Transverse-momentum and pseudorapidity distributions of charged hadrons in pp collisions at square root of s = 7 TeV.

Transverse-Momentum and Pseudorapidity Distributions of Charged Hadrons in pp Collisions at ffiffiffi

p s

¼ 7 TeV

V. Khachatryanet al.* (CMS Collaboration)

(Received 18 May 2010; published 6 July 2010)

Charged-hadron transverse-momentum and pseudorapidity distributions in proton-proton collisions at ffiffiffis

p ¼7 TeVare measured with the inner tracking system of the CMS detector at the LHC. The charged- hadron yield is obtained by counting the number of reconstructed hits, hit pairs, and fully reconstructed charged-particle tracks. The combination of the three methods gives a charged-particle multiplicity per unit of pseudorapiditydNch=dj_jj<0:5¼5:780:01ðstatÞ 0:23ðsystÞfor non-single-diffractive events, higher than predicted by commonly used models. The relative increase in charged-particle multiplicity from ffiffiffi

ps

¼0:9to 7 TeV is½66:11:0ðstatÞ 4:2ðsystÞ%. The mean transverse momentum is measured to be0:5450:005ðstatÞ 0:015ðsystÞGeV=c. The results are compared with similar measurements at lower energies.

DOI:10.1103/PhysRevLett.105.022002 PACS numbers: 13.85.Ni

Introduction.—Measurements of particle yields and kin- ematic distributions are an essential first step in exploring a new energy regime of particle collisions. Such studies contribute to our understanding of the physics of hadron production, including the relative roles of soft and hard scattering contributions, and help construct a solid founda- tion for other investigations. In the complicated environ- ment of LHCppcollisions [1], firm knowledge of the rates and distributions of inclusive particle production is needed to distinguish rare signal events from the much larger backgrounds of soft hadronic interactions. They will also serve as points of reference for the measurement of nuclear-medium effects in Pb-Pb collisions in the LHC heavy ion program.

The bulk of the particles produced inppcollisions arise from soft interactions, which are modeled only phenom- enologically. Experimental results provide the critical guidance for tuning these widely used models and event generators. Soft collisions are commonly classified as elas- tic scattering, inelastic single-diffractive (SD) dissociation, double-diffractive (DD) dissociation, and inelastic nondif- fractive (ND) scattering [2]. (Double-Pomeron exchange is treated as DD in this Letter.) All results presented here refer to inelastic non-single-diffractive (NSD) interactions, and are based on an event selection that retains a large fraction of the ND and DD events, while disfavoring SD events.

The measurements focus on transverse-momentum p_T and pseudorapidity distributions. The pseudorapidity,

commonly used to characterize the direction of particle emission, is defined as¼ ln tanð=2Þ, whereis the polar angle of the direction of the particle with respect to the anticlockwise beam direction. The count of primary charged hadrons N_ch is defined to include decay products of particles with proper lifetimes less than 1 cm. Products of secondary interactions are excluded, and a percent-level correction is applied for prompt leptons. The measure- ments reported here are of dN_ch=d and dN_ch=dp_T in the pseudorapidity range jj<2:4 and closely follow our previous analysis of minimum-bias data at lower center-of-mass energies of ffiffiffi

ps

¼0:9 and 2.36 TeV as re- ported in Ref. [3].

The data for this study are drawn from an integrated luminosity of1:1b¹ recorded with the Compact Muon Solenoid (CMS) experiment [4] on 30 March 2010, during the first hour of the LHC operation at ffiffiffi

ps

¼7 TeV. These results are the highest center-of-mass energy measure- ments of the dN_ch=d and dN_ch=dp_T distributions con- ducted at a particle collider so far and complement the other recent measurements of the ALICE experiment at 7 TeV [5].

Experimental methods.—A detailed description of the CMS experiment can be found in Ref. [4]. The detectors used for the present analysis are the pixel and silicon-strip tracker, covering the region jj<2:5and immersed in a 3.8 T axial magnetic field. The pixel tracker consists of three barrel layers and two end-cap disks at each barrel end. The forward calorimeter (HF), which covers the re- gion 2:9<jj<5:2, was also used for event selection.

The detailed Monte Carlo (MC) simulation of the CMS detector response is based onGEANT4[6].

The event selection and analysis methods in this Letter are identical to those used in Ref. [3], where more details can be found. The inelastic pp collision rate was about 50 Hz. At these rates, the fraction of events in the data,

*Full author list given at the end of the article.

Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distri- bution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

where two or more minimum-bias collisions occurred in the same bunch crossing, is estimated to be less than 0.3%

and was neglected. Any hit in the beam scintillator coun- ters (BSC, 3:23<jj<4:65) coinciding with colliding proton bunches was used for triggering the data acquisi- tion. A sample mostly populated with NSD events was selected by requiring a primary vertex (PV) to be recon- structed with the tracker, together with at least one HF tower in each end with more than 3 GeV total energy.

