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EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH

CERN-PH-EP-2011-16130.09.2011

Particle-yield modification in jet-like azimuthal di-hadr on correlations inPb–Pb collisions at

√sNN = 2.76TeV

The ALICE Collaboration∗

Abstract

The yield of charged particles associated with high-pt trigger particles (8< pt < 15GeV/c) is mea-sured with the ALICE detector in Pb–Pb collisions at

√sNN = 2.76TeV relative to proton-proton

collisions at the same energy. The conditional per-triggeryields are extracted from the narrow jet-like correlation peaks in azimuthal di-hadron correlations. In the 5% most central collisions, weobserve that the yield of associated charged particles withtransverse momentapt > 3GeV/c on theaway-side drops to about 60% of that observed in pp collisions, while on the near-side a moderateenhancement of 20-30% is found.

∗See Appendix A for the list of collaboration members

Particle-yield modification in jet-like azimuthal di-hadron correlations in Pb–Pb . . . 3

1 Introduction

Ultra-relativistic heavy ion-collisions produce the quark–gluon plasma (QGP), the deconfined state ofquarks and gluons, and are used to explore its properties. Inthe last decade, important information aboutthe dynamical behavior of the QGP has been obtained from the study of hadron jets, the fragmentationproducts of high transverse momentum (pt) partons that are produced in initial hard scatterings of partonsfrom the incoming nuclei [1, 2]. It is generally accepted that prior to hadronization, partons lose energyin the high color-density medium due to gluon radiation and multiple collisions. These phenomena arebroadly known as jet quenching [3].

The energy loss was first observed at the Relativistic Heavy Ion Collider (RHIC) in Au–Au collisionsat

√sNN = 130GeV as a suppression of hadron yields with respect to the reference from pp collisions

at high pt (3-6 GeV/c) [4, 5]. At RHIC, distributions in relative azimuth∆ϕ = ϕtrig −ϕassocbetweenassociated particles with transverse momentapt,assocand trigger particles withpt,trig have been measured.These studies indicate that the peak shapes from high-pt (pt,trig > 4GeV/c and 2GeV/c < pt,assoc<pt,trig) di-hadron correlations in central Au–Au collisions are similar to those in small systems like ppand d–Au [6, 7], where correlations are dominated by jet fragmentation. The near-side peak at∆ϕ = 0 iscomparable in magnitude between all collision systems, while the away-side peak at∆ϕ = π is stronglysuppressed, corroborating the jet quenching patterns observed at RHIC. In central Au–Au collisions at√

sNN = 200GeV, the suppression amounts to a factor of 3−5 in the range 0.35< pt,assoc/pt,trig < 0.95for 8< pt,trig < 15GeV/c andpt,assoc> 3GeV/c [8].

At the LHC, the suppression of charged hadrons in central Pb–Pb collisions at√

sNN = 2.76TeV asexpressed by the nuclear modification factorRAA drops to 0.14 around 7GeV/c [9]. Furthermore, astrong di-jet energy asymmetry has been reported by the ATLAS and CMS collaborations [10, 11]. Adetailed study of the overall momentum balance in the di-jetevents shows evidence for sizable low-pt

radiation outside the cone of the subleading jet [11]. Theseanalyses use full event-by-event recon-struction of di-jets for leading jet transverse momenta above 100GeV/c. At lower transverse momenta(pt,jet < 50GeV/c) background fluctuations due to the underlying event dominate [12] and event-by-event jet reconstruction becomes difficult. Hence, di-hadron correlations are an interesting alternativeprobe. Measurements of di-hadron correlations in central Pb–Pb collisions compared to PYTHIA 8 [13]pp simulations have been presented in [14].

The extraction of the particle yield associated with a jet requires the removal of non-jet related back-ground which is primarily of collective origin (e.g., flow) at lower pt. this is non-trivial and, therefore,we concentrate in this letter on a regime where jet-like correlations dominate over collective effects:8< pt,trig < 15GeV/c for the trigger particle andpt,assoc> 3GeV/c for the associated particle [15]. Wepresent ratios of yields of central to peripheral collisions (ICP) and, for different centralities, of Pb–Pbto pp collisions (IAA ). IAA probes the interplay between the parton production spectrum, the relativeimportance of quark–quark, gluon–gluon and quark–gluon final states, and energy loss in the medium.On the near-side,IAA provides information about the fragmenting jet leaving themedium, while on theaway-side it additionally reflects the probability that therecoiling parton survives the passage throughthe medium. The sensitivity ofIAA andRAA to different properties of the medium makes the combinationparticularly effective in constraining models [16, 17].

2 Detector, Data Sets and Analysis

The ALICE detector is described in detail in [18]. The Inner Tracking System (ITS) and the TimeProjection Chamber (TPC) are used for vertex finding and tracking. The collision centrality is determinedwith the forward scintillators (VZERO) as well as for the estimation of the systematic uncertainty withthe first two layers of the ITS (Silicon Pixel Detector, SPD) and the Zero Degree Calorimeters (ZDCs).Details can be found in [19]. The main tracking detector is the TPC which allows reconstruction of

4 The ALICE Collaboration

0 2 40.4

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Pb-Pb 60-90% centrality

pp

c) background subtracted

Fig. 1: Corrected per-trigger pair yield for 4< pt,assoc< 6GeV/c for central Pb–Pb events (histogram), peripheralPb–Pb events (red circles) and pp events (blue squares). a) azimuthal correlation; b) zoom on the region wherethe pedestal values (horizontal lines) and thev2 component (cos2∆ϕ) are indicated. Solid lines are used in theyield extraction while the dashed lines are used for the estimation of the uncertainty of the pedestal calculation; c)background-subtracted distributions using the flat pedestal. Error bars indicate statistical uncertainties only.

good-quality tracks with a pseudorapidity coverage of|η | < 1.0 uniform in azimuth. The reconstructedvertex is used to select primary track candidates and to constrain thept of the track.

In this analysis 14 million minimum-bias Pb–Pb events recorded in fall 2010 at√

sNN = 2.76TeV as wellas 37 million pp events from March 2011 (

√s = 2.76TeV) are used. These include only events where

the TPC was fully efficient to ensure uniform azimuthal acceptance. Events are accepted which havea reconstructed vertex less than 7cm from the nominal interaction point in beam direction. Tracks areselected by requiring at least 70 (out of up to 159) associated clusters in the TPC, and aχ2 per space pointof the momentum fit smaller than 4 (with 2 degrees of freedom per space point). In addition, tracks arerequired to originate from within 2.4 cm (3.2 cm) in transverse (longitudinal) distance from the primaryvertex.

For the measurement ofIAA andICP the yield of associated particles per trigger particle is studied as afunction of the azimuthal angle difference∆ϕ . This distribution is given by 1/Ntrig dNassoc/d∆ϕ whereNtrig is the number of trigger particles andNassocis the number of associated particles. We measure thisquantity for all pairs of particles wherept,assoc< pt,trig within |η | < 1.0 as a function ofpt,assoc. Pairacceptance corrections have been evaluated with a mixed-event technique but found to be negligible forthe yield ratios due to the constant acceptance inϕ and the same detector conditions for the differentdata sets.

