



→

p

π

+),whichhasabranchingratioof63.9% [56].The combi-natorialbackgroundisreducedbyrequiringthedistanceofclosest approachbetweenthedaughtertracksatthesecondaryvertexto be smallerthan 1.5 cm.A straight lineconnectingthe secondary vertexwiththePVdefinesthetrajectoryofthe



candidate. Pri-mary



baryons areselectedbyrequiringacosineofthepointing angle (CPA) between the momentum vector of the



candidate anditstrajectorytobelargerthan0.99.Thereconstructed daugh-terparticletracksare requiredtohaveanassociatedhit eitherin theSiliconPixelDetector(SPD) ortheSiliconStripDetector(SSD) layersofthe ITS or the TOF detectorinorder tousetheir timing information to reduce the remaining contributions from out-of-bunchpile-up.Theproton-pioninvariantmassdistributionisfitted using the sum of a double Gaussian to describe the signal and a second order polynomial for the combinatorial background. In the pT rangebetween0.3to4.3 GeV

/

c,the



and



candidates

arereconstructedwithamassresolutionbetween1.5 MeV

/

c2 _and

1.8 MeV

/

c2. Choosing a mass window of 4 MeV

/

c2 around the nominal mass [56] results in a pT-averaged purity of 96%.

Sim-ilarly to the case of protons, CPA templates of the primary and secondarycontributionsaregeneratedusingMCsimulations.These andaproductionratiobetween



and



0 of1/3 [57–60],areused to decompose the sample ofselected



and



candidates. It is found to consist of 59%



baryons directly produced in the col-lision, while19% originate from electromagneticdecays of a



0. Additionalcontributionsfromweakdecaysof



− and



0 amount to11%each.

3. Correlationfunction

The observable in femtoscopic measurements is the correla-tionfunction C

(

k∗

)

,wherek∗

=

₂1

· |

p∗₂

−

p∗₁

|

denotes therelative momentum of particle pairs and p∗₁ and p∗₂ are the particle mo-menta inthe pair rest frame (PRF, p₁∗

= −

p∗₂). It is computed as C

(

k∗

)

=

N

_BA(_(kk∗∗)₎,where A

(

k∗

)

istherelativemomentum

distribu-tion of correlated particle pairs, obtained from the same event, and B

(

k∗

)

the corresponding distribution of uncorrelated pairs. Thelatter isobtainedby pairingidentified particles ofone event withparticlesfroma different(“mixed”)event. In ordertoavoid

Table 1

Weightparametersoftheindividualcomponentsofthep–p andp–correlationfunction.Misidentifications ofparticlespeciesXaredenotedasX and˜ feed-downcontributionshavethemotherparticlelistedasa sub-index.Forthecontributionsinboldtext,thecorrelationfunctionsaremodeledaccordingtotheinteraction potential,whiletheothersareassumedtobeflat.

p–p p–

Pair λparameter(%) Pair λparameter(%) Pair λparameter(%)

pp 67.0 p 46.1 p+0 0.5 pp 20.3 p− 8.5 p+0 1.0 pp 1.5 p0 8.5 p˜ 0.3 p+p 8.5 p0 15.4 p˜ − 0.1 p+p+ 0.3 p 7.0 p˜ 0 0.1 pp+ 1.3 p− 1.3 p˜ 0 0.1 ˜ pp 0.9 p0 1.3 p˜ 3.3 ˜ pp 0.1 p0 2.3 p˜ 0.5 ˜ pp+ 0.1 p+ 2.9 p+˜ 0.2 ˜ p˜p 0 p+− 0.5 p˜˜ 0

anybias duetoacceptanceandreconstruction effects,only those eventsare mixed,forwhich thedifferencebetweenthepositions ofthevertexin z directionislessthan2 cmandthenumbersof globaltrackswithin

|η|

<

0

.

8 differbylessthanfour.The normal-izationfactor

N

iscalculatedintheregionk∗

∈ [

240

,

340

]

MeV

/

c, where no femtoscopic signal is present and C

(

k∗

)

theoretically approachesunity. In thelaboratory frame,the single-particle tra-jectoriesofp–p and p–p pairsatlowk∗ arealmostcollinearand hencehavea



η

and



ϕ

∗

∼

0.Here,

η

referstothe pseudorapid-ityofthetrackand

ϕ

∗istheazimuthaltrackcoordinatemeasured at9radii inthe TPC,rangingfrom85 cm to245 cm,takinginto accounttrackbendingbecauseofthemagneticfield.Dueto detec-toreffectsliketracksplittingandmerging [18] thereconstruction efficiency for pairs in same and mixed events differs. In order to avoid a bias in the correlation function, a close-pair-rejection (CPR) criterion is applied by removing p–p and p–p pairs fulfill-ing





η

2

_{+ ϕ}

∗2

_<

₀

_.

_01.Forp–

_

_andp–

_

_{pairsnorejectionis}

considered.

A totalnumberof 1

.

7

×

106 (1

.

3

×

106) p–p (p–p) and0

.

6

×

106 ₍₀

_.

₅

_×

₁₀6_{) p–}

_

_(p–

_

_{) pairs are found in the region k}∗

_<

200 MeV

/

c.Thecorrelationfunctionsofbaryon–baryonpairsagree within statistical uncertainties with their antibaryon–antibaryon pairs [18,61]. Therefore inthe following p–p denotes the combi-nation of p–p

⊕

p–p and accordinglyforp–



. The p–p and p–



correlation functionswere obtainedseparately in7 and6mT

in-tervals,respectively,chosensuchthat thetotalamountofparticle pairsisevenlydistributed.