Beam-halo and other beam-background events were re- jected as described in Ref. [3]. The remaining fraction of background events in the data was found to be less than 210⁵. The numbers of events satisfying the selection criteria are listed in TableI.

The event selection efficiency was estimated with simu- lated events using thePYTHIA[7,8] andPHOJET[9,10] event generators. The relative event fractions of SD, DD, and ND processes and their respective event selection efficiencies are listed in TableII. The fraction of diffractive events is predicted by the models to decrease as a function of collision energy, while the selection efficiency increases.

At ffiffiffi ps

¼7 TeV, the fraction of SD (DD) events in the selected data sample, estimated withPYTHIA andPHOJET, are 6.8% (5.8%) and 5.0% (3.8%), respectively, somewhat higher than at ffiffiffi

ps

¼0:9and 2.36 TeV [3]. WithPYTHIA, the overall correction for the selection efficiency of NSD processes and for the fraction of SD events remaining in the data sample lowers the measured charged-particle multiplicity by 6% compared with the uncorrected distribution.

ThedNch=ddistributions were obtained, as in Ref. [3], with three methods, based on counting the following quan- tities: (i) reconstructed clusters in the barrel part of the

pixel detector; (ii) pixel tracklets composed of pairs of clusters in different pixel barrel layers; and (iii) tracks reconstructed in the full tracker volume. The third method also allows a measurement of thedN_ch=dp_T distribution.

All three methods rely on the reconstruction of a PV [11].

The PV reconstruction efficiency was found to be 98.3%

(98.0%) in data (MC), evaluated after all other event se- lection cuts. In case of multiple PV candidates, the vertex with the largest track multiplicity was chosen. The three methods are sensitive to the measurement of particles down to pT values of about 30, 50, and 100 MeV=c, respectively. Only 0.5, 1.5, and 5% of all charged particles are estimated to be produced below these pT values, re- spectively, and these fractions were corrected for.

The measurements were corrected for the geometrical acceptance (2%), efficiency (5%–10%), fake (<1%) and duplicate tracks (<0:5%), low-p_T particles curling in the axial magnetic field (<1%), decay products of long- lived hadrons (<2%) and photon conversions (<1%), and inelastic hadronic interactions in the detector material (1%–2%), where the size of the corrections in parenthe- ses refers to the tracking method. ThePYTHIAparameter set from Ref. [8] was chosen to determine the corrections, because it reproduces the dNch=d and charged-particle multiplicity distributions, as well as other control distribu- tions at 7 TeV, better than other available tuning parameter sets. Although the corrections do not depend significantly on the model used, it is indeed important that the simulated data set contains a sufficient number of high-multiplicity events to determine these corrections with the desired accuracy.

Results.—For the measurement of the dN_ch=dp_T distri- bution, charged-particle tracks with p_T in excess of 0:1 GeV=cwere used in 12 differentjj bins, from 0 to 2.4. The average charged-hadron yields in NSD events are shown in Fig. 1as a function of pT andjj. The Tsallis parametrization [12–14],

Ed³N_ch dp³ ¼ 1

2p_T E p

d²N_ch d dpT

¼CdN_ch dy

1þE_T

nT

_n

; (1) where y¼0:5ln½ðEþpzÞ=ðEpzÞ, ET¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi

m²þp²_T

q m,

andmis the charged pion mass, was fitted to the data. The p_Tspectrum of charged hadrons,1=ð2p_TÞd²N_ch=d dp_T, measured in the rangejj<2:4, is shown in Fig.2for data

TABLE II. Fractions of SD, DD, ND, and NSD processes obtained from the PYTHIA and PHOJETevent generators before any selection, and the corresponding selection efficiencies determined from the MC simulation.

PYTHIA PHOJET

Fractions Selection efficiencies Fractions Selection efficiencies

SD 19.2% 26.7% 13.8% 30.7%

DD 12.9% 33.6% 6.6% 48.3%

ND 67.9% 96.4% 79.6% 97.1%

NSD 80.8% 86.3% 86.2% 93.4%

TABLE I. Numbers of events passing the selection cuts. The selection criteria are applied in sequence, i.e., each line includes the selection from the previous ones.

Selection Number of events

CollidingbunchesþoneBSC signal 68 512

Reconstructed PV 61 551

HF coincidence 55 113

Beam-halo rejection 55 104

Other beam-background rejection 55 100

at 0.9, 2.36, and 7 TeV. The high-p_T reach of the data is limited by the increase of systematic uncertainties withpT. The fit to the data [Eq. (1)] is mainly used for extrapola- tions top_T ¼0, but is not expected to give a good descrip- tion of the data in allbins with only two parameters. The parameter T and the exponent n were found to be T ¼ 0:1450:005ðsystÞ GeV and n¼6:60:2ðsystÞ. The averagep_T, calculated from a combination of the measured data points and the low- and high-pT contributions as determined from the fit, is hpTi ¼0:5450:005ðstatÞ 0:015ðsystÞGeV=c.