Corrections for detector efficiency (17-18% depending on collision system,pt and centrality) and con-tamination (4-8%) by secondary particles from particle–material interactions,γ conversions and weak-

Particle-yield modification in jet-like azimuthal di-hadron correlations in Pb–Pb . . . 5

decay products of long-lived particles are applied for trigger and associated particles, separately. Addi-tional secondary particles correlated with the trigger particle are found close to∆ϕ = 0 in particular dueto decays andγ conversions. We correct for this contribution (2-4%). These corrections are evaluatedwith the HIJING 1.36 [20] Monte Carlo (MC) generator which was tuned to reproduce the measuredmultiplicity density [19] for Pb–Pb and the PYTHIA 6 [21] MC with tune Perugia-0 [22] for pp usingin both cases a detector simulation based on GEANT3 [23]. MC simulations underestimate the numberof secondary particles. Therefore, we study the distribution of the distance of closest approach betweentracks and the event vertex. The tail of this distribution isdominantly populated by secondary particlesand the comparison of data and MC shows that the secondary yield in MC needs to be increased by about10% (depending onpt). An MC study shows that effects of the event selection and vertex reconstruc-tion are negligible for the extracted observables. The correction procedure was validated by comparingcorrected simulated events with the MC truth.

Figure 1a shows a typical distribution of the corrected per-trigger pair yield before background subtrac-tion. The fact that the∆ϕ distribution is flat outside the near- and away-side region gives us confidencethat the background can be estimated with the zero yield at minimum (ZYAM) assumption. This proce-dure estimates the pedestal value by fitting the flat region close to the minimum of the∆ϕ distribution(|∆ϕ −π/2|< 0.4) with a constant. The validity of the ZYAM assumption has been questioned in caseswhere collective effects dominate [24, 25]; however, for the high-pt correlations of this analysis, thenarrow width and large amplitude of the correlated signal compared to the flow modulation drasticallyreduce the ZYAM bias. Therefore, we define the integrated associated yield as the signal over a flatuncorrelated background. Figure 1b illustrates the background determination. Also indicated is a back-ground shape accounting for elliptic flowv2, the second coefficient of the particle azimuthal distributionmeasured with respect to the reaction plane. It is given by 2v2,trigv2,assoccos2∆ϕ wherev2,trig (v2,assoc)is the elliptic flow of the trigger (associated) particles. The v2 values are taken from an independentmeasurement [26] which shows a measurement ofv2 up to pt = 5GeV/c. As an upper limit we use themeasuredv2 for pt = 5GeV/c also for largerpt wherev2 is expected to decrease. For the centrality class60-90% nov2 measurement is available, therefore, as an upper limit,v2 is taken from the 40-50% cen-trality class. Sincev2 decreases from mid-central to peripheral collisions and the flat pedestal assumesv2 = 0, this includes all reasonable values ofv2.

Contributions from∆η-independent correlations (e.g., due to flow harmonics) canalso be removed onthe near-side (where the jet peak is centered around∆η ≈ 0) by calculating the per-trigger pair yield inthe region|∆η |< 1 and subtracting the contribution from 1< |∆η | < 2 normalized for the acceptance.This prescription, which we call theη-gap method, provides a measurement independent of the flowstrength.

In Fig. 1c the flat-pedestal subtracted distributions of central and peripheral Pb–Pb collisions are com-pared to that of pp collisions. The integral over those distributions in the region where the signal issignificantly above the background, i.e., within∆ϕ of ±0.7 andπ ±0.7 results in the near- and away-side yields per trigger particle (Y ), respectively. This procedure samples the same fraction of the signalin Pb–Pb and pp collisions, since in thept-range used for this study the width of the peaks is similar forboth systems. The yields are used to compute the ratioIAA = YPb−Pb/Ypp whereYPb−Pb (Ypp) is the yieldin Pb–Pb (pp) collisions and the ratioICP = Y0-5%/Y60-90% whereY0-5% (Y60-90%) is the yield in central(peripheral) Pb–Pb collisions.

Systematic Uncertainties The uncertainty from the pedestal determination has been estimated bycomparing different pedestal evaluation strategies (see Fig. 1b). The constant-fit region has been shiftedand an average of the 8 (out of 36) lowest∆ϕ points has been used. The integration window for thenear- and away-side has been varied between±0.5 and±0.9. The effect of detector efficiency and trackselection has been studied by systematically varying the track cuts. Track splitting and merging effectswere assessed by studying the tracking performance as a function of the distance of closest approach of

6 The ALICE Collaboration

Uncertainty IAA ICP

Near-S. Away-S. Near-S. Away-S.Pedestal calculation 5% 5-20% 5% 20%Integration window 0 3% 0 3%Tracking efficiency 4%Two-track effects < 1%

Corrections 2% 1%Centrality selection 2% 3%

Total 7% 8-21% 7% 21%

Table 1: Systematic uncertainties evaluated separately for near-side and away-side. Ranges indicate differentvalues for different centrality ranges: the smaller (larger) number is for peripheral (central) events.

the track pairs in the detector volume. A bias due to thept resolution on the extracted yields was evalu-ated by folding the detector resolution with the extracted associated spectrum and found to be negligible.The sensitivity of the corrections to details of the MC has been studied by varying the particle compo-sition, the material budget and the MC generator (using AMPT [27] and PHOJET [28]). Uncertainties inthe centrality determination were evaluated by comparing results obtained with the different centralityestimates from the VZERO, the SPD and ZDCs [19]. Table 1 liststhe size of the different contributionsto the systematic uncertainties forIAA andICP as well as their sum in quadrature.

3 Results

Figure 2a shows the yield ratioIAA for central (0-5% Pb–Pb/pp) and peripheral (60-90% Pb–Pb/pp)collisions using the three background subtraction schemesdiscussed. The fact that the only significantdifference between the different background subtraction schemes is in the lowest bin ofpt,assocconfirmsthe assumption of only a small bias due to flow anisotropies inthis pt region. In central collisions, anaway-side suppression consistent with in-medium energy loss is observed (IAA ≈ 0.6). Moreover, thereis an enhancement above unity of 20-30% on the near-side which has not been observed previously withany significance at lower collision energies [8]. In peripheral collisions, both the near- and away-sideIAA measurements approach, as expected, unity.

Figure 2b shows the yield ratioICP. As for IAA , the influence of the flow modulation is small and onlysignificant in the lowestpt,assocbin. ICP is consistent withIAA in central collisions with respect to thenear-side enhancement and the away-side suppression.

Comparison to RHIC Similar measurements have been performed at RHIC. Althoughthe same rangein pt,trig does not necessarily probe the same partonpt region at different

√s, we assess changes from

RHIC to LHC in the following. The STAR measurement [8] (whichincludes only statistical uncer-tainties) of the near-sideIAA is consistent with unity, albeit with a large uncertainty (18-40%). On theaway-side the result from STAR is about 50% lower than the results shown in Fig. 2. We also calculatedIAA for the 20% most central events to compare to PHENIX [7] (onlyv2-subtracted data on the away-sideavailable). Forpt,assoc< 4GeV/c, the flow influence in this centrality interval is about 75%, too large toprovide a reliable measurement. For 4< pt,assoc< 10GeV/c, thev2-subtractedIAA is 0.5−0.6±0.08.This result is slightly larger than results from PHENIX in a similar pt,trig-region of 7< pt,trig < 9GeV/c:0.31± 0.07 and 0.38± 0.11 for pt,assoc≈ 3.5GeV/c and 5.8GeV/c, respectively. In conclusion, theobserved away-side suppression at LHC is less than at RHIC (IAA is larger), while the single-hadronsuppressionRAA is found to be slightly larger (RAA is smaller) than at RHIC [9].