The theoretical correlation function is related to the two-particle emittingsource S

(

r∗

)

andwave function

ψ( 

r∗

,

k



∗

)

[5]. It canbewrittenas

C

(

k∗

)

=



d3r∗S

(

r∗

)

|ψ( 

r∗

, 

k∗

)

|

2

,

(1)

wherer∗ istherelativedistancebetweentheparticlepairdefined inthePRF. Whenfittingthisfunction tothedatainthisanalysis, the freeparameters aresolely relatedto S

(

r∗

)

.The

ψ( 

r∗

,

k



∗

)

and theresultingC

(

k∗

)

canbedeterminedwiththehelpofthe corre-lationanalysistoolusingtheSchrödingerequation(CATS) [62].The frameworkwas developedinordertomodelthecorrelation func-tioninsmallsystems,wherethestronginteractioncangiveriseto aparticularlypronouncedcorrelationsignal.Therefore,

ψ( 

r∗

,

k



∗

)

is preciselycalculatedasthenumericalsolutionofthesingle-channel Schrödinger equation,such thatadditionallytoquantumstatistics and Coulomb interactions the strong interaction can be included viaalocalpotential V

(

r∗

)

.

Residual correlationsfrom impurities and feed-down of long-lived resonances decayingweakly or electromagnetically [34] are taken into account by calculating the model correlation function Cmodel

(

k∗

)

as

Cmodel

(

k∗

)

=

1

+



i

λ

i

(

Ci

(

k∗

)

−

1

),

(2)

wherethe sumruns overall contributions andwith themethod discussedinRef. [41].Inparticulartheweights

λ

i,whicharelisted separatelyforp–p andp–



inTable1,arecalculatedfrompurity andfeed-downfractionsreportedinSec.2.

Tomodelthe p–p (p–



)correlation function,residual correla-tionsduetothefeed-downfromp–



(p–



0 _andp–

_

−_)pairsare

explicitlyconsidered,whileallothercontributionsareassumedto be flat. The residual correlations are modeled with CATS assum-ing the same source radius as the initial particle pair and use theoreticaldescriptions oftheir interactions followingRef. [63,64] forp–



− and Ref. [65–67] for p–



0. The models describing the p–



interactionwillbediscussedlaterinthissection.The contri-butions of thesepairs to the p–p and p–



correlation functions have to be scaled by

λ

i and their signal smeared via a decay matrix [41,68] whichisbuiltaccordingtothekinematicsofthe de-cay.Therefore,theresidualsignaloftheinitialpairistransformed to the momentum basis ofthe measured pair. Additionally, each contribution Ci is smearedto take into account effects ofthe fi-nite momentum resolution of the ALICE detector. Exceptfor the genuinecorrelations,thesestepsresultinaCi

(

k∗

)

∼

1 forall com-binations, in particular due to the rather small

λ

parameters of mostresidualcontributionsasshowninTable1.Eitheraconstant oralinearbaselineC_non−femto

(

k∗

)

isincludedinthetotalfit func-tion Cfit

(

k∗

)

=

Cnon−femto

(

k∗

)

·

Cmodel

(

k∗

)

. Theconstant factorcan,

ifnecessary,introduceaslightcorrectionofthenormalization

N

. The linear baseline function extrapolates any remaining slope of C

(

k∗

)

inthenormalizationregion,whichmayariseduetoenergy and momentum conservation [41,69], to the femtoscopic region. Thedefaultassumptionisaconstant,withCnon−femto

(

k∗

)

=

a.

ThesourcefunctionS

(

r∗

)

isassumedtohaveaGaussianprofile

S

(

r∗

)

=

1

(

4

π

r₀2

)

3/2exp



−

r∗2 4r2₀



,

(3)

where r0 represents the source radius. The best fit to the p–p

correlationfunction withCfit

(

k∗

)

isperformedinthe regionk∗

∈

[

0

,

375

]

MeV

/

c and determines simultaneously all free parame-ters,namely r0 and the onesrelated to Cnon−femto

(

k∗

)

.The

gen-uine p–p correlation function is calculated by using CATS [62] andthestrongArgonne v18 potential [70] in S, P ,and D waves.

Thesystematicuncertaintiesonr0 associatedwiththefitting

pro-cedure are estimated by i) modifying the upper limit of the fit regionto350 MeV

/

c and400 MeV

/

c,ii)replacingthe normaliza-tionCnon−femto

(

k∗

)

=

a byalinearfunction,iii)employingdifferent

modelsdescribingthe residualp–



interaction asdiscussedlater in the text, and iv) modifying the

λ

parameters by varying the composition of secondary contributions by

±

20%, while keeping thesumofprimaryandsecondaryfractionsconstant.

Fig. 1. Thecorrelationfunctionofp–p (left)andp–(right)asafunctionofk∗inoneexemplarymTinterval.Statistical(bars)andsystematic(boxes)uncertaintiesare shownseparately.Thefilledbandsdepict1σ uncertaintiesofthefitswithCfit(k∗)andareobtainedbyusingtheArgonnev18[70] (blue),χEFTLO [71] (green)andχEFT NLO [74] (red)potentials.Seetextfordetails.