Experimental uncertainties related to the trigger and event selection are common to all the analysis methods.

The uncertainty related to the presence of SD (DD) events in the final sample was estimated to be 1.4% (1.1%), based on consistency checks between data and simulation for diffractive event candidates. The total event selection un- certainty, which also includes the selection efficiency of the BSC and HF, was found to be 3.5%. Based on studies similar to those presented in Ref. [3], additional 3% and 2% uncertainties were assigned to the tracklet and track reconstruction algorithm efficiencies, respectively.

Corrections at the percent level were applied to the final results to extrapolate topT ¼0. The uncertainty on these extrapolation corrections was found to be less than 1%. All other uncertainties are identical to those listed in Ref. [3].

The dNch=dmeasurements were repeated on a separate

data sample without any magnetic field, for which almost nopT extrapolation is needed, and gave results consistent within 1.5%. The final systematic uncertainties for the pixel counting, tracklet, and track methods were found to be 5.7%, 4.6%, and 4.3%, respectively, and are strongly correlated.

For thedNch=dmeasurements, the results for the three individual layers within the cluster-counting method were found to be consistent within 1.2% and were combined.

The three layer pairs in the pixel-tracklet method provided results that agreed within 0.6% and were also combined.

Finally, the results from the three different measurement methods, which agree with the combined result within 1%

to 4% depending on, were averaged. The finaldNch=d distributions are shown in Fig. 3 for ffiffiffi

ps

¼0:9, 2.36, and 7 TeV. The CMS results are compared with measurements made by other experiments. In the ATLAS Collaboration analysis [15], events and particles were selected in a differ- ent region of phase space, which makes a direct compari- son difficult. Their results are therefore not included in the figure.

The results can also be compared to earlier experiments as a function of ffiffiffi

ps

. The energy dependence of the average charged hadron p_T can be described by a quadratic func- tion oflns[16]. As shown in Fig.4, the present measure-

[GeV/c]

p

T

0 0.5 1 1.5 2

]

-1

[(GeV/c)

T

dp η / d

ch

N

2

d

0 10 20 30 40 50 60 70 80 90

|=0.1 η

|

|=0.3 η

|

|=0.5 η

|

|=0.7 η

|

|=0.9 η

|

|=1.1 η

|

|=1.3 η

|

|=1.5 η

|

|=1.7 η

|

|=1.9 η

|

|=2.1 η

|

|=2.3 η

| 7 TeV pp, NSD

Tsallis fit

CMS

FIG. 1. Differential yield of charged hadrons in the range jj<2:4in 0.2-unit-wide bins ofjjin NSD events. The solid curves represent fits of Eq. (1) to the data. The measurements with increasingare successively shifted by six units along the vertical axis.

[GeV/c]

p

T

0 1 2 3 4 5 6

]

-2

[(GeV/c)

T

dp η /d

ch

N

2

) d

T

p π 1/(2

^-510

10-4

10-3

10-2

10-1

1 10

7 TeV pp, NSD 2.36 TeV pp, NSD 0.9 TeV pp, NSD Tsallis fits

CMS

FIG. 2. Charged-hadron yield in the rangejj<2:4in NSD events as a function of pT; the systematic uncertainties are smaller than the symbols. The measurements at ffiffiffi

ps

¼0:9 and 2.36 TeV [3] are also shown. The solid lines represent fits of Eq.

(1) to the data.

ment follows this trend. The choice of thejjinterval can influence the averagep_T value by a few percent.

Forjj<0:5, the average charged multiplicity density is dN_ch=d¼5:780:01ðstatÞ 0:23ðsystÞ for NSD events. The ffiffiffi

ps

dependence of the measured dN_ch= dj₀ is shown in Fig. 5, which includes data from various other experiments. The dNch=dresults reported here show a rather steep increase between 0.9 and 7 TeV, which is measured to be ½66:11:0ðstatÞ 4:2ðsystÞ%. Using a somewhat different event selection, the ALICE Collaboration has found a similar increase of ½57:6 0:4ðstatÞ^þ3:6_1:8ðsystÞ% [5]. The measured charged-particle multiplicity is accurate enough to distinguish among most sets of event-generator tuning parameter values and various models. The measured value at 7 TeV significantly exceeds the prediction of 4.57 fromPHOJET[9,10], and the predictions of 3.99, 4.18, and 4.34 from the DW [17],

PROQ20 [18], and Perugia0 [19] tuning parameter values ofPYTHIA, respectively, while it is closer to the prediction of 5.48 from thePYTHIAparameter set from Ref. [8] and to the recent model predictions of 5.58 and 5.78 from Refs. [20,21]. The measured excess of the number of charged hadrons with respect to the event generators is independent of and concentrated in thepT<1 GeV=c

-2

η

0 2

η /d

ch

dN

0 2 4 6

CMS NSD ALICE NSD UA5 NSD 0.9 TeV

2.36 TeV 7 TeV

CMS

FIG. 3. Distributions of dNch=d, averaged over the three measurement methods and compared with data from UA5 [23]

(pp, with statistical errors only) and ALICE [24] (with system- atic uncertainties). The shaded band shows systematic uncer- tainties of the CMS data. The CMS and UA5 data are averaged over negative and positive values of.

