Observation of a new Ξ b baryon

Observation of a New 

Baryon

S. Chatrchyan et al.*

(CMS Collaboration)

(Received 26 April 2012; published 21 June 2012)

The observation of a new b baryon via its strong decay into

_b
^þ(plus charge conjugates) is reported.

The measurement uses a data sample of pp collisions at ffiffiffi ps

¼ 7 TeV collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 5:3 fb
¹. The known

_b baryon is reconstructed via the decay chain

_b ! J=c

! ^þ
⁰

, with ⁰! p

. A peak is observed in the distribution of the difference between the mass of the

_b
^þ system and the sum of the masses of the

_b and
^þ, with a significance exceeding 5 standard deviations. The mass difference of the peak is 14:84  0:74ðstatÞ  0:28ðsystÞ MeV. The new state most likely corresponds to the J^P¼ 3=2^þ compan- ion of the
b.

DOI:10.1103/PhysRevLett.108.252002 PACS numbers: 14.20.Mr

According to the well-established quark model and cor- responding spectroscopy of baryons, there are several pre- dicted baryons containing one strange and one beauty valence quark. These include the
_b (ground state) and

⁰_b, both with total angular momentum and parity J^P ¼ 1=2^þ, a J^P¼ 3=2^þ state with angular momentum L ¼ 0 (often referred to, as will be done in this Letter, as
^_b), and two states with J^P ¼ 1=2
and 3=2
, both with angular momentum L ¼ 1. These baryons can be neutral (valence quark content u
s
b) or negatively charged (d
s
b). At the Tevatron, baryons with masses and decay modes consistent with the theoretical predictions for the ground state
bbaryons have been observed [1–3], although their quantum numbers have not yet been established. The al- lowed decays of the experimentally missing
_b states should be analogous to the charmed sector [4–6]. In addi- tion, theoretical calculations [7–11] predict the mass dif- ference between the
⁰_band
_bto be smaller than the mass of the pion, in which case the strong decay
⁰_b !
_b is kinematically forbidden. The mass difference between the

^_b and
_b, however, is expected to be large enough to allow such a decay.

This Letter presents a search for the decay
^0_b !

_b
^þ, with

_b ! J=c

, J=c! ^þ
,

!

⁰

, and ⁰ ! p

. Charge conjugate states are im- plied throughout. The reconstruction of such decays in- volves the presence of three secondary vertices, where the

_b,

, and ⁰decay, which are well separated from the primary interaction vertex. The analysis is based on a data sample of pp collisions at ffiffiffi

ps

¼ 7 TeV, collected in 2011 by the Compact Muon Solenoid (CMS) experiment at the

Large Hadron Collider (LHC), corresponding to an inte- grated luminosity of 5:3 fb
¹.

The CMS apparatus is described in detail in Ref. [12]. Its central feature is a superconducting solenoid, of 6 m inter- nal diameter, providing a field of 3.8 T. The main subde- tectors used in this analysis are the silicon tracker and the muon systems. The silicon tracker, composed of pixel and strip detector modules, is immersed in the magnetic field, and enables the measurement of charged particle momenta over the pseudorapidity range jj < 2:5, where  ¼

lnðtan=2Þ and  is the polar angle of the track relative to the counterclockwise beam direction. Muons are iden- tified in the rangejj < 2:4 using gas-ionization detectors embedded in the steel return yoke of the magnet.

The events used in this analysis were collected using the two-level trigger system of CMS. The first level consists of custom hardware processors and uses information from the muon systems to select events with two muons. The ‘‘high- level trigger’’ processor farm further decreases the event rate before data storage, requiring two opposite-sign muons compatible with being the decay products of a J=c, either promptly produced or displaced from the primary vertex (PV). The nonprompt J=c trigger requires two opposite-sign muons with an invariant mass within 200 MeV of the J=c mass [13], single muon transverse momentum p_T> 3, 3.5, 4, or 5 GeV, and dimuon vertex fit

² probability larger than 10% or 15%. The requirements were made tighter depending on the LHC instantaneous luminosity so as to limit the trigger rate. In addition, the dimuon vertex must be separated from the beam line by more than 3 times the uncertainty on the separation vertex, which includes the transverse vertex resolution (indepen- dently estimated for each event) and the beam line position uncertainty. Finally, the requirement cos > 0:9 is also applied, where  is the angle, in the plane transverse to the beam, between the dimuon momentum and the direc- tion from the beam line to the dimuon vertex. The prompt J=c trigger requires two opposite-sign muons with an

*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.

invariant mass within 250 MeV of the J=c ^{mass [13],} dimuon pT> 10 or 13 GeV (depending on the instanta- neous luminosity), dimuon rapidityjyj < 1:25, and dimuon vertex fit ² probability greater than 0.5%.