Near-Side Enhancement These measurements represent the first observation of a significant near-sideenhancement ofIAA andICP in the pt region studied, suggesting that the near-side parton is also subject

Particle-yield modification in jet-like azimuthal di-hadron correlations in Pb–Pb . . . 7

)c (GeV/t,assoc

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Flat bkg bkg2v

-gapη

Fig. 2: a) IAA for central (0-5% Pb–Pb/pp, open black symbols) and peripheral (60-90% Pb–Pb/pp, filled redsymbols) collisions and b)ICP. Results using different background subtraction schemes are presented: using aflat pedestal (squares), usingv2 subtraction (diamonds) and subtracting the large|∆η |-region (circles, only on thenear-side). The line shows a PYTHIA 8 study illustrating the effect of gluon filtering in the medium. For detailssee text. For clarity, the data points are slightly displaced on thept,assoc-axis. The shaded bands denote systematicuncertainties.

to medium effects. Two other observations in the same transverse momentum region can provide insightinto possible explanations of the near-side enhancement: the strong suppression of the trigger particles(RAA ≈ 0.2) and the rising slope ofRAA(pt) [9]. The productRAA(pt,trig)IAA (pt,trig, pt,assoc) measuresthe hadron-pair suppressionJAA (pt,trig, pt,assoc) [29]. Assuming no modification of the fragmentationfunction, on the near-side,JAA (pt,trig, pt,assoc) is approximatelyRAA(pt,trig + pt,assoc). Then a risingRAA

directly leads to anIAA above unity, increasing withpt,assoc.

Another argument for the modification ofIAA on the near-side can be derived from the fact that gluonshave a stronger coupling to the medium and are therefore subject to a larger energy loss as comparedto quarks. Hence, in Pb–Pb collisions the trigger particlesmay come predominantly from quark frag-mentation as opposed to the gluon dominated pp reference [30]. At LHC energies, hadrons from quark

8 The ALICE Collaboration

fragmentation carry a higher fraction of the initial partonmomentum than those from gluons. Therefore,these hadrons originate from a smaller partonpt on average, leading to a diminished associated particleproduction. This in turn would lead toIAA < 1. We use the PYTHIA 8.15 event generator (tune 4C) [13]to quantify this effect. The solid line in Fig. 2a shows the associated hadron yield from quarks relative tothe one from the standard quark and gluon mixture.

Following the above arguments, we note that the combined measurement ofRAA andIAA is sensitive tothe interplay of energy loss and the change of the fragmentation pattern in the medium.

In summary, the modification of the per-trigger yield of associated particles,IAA and ICP, has beenextracted from di-hadron correlations in Pb–Pb collisionsat

√sNN = 2.76TeV. In central collisions, on

the away-side, suppression (IAA ≈ 0.6) is observed as expected from strong in-medium energy loss. Onthe near-side, a significant enhancement (IAA ≈ 1.2) has been reported for the first time. Along with themeasurement ofRAA , IAA provides strong constraints on the quenching mechanism in the hot and densematter produced.

4 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 acknowledges the following funding agencies for their support in building andrunning the ALICE detector: Department of Science and Technology, South Africa; Calouste GulbenkianFoundation from Lisbon and Swiss Fonds Kidagan, Armenia; Conselho Nacional de DesenvolvimentoCientıfico e Tecnologico (CNPq), Financiadora de Estudose Projetos (FINEP), Fundacao de Amparo aPesquisa do Estado de Sao Paulo (FAPESP); National NaturalScience Foundation of China (NSFC), theChinese Ministry of Education (CMOE) and the Ministry of Science and Technology of China (MSTC);Ministry of Education and Youth of the Czech Republic; Danish Natural Science Research Council, theCarlsberg Foundation and the Danish National Research Foundation; The European Research Councilunder the European Community’s Seventh Framework Programme; Helsinki Institute of Physics andthe Academy of Finland; French CNRS-IN2P3, the ‘Region Paysde Loire’, ‘Region Alsace’, ‘RegionAuvergne’ and CEA, France; German BMBF and the Helmholtz Association; General Secretariat forResearch and Technology, Ministry of Development, Greece;Hungarian OTKA and National Officefor Research and Technology (NKTH); Department of Atomic Energy and Department of Science andTechnology of the Government of India; Istituto Nazionale di Fisica Nucleare (INFN) of Italy; MEXTGrant-in-Aid for Specially Promoted Research, Japan; Joint Institute for Nuclear Research, Dubna; Na-tional Research Foundation of Korea (NRF); CONACYT, DGAPA,Mexico, ALFA-EC and the HELENProgram (High-Energy physics Latin-American–European Network); Stichting voor Fundamenteel On-derzoek der Materie (FOM) and the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO),Netherlands; Research Council of Norway (NFR); Polish Ministry of Science and Higher Education;National Authority for Scientific Research - NASR (Autoritatea Nationala pentru Cercetare Stiintifica- ANCS); Federal Agency of Science of the Ministry of Education and Science of Russian Federation,International Science and Technology Center, Russian Academy of Sciences, Russian Federal Agencyof Atomic Energy, Russian Federal Agency for Science and Innovations and CERN-INTAS; Ministry ofEducation of Slovakia; CIEMAT, EELA, Ministerio de Educacion y Ciencia of Spain, Xunta de Gali-cia (Consellerıa de Educacion), CEADEN, Cubaenergıa, Cuba, and IAEA (International Atomic EnergyAgency); Swedish Reseach Council (VR) and Knut & Alice Wallenberg Foundation (KAW); UkraineMinistry of Education and Science; United Kingdom Science and Technology Facilities Council (STFC);The United States Department of Energy, the United States National Science Foundation, the State ofTexas, and the State of Ohio.

Particle-yield modification in jet-like azimuthal di-hadron correlations in Pb–Pb . . . 9