[GeV]

s

10 10² 10³ 10⁴

[GeV/c] 〉

T

p 〈

0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65

ISR inel.

UA1 NSD E735 NSD CDF NSD CMS NSD

2s + 0.00143 ln s

0.413 - 0.0171 ln

CMS

FIG. 4. Average pT of charged hadrons as a function of the center-of-mass energy. The CMS measurements are for jj<

2:4. Also shown are measurements from the ISR [25] (pp), E735 [26] (pp), and CDF [27] (pp) forjj<0:5, and from UA1 [16]

(pp) forjj<2:5. The solid line is a fit of the functional form hp_Ti ¼0:4130:0171 lnsþ0:001 43ln²sto the data. The error bars on the CMS data include the systematic uncertainties.

[GeV]

s

10 10² 10³ 10⁴

0≈η

⏐η /d

ch

dN

0 1 2 3 4 5 6

7 ^{UA1 NSD}

STAR NSD UA5 NSD CDF NSD ALICE NSD CMS NSD

NAL B.C. inel.

ISR inel.

UA5 inel.

PHOBOS inel.

ALICE inel.

2s + 0.0267 ln s

2.716 - 0.307 ln

2s + 0.0155 ln s

1.54 - 0.096 ln

CMS

FIG. 5. Average value ofdNch=din the centralregion as a function of center-of-mass energy inppandppcollisions. Also shown are NSD and inelastic measurements from the NAL Bubble Chamber [28] (pp), ISR [29] (pp), UA1 [16] (pp), UA5 [23] (pp), CDF [30] (pp), STAR [31] (pp), PHOBOS [32]

(pp), and ALICE [24] (pp). The curves are second-order poly- nomial fits for the inelastic (solid) and NSD event selections (dashed). The error bars include systematic uncertainties, when available. Data points at 0.9 and 2.36 TeV are slightly displaced horizontally for visibility.

range. These differences indicate the need for a continued model development and simulation tuning. Work on up- dated event generators based on LHC data is currently under way.

Summary.—Charged-hadron transverse-momentum and pseudorapidity distributions have been measured in proton-proton collisions at ffiffiffi

ps

¼7 TeV. The numerical values of the data presented in this Letter can be found in the HEPDATA database [22]. The combined result for the central pseudorapidity density, from three mutually con- sistent methods of measurement, is dNch=djjj<0:5 ¼ 5:780:01ðstatÞ 0:23ðsystÞ for non-single-diffractive events. This value is higher than most predictions and provides new information to constrain ongoing improve- ments of soft particle production models and event gener- ators. The mean transverse momentum has been measured to be 0:5450:005ðstatÞ 0:015ðsystÞGeV=c. These studies are the first steps in the exploration of particle production at the new center-of-mass energy frontier, and contribute to the understanding of the dynamics in soft hadronic interactions.

We congratulate and express our gratitude to our col- leagues in the CERN accelerator departments for the ex- cellent performance of the LHC. We thank the technical and administrative staff at CERN and other CMS institutes, and acknowledge support from the following: FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN;

CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); Academy of Sciences and NICPB (Estonia); Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France);

BMBF, DFG, and HGF (Germany); GSRT (Greece);

OTKA and NKTH (Hungary); DAE and DST (India);

IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia);

MSTDS (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei);

TUBITAK and TAEK (Turkey); STFC (U.K.); DOE and NSF (U.S.).

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V. Khachatryan,¹A. M. Sirunyan,¹A. Tumasyan,¹W. Adam,²T. Bergauer,²M. Dragicevic,²J. Ero¨,²C. Fabjan,² M. Friedl,²R. Fru¨hwirth,²V. M. Ghete,²J. Hammer,^2,bS. Ha¨nsel,²M. Hoch,²N. Ho¨rmann,²J. Hrubec,²M. Jeitler,² G. Kasieczka,²W. Kiesenhofer,²M. Krammer,²D. Liko,²I. Mikulec,²M. Pernicka,²H. Rohringer,²R. Scho¨fbeck,²

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S. M. Silva Do Amaral,¹¹A. Sznajder,¹¹F. Torres Da Silva De Araujo,¹¹F. A. Dias,¹²M. A. F. Dias,¹² T. R. Fernandez Perez Tomei,¹²E. M. Gregores,¹²F. Marinho,¹²S. F. Novaes,¹²Sandra S. Padula,¹²N. Darmenov,^13,b L. Dimitrov,¹³V. Genchev,^13,bP. Iaydjiev,¹³S. Piperov,¹³S. Stoykova,¹³G. Sultanov,¹³R. Trayanov,¹³I. Vankov,¹³