The reconstruction of the

_b ! J=c

candidates begins by identifying J=c ! ^þ
decays. The candi- date J=c mesons are built by combining pairs of oppo- sitely charged muons (tracks in the silicon tracker matched to tracks in the muon detectors) satisfying the trigger conditions and having an invariant mass within 150 MeV of the J=c mass. Candidate ⁰ baryons are reconstructed in decays to a pion (
) and a proton (p) with opposite charges, where the higher momentum track is assumed to be the proton. Both tracks are required to have a track fit

²=ndf < 5, where ndf is the number of degrees of free- dom, and at least six hits in the silicon tracker. The ⁰ candidate vertex must have a fit ²=ndf < 7 and be dis- placed from the beam line by more than 10vertex. Possible contamination from misreconstructed KS mesons is re- moved by requiring that the candidate mass, when assum- ing that both tracks are pions, differs from the KSmass [13]

by more than 20 MeV. Candidate

baryons are recon- structed by combining a ⁰candidate with a track (

) of the same charge as the
. A kinematic vertex fit [14] is performed, assuming that the track is a pion, and with the

⁰ candidate mass constrained to its world-average value [13]. A veto window of 20 MeV around the 
mass [13] is applied when assuming that the

candidate is a kaon.

The

is then combined with the J=c to form a

_b candidate, with a kinematic vertex fit constraining their masses to the world-average values [13]. On average, the events used in this analysis have around eight recon- structed primary vertices (PV). The PV closest in three dimensions to the

_b trajectory is taken as the one where the

_b was produced.

The

_b signal selection criteria are chosen by an iter- ative algorithm that maximizes both the signal yield and the significance, calculated as S= ffiffiffiffiffiffiffiffiffiffiffiffiffi

S þ B

p , where the signal (S) and background (B) yields are evaluated in a window of

40 MeV around the

_b mass, 5790:5  2:7 MeV [13].

The value of B is linearly interpolated to this signal region from the two mass sidebands, located between 40 and 100 MeV away from the peak value. Thirty variables are used to optimize the

_b signal selection. At every itera- tion, two variables are chosen randomly, where one of them is tightened and the other loosened. If S and the signifi- cance increase, the new set of values is accepted. To avoid ending up in a local maximum, an iteration is accepted if the significance decreases by less than a random number uniformly generated between 0 and 10%. The variables used for the selection include the p_Tof both muons, and of the J=c, p,
,

,

, and

_b. The muons and

_b can have different p_Tselections in the pseudorapidity regions jj < 1:2 and jj > 1:2, where jj ¼ 1:2 is the transition between the barrel and endcap detectors. The algorithm

also tunes the requirements on the differences between the reconstructed masses and the world-average masses for the

⁰,

, and J=c, with the latter case being different for jðJ=cÞj < 1:2 and jðJ=cÞj > 1:2. Also, the total J=c pseudorapidity coverage can be adjusted to be smaller than the fulljðJ=cÞj < 2:4 range.

To select a

_b sample with a good signal-over- background ratio, it is important to reject promptly pro- duced tracks. This is done via a selection on their trans- verse impact parameter significances D_ip=_Dip, where the impact parameter Dipis calculated with respect to the beam line and _Dipis its uncertainty. This procedure is applied to the p,
, and

tracks, as well as to the ⁰ and

trajectories. Long-lived particles (⁰,

, and

_b) are selected by requirements on their transverse decay lengths and on the significance Lxy=Lxyof the transverse distance between their production and decay vertices L_xy, where

Lxy is the uncertainty of Lxy. Minimal fit confidence levels are required on the ⁰,

, and

_b decay vertices, while the three-dimensional distance significance must be smaller than the optimized thresholds for the distances between the

trajectory and the J=c decay vertex, as well as between the

_b trajectory and the chosen PV.

The J=c

invariant-mass distribution for the

_b candidates passing the selection criteria is shown in Fig. 1, together with the result of a fit with a Gaussian function representing the signal plus a second-order poly- nomial representing the background, which gives a signal yield of 108  14 events. The same figure also displays the invariant-mass distribution for background events, in which the

and proton have the same charge, giving

) [GeV]

Ξ-

ψ M(J/

5.6 5.7 5.8 5.9 6 6.1

candidates per 20 MeV- bΞ

0 10 20 30 40 50 60 70

data

-

Ξb

πΞ

Opposite-sign p πΞ

Same-sign p

Signal+background fit Background fit CMS

= 7 TeV s pp, L = 5.3 fb-1

FIG. 1 (color online). Invariant-mass distributions of the se- lected

_b candidates (closed circles) and of the J=c

pairs where the proton and

have the same charge (open squares).