In comparison to p–p, the theoretical models describing the p–



interaction are much less constrained since data from hy-pernuclei and scattering experiments are scarce [41,71–74]. The femtoscopicfitisperformedintherangek∗

∈ [

0

,

224

]

MeV

/

c.The limitedamountofexperimentaldataleavesroomfordifferent the-oretical descriptions of the p–



interaction. In the measurement this is accounted for by performing the fits twice, where the S wave function of the p–



pair is obtained once from chiral ef-fective field theorycalculations(

χ

EFT)atleading order(LO) [71] and once from the one at next-to-leading order (NLO) [74]. The systematic uncertainties on r0 associated with the fit procedure

are estimated by i) changingthe upper limit ofthe fit region to 204 MeV

/

c and 244 MeV

/

c,ii) replacing the normalization con-stantCnon−femto

(

k∗

)

=

a byalinearfunction,andiii)modifyingthe

λ

parametersbyvaryingR_0_/by

±

20%.

Thesystematicuncertainties oftheexperimentalp–p andp–



correlation function take into consideration all single-particle se-lectioncriteria introduced inthe previous section,as well asthe CPRcriteriaonthep–p pairs.Allcriteriaarevariedsimultaneously up to 20%around thenominalvalues.To limitthe biasof statis-ticalfluctuations, only variations witha maximumchangeof the pairyieldof20%areconsidered.Toobtainthefinalsystematic un-certainty on the source size,the fit procedureis repeatedfor all variationsoftheexperimentalcorrelationfunction,usingall possi-bleconfigurationsofthefitfunction.Thestandarddeviationofthe resulting distribution for r0 is considered as the final systematic

uncertainty.

In Fig. 1 the p–p and p–



correlation functions of one rep-resentative mT interval are shown. The grey boxes represent the

systematicuncertaintiesofthedataandcorrespondtothe1

σ

in-terval extractedfrom the variations of the selection criteria. The resulting relative uncertaintyof the p–p (p–



) correlation func-tionreachesamaximumof2.4%(6.3%)inthelowestmeasuredk∗ interval.Unlikeformeson–mesonorbaryon–antibaryonpairs,the broadbackgroundrelatedtomini-jetsisabsentforbaryon–baryon pairs [41,75]. The width ofthe fit curves corresponds to the 1

σ

intervalextractedfromthevariationsofallthefits.Incaseofthe p–p correlationfunction,thisresultsina

χ

2

_/

_ndf

₌

₁

_.

_9.Thefitof

thep–



correlationfunctionusing

χ

EFTcalculationsatLOyieldsa

χ

2

_/

_ndf

₌

₀

_.

_{91 whilethefitusing}

_χ

_{EFTcalculationsatNLOyields}

a

χ

2

_/

_ndf

₌

₀

_.

_67.

EachcorrelationfunctionineverymT intervalisfittedandthe

resultingradii are showninFig.2.The central valuecorresponds to themean estimatedfromthedistribution ofr0 obtainedfrom

Fig. 2. Sourceradiusr0asafunctionof mTfortheassumptionofapurely Gaus-siansource.Thebluecrossesresultfromfittingthep–p correlationfunctionwith thestrong Argonne v18 [70] potential.Thegreensquared crosses(red diagonal crosses)resultfrom fittingthe p– correlation functionswith thestrong χEFT LO [71] (NLO [74])potential.Statistical(lines)andsystematic(boxes)uncertainties areshownseparately.

thesystematicvariations. The statisticaluncertaintiesare marked withsolidlines,whiletheboxescorrespondtothesystematic un-certainties.Therelativevalue ofthelatterisatmost2.4%forthe radiiextractedfromp–p correlationsand8.3% and5.7%forthose extracted from p–



correlations using the NLO and LO calcula-tions,respectively.Thedecreaseofthesourcesizewithincreasing mT is consistent with a hydrodynamic picture, however, the

ex-pectedcommonscaling [16] ofthedifferentparticlespeciesisnot observedforthetwoconsideredpairtypes.Thetwomeasurements show a similar trend that is shifted by an offset, indicating that therearedifferencesintheemissionofparticles.

4. Modelingtheshort-livedresonances

Theeffectofshort-lived resonances(c

τ



10 fm)feedinginto protons and



baryons could be a possible explanation for the difference between the source sizes determined from p–p and p–



correlations,whichwasobservedinFig.2.Inthepast, Bose-Einsteincorrelationsbetweenidenticalpions,measured in heavy-ion collisions, were interpreted in terms of a two-component source.It constitutes a core, which is the originof primary

par-Fig. 3. Asketchrepresentingthemodificationofrcore∗ intor∗(dash-dottedlines),duetothepresenceofresonances(graydisks),decayingintotheparticlesofinterest(blue disks).ThecoordinatesystemisdeterminedbytherestframeofthetwodaughtersandconsistentwithEq. (1),wherek∗representstheirmomenta(solidbluelines).The bluedottedlinesrepresenttheremainingdecayproducts,whichareassumedtobesinglepions.Incaseofaprimordialparticleintheinitialstateinsteadofaresonance, thelatterisnotconsidered(s∗res,i=0).

ticles, and a halo, which is the origin of pions produced by the decay of resonances [76]. In a detailedinvestigation of MC sim-ulations of heavy-ion collisions the source sizes were extracted from

π

–

π

pairs for systems both withand without the presence ofthesecontributions,andindeeddifferencesofabout1 fmwere found [35,77]. Similar effects are expected to arise for baryons, sinceshort-livedresonancessuchas



andN∗ decaymainlyintoa baryonandapion.Theexponentialnatureofthedecayisreflected in the appearance of exponential tails in the source distribution andan effective increaseof thesource size.Inspired by this pic-ture, a source distribution forbaryons is builtstarting fromtwo components:aGaussiancoreandanon-Gaussianhalo.