M. Dyulendarova,¹⁴R. Hadjiiska,¹⁴V. Kozhuharov,¹⁴L. Litov,¹⁴E. Marinova,¹⁴M. Mateev,¹⁴B. Pavlov,¹⁴ P. Petkov,¹⁴J. G. Bian,¹⁵G. M. Chen,¹⁵H. S. Chen,¹⁵C. H. Jiang,¹⁵D. Liang,¹⁵S. Liang,¹⁵J. Wang,¹⁵J. Wang,¹⁵

X. Wang,¹⁵Z. Wang,¹⁵M. Yang,¹⁵J. Zang,¹⁵Z. Zhang,¹⁵Y. Ban,¹⁶S. Guo,¹⁶Z. Hu,¹⁶Y. Mao,¹⁶S. J. Qian,¹⁶ H. Teng,¹⁶B. Zhu,¹⁶A. Cabrera,¹⁷C. A. Carrillo Montoya,¹⁷B. Gomez Moreno,¹⁷A. A. Ocampo Rios,¹⁷ A. F. Osorio Oliveros,¹⁷J. C. Sanabria,¹⁷N. Godinovic,¹⁸D. Lelas,¹⁸K. Lelas,¹⁸R. Plestina,^18,cD. Polic,¹⁸ I. Puljak,¹⁸Z. Antunovic,¹⁹M. Dzelalija,¹⁹V. Brigljevic,²⁰S. Duric,²⁰K. Kadija,²⁰S. Morovic,²⁰A. Attikis,²¹ R. Fereos,²¹M. Galanti,²¹J. Mousa,²¹C. Nicolaou,²¹A. Papadakis,²¹F. Ptochos,²¹P. A. Razis,²¹H. Rykaczewski,²¹ D. Tsiakkouri,²¹Z. Zinonos,²¹M. Mahmoud,²²A. Hektor,²³M. Kadastik,²³K. Kannike,²³M. Mu¨ntel,²³M. Raidal,²³ L. Rebane,²³V. Azzolini,²⁴P. Eerola,²⁴S. Czellar,²⁵J. Ha¨rko¨nen,²⁵A. Heikkinen,²⁵V. Karima¨ki,²⁵R. Kinnunen,²⁵ J. Klem,²⁵M. J. Kortelainen,²⁵T. Lampe´n,²⁵K. Lassila-Perini,²⁵S. Lehti,²⁵T. Linde´n,²⁵P. Luukka,²⁵T. Ma¨enpa¨a¨,²⁵

E. Tuominen,²⁵J. Tuominiemi,²⁵E. Tuovinen,²⁵D. Ungaro,²⁵L. Wendland,²⁵K. Banzuzi,²⁶A. Korpela,²⁶ T. Tuuva,²⁶D. Sillou,²⁷M. Besancon,²⁸M. Dejardin,²⁸D. Denegri,²⁸J. Descamps,²⁸B. Fabbro,²⁸J. L. Faure,²⁸ F. Ferri,²⁸S. Ganjour,²⁸F. X. Gentit,²⁸A. Givernaud,²⁸P. Gras,²⁸G. Hamel de Monchenault,²⁸P. Jarry,²⁸E. Locci,²⁸

J. Malcles,²⁸M. Marionneau,²⁸L. Millischer,²⁸J. Rander,²⁸A. Rosowsky,²⁸D. Rousseau,²⁸M. Titov,²⁸ P. Verrecchia,²⁸S. Baffioni,²⁹L. Bianchini,²⁹M. Bluj,^29,dC. Broutin,²⁹P. Busson,²⁹C. Charlot,²⁹L. Dobrzynski,²⁹ S. Elgammal,²⁹R. Granier de Cassagnac,²⁹M. Haguenauer,²⁹A. Kalinowski,²⁹P. Mine´,²⁹P. Paganini,²⁹D. Sabes,²⁹

Y. Sirois,²⁹C. Thiebaux,²⁹A. Zabi,²⁹J.-L. Agram,³⁰A. Besson,³⁰D. Bloch,³⁰D. Bodin,³⁰J.-M. Brom,³⁰ M. Cardaci,³⁰E. Conte,³⁰F. Drouhin,³⁰C. Ferro,³⁰J.-C. Fontaine,³⁰D. Gele´,³⁰U. Goerlach,³⁰S. Greder,³⁰ P. Juillot,³⁰M. Karim,³⁰A.-C. Le Bihan,³⁰Y. Mikami,³⁰J. Speck,³⁰P. Van Hove,³⁰F. Fassi,³¹D. Mercier,³¹ C. Baty,³²N. Beaupere,³²M. Bedjidian,³²O. Bondu,³²G. Boudoul,³²D. Boumediene,³²H. Brun,³²N. Chanon,³²

R. Chierici,³²D. Contardo,³²P. Depasse,³²H. El Mamouni,³²J. Fay,³²S. Gascon,³²B. Ille,³²T. Kurca,³² T. Le Grand,³²M. Lethuillier,³²L. Mirabito,³²S. Perries,³²S. Tosi,³²Y. Tschudi,³²P. Verdier,³²H. Xiao,³²