The blue solid curve represents the result of the signal-plus- background fit to the

_b distribution, while the red dashed line shows the corresponding background component.

PRL108, 252002 (2012) P H Y S I C A L R E V I E W L E T T E R S 22 JUNE 2012

further evidence that the observed peak corresponds to a real

_b signal. The

_b mass extracted from the fit is 5795:0  3:1ðstatÞ MeV, in good agreement with the world-average value [13]. The corresponding mass resolu- tion is 23:7  3:2ðstatÞ MeV, in agreement with the value 22:5  4:7 MeV, obtained from a detailed Monte Carlo (MC) simulation of the CMS detector response, using

PYTHIA 6.409[15],EVTGEN[16], andGEANT4[17].

To search for
^0_b baryons, the

_b candidates with a mass within 2.5 standard deviations of the fitted peak value are combined with tracks, assumed to be pions, with a charge opposite to the

charge (opposite-sign pairs) and coming from the selected PV, with a significance less than 3 standard deviations on the distance between the track trajectory and the PV. Other quality requirements applied to the tracks are p_T> 0:25 GeV, at least two hits in the silicon pixel layers, at least five hits in the entire tracker, and a track fit ²=ndf < 2:5.

The
^0_b search uses the mass difference Q between the measured J=c


^þ invariant mass and the sum of the masses of the decay products, Q ¼ MðJ=c


^þÞ
MðJ=c

Þ
Mð
Þ, where Mð
Þ is the charged-pion mass [13]. The search for new resonances in the Q distri- bution requires a reliable background shape. A background model is built using candidates where the prompt pion and the

_b have the same charge (same-sign pairs), given that the background is expected to be dominated by combina- torial sources, as checked by MC studies. The measured momentum distributions of

_b candidates and same-sign pions (pð
bÞ, pð
Þ), together with the distribution of the angle between them (), are used to randomly generate uncorrelated values for pð
bÞ, pð
Þ, and . Given the limited statistical precision of the

_b momentum distri- bution, the corresponding random numbers are generated from a parametrized version using the fit function f

_bðpÞ ¼ p^k1e
^k2p, where ki are free parameters. The three random values are then combined to calculate a Q value for predicting the combinatorial background distri- bution. One hundred million Q values are generated in this way and the resulting distribution is fitted to the function Q^c1ðe
^c2Qþ e
^c3Qþ e
^c4QÞ, where ci are free parame- ters. Figure 2(a) compares the Q distribution of the same-sign
^0_b candidates with the predicted background shape. Alternative functional forms of f

_bðpÞ are used to estimate the systematic uncertainty associated with this method, which contributes to the determination of the background parameters.

The measured opposite-sign Q distribution is displayed in Fig. 2(b) for the range 0–50 MeV. The 21 events ob- served in the region 12 < Q < 18 MeV represent a clear excess with respect to the expected background yield of 3:0  1:4 events, evaluated by integrating the background function in this Q window. An unbinned maximum- likelihood fit is performed to the opposite-sign Q distribu- tion with a Breit-Wigner distribution convolved with a

Gaussian function, added to the background function pre- viously described. The Gaussian resolution of the peak is constrained to 1:91  0:11 MeV, as determined in the signal MC simulation, and the background parameters are allowed to float within their total uncertainties (statis- tical plus systematic, added in quadrature). Figure2(b)also shows the result of the fit. A peak is clearly visible above the background continuum. The fitted parameters of the peak are Q ¼ 14:84  0:74ðstatÞ MeV and Breit-Wigner width  ¼ 2:1  1:7ðstatÞ MeV. The fitted Breit-Wigner width agrees with  ¼ 0:51  0:16 MeV, the value ob- tained following Eq. (102) of Ref. [18], based on lattice quantum chromodynamic calculations.