Inthiswork,theresonanceyieldsaretakenfromthestatistical hadronizationmodel(SHM) [78].Since thisstudyaims at quanti-fyingtheeffectofstronglydecayingresonancesonthesource dis-tribution,inthefollowingonlyprimordialparticlesandsecondary decay products of short-lived resonances will be considered. Ac-cordingtotheSHM,theamountofprimordialprotons(



baryons) areonly Pp

=

35

.

8% ( P

=

35

.

6%) [79],implyingthattheeffectof

thesecondariesissubstantial.Forprotons,57differentresonances withlifetimes0

.

5fm

<

c

τ

<

13fm areconsidered.Relativetothe total numberofprotons, 22% originatefrom thedecayof a



++

resonance,15%fromthedecayofa



+ resonance,and7.2%from a



0 resonance.The remaining secondary protonsoriginate from heavier N∗,



and



resonances, which contribute individually with less than 2%. Similarly, secondary



baryons stem from 32 considered resonanceswithlifetimes 0

.

5 fm

<

c

τ

<

8

.

5 fm. Most prominently



∗+,



∗0,and



∗− are eachtheoriginof12% ofall



baryons,whiledecaysofheavierN∗,



,and



resonances indi-viduallycontributewithlessthan1%.Theweightedaverageofthe lifetimes(c

τ

res)oftheresonancesfeedingintoprotons(



baryons)

is 1.65 fm (4.69 fm),while the weighted average of the masses is1.36 GeV

/

c2 _{(1.46 GeV}

_/

_c2_{).Althoughtheamountofsecondaries}

is similarfor protonsand



baryons,there isa significant differ-enceinthemeanlifetimeofthecorrespondingresonances,which ismuchlongerforthe



.Qualitativelythiswillimplyalarger ef-fectivesourcesizeforp–



,asobservedinFig.2.

Inthefollowingthesourcefunction S

(

r∗

)

isconstructed includ-ingtheeffectofshort-livedresonances,assumingthatall primor-dialparticlesandresonancesareemittedfromacommonGaussian sourceofwidthrcore.Consequently,theparticlesstudiedinthe

fi-nalstatecaneitherbeprimordialsordecayproductsofshort-lived resonances.Forapairofparticlestherearefourdifferentscenarios regardingtheirorigin,thefrequencyofeachgivenby P1P2, P1P

˜

2,

˜

P1P2 and P

˜

1P

˜

2.Here P1,2 are the fractions of primordial

parti-clesand P

˜

1,2

=

1

−

P1,2 thefractionsofparticlesoriginatingfrom

short-livedresonances.Thetotalsourceis

S

(

r∗

)

=

P1P2

×

SP1P2

(

r∗

)

+

P1P

˜

2

×

SP1P˜2

(

r ∗

₎

+ ˜

P1P2

×

SP˜1P2

(

r ∗

₎

_{+ ˜}

_P 1P

˜

2

×

SP˜1P˜2

(

r ∗

_).

₍₄₎

To evaluate S

(

r∗

)

, the required ingredients are the fractions of primordial and secondary particles, and the individual source functionscorresponding tothepossiblecombinationsforthe par-ticleemission.Dependingontheaveragemassandlifetimeofthe resonances feeding to the particle pair of interest,each of these scenarios willresultin slightlydifferentsource sizes andshapes. These composite source functions are difficult to compute ana-lytically,however, a simplenumerical evaluation, outlined in the following, allows to iteratively build the full source distribution S

(

r∗

)

for a givenrcore. The primordialemission of particles with

arelativedistancer∗_coreisrandomlysampledfromaGaussianwith widthequaltorcore.Theresultingparticlesarethen,basedonthe

probabilities P1,2 andP

˜

1,2,assignedtobeeitherprimordial

parti-clesorresonances.Theresonancesarepropagatedandtheirdecays are simulated. Forsimplicity it is assumed that each decay pro-ducesoneproton(



)andonepion.Itwascheckedthatincluding three-bodydecaysatthisstage wouldhavea negligibleeffecton theextractedradii.

Fig.3isaschematicrepresentationofthesourcemodification, whichinvectorformisgivenas:



r∗

= 

r∗_core

− 

s∗_res,1

+ 

s∗_res,2

,

(5)

where



s∗_res,1(2) isthe distancetraveledby the first(second) reso-nance.Thisislinkedtotheflighttimetres,whichissampledfrom

anexponentialdistributionbasedonthelifetimeoftheresonance

τ

res:



s∗_res

= β

_res∗

γ

_res∗tres

=



p∗_res

Mres

tres

,

(6)

where



p∗_res is the momentum and Mres the mass of the

corre-spondingresonance.Fortheone-dimensionalsourcefunctionS

(

r∗

)

theabsolutevaluer∗

= |

r∗

|

needstobeevaluated.Giventhe defi-nitionsinEq. (5) andEq. (6),therequiredingredientsarer∗_core,the momenta,massesandlifetimes oftheresonances, aswell asthe anglesformedbythethreevectors



r∗_core,



s∗_res,1 and



s∗_res,2.

Fig. 4. Thesourcefunctionsforp–p (bluecircles)andp–(redopencircles), gener-atedbyfoldingtheexponentialexpansionduetothedecayoftherespectiveparent resonanceswithacommonGaussiancorewithrcore=1.2 fm(dashedblackline). AdditionallyshownarefitswithGaussiandistributions(dottedlines)toextractthe effectiveGaussiansourcesizes.

The masses and lifetimes of the resonances are fixed to the average values reportedabove. The remaining unknown parame-ters,themomentaoftheresonancesandtheirrelativeorientation withrespectto



r∗core,arerelatedtothekinematicsoftheemission.