V. Roinishvili,³³G. Anagnostou,³⁴M. Edelhoff,³⁴L. Feld,³⁴N. Heracleous,³⁴O. Hindrichs,³⁴R. Jussen,³⁴ K. Klein,³⁴J. Merz,³⁴N. Mohr,³⁴A. Ostapchuk,³⁴A. Perieanu,³⁴F. Raupach,³⁴J. Sammet,³⁴S. Schael,³⁴ D. Sprenger,³⁴H. Weber,³⁴M. Weber,³⁴B. Wittmer,³⁴O. Actis,³⁵M. Ata,³⁵W. Bender,³⁵P. Biallass,³⁵ M. Erdmann,³⁵J. Frangenheim,³⁵T. Hebbeker,³⁵A. Hinzmann,³⁵K. Hoepfner,³⁵C. Hof,³⁵M. Kirsch,³⁵ T. Klimkovich,³⁵P. Kreuzer,^35,bD. Lanske,^35,aC. Magass,³⁵M. Merschmeyer,³⁵A. Meyer,³⁵P. Papacz,³⁵H. Pieta,³⁵

H. Reithler,³⁵S. A. Schmitz,³⁵L. Sonnenschein,³⁵M. Sowa,³⁵J. Steggemann,³⁵D. Teyssier,³⁵C. Zeidler,³⁵ M. Bontenackels,³⁶M. Davids,³⁶M. Duda,³⁶G. Flu¨gge,³⁶H. Geenen,³⁶M. Giffels,³⁶W. Haj Ahmad,³⁶ D. Heydhausen,³⁶T. Kress,³⁶Y. Kuessel,³⁶A. Linn,³⁶A. Nowack,³⁶L. Perchalla,³⁶O. Pooth,³⁶P. Sauerland,³⁶

A. Stahl,³⁶M. Thomas,³⁶D. Tornier,³⁶M. H. Zoeller,³⁶M. Aldaya Martin,³⁷W. Behrenhoff,³⁷U. Behrens,³⁷ M. Bergholz,³⁷K. Borras,³⁷A. Campbell,³⁷E. Castro,³⁷D. Dammann,³⁷G. Eckerlin,³⁷A. Flossdorf,³⁷G. Flucke,³⁷

A. Geiser,³⁷J. Hauk,³⁷H. Jung,³⁷M. Kasemann,³⁷I. Katkov,³⁷C. Kleinwort,³⁷H. Kluge,³⁷A. Knutsson,³⁷ E. Kuznetsova,³⁷W. Lange,³⁷W. Lohmann,³⁷R. Mankel,³⁷M. Marienfeld,³⁷I.-A. Melzer-Pellmann,³⁷

A. B. Meyer,³⁷J. Mnich,³⁷A. Mussgiller,³⁷J. Olzem,³⁷A. Parenti,³⁷A. Raspereza,³⁷R. Schmidt,³⁷ T. Schoerner-Sadenius,³⁷N. Sen,³⁷M. Stein,³⁷J. Tomaszewska,³⁷D. Volyanskyy,³⁷C. Wissing,³⁷C. Autermann,³⁸

J. Draeger,³⁸D. Eckstein,³⁸H. Enderle,³⁸U. Gebbert,³⁸K. Kaschube,³⁸G. Kaussen,³⁸R. Klanner,³⁸B. Mura,³⁸ S. Naumann-Emme,³⁸F. Nowak,³⁸C. Sander,³⁸H. Schettler,³⁸P. Schleper,³⁸M. Schro¨der,³⁸T. Schum,³⁸ J. Schwandt,³⁸H. Stadie,³⁸G. Steinbru¨ck,³⁸J. Thomsen,³⁸R. Wolf,³⁸J. Bauer,³⁹V. Buege,³⁹A. Cakir,³⁹ T. Chwalek,³⁹D. Daeuwel,³⁹W. De Boer,³⁹A. Dierlamm,³⁹G. Dirkes,³⁹M. Feindt,³⁹J. Gruschke,³⁹C. Hackstein,³⁹

F. Hartmann,³⁹M. Heinrich,³⁹H. Held,³⁹K. H. Hoffmann,³⁹S. Honc,³⁹T. Kuhr,³⁹D. Martschei,³⁹S. Mueller,³⁹ Th. Mu¨ller,³⁹M. Niegel,³⁹O. Oberst,³⁹A. Oehler,³⁹J. Ott,³⁹T. Peiffer,³⁹D. Piparo,³⁹G. Quast,³⁹K. Rabbertz,³⁹