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10 The ALICE Collaboration

A The ALICE Collaboration

K. Aamodt1 , B. Abelev2 , A. Abrahantes Quintana3 , D. Adamova4 , A.M. Adare5 , M.M. Aggarwal6 ,G. Aglieri Rinella7 , A.G. Agocs8 , A. Agostinelli9 , S. Aguilar Salazar10 , Z. Ahammed11 , N. Ahmad12 ,A. Ahmad Masoodi12 , S.U. Ahn13 ,i, A. Akindinov14 , D. Aleksandrov15 , B. Alessandro16 , R. Alfaro Molina10 ,A. Alici 17 ,ii, A. Alkin18 , E. Almaraz Avina10 , J. Alme19 , T. Alt20 , V. Altini 21 , S. Altinpinar1 , I. Altsybeev22 ,C. Andrei23 , A. Andronic24 , V. Anguelov20 ,iii, J. Anielski25 , T. Anticic26 , F. Antinori27 , P. Antonioli28 ,L. Aphecetche29 , H. Appelshauser30 , N. Arbor31 , S. Arcelli9 , A. Arend30 , N. Armesto32 , R. Arnaldi16 ,T. Aronsson5 , I.C. Arsene24 , M. Arslandok30 , A. Asryan22 , A. Augustinus7 , R. Averbeck24 , T.C. Awes33 ,J. Aysto34 , M.D. Azmi12 , M. Bach20 , A. Badala35 , Y.W. Baek13 ,iv, R. Bailhache30 , R. Bala16 ,R. Baldini Ferroli17 , A. Baldisseri36 , A. Baldit37 , F. Baltasar Dos Santos Pedrosa7 , J. Ban38 , R.C. Baral39 ,R. Barbera40 , F. Barile21 , G.G. Barnafoldi8 , L.S. Barnby41 , V. Barret37 , J. Bartke42 , M. Basile9 , N. Bastid37 ,B. Bathen25 , G. Batigne29 , B. Batyunya43 , C. Baumann30 , I.G. Bearden44 , H. Beck30 , I. Belikov45 , F. Bellini9 ,R. Bellwied46 , E. Belmont-Moreno10 , S. Beole47 , I. Berceanu23 , A. Bercuci23 , Y. Berdnikov48 , D. Berenyi8 ,C. Bergmann25 , L. Betev7 , A. Bhasin49 , A.K. Bhati6 , L. Bianchi47 , N. Bianchi50 , C. Bianchin51 , J. Bielcık52 ,J. Bielcıkova4 , A. Bilandzic53 , E. Biolcati47 , F. Blanco54 , F. Blanco46 , D. Blau15 , C. Blume30 , N. Bock55 ,A. Bogdanov56 , H. Bøggild44 , M. Bogolyubsky57 , L. Boldizsar8 , M. Bombara58 , C. Bombonati51 , J. Book30 ,H. Borel36 , A. Borissov59 , C. Bortolin51 ,v, S. Bose60 , F. Bossu47 , M. Botje53 , S. Bottger61 , B. Boyer62 ,P. Braun-Munzinger24 , M. Bregant29 , T. Breitner61 , M. Broz63 , R. Brun7 , E. Bruna5 ,vi, G.E. Bruno21 ,D. Budnikov64 , H. Buesching30 , S. Bufalino16 , K. Bugaiev18 , O. Busch65 , Z. Buthelezi66 , D. Caffarri51 ,X. Cai67 , H. Caines5 , E. Calvo Villar68 , P. Camerini69 , V. Canoa Roman70 ,vii, G. Cara Romeo28 , F. Carena7 ,W. Carena7 , F. Carminati7 , A. Casanova Dıaz50 , M. Caselle7 , J. Castillo Castellanos36 , E.A.R. Casula71 ,V. Catanescu23 , C. Cavicchioli7 , J. Cepila52 , P. Cerello16 , B. Chang34 , S. Chapeland7 , J.L. Charvet36 ,S. Chattopadhyay60 , S. Chattopadhyay11 , M. Cherney72 , C. Cheshkov73 , B. Cheynis73 , E. Chiavassa16 ,V. Chibante Barroso7 , D.D. Chinellato74 , P. Chochula7 , M. Chojnacki75 , P. Christakoglou75 ,C.H. Christensen44 , P. Christiansen76 , T. Chujo77 , S.U. Chung78 , C. Cicalo79 , L. Cifarelli9 ,viii , F. Cindolo28 ,J. Cleymans66 , F. Coccetti17 , J.-P. Coffin45 , F. Colamaria21 , D. Colella21 , G. Conesa Balbastre31 ,Z. Conesa del Valle45 ,ix, P. Constantin65 , G. Contin69 , J.G. Contreras70 , T.M. Cormier59 ,Y. Corrales Morales47 , I. Cortes Maldonado80 , P. Cortese81 , M.R. Cosentino74 ,x, F. Costa7 , M.E. Cotallo54 ,P. Crochet37 , E. Cruz Alaniz10 , E. Cuautle82 , L. Cunqueiro50 , G. D Erasmo21 , A. Dainese27 , H.H. Dalsgaard44 ,A. Danu83 , D. Das60 , I. Das60 , K. Das60 , A. Dash74 , S. Dash16 , S. De11 , A. De Azevedo Moregula50 ,G.O.V. de Barros84 , A. De Caro85 ,xi, G. de Cataldo86 , J. de Cuveland20 , A. De Falco71 , D. De Gruttola85 ,N. De Marco16 , S. De Pasquale85 , R. de Rooij75 , E. Del Castillo Sanchez7 , H. Delagrange29 , A. Deloff87 ,V. Demanov64 , E. Denes8 , A. Deppman84 , D. Di Bari21 , C. Di Giglio21 , S. Di Liberto88 , A. Di Mauro7 ,P. Di Nezza50 , T. Dietel25 , R. Divia7 , Ø. Djuvsland1 , A. Dobrin59 , T. Dobrowolski87 , I. Domınguez82 ,B. Donigus24 , O. Dordic89 , O. Driga29 , A.K. Dubey11 , L. Ducroux73 , P. Dupieux37 , A.K. Dutta Majumdar60 ,M.R. Dutta Majumdar11 , D. Elia86 , D. Emschermann25 , H. Engel61 , H.A. Erdal19 , B. Espagnon62 ,M. Estienne29 , S. Esumi77 , D. Evans41 , G. Eyyubova89 , D. Fabris27 , J. Faivre31 , D. Falchieri9 , A. Fantoni50 ,M. Fasel24 , R. Fearick66 , A. Fedunov43 , D. Fehlker1 , D. Felea83 , B. Fenton-Olsen90 , G. Feofilov22 ,A. Fernandez Tellez80 , E.G. Ferreiro32 , A. Ferretti47 , R. Ferretti81 , J. Figiel42 , M.A.S. Figueredo84 ,S. Filchagin64 , R. Fini86 , D. Finogeev91 , F.M. Fionda21 , E.M. Fiore21 , M. Floris7 , S. Foertsch66 , P. Foka24 ,S. Fokin15 , E. Fragiacomo92 , M. Fragkiadakis93 , U. Frankenfeld24 , U. Fuchs7 , C. Furget31 , M. Fusco Girard85 ,J.J. Gaardhøje44 , M. Gagliardi47 , A. Gago68 , M. Gallio47 , D.R. Gangadharan55 , P. Ganoti33 , C. Garabatos24 ,E. Garcia-Solis94 , I. Garishvili2 , J. Gerhard20 , M. Germain29 , C. Geuna36 , A. Gheata7 , M. Gheata7 ,B. Ghidini21 , P. Ghosh11 , P. Gianotti50 , M.R. Girard95 , P. Giubellino47 ,ix, E. Gladysz-Dziadus42 , P. Glassel65 ,R. Gomez96 , L.H. Gonzalez-Trueba10 , P. Gonzalez-Zamora54 , S. Gorbunov20 , A. Goswami97 , S. Gotovac98 ,V. Grabski10 , L.K. Graczykowski95 , R. Grajcarek65 , A. Grelli75 , A. Grigoras7 , C. Grigoras7 , V. Grigoriev56 ,A. Grigoryan99 , S. Grigoryan43 , B. Grinyov18 , N. Grion92 , J.F. Grosse-Oetringhaus7 , J.-Y. Grossiord73 ,F. Guber91 , R. Guernane31 , C. Guerra Gutierrez68 , B. Guerzoni9 , M. Guilbaud73 , K. Gulbrandsen44 ,T. Gunji100 , A. Gupta49 , R. Gupta49 , H. Gutbrod24 , Ø. Haaland1 , C. Hadjidakis62 , M. Haiduc83 ,H. Hamagaki100 , G. Hamar8 , L.D. Hanratty41 , Z. Harmanova58 , J.W. Harris5 , M. Hartig30 , D. Hasegan83 ,D. Hatzifotiadou28 , A. Hayrapetyan99 ,viii, M. Heide25 , H. Helstrup19 , A. Herghelegiu23 , G. Herrera Corral70 ,N. Herrmann65 , K.F. Hetland19 , B. Hicks5 , P.T. Hille5 , B. Hippolyte45 , T. Horaguchi77 , Y. Hori100 ,P. Hristov7 , I. Hrivnacova62 , M. Huang1 , S. Huber24 , T.J. Humanic55 , D.S. Hwang101 , R. Ichou37 , R. Ilkaev64 ,I. Ilkiv 87 , M. Inaba77 , E. Incani71 , G.M. Innocenti47 , M. Ippolitov15 , M. Irfan12 , C. Ivan24 , A. Ivanov22 ,M. Ivanov24 , V. Ivanov48 , O. Ivanytskyi18 , P.M. Jacobs90 , L. Jancurova43 , S. Jangal45 , M.A. Janik95 ,R. Janik63 , P.H.S.Y. Jayarathna46 , S. Jena102 , R.T. Jimenez Bustamante82 , L. Jirden7 , P.G. Jones41 , H. Jung13 ,