In this work, the EPOS transport model [80] is used to quan-tify these parameters, by generating high-multiplicity pp events at

√

s

=

13 TeV and selecting the produced primordial protons,



baryons andresonancesthatfeedintotheseparticles.Sincethe yields oftheheavierresonances areover-predictedbyEPOS,they are weighted such that their average mass Mres reproduces the

expectation fromthe SHM. The source function S

(

r∗

)

is builtby selecting a random r∗_core and a random emission scenario based on theweights P1,2,which areknown fromtheSHM. A random

EPOSeventwiththesameemissionscenarioisusedtodetermine



p∗_res,1(2) andtheir relative directiontor



_core∗ .To obtainr∗ the res-onancesarepropagated,usingEq.(5) and(6), andthek∗ oftheir daughtersisevaluated.Onlyeventswithsmallk∗ arerelevantfor femtoscopy, thus, if the resulting k∗

>

200 MeV

/

c, a new EPOS eventispicked.Theaboveprocedureisrepeateduntiltheresulting S

(

r∗

)

achievesthedesiredstatisticalsignificance.

With thismethod, the modification ofthe source size due to the decay of resonances is fixed based on the SHM and EPOS, while the onlyfree fitparameter is thesize rcore of the

primor-dial (core) source. This procedure is used to refit the p–p and p–



correlation functions. Theuncertainties are evaluated in the same wayasinthe caseofthe pure Gaussian source.Additional uncertainties duetoshort-lived resonances decayingintoprotons (



baryons)areaccountedforbyrepeatingthefitandalteringthe massby0.2%(0.6%)andthelifetimesby2%(13%) [56].When com-paring the individual fits of the correlation functions in one mT

intervalwiththeonesassumingapureGaussiansourcethe result-ing

χ

2 _{is found tobe similar. This impliesthat each systemcan}

still be described by an effective Gaussian source, albeit loosing thedirectphysicalinterpretationofthesourcesize.Thisproperty becomesevident fromFig. 4,in whichthe differentsource func-tions, used to describe the mT bin plotted in Fig. 1, are shown.

As expected, aftertheinclusion oftheresonances, thesamecore functionresultsindifferenteffectivesourcesforp–p andp–



.The Gaussian parametrizationyields an almost equivalent description of the source function up to about r∗

∼

6 fm, while for larger values thenew parametrizationwithinclusion of the resonances shows an exponential tail. Since most of the particles are emit-tedatlowerr∗ values,thecorrespondingcorrelationfunctionsare similar. However, one major differencewiththe newapproach is the resulting source size, as the Gaussian coreis more compact than the effective sources. The resultingmT dependence of rcore

measuredwithp–p andp–



pairsisshowninFig.5.Therelative

Fig. 5. Sourceradiusrcore asafunctionof mTfortheassumptionofaGaussian sourcewithaddedresonances.Thebluecrossesresultfromfittingthep–p correla-tionfunctionwiththestrongArgonnev18[70] potential.Thegreensquaredcrosses (reddiagonalcrosses)resultfromfittingthe p– correlationfunctionswiththe strongχEFTLO [71] (NLO [74])potential.Statistical(lines)andsystematic(boxes) uncertaintiesareshownseparately.

systematicuncertaintyisatmost2.6%forthecoreradiiextracted fromp–p correlationsand8.4%and6.2%forthoseextractedfrom p–



correlationsusingthe NLO andLOcalculations, respectively. Incontrast toa Gaussian source, thenew parametrizationofthe source function provides a common mT scaling of rcore for both

p–p andp–



.Thisresultiscompatiblewiththepictureofa com-monemissionsourceforallbaryonsandtheirparentresonances.

5. Summary

The results forp–p and p–



correlationsin high-multiplicity ppcollisionsat

√

s

=

13 TeVdemonstrateacleardifferenceinthe effective proton and



source sizes if a simple Gaussian source is assumed. A newprocedure was developed to quantify forthe first time the modification of thesource function dueto the ef-fect of short-lived resonances. The required input is provided by thestatisticalhadronizationmodelandtheEPOStransportmodel. Theansatz is thatthe sourcefunction isdetermined by the con-volution of a universal Gaussian core source of size rcore and a

non-Gaussianhalo.Theformerrepresentsauniversalemission re-gionforallprimordialparticlesandresonances,whilethelatteris formedbythedecaypointsoftheshort-livedresonances.This pic-tureisconfirmed by theobservationof a commonmT scaling of rcore forthe p–p andp–



pairsinhigh-multiplicity ppcollisions,

withrcore

∈ [

0

.

85

,

1

.

3

]

fmformT

∈ [

1

.

1

,

2

.

2

]

GeV

/

c2.Comparedto

thevaluesobtainedwhenaneffectiveGaussianparametrizationis used,theoverallvaluesaresignificantlydecreasedbyupto20%.

The measurement of the core size of a common particle-emittingsource,correctedfortheeffectofstrongresonances,will allow for direct comparisons with theoretical models. Addition-ally,detailedstudiesofthemT dependenceofthecoreradiuswill

enable complementary investigations of collective phenomena in smallcollisionsystems.