F. Ratnikov,³⁹M. Renz,³⁹A. Sabellek,³⁹C. Saout,^39,bA. Scheurer,³⁹P. Schieferdecker,³⁹F.-P. Schilling,³⁹ G. Schott,³⁹H. J. Simonis,³⁹F. M. Stober,³⁹D. Troendle,³⁹J. Wagner-Kuhr,³⁹M. Zeise,³⁹V. Zhukov,^39,e E. B. Ziebarth,³⁹G. Daskalakis,⁴⁰T. Geralis,⁴⁰A. Kyriakis,⁴⁰D. Loukas,⁴⁰I. Manolakos,⁴⁰A. Markou,⁴⁰ C. Markou,⁴⁰C. Mavrommatis,⁴⁰E. Petrakou,⁴⁰L. Gouskos,⁴¹P. Katsas,⁴¹A. Panagiotou,^41,bI. Evangelou,⁴² P. Kokkas,⁴²N. Manthos,⁴²I. Papadopoulos,⁴²V. Patras,⁴²F. A. Triantis,⁴²A. Aranyi,⁴³G. Bencze,⁴³L. Boldizsar,⁴³

G. Debreczeni,⁴³C. Hajdu,^43,bD. Horvath,^43,fA. Kapusi,⁴³K. Krajczar,⁴³A. Laszlo,⁴³F. Sikler,⁴³ G. Vesztergombi,⁴³N. Beni,⁴⁴J. Molnar,⁴⁴J. Palinkas,⁴⁴Z. Szillasi,^44,bV. Veszpremi,⁴⁴P. Raics,⁴⁵Z. L. Trocsanyi,⁴⁵

B. Ujvari,⁴⁵S. Bansal,⁴⁶S. B. Beri,⁴⁶V. Bhatnagar,⁴⁶M. Jindal,⁴⁶M. Kaur,⁴⁶J. M. Kohli,⁴⁶M. Z. Mehta,⁴⁶ N. Nishu,⁴⁶L. K. Saini,⁴⁶A. Sharma,⁴⁶R. Sharma,⁴⁶A. P. Singh,⁴⁶J. B. Singh,⁴⁶S. P. Singh,⁴⁶S. Ahuja,⁴⁷ S. Bhattacharya,^47,gS. Chauhan,⁴⁷B. C. Choudhary,⁴⁷P. Gupta,⁴⁷S. Jain,⁴⁷S. Jain,⁴⁷A. Kumar,⁴⁷K. Ranjan,⁴⁷

R. K. Shivpuri,⁴⁷R. K. Choudhury,⁴⁸D. Dutta,⁴⁸S. Kailas,⁴⁸S. K. Kataria,⁴⁸A. K. Mohanty,⁴⁸L. M. Pant,⁴⁸ P. Shukla,⁴⁸P. Suggisetti,⁴⁸T. Aziz,⁴⁹M. Guchait,^49,hA. Gurtu,⁴⁹M. Maity,⁴⁹D. Majumder,⁴⁹G. Majumder,⁴⁹

K. Mazumdar,⁴⁹G. B. Mohanty,⁴⁹A. Saha,⁴⁹K. Sudhakar,⁴⁹N. Wickramage,⁴⁹S. Banerjee,⁵⁰S. Dugad,⁵⁰ N. K. Mondal,⁵⁰H. Arfaei,⁵¹H. Bakhshiansohi,⁵¹A. Fahim,⁵¹A. Jafari,⁵¹M. Mohammadi Najafabadi,⁵¹ S. Paktinat Mehdiabadi,⁵¹B. Safarzadeh,⁵¹M. Zeinali,⁵¹M. Abbrescia,^52a,52bL. Barbone,^52aA. Colaleo,^52a D. Creanza,^52a,52cN. De Filippis,^52aM. De Palma,^52a,52bA. Dimitrov,^52aF. Fedele,^52aL. Fiore,^52aG. Iaselli,^52a,52c L. Lusito,^52a,52b,bG. Maggi,^52a,52cM. Maggi,^52aN. Manna,^52a,52bB. Marangelli,^52a,52bS. My,^52a,52cS. Nuzzo,^52a,52b

G. A. Pierro,^52aA. Pompili,^52a,52bG. Pugliese,^52a,52cF. Romano,^52a,52cG. Roselli,^52a,52bG. Selvaggi,^52a,52b L. Silvestris,^52aR. Trentadue,^52aS. Tupputi,^52a,52bG. Zito,^52aG. Abbiendi,^53aA. C. Benvenuti,^53aD. Bonacorsi,^53a

S. Braibant-Giacomelli,^53a,53bA. Castro,^53a,53bF. R. Cavallo,^53aG. Codispoti,^53a,53b G. M. Dallavalle,^53a,b F. Fabbri,^53aA. Fanfani,^53a,53bD. Fasanella,^53aP. Giacomelli,^53aM. Giunta,^53a,bC. Grandi,^53aS. Marcellini,^53a

G. Masetti,^53a,53bA. Montanari,^53aF. L. Navarria,^53a,53bF. Odorici,^53aA. Perrotta,^53aA. M. Rossi,^53a,53b T. Rovelli,^53a,53bG. Siroli,^53a,53bR. Travaglini,^53a,53bS. Albergo,^54a,54bG. Cappello,^54a,54bM. Chiorboli,^54a,54b S. Costa,^54a,54bA. Tricomi,^54a,54bC. Tuve,^54aG. Barbagli,^55aG. Broccolo,^55a,55bV. Ciulli,^55a,55bC. Civinini,^55a