Particle-yield modification in jet-like azimuthal di-hadron correlations in Pb–Pb . . . 11

W. Jung13 , A. Jusko41 , S. Kalcher20 , P. Kalinak38 , M. Kalisky25 , T. Kalliokoski34 , A. Kalweit103 , K. Kanaki1 ,J.H. Kang104 , V. Kaplin56 , A. Karasu Uysal7 , O. Karavichev91 , T. Karavicheva91 , E. Karpechev91 ,A. Kazantsev15 , U. Kebschull61 , R. Keidel105 , M.M. Khan12 , P. Khan60 , S.A. Khan11 , A. Khanzadeev48 ,Y. Kharlov57 , B. Kileng19 , B. Kim104 , D.J. Kim34 , D.W. Kim13 , J.H. Kim101 , J.S. Kim13 , M. Kim104 ,S. Kim101 , S.H. Kim13 , T. Kim104 , S. Kirsch20 , I. Kisel20 , S. Kiselev14 , A. Kisiel7 ,xii, J.L. Klay106 , J. Klein65 ,C. Klein-Bosing25 , M. Kliemant30 , A. Kluge7 , M.L. Knichel24 , K. Koch65 , M.K. Kohler24 , A. Kolojvari22 ,V. Kondratiev22 , N. Kondratyeva56 , A. Konevskikh91 , C. Kottachchi Kankanamge Don59 , R. Kour41 ,M. Kowalski42 , S. Kox31 , G. Koyithatta Meethaleveedu102, J. Kral34 , I. Kralik38 , F. Kramer30 , I. Kraus24 ,T. Krawutschke65 ,xiii, M. Kretz20 , M. Krivda41 ,xiv, F. Krizek34 , M. Krus52 , E. Kryshen48 , M. Krzewicki53 ,Y. Kucheriaev15 , C. Kuhn45 , P.G. Kuijer53 , P. Kurashvili87 , A. Kurepin91 , A.B. Kurepin91 , A. Kuryakin64 ,S. Kushpil4 , V. Kushpil4 , M.J. Kweon65 , Y. Kwon104 , P. La Rocca40 , P. Ladron de Guevara82 , I. Lakomov22 ,C. Lara61 , A. Lardeux29 , D.T. Larsen1 , C. Lazzeroni41 , Y. Le Bornec62 , R. Lea69 , M. Lechman7 , K.S. Lee13 ,S.C. Lee13 , F. Lefevre29 , J. Lehnert30 , L. Leistam7 , M. Lenhardt29 , V. Lenti86 , I. Leon Monzon96 ,H. Leon Vargas30 , P. Levai8 , X. Li107 , J. Lien1 , R. Lietava41 , S. Lindal89 , V. Lindenstruth20 , C. Lippmann24 ,M.A. Lisa55 , L. Liu1 , P.I. Loenne1 , V.R. Loggins59 , V. Loginov56 , S. Lohn7 , D. Lohner65 , C. Loizides90 ,K.K. Loo34 , X. Lopez37 , E. Lopez Torres3 , G. Løvhøiden89 , X.-G. Lu65 , P. Luettig30 , M. Lunardon51 ,J. Luo67 , G. Luparello47 , L. Luquin29 , C. Luzzi7 , R. Ma5 , A. Maevskaya91 , M. Mager7 , D.P. Mahapatra39 ,A. Maire45 , M. Malaev48 , I. Maldonado Cervantes82 , L. Malinina43 ,xv, D. Mal’Kevich14 , P. Malzacher24 ,A. Mamonov64 , L. Manceau16 , V. Manko15 , F. Manso37 , V. Manzari86 , Y. Mao67 ,xvi, M. Marchisone47 ,i,J. Mares108 , G.V. Margagliotti69 , A. Margotti28 , A. Marın24 , C. Markert109 , I. Martashvili110 , P. Martinengo7 ,M.I. Martınez80 , A. Martınez Davalos10 , G. Martınez Garcıa29 , Y. Martynov18 , A. Mas29 , S. Masciocchi24 ,M. Masera47 , A. Masoni79 , L. Massacrier73 , M. Mastromarco86 , A. Mastroserio7 ,xvii, Z.L. Matthews41 ,A. Matyja42 ,xviii, D. Mayani82 , C. Mayer42 , M.A. Mazzoni88 , F. Meddi111 , A. Menchaca-Rocha10 ,J. Mercado Perez65 , M. Meres63 , Y. Miake77 , A. Michalon45 , J. Midori112 , L. Milano47 , J. Milosevic89 ,xix,A. Mischke75 , A.N. Mishra97 , D. Miskowiec7 , C. Mitu83 , J. Mlynarz59 , A.K. Mohanty7 , B. Mohanty11 ,L. Molnar7 , L. Montano Zetina70 , M. Monteno16 , E. Montes54 , T. Moon104 , M. Morando51 ,D.A. Moreira De Godoy84 , S. Moretto51 , A. Morsch7 , V. Muccifora50 , E. Mudnic98 , H. Muller7 , S. Muhuri11 ,M.G. Munhoz84 , L. Musa7 , A. Musso16 , B.K. Nandi102 , R. Nania28 , E. Nappi86 , C. Nattrass110 ,N.P. Naumov64 , S. Navin41 , T.K. Nayak11 , S. Nazarenko64 , G. Nazarov64 , A. Nedosekin14 , M. Nicassio21 ,B.S. Nielsen44 , T. Niida77 , S. Nikolaev15 , V. Nikolic26 , S. Nikulin15 , V. Nikulin48 , B.S. Nilsen72 ,M.S. Nilsson89 , F. Noferini17 ,ii, P. Nomokonov43 , G. Nooren75 , N. Novitzky34 , A. Nyanin15 , A. Nyatha102 ,C. Nygaard44 , J. Nystrand1 , H. Obayashi112 , A. Ochirov22 , H. Oeschler103 , S.K. Oh13 , J. Oleniacz95 ,C. Oppedisano16 , A. Ortiz Velasquez82 , G. Ortona47 , A. Oskarsson76 , I. Otterlund76 , J. Otwinowski24 ,G. Øvrebekk1 , K. Oyama65 , Y. Pachmayer65 , M. Pachr52 , F. Padilla47 , P. Pagano85 , G. Paic82 , F. Painke20 ,C. Pajares32 , S. Pal36 , S.K. Pal11 , A. Palaha41 , A. Palmeri35 , G.S. Pappalardo35 , W.J. Park24 , A. Passfeld25 ,D.I. Patalakha57 , V. Paticchio86 , A. Pavlinov59 , T. Pawlak95 , T. Peitzmann75 , E. Pereira De Oliveira Filho84 ,D. Peresunko15 , C.E. Perez Lara53 , E. Perez Lezama82 , D. Perini7 , D. Perrino21 , W. Peryt95 , A. Pesci28 ,V. Peskov7 ,xx, Y. Pestov113 , V. Petracek52 , M. Petran52 , M. Petris23 , P. Petrov41 , M. Petrovici23 , C. Petta40 ,S. Piano92 , A. Piccotti16 , M. Pikna63 , P. Pillot29 , O. Pinazza7 , L. Pinsky46 , N. Pitz30 , F. Piuz7 ,D.B. Piyarathna46 , M. Płoskon90 , J. Pluta95 , T. Pocheptsov43 , S. Pochybova8 , P.L.M. Podesta-Lerma96 ,M.G. Poghosyan47 , B. Polichtchouk57 , A. Pop23 , S. Porteboeuf-Houssais37 , V. Pospısil52 , B. Potukuchi49 ,S.K. Prasad59 , R. Preghenella17 ,ii, F. Prino16 , C.A. Pruneau59 , I. Pshenichnov91 , G. Puddu71 , A. Pulvirenti40 ,V. Punin64 , M. Putis58 , J. Putschke5 ,xxi, E. Quercigh7 , H. Qvigstad89 , A. Rachevski92 , A. Rademakers7 ,S. Radomski65 , T.S. Raiha34 , J. Rak34 , A. Rakotozafindrabe36 , L. Ramello81 , A. Ramırez Reyes70 ,R. Raniwala97 , S. Raniwala97 , S.S. Rasanen34 , B.T. Rascanu30 , D. Rathee6 , K.F. Read110 , J.S. Real31 ,K. Redlich87 , P. Reichelt30 , M. Reicher75 , R. Renfordt30 , A.R. Reolon50 , A. Reshetin91 , F. Rettig20 ,J.-P. Revol7 , K. Reygers65 , H. Ricaud103 , L. Riccati16 , R.A. Ricci114 , M. Richter1 ,xxii, P. Riedler7 ,W. Riegler7 , F. Riggi40 , M. Rodrıguez Cahuantzi80 , D. Rohr20 , D. Rohrich1 , R. Romita24 , F. Ronchetti50 ,P. Rosnet37 , S. Rossegger7 , A. Rossi51 , F. Roukoutakis93 , C. Roy45 , P. Roy60 , A.J. Rubio Montero54 , R. Rui69 ,E. Ryabinkin15 , A. Rybicki42 , S. Sadovsky57 , K. Safarık7 , P.K. Sahu39 , J. Saini11 , H. Sakaguchi112 , S. Sakai90 ,D. Sakata77 , C.A. Salgado32 , S. Sambyal49 , V. Samsonov48 , X. Sanchez Castro82 , L. Sandor38 , A. Sandoval10 ,M. Sano77 , S. Sano100 , R. Santo25 , R. Santoro86 ,ix, J. Sarkamo34 , E. Scapparone28 , F. Scarlassara51 ,R.P. Scharenberg115, C. Schiaua23 , R. Schicker65 , C. Schmidt24 , H.R. Schmidt24 ,xxiii, S. Schreiner7 ,S. Schuchmann30 , J. Schukraft7 , Y. Schutz29 ,viii, K. Schwarz24 , K. Schweda65 ,xxiv, G. Scioli9 , E. Scomparin16 ,P.A. Scott41 , R. Scott110 , G. Segato51 , I. Selyuzhenkov24 , S. Senyukov81 ,xxv, S. Serci71 , E. Serradilla10 ,xxvi,A. Sevcenco83 , I. Sgura86 , G. Shabratova43 , R. Shahoyan7 , N. Sharma6 , S. Sharma49 , K. Shigaki112 ,