Ontheother hand,the assumptionof acommoncoresource, modified by the resonances feeding to the particle pairof inter-est,allowsforaquantitativedeterminationoftheeffectivesource foranykindofparticlepair. Firstofall, itenableshigh-precision studiesoftheinteractionpotentialsofmoreexoticbaryon–baryon pairs [41,42,44] thatrelyontwo-particlecorrelationmeasurements in momentum space anduse the p–p correlation asa reference tofix the emission source.It is alsorelevant forcoalescence ap-proachesaddressingtheproductionof(anti)(hyper)nuclear clus-ters.A crucial next step is to investigatethe applicability ofthe

newmethodformeson–meson andbaryon–mesoncorrelations. If the samemT scaling isobserved asforbaryons,thiswill provide

an even more precisequantitative understanding ofthe common particle-emitting source.In anycase, such a study will shed fur-therlightontheproductionmechanismofparticlesandwillbea valuableinputfortransportmodels.

Declarationofcompetinginterest

Theauthorsdeclarethattheyhavenoknowncompeting finan-cialinterestsorpersonalrelationshipsthatcouldhaveappearedto influencetheworkreportedinthispaper.

Acknowledgements

The ALICE Collaboration would like to thank all its engineers andtechniciansfortheirinvaluablecontributionstothe construc-tion of the experiment and the CERN accelerator teams for the outstanding performance of the LHC complex. The ALICE Collab-oration gratefully acknowledges the resources and support pro-videdbyallGridcentresandtheWorldwideLHCComputingGrid (WLCG) collaboration. The ALICE Collaboration acknowledges the following fundingagenciesfortheir supportinbuildingand run-ningtheALICEdetector:A.I.AlikhanyanNationalScience Labora-tory(YerevanPhysicsInstitute)Foundation (ANSL),State Commit-teeofScienceandWorldFederationofScientists(WFS),Armenia; Austrian Academy of Sciences, Austrian Science Fund (FWF): [M 2467-N36] and Nationalstiftung für Forschung, Technologie und Entwicklung,Austria;MinistryofCommunicationsandHigh Tech-nologies, National Nuclear Research Center, Azerbaijan; Conselho Nacional de DesenvolvimentoCientífico e Tecnológico (CNPq), Fi-nanciadora de Estudose Projetos(Finep), Fundação de Amparoà Pesquisa do Estado de SãoPaulo (FAPESP) andUniversidade Fed-eraldoRioGrandedoSul(UFRGS),Brazil;MinistryofEducationof China (MOEC), MinistryofScience& Technology ofChina (MSTC) and NationalNatural Science Foundation of China (NSFC), China; Ministry of Science and Education and Croatian Science Founda-tion,Croatia;CentrodeAplicacionesTecnológicasyDesarrollo Nu-clear (CEADEN),Cubaenergía, Cuba;Ministry of Education, Youth and Sports of the Czech Republic, Czech Republic; The Danish Council for Independent Research | Natural Sciences, the Villum Fonden and Danish National Research Foundation (DNRF), Den-mark;Helsinki Institute ofPhysics(HIP), Finland;Commissariatà l’Énergie Atomique (CEA) and Institut National de Physique Nu-cléaire etde Physique desParticules(IN2P3)andCentre National de la Recherche Scientifique (CNRS), France; Bundesministerium für Bildung und Forschung (BMBF) and GSI Helmholtzzentrum fürSchwerionenforschungGmbH,Germany;GeneralSecretariatfor ResearchandTechnology,MinistryofEducation,Researchand Re-ligions,Greece;NationalResearchDevelopmentandInnovation Of-fice,Hungary; DepartmentofAtomicEnergy, GovernmentofIndia (DAE),DepartmentofScienceandTechnology,GovernmentofIndia (DST), University Grants Commission,Government ofIndia (UGC) andCouncil ofScientific andIndustrialResearch,India (CSIR), In-dia; Indonesian Institute of Science, Indonesia; Centro Fermi -MuseoStorico dellaFisica eCentroStudi e RicercheEnricoFermi andIstitutoNazionalediFisica Nucleare(INFN),Italy;Institutefor Innovative Science and Technology, Nagasaki Institute of Applied Science(IIST),JapaneseMinistryofEducation,Culture,Sports, Sci-enceandTechnology (MEXT)andJapan SocietyforthePromotion of Science (JSPS) KAKENHI, Japan; Consejo Nacional de Ciencia (CONACYT) y Tecnología, through Fondo de Cooperación Interna-cional enCienciay Tecnología(FONCICYT)andDirección General deAsuntosdelPersonalAcademico(DGAPA),Mexico;Nederlandse OrganisatievoorWetenschappelijkOnderzoek(NWO),Netherlands; TheResearchCouncil ofNorway, Norway;CommissiononScience

andTechnology forSustainableDevelopment inthe South (COM-SATS),Pakistan;PontificiaUniversidadCatólicadelPerú,Peru; Min-istry of Science and Higher Education, National Science Centre andWUT ID-UB,Poland; Korea Institute ofScience and Technol-ogyInformationandNationalResearchFoundationofKorea(NRF), Republicof Korea;Ministry of Education andScientific Research, Institute ofAtomic Physics andMinistryof Researchand Innova-tion andInstitute of Atomic Physics, Romania; Joint Institute for NuclearResearch(JINR), MinistryofEducationandScienceofthe Russian Federation, National Research Centre Kurchatov Institute, RussianScience Foundation andRussianFoundation forBasic Re-search,Russia;MinistryofEducation,Science,ResearchandSport oftheSlovak Republic, Slovakia; NationalResearchFoundation of South Africa, South Africa; Swedish Research Council (VR) and KnutandAliceWallenberg Foundation (KAW),Sweden;European OrganizationforNuclear Research,Switzerland;Suranaree Univer-sityofTechnology (SUT), NationalScienceandTechnology Devel-opmentAgency(NSDTA)andOfficeoftheHigherEducation Com-missionunderNRU project ofThailand,Thailand;Turkish Atomic Energy Agency (TAEK), Turkey; National Academy of Sciences of Ukraine,Ukraine;ScienceandTechnologyFacilitiesCouncil(STFC), UnitedKingdom;NationalScienceFoundationoftheUnitedStates ofAmerica(NSF) andUnited StatesDepartmentofEnergy, Office ofNuclearPhysics(DOENP),UnitedStatesofAmerica.