To evaluate the significance of the signal, the likelihood Lsþbof the signal-plus-background fit is determined. The

) [MeV]

π ) - M(

Ξ-

ψ ) - M(J/

π+

Ξ-

ψ M(J/

0 100 200 300 400

candidates per 10 MeV*0 bΞ

0 5 10 15 20 25 30

Same-sign data Background CMS

= 7 TeV s pp, L = 5.3 fb-1

(a)

) [MeV]

π ) - M(

Ξ-

ψ ) - M(J/

π+

Ξ-

ψ M(J/

0 10 20 30 40 50

candidates per 2 MeV*0 bΞ

0 2 4 6 8 10 12 14 16

(b)

Opposite-sign data Signal+background fit Background CMS

= 7 TeV s pp, L = 5.3 fb-1

FIG. 2 (color online). (a) Same-sign Q distribution (closed circles) and result of a fit with the background model (red dashed curve) in the range 0 < Q < 400 MeV. (b) Opposite-sign Q distribution (closed circles) in the 0 < Q < 50 MeV range, along with the result of the signal-plus-background fit (blue solid curve); the background term is also shown (red dashed curve).

fit is then repeated using the background-only model to obtain a new likelihood Lb. The parameters obtained from the background fit are allowed to float so that their uncer- tainties and correlations contribute to the calculation of the significance. The logarithmic likelihood ratioffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi

lnðL_sþb=L_bÞ

p would indicate a statistical significance of 6.9 standard deviations (), corresponding to a probability of 2:5  10
¹²for a background fluctuation of this signifi- cance or more to be observed. The significance remains the same if the fit is repeated using the theoretically expected width, allowing it to vary within the range of the theoretical uncertainty. The signal significance is also evaluated by generating pseudoexperiments in which the background distribution is varied within its statistical uncertainty, and determining the background fluctuation probability (‘‘p value’’) as the number of experiments that give a fit with the same significance or higher than in the data. The ‘‘look- elsewhere effect’’ [19] is assessed by searching for a peak, of width  between 0 and 25 MeV, in the extended mass range 0 < Q < 50 MeV, where the
^0_b is theoretically expected. The resulting background fluctuation probability is p ¼ 1:3  10
⁸, which corresponds to a 5:7 equivalent Gaussian significance. If the search range is further ex- tended to 0 < Q < 400 MeV, the equivalent Gaussian sig- nificance becomes 5:3.

This analysis has been repeated using simulated B^þ, B⁰, Bs, and bsamples, obtained by the detailed MC simula- tion of the CMS detector already mentioned. The samples contain events in which the b hadron is forced to decay to a J=c, which decays to ^þ
. No evidence of peaks due to partially reconstructed b-hadron decays is observed in these samples. The opposite-sign Q distribution obtained using

_b candidates from the lower- and higher-mass sidebands of the signal peak also shows no excess, indicat- ing that the observed peak is not caused by fake

_b candidates.

The systematic uncertainty on the measured Q value is evaluated through the signal MC simulation. The recon- structed Q value in MC simulations is measured to be 0:23  0:10 MeV above the generated value. This is con- sistent with the observation that the measured ⁰ and

masses are 0:16  0:05 and 0:18  0:14 MeV, respec- tively, above their world averages. The sum in quadrature of the shift and its statistical uncertainty, 0.25 MeV, is considered as the systematic uncertainty due to this effect.

As an extreme fitting scenario, a flat function is used for the background shape, leading to a Q value 0.12 MeV higher than the value measured with the nominal background model. Adding in quadrature this uncertainty with the previous one results in a total Q systematic uncertainty of 0.28 MeV.

The observation of this resonance, corresponding to the one observed in the charm sector [4], and its mass mea- surement add valuable information to the understanding of the interactions between quarks within a baryon.

In summary, a new
_bbaryon has been observed in pp collisions at ffiffiffi

ps

¼ 7 TeV, using data collected by the CMS experiment, corresponding to an integrated luminosity of 5:3 fb
¹. The signal is observed with a significance exceeding 5 standard deviations. The measured Q ¼ MðJ=c


^þÞ
MðJ=c

Þ
Mð
Þ value is 14:84  0:74ðstatÞ  0:28ðsystÞ MeV. Given the charged-pion and

_b masses [13], the resulting b-baryon mass is 5945:0  0:7ðstatÞ  0:3ðsystÞ  2:7ðPDGÞ MeV, where the last un- certainty reflects the present accuracy of the

_b mass from the Particle Data Group [13]. While the width of the new baryon is not measured with good statistical precision, it is compatible with theoretical expectations [18]. Given its measured mass and decay mode, the new baryon is likely to be the
^0_b , with J^P¼ 3=2^þ.

We congratulate our colleagues in the CERN accelerator departments for the excellent performance of the LHC machine. We thank the technical and administrative staff at CERN and other CMS institutes, and acknowledge sup- port from: 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); MoER, SF0690030s09 and ERDF (Estonia);

Academy of Finland, MEC, 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); MSI (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal);

JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan);

MON, RosAtom, RAS and RFBR (Russia); MSTD (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA).

[1] V. M. Abazov et al., Phys. Rev. Lett. 99, 052001 (2007).

[2] T. Aaltonen et al., Phys. Rev. Lett. 99, 052002 (2007).

[3] T. Aaltonen et al.,Phys. Rev. Lett.107, 102001 (2011).

[4] P. Avery et al.,Phys. Rev. Lett.75, 4364 (1995).

[5] J. Alexander et al.,Phys. Rev. Lett.83, 3390 (1999).

[6] S. Csorna et al.,Phys. Rev. Lett.86, 4243 (2001).

[7] N. Mathur, R. Lewis, and R. M. Woloshyn,Phys. Rev. D 66, 014502 (2002).

[8] E. E. Jenkins,Phys. Rev. D77, 034012 (2008).

[9] R. Lewis and R. M. Woloshyn,Phys. Rev. D 79, 014502 (2009).

[10] D. Ebert, R. N. Faustov, and V. O. Galkin,Phys. Rev. D84, 014025 (2011).

PRL108, 252002 (2012) P H Y S I C A L R E V I E W L E T T E R S 22 JUNE 2012

[11] M. Karliner, B. Keren-Zur, H. J. Lipkin, and J. L. Rosner, Ann. Phys. (N.Y.)324, 2 (2009).

[12] S. Chatrchyan et al. (CMS Collaboration), JINST 3, S08004 (2008).

[13] K. Nakamura et al.,J. Phys. G37, 075021 (2010).

[14] G. E. Forden and D. H. Saxon, Nucl. Instrum. Methods Phys. Res., Sect. A248, 439 (1986).

[15] T. Sjostrand, S. Mrenna, and P. Z. Skands,J. High Energy Phys. 05 (2006) 026.

[16] D. J. Lange,Nucl. Instrum. Methods Phys. Res., Sect. A 462, 152 (2001).

[17] S. Agostinelli et al.,Nucl. Instrum. Methods Phys. Res., Sect. A506, 250 (2003).

[18] W. Detmold, C.-J. D. Lin, and S. Meinel, arXiv:1203.3378.

[19] L. Demortier, in PHYSTAT-LHC Workshop on Statistical Issues for LHC Physics, edited by L. Lyons, H. Prosper, and A. de Roeck (CERN, Geneva, 2008).

S. Chatrchyan,¹V. Khachatryan,¹A. M. Sirunyan,¹A. Tumasyan,¹W. Adam,²T. Bergauer,²M. Dragicevic,²J. Ero¨,² C. Fabjan,^2,bM. Friedl,²R. Fru¨hwirth,^2,bV. M. Ghete,²J. Hammer,²N. Ho¨rmann,²J. Hrubec,²M. Jeitler,^2,b W. Kiesenhofer,²V. Knu¨nz,²M. Krammer,^2,bD. Liko,²I. Mikulec,²M. Pernicka,^2,aB. Rahbaran,²C. Rohringer,²

H. Rohringer,²R. Scho¨fbeck,²J. Strauss,²A. Taurok,²P. Wagner,²W. Waltenberger,²G. Walzel,²E. Widl,² C.-E. Wulz,^2,bV. Mossolov,³N. Shumeiko,³J. Suarez Gonzalez,³S. Bansal,⁴T. Cornelis,⁴E. A. De Wolf,⁴ X. Janssen,⁴S. Luyckx,⁴T. Maes,⁴L. Mucibello,⁴S. Ochesanu,⁴B. Roland,⁴R. Rougny,⁴M. Selvaggi,⁴ Z. Staykova,⁴H. Van Haevermaet,⁴P. Van Mechelen,⁴N. Van Remortel,⁴A. Van Spilbeeck,⁴F. Blekman,⁵ S. Blyweert,⁵J. D’Hondt,⁵R. Gonzalez Suarez,⁵A. Kalogeropoulos,⁵M. Maes,⁵A. Olbrechts,⁵W. Van Doninck,⁵ P. Van Mulders,⁵G. P. Van Onsem,⁵I. Villella,⁵O. Charaf,⁶B. Clerbaux,⁶G. De Lentdecker,⁶V. Dero,⁶A. P. R. Gay,⁶ T. Hreus,⁶A. Le´onard,⁶P. E. Marage,⁶T. Reis,⁶L. Thomas,⁶C. Vander Velde,⁶P. Vanlaer,⁶J