12 The ALICE Collaboration

M. Shimomura77 , K. Shtejer3 , Y. Sibiriak15 , M. Siciliano47 , E. Sicking7 , S. Siddhanta79 , T. Siemiarczuk87 ,D. Silvermyr33 , G. Simonetti7 , R. Singaraju11 , R. Singh49 , S. Singha11 , B.C. Sinha11 , T. Sinha60 , B. Sitar63 ,M. Sitta81 , T.B. Skaali89 , K. Skjerdal1 , R. Smakal52 , N. Smirnov5 , R. Snellings75 , C. Søgaard44 , R. Soltz2 ,H. Son101 , J. Song78 , M. Song104 , C. Soos7 , F. Soramel51 , M. Spyropoulou-Stassinaki93 , B.K. Srivastava115 ,J. Stachel65 , I. Stan83 , G. Stefanek87 , G. Stefanini7 , T. Steinbeck20 , M. Steinpreis55 , E. Stenlund76 ,G. Steyn66 , D. Stocco29 , M. Stolpovskiy57 , P. Strmen63 , A.A.P. Suaide84 , M.A. Subieta Vasquez47 ,T. Sugitate112 , C. Suire62 , M. Sukhorukov64 , R. Sultanov14 , M. Sumbera4 , T. Susa26 , A. Szanto de Toledo84 ,I. Szarka63 , A. Szostak1 , C. Tagridis93 , J. Takahashi74 , J.D. Tapia Takaki62 , A. Tauro7 , G. Tejeda Munoz80 ,A. Telesca7 , C. Terrevoli21 , J. Thader24 , D. Thomas75 , J.H. Thomas24 , R. Tieulent73 , A.R. Timmins46 ,D. Tlusty52 , A. Toia7 , H. Torii112 ,xxvii, F. Tosello16 , T. Traczyk95 , W.H. Trzaska34 , T. Tsuji100 , A. Tumkin64 ,R. Turrisi27 , A.J. Turvey72 , T.S. Tveter89 , J. Ulery30 , K. Ullaland1 , J. Ulrich61 , A. Uras73 , J. Urban58 ,G.M. Urciuoli88 , G.L. Usai71 , M. Vajzer52 ,xxviii, M. Vala43 ,xiv, L. Valencia Palomo62 , S. Vallero65 ,N. van der Kolk53 , M. van Leeuwen75 , P. Vande Vyvre7 , L. Vannucci114, A. Vargas80 , R. Varma102 ,M. Vasileiou93 , A. Vasiliev15 , V. Vechernin22 , M. Veldhoen75 , M. Venaruzzo69 , E. Vercellin47 , S. Vergara80 ,D.C. Vernekohl25 , R. Vernet116 , M. Verweij75 , L. Vickovic98 , G. Viesti51 , O. Vikhlyantsev64 , Z. Vilakazi66 ,O. Villalobos Baillie41 , A. Vinogradov15 , L. Vinogradov22 , Y. Vinogradov64 , T. Virgili 85 , Y.P. Viyogi11 ,A. Vodopyanov43 , K. Voloshin14 , S. Voloshin59 , G. Volpe21 ,ix, B. von Haller7 , D. Vranic24 , J. Vrlakova58 ,B. Vulpescu37 , A. Vyushin64 , B. Wagner1 , V. Wagner52 , R. Wan45 ,xxix, D. Wang67 , M. Wang67 , Y. Wang65 ,Y. Wang67 , K. Watanabe77 , J.P. Wessels25 ,ix, U. Westerhoff25 , J. Wiechula65 ,xxiii, J. Wikne89 , M. Wilde25 ,A. Wilk 25 , G. Wilk87 , M.C.S. Williams28 , B. Windelband65 , L. Xaplanteris Karampatsos109 , H. Yang36 ,S. Yasnopolskiy15 , J. Yi78 , Z. Yin67 , H. Yokoyama77 , I.-K. Yoo78 , J. Yoon104 , W. Yu30 , X. Yuan67 ,I. Yushmanov15 , C. Zach52 , C. Zampolli7 ,xxx, S. Zaporozhets43 , A. Zarochentsev22 , P. Zavada108 ,N. Zaviyalov64 , H. Zbroszczyk95 , P. Zelnicek61 , I. Zgura83 , M. Zhalov48 , X. Zhang67 ,i, D. Zhou67 , F. Zhou67 ,Y. Zhou75 , X. Zhu67 , A. Zichichi9 ,xxxi, A. Zimmermann65 , G. Zinovjev18 , Y. Zoccarato73 , M. Zynovyev18