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ALICECollaboration

S. Acharya

141

,

D. Adamová

95

,

A. Adler

74

,

J. Adolfsson

81

,

M.M. Aggarwal

100

,

G. Aglieri Rinella

34

,

M. Al-Turany

107

,

S.N. Alam

40

,

141

,

D.S.D. Albuquerque

122

,

D. Aleksandrov

88

,

B. Alessandro

59

,

H.M. Alfanda

6

,

R. Alfaro Molina

71

,

B. Ali

16

,

Y. Ali

14

,

A. Alici

10

,

26

,

54

,

A. Alkin

2

,

34

,

J. Alme

21

,

T. Alt

68

,

L. Altenkamper

21

,

I. Altsybeev

113

,

M.N. Anaam

6

,

C. Andrei

48

,

D. Andreou

34

,

H.A. Andrews

111

,

A. Andronic

144

,

M. Angeletti

34

,

V. Anguelov

104

,

C. Anson

15

,

T. Antiˇci ´c

108

,

F. Antinori

57

,

P. Antonioli

54

,

N. Apadula

80

,

L. Aphecetche

115

,

H. Appelshäuser

68

,

S. Arcelli

26

,

R. Arnaldi

59

,

M. Arratia

80

,

I.C. Arsene

20

,

M. Arslandok

104

,

A. Augustinus

34

,

R. Averbeck

107

,

S. Aziz

78

,

M.D. Azmi

16

,

A. Badalà

56

,

Y.W. Baek

41

,

S. Bagnasco

59

,

X. Bai

107

,

R. Bailhache

68

,

R. Bala

101

,

A. Balbino

30

,

A. Baldisseri

137

,

M. Ball

43

,

S. Balouza

105

,

D. Banerjee

3

,

R. Barbera

27

,

L. Barioglio

25

,

G.G. Barnaföldi

145

,

L.S. Barnby

94

,

V. Barret

134

,

P. Bartalini

6

,

K. Barth

34

,

E. Bartsch

68

,

F. Baruffaldi

28

,

N. Bastid

134

,

S. Basu

143

,

G. Batigne

115

,

B. Batyunya

75

,

D. Bauri

49

,

J.L. Bazo Alba

112

,

I.G. Bearden

89

,

C. Beattie

146

,

C. Bedda

63

,

N.K. Behera

61

,

I. Belikov

136

,

A.D.C. Bell Hechavarria

144

,

F. Bellini

34

,

R. Bellwied

125

,

V. Belyaev

93

,

G. Bencedi

145

,

S. Beole

25

,

A. Bercuci

48

,

Y. Berdnikov

98

,

D. Berenyi

145

,

R.A. Bertens

130

,

D. Berzano

59

,

M.G. Besoiu

67

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L. Betev

34

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A. Bhasin

101

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I.R. Bhat

101

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M.A. Bhat

3

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H. Bhatt

49

,

B. Bhattacharjee

42

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A. Bianchi

25

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L. Bianchi

25

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N. Bianchi

52

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J. Bielˇcík

37

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J. Bielˇcíková

95

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A. Bilandzic

105

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G. Biro

145

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R. Biswas

3

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S. Biswas

3

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J.T. Blair

119

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D. Blau

88

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C. Blume

68

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G. Boca

139

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F. Bock

96

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A. Bogdanov

93

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S. Boi

23

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J. Bok

61

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L. Boldizsár

145

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A. Bolozdynya

93

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M. Bombara

38

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G. Bonomi

140

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H. Borel

137

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A. Borissov

93

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H. Bossi

146

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E. Botta

25

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L. Bratrud

68

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P. Braun-Munzinger

107

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M. Bregant

121

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M. Broz

37

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E. Bruna

59

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G.E. Bruno

106

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M.D. Buckland

127

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D. Budnikov

109

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H. Buesching

68

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S. Bufalino

30

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O. Bugnon

115

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P. Buhler

114

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P. Buncic

34

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Z. Buthelezi

72

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131

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J.B. Butt

14

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S.A. Bysiak

118

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D. Caffarri

90

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A. Caliva

107

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E. Calvo Villar

112

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R.S. Camacho

45

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P. Camerini

24

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A.A. Capon

114

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F. Carnesecchi

26

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R. Caron