R. D’Alessandro,^55a,55bE. Focardi,^55a,55bS. Frosali,^55a,55bE. Gallo,^55aC. Genta,^55a,55bP. Lenzi,^55a,55b,b M. Meschini,^55aS. Paoletti,^55aG. Sguazzoni,^55aA. Tropiano,^55aL. Benussi,⁵⁶S. Bianco,⁵⁶S. Colafranceschi,⁵⁶ F. Fabbri,⁵⁶D. Piccolo,⁵⁶P. Fabbricatore,⁵⁷R. Musenich,⁵⁷A. Benaglia,^58a,58bG. B. Cerati,^58a,58b,bF. De Guio,^58a,58b

L. Di Matteo,^58a,58bA. Ghezzi,^58a,58b,bP. Govoni,^58a,58bM. Malberti,^58a,58b,bS. Malvezzi,^58aA. Martelli,^58a,58b,c A. Massironi,^58a,58bD. Menasce,^58aV. Miccio,^58a,58bL. Moroni,^58aP. Negri,^58a,58bM. Paganoni,^58a,58bD. Pedrini,^58a

S. Ragazzi,^58a,58bN. Redaelli,^58aS. Sala,^58aR. Salerno,^58a,58bT. Tabarelli de Fatis,^58a,58bV. Tancini,^58a,58b S. Taroni,^58a,58bS. Buontempo,^59aA. Cimmino,^59a,59bA. De Cosa,^59a,59b,bM. De Gruttola,^59a,59b,bF. Fabozzi,^59a

A. O. M. Iorio,^59aL. Lista,^59aP. Noli,^59a,59bP. Paolucci,^59aP. Azzi,^60aN. Bacchetta,^60aP. Bellan,^60a,60b,b M. Bellato,^60aM. Biasotto,^60aD. Bisello,^60a,60bR. Carlin,^60a,60bP. Checchia,^60aM. De Mattia,^60a,60bT. Dorigo,^60a

F. Fanzago,^60aF. Gasparini,^60a,60bP. Giubilato,^60a,60bA. Gresele,^60a,60cS. Lacaprara,^60aI. Lazzizzera,^60a,60c M. Margoni,^60a,60bG. Maron,^60aA. T. Meneguzzo,^60a,60bM. Nespolo,^60aL. Perrozzi,^60aN. Pozzobon,^60a,60b P. Ronchese,^60a,60bF. Simonetto,^60a,60bE. Torassa,^60aM. Tosi,^60a,60bA. Triossi,^60aS. Vanini,^60a,60bG. Zumerle,^60a,60b P. Baesso,^61a,61bU. Berzano,^61aC. Riccardi,^61a,61bP. Torre,^61a,61bP. Vitulo,^61a,61bC. Viviani,^61a,61bM. Biasini,^62a,62b

G. M. Bilei,^62aB. Caponeri,^62a,62bL. Fano`,<sup>62a</sup>P. Lariccia,<sup>62a,62b</sup>A. Lucaroni,<sup>62a,62b</sup>G. Mantovani,<sup>62a,62b</sup> M. Menichelli,<sup>62a</sup>A. Nappi,<sup>62a,62b</sup>A. Santocchia,<sup>62a,62b</sup>L. Servoli,<sup>62a</sup>M. Valdata,<sup>62a</sup>R. Volpe,<sup>62a,62b,b</sup> P. Azzurri,<sup>63a,63c</sup>G. Bagliesi,<sup>63a</sup>J. Bernardini,<sup>63a,63b,b</sup>T. Boccali,<sup>63a</sup>R. Castaldi,<sup>63a</sup>R. T. Dagnolo,<sup>63a,63c</sup> R. Dell’Orso,<sup>63a</sup>F. Fiori,<sup>63a,63b</sup>L. Foa`,^63a,63cA. Giassi,^63aA. Kraan,^63aF. Ligabue,^63a,63cT. Lomtadze,^63a L. Martini,^63aA. Messineo,^63a,63bF. Palla,^63aF. Palmonari,^63aG. Segneri,^63aA. T. Serban,^63aP. Spagnolo,^63a,b

R. Tenchini,^63a,bG. Tonelli,^63a,63b,bA. Venturi,^63aP. G. Verdini,^63aL. Barone,^64a,64bF. Cavallari,^64a,b D. Del Re,^64a,64bE. Di Marco,^64a,64bM. Diemoz,^64aD. Franci,^64a,64bM. Grassi,^64aE. Longo,^64a,64b G. Organtini,^64a,64bA. Palma,^64a,64bF. Pandolfi,^64a,64bR. Paramatti,^64a,bS. Rahatlou,^64a,64b,bN. Amapane,^65a,65b