Affiliation notesi Also at Laboratoire de Physique Corpusculaire (LPC), Clermont Universite, Universite Blaise Pascal,CNRS–IN2P3, Clermont-Ferrand, France

ii Also at Sezione INFN, Bologna, Italyiii Now at Physikalisches Institut, Ruprecht-Karls-Universitat Heidelberg, Heidelberg, Germanyiv Now at Laboratoire de Physique Corpusculaire (LPC), Clermont Universite, Universite Blaise Pascal,

CNRS–IN2P3, Clermont-Ferrand, Francev Also at Dipartimento di Fisica dell’Universita, Udine, Italyvi Now at Sezione INFN, Turin, Italyvii Also at Benemerita Universidad Autonoma de Puebla, Puebla, Mexicoviii Also at European Organization for Nuclear Research (CERN),Geneva, Switzerlandix Now at European Organization for Nuclear Research (CERN), Geneva, Switzerlandx Now at Lawrence Berkeley National Laboratory, Berkeley, California, United Statesxi Now at Centro Fermi – Centro Studi e Ricerche e Museo Storico della Fisica “Enrico Fermi”, Rome, Italyxii Now at Warsaw University of Technology, Warsaw, Polandxiii Also at Fachhochschule Koln, Koln, Germanyxiv Also at Institute of Experimental Physics, Slovak Academy of Sciences, Kosice, Slovakiaxv Also at M.V.Lomonosov Moscow State University, D.V.Skobeltsyn Institute of Nuclear Physics, Moscow,

Russiaxvi Also at Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Universite Joseph Fourier,

CNRS-IN2P3, Institut Polytechnique de Grenoble, Grenoble, Francexvii Now at Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy

xviii Now at SUBATECH, Ecole des Mines de Nantes, Universite de Nantes, CNRS-IN2P3, Nantes, Francexix Also at ”Vinca” Institute of Nuclear Sciences, Belgrade, Serbiaxx Also at Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Mexico City, Mexicoxxi Now at Wayne State University, Detroit, Michigan, United Statesxxii Now at Department of Physics, University of Oslo, Oslo, Norway

xxiii Now at Eberhard Karls Universitat Tubingen, Tubingen, Germanyxxiv Now at Research Division and ExtreMe Matter Institute EMMI,GSI Helmholtzzentrum fur

Schwerionenforschung, Darmstadt, Germanyxxv Now at Institut Pluridisciplinaire Hubert Curien (IPHC), Universite de Strasbourg, CNRS-IN2P3,

Particle-yield modification in jet-like azimuthal di-hadron correlations in Pb–Pb . . . 13

Strasbourg, Francexxvi Also at Centro de Investigaciones Energeticas Medioambientales y Tecnologicas (CIEMAT), Madrid,

Spainxxvii Now at University of Tokyo, Tokyo, Japanxxviii Also at Nuclear Physics Institute, Academy of Sciences of the Czech Republic,Rez u Prahy, Czech

Republicxxix Also at Hua-Zhong Normal University, Wuhan, Chinaxxx Now at Sezione INFN, Bologna, Italyxxxi Also at Centro Fermi – Centro Studi e Ricerche e Museo Storicodella Fisica “Enrico Fermi”, Rome, Italy

Collaboration Institutes1 Department of Physics and Technology, University of Bergen, Bergen, Norway2 Lawrence Livermore National Laboratory, Livermore, California, United States3 Centro de Aplicaciones Tecnologicas y Desarrollo Nuclear(CEADEN), Havana, Cuba4 Nuclear Physics Institute, Academy of Sciences of the CzechRepublic,Rez u Prahy, Czech Republic5 Yale University, New Haven, Connecticut, United States6 Physics Department, Panjab University, Chandigarh, India7 European Organization for Nuclear Research (CERN), Geneva, Switzerland8 KFKI Research Institute for Particle and Nuclear Physics, Hungarian Academy of Sciences, Budapest,

Hungary9 Dipartimento di Fisica dell’Universita and Sezione INFN,Bologna, Italy

10 Instituto de Fısica, Universidad Nacional Autonoma de M´exico, Mexico City, Mexico11 Variable Energy Cyclotron Centre, Kolkata, India12 Department of Physics Aligarh Muslim University, Aligarh,India13 Gangneung-Wonju National University, Gangneung, South Korea14 Institute for Theoretical and Experimental Physics, Moscow, Russia15 Russian Research Centre Kurchatov Institute, Moscow, Russia16 Sezione INFN, Turin, Italy17 Centro Fermi – Centro Studi e Ricerche e Museo Storico della Fisica “Enrico Fermi”, Rome, Italy18 Bogolyubov Institute for Theoretical Physics, Kiev, Ukraine19 Faculty of Engineering, Bergen University College, Bergen, Norway20 Frankfurt Institute for Advanced Studies, Johann WolfgangGoethe-Universitat Frankfurt, Frankfurt,

Germany21 Dipartimento Interateneo di Fisica ‘M. Merlin’ and SezioneINFN, Bari, Italy22 V. Fock Institute for Physics, St. Petersburg State University, St. Petersburg, Russia23 National Institute for Physics and Nuclear Engineering, Bucharest, Romania24 Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum fur

Schwerionenforschung, Darmstadt, Germany25 Institut fur Kernphysik, Westfalische Wilhelms-Universitat Munster, Munster, Germany26 Rudjer Boskovic Institute, Zagreb, Croatia27 Sezione INFN, Padova, Italy28 Sezione INFN, Bologna, Italy29 SUBATECH, Ecole des Mines de Nantes, Universite de Nantes,CNRS-IN2P3, Nantes, France30 Institut fur Kernphysik, Johann Wolfgang Goethe-Universitat Frankfurt, Frankfurt, Germany31 Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Universite Joseph Fourier, CNRS-IN2P3,

Institut Polytechnique de Grenoble, Grenoble, France32 Departamento de Fısica de Partıculas and IGFAE, Universidad de Santiago de Compostela, Santiago de

Compostela, Spain33 Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States34 Helsinki Institute of Physics (HIP) and University of Jyvaskyla, Jyvaskyla, Finland35 Sezione INFN, Catania, Italy36 Commissariat a l’Energie Atomique, IRFU, Saclay, France37 Laboratoire de Physique Corpusculaire (LPC), Clermont Universite, Universite Blaise Pascal,

CNRS–IN2P3, Clermont-Ferrand, France38 Institute of Experimental Physics, Slovak Academy of Sciences, Kosice, Slovakia39 Institute of Physics, Bhubaneswar, India

14 The ALICE Collaboration

40 Dipartimento di Fisica e Astronomia dell’Universita and Sezione INFN, Catania, Italy41 School of Physics and Astronomy, University of Birmingham,Birmingham, United Kingdom42 The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Cracow, Poland43 Joint Institute for Nuclear Research (JINR), Dubna, Russia44 Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark45 Institut Pluridisciplinaire Hubert Curien (IPHC), Universite de Strasbourg, CNRS-IN2P3, Strasbourg,

France46 University of Houston, Houston, Texas, United States47 Dipartimento di Fisica Sperimentale dell’Universita andSezione INFN, Turin, Italy48 Petersburg Nuclear Physics Institute, Gatchina, Russia49 Physics Department, University of Jammu, Jammu, India50 Laboratori Nazionali di Frascati, INFN, Frascati, Italy51 Dipartimento di Fisica dell’Universita and Sezione INFN,Padova, Italy52 Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague,

Czech Republic53 Nikhef, National Institute for Subatomic Physics, Amsterdam, Netherlands54 Centro de Investigaciones Energeticas Medioambientalesy Tecnologicas (CIEMAT), Madrid, Spain55 Department of Physics, Ohio State University, Columbus, Ohio, United States56 Moscow Engineering Physics Institute, Moscow, Russia57 Institute for High Energy Physics, Protvino, Russia58 Faculty of Science, P.J.Safarik University, Kosice, Slovakia59 Wayne State University, Detroit, Michigan, United States60 Saha Institute of Nuclear Physics, Kolkata, India61 Kirchhoff-Institut fur Physik, Ruprecht-Karls-Universitat Heidelberg, Heidelberg, Germany62 Institut de Physique Nucleaire d’Orsay (IPNO), Universite Paris-Sud, CNRS-IN2P3, Orsay, France63 Faculty of Mathematics, Physics and Informatics, ComeniusUniversity, Bratislava, Slovakia64 Russian Federal Nuclear Center (VNIIEF), Sarov, Russia65 Physikalisches Institut, Ruprecht-Karls-Universitat Heidelberg, Heidelberg, Germany66 Physics Department, University of Cape Town, iThemba LABS,Cape Town, South Africa67 Hua-Zhong Normal University, Wuhan, China68 Seccion Fısica, Departamento de Ciencias, Pontificia Universidad Catolica del Peru, Lima, Peru69 Dipartimento di Fisica dell’Universita and Sezione INFN,Trieste, Italy70 Centro de Investigacion y de Estudios Avanzados (CINVESTAV), Mexico City and Merida, Mexico71 Dipartimento di Fisica dell’Universita and Sezione INFN,Cagliari, Italy72 Physics Department, Creighton University, Omaha, Nebraska, United States73 Universite de Lyon, Universite Lyon 1, CNRS/IN2P3, IPN-Lyon, Villeurbanne, France74 Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil75 Nikhef, National Institute for Subatomic Physics and Institute for Subatomic Physics of Utrecht University,

Utrecht, Netherlands76 Division of Experimental High Energy Physics, University of Lund, Lund, Sweden77 University of Tsukuba, Tsukuba, Japan78 Pusan National University, Pusan, South Korea79 Sezione INFN, Cagliari, Italy80 Benemerita Universidad Autonoma de Puebla, Puebla, Mexico81 Dipartimento di Scienze e Tecnologie Avanzate dell’Universita del Piemonte Orientale and Gruppo

Collegato INFN, Alessandria, Italy82 Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Mexico City, Mexico83 Institute of Space Sciences (ISS), Bucharest, Romania84 Universidade de Sao Paulo (USP), Sao Paulo, Brazil85 Dipartimento di Fisica ‘E.R. Caianiello’ dell’Universit`a and Gruppo Collegato INFN, Salerno, Italy86 Sezione INFN, Bari, Italy87 Soltan Institute for Nuclear Studies, Warsaw, Poland88 Sezione INFN, Rome, Italy89 Department of Physics, University of Oslo, Oslo, Norway90 Lawrence Berkeley National Laboratory, Berkeley, California, United States91 Institute for Nuclear Research, Academy of Sciences, Moscow, Russia

Particle-yield modification in jet-like azimuthal di-hadron correlations in Pb–Pb . . . 15

92 Sezione INFN, Trieste, Italy93 Physics Department, University of Athens, Athens, Greece94 Chicago State University, Chicago, United States95 Warsaw University of Technology, Warsaw, Poland96 Universidad Autonoma de Sinaloa, Culiacan, Mexico97 Physics Department, University of Rajasthan, Jaipur, India98 Technical University of Split FESB, Split, Croatia99 Yerevan Physics Institute, Yerevan, Armenia

100 University of Tokyo, Tokyo, Japan101 Department of Physics, Sejong University, Seoul, South Korea102 Indian Institute of Technology, Mumbai, India103 Institut fur Kernphysik, Technische Universitat Darmstadt, Darmstadt, Germany104 Yonsei University, Seoul, South Korea105 Zentrum fur Technologietransfer und Telekommunikation (ZTT), Fachhochschule Worms, Worms,

Germany106 California Polytechnic State University, San Luis Obispo,California, United States107 China Institute of Atomic Energy, Beijing, China108 Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic109 The University of Texas at Austin, Physics Department, Austin, TX, United States110 University of Tennessee, Knoxville, Tennessee, United States111 Dipartimento di Fisica dell’Universita ‘La Sapienza’ andSezione INFN, Rome, Italy112 Hiroshima University, Hiroshima, Japan113 Budker Institute for Nuclear Physics, Novosibirsk, Russia114 Laboratori Nazionali di Legnaro, INFN, Legnaro, Italy115 Purdue University, West Lafayette, Indiana, United States116 Centre de Calcul de l’IN2P3, Villeurbanne, France