137

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J. Castillo Castellanos

137

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A.J. Castro

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E.A.R. Casula

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F. Catalano

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C. Ceballos Sanchez

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P. Chakraborty

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S. Chandra

141

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W. Chang

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S. Chapeland

34

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M. Chartier

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S. Chattopadhyay

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S. Chattopadhyay

110

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A. Chauvin

23

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C. Cheshkov

135

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B. Cheynis

135

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V. Chibante Barroso

34

,

D.D. Chinellato

122

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S. Cho

61

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P. Chochula

34

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T. Chowdhury

134

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P. Christakoglou

90

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C.H. Christensen

89

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P. Christiansen

81

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T. Chujo

133

,

C. Cicalo

55

,

L. Cifarelli

10

,

26

,

F. Cindolo

54

,

G. Clai

54

,

ii

,

J. Cleymans

124

,

F. Colamaria

53

,

D. Colella

53

,

A. Collu

80

,

M. Colocci

26

,

M. Concas

59

,

iii

,

G. Conesa Balbastre

79

,

Z. Conesa del Valle

78

,

G. Contin

24

,

60

,

J.G. Contreras

37

,

T.M. Cormier

96

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Y. Corrales Morales

25

,

P. Cortese

31

,

M.R. Cosentino

123

,

F. Costa

34

,

S. Costanza

139

,

P. Crochet

134

,

E. Cuautle

69

,

P. Cui

6

,

L. Cunqueiro

96

,

D. Dabrowski

142

,

T. Dahms

105

,

A. Dainese

57

,

F.P.A. Damas

115

,

137

,

M.C. Danisch

104

,

A. Danu

67

,

D. Das

110

,

I. Das

110

,

P. Das

86

,

P. Das

3

,

S. Das

3

,

A. Dash

86

,

S. Dash

49

,

S. De

86

,

A. De Caro

29

,

G. de Cataldo

53

,

J. de Cuveland

39

,

A. De Falco

23

,

D. De Gruttola

10

,

N. De Marco

59

,

S. De Pasquale

29

,

S. Deb

50

,

H.F. Degenhardt

121

,

K.R. Deja

142

,

A. Deloff

85

,

S. Delsanto

25

,

131

,

W. Deng

6

,

D. Devetak

107

,

P. Dhankher

49

,

D. Di Bari

33

,

A. Di Mauro

34

,

R.A. Diaz

8

,

T. Dietel

124

,

P. Dillenseger

68

,

Y. Ding

6

,

R. Divià

34

,

D.U. Dixit

19

,

Ø. Djuvsland

21

,

U. Dmitrieva

62

,

A. Dobrin

67

,

B. Dönigus

68

,

O. Dordic

20

,

A.K. Dubey

141

,

A. Dubla

90

,

107

,

S. Dudi

100

,

M. Dukhishyam

86

,

P. Dupieux

134

,

R.J. Ehlers

96

,

146

,

V.N. Eikeland

21

,

D. Elia

53

,

E. Epple

146

,

B. Erazmus

115

,

F. Erhardt

99

,

A. Erokhin

113

,

M.R. Ersdal

21

,

B. Espagnon

78

,

G. Eulisse

34

,

D. Evans

111

,

S. Evdokimov

91

,

L. Fabbietti

105

,

M. Faggin

28

,

J. Faivre

79

,

F. Fan

6

,

A. Fantoni

52

,

M. Fasel

96

,

P. Fecchio

30

,

A. Feliciello

59

,

G. Feofilov

113

,

A. Fernández Téllez

45

,

A. Ferrero

137

,

A. Ferretti

25

,

A. Festanti

34

,

V.J.G. Feuillard

104

,

J. Figiel

118

,

S. Filchagin

109

,

D. Finogeev

62

,

F.M. Fionda

21

,

G. Fiorenza

53

,

F. Flor

125

,

A.N. Flores

119

,

S. Foertsch

72

,

P. Foka

107

,

S. Fokin

88

,

E. Fragiacomo

60

,

U. Frankenfeld

107

,

U. Fuchs

34

,

C. Furget

79

,

A. Furs

62

,

M. Fusco Girard

29

,

J.J. Gaardhøje

89

,

M. Gagliardi

25

,

A.M. Gago

112

,

A. Gal

136

,

C.D. Galvan

120

,

P. Ganoti

84

,

C. Garabatos

107

,

E. Garcia-Solis

11

,

K. Garg

115

,

C. Gargiulo

34

,

A. Garibli

87

,

K. Garner

144

,

P. Gasik

105

,

107

,

E.F. Gauger

119

,

M.B. Gay Ducati

70

,

M. Germain

115

,

J. Ghosh

110

,

P. Ghosh

141

,

S.K. Ghosh

3

,

M. Giacalone

26

,

P. Gianotti

52

,

P. Giubellino

59

,

107

,

P. Giubilato

28

,

P. Glässel

104

,

A. Gomez Ramirez

74

,

V. Gonzalez

107

,

143

,

L.H. González-Trueba

71

,

S. Gorbunov

39

,

L. Görlich

118

,

A. Goswami

49

,

S. Gotovac

35

,

V. Grabski

71

,

L.K. Graczykowski

142

,

K.L. Graham

111

,

L. Greiner

80

,

A. Grelli

63

,

C. Grigoras

34

,

V. Grigoriev

93

,

A. Grigoryan

1

,

S. Grigoryan

75

,

O.S. Groettvik

21

,

F. Grosa

30

,

59

,

J.F. Grosse-Oetringhaus

34

,

R. Grosso

107

,

R. Guernane

79

,

M. Guittiere

115

,

K. Gulbrandsen

89

,

T. Gunji

132

,

A. Gupta

101

,

R. Gupta

101

,

I.B. Guzman

45

,

R. Haake

146

,

M.K. Habib

107

,

C. Hadjidakis

78

,

H. Hamagaki

82

,

G. Hamar

145

,

M. Hamid

6

,

R. Hannigan

119

,

M.R. Haque

63

,

86

,

A. Harlenderova

107

,

J.W. Harris

146

,

A. Harton

11

,

J.A. Hasenbichler

34

,

H. Hassan

96

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D. Hatzifotiadou

10

,

54

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P. Hauer

43

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L.B. Havener

146

,

S. Hayashi

132

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S.T. Heckel

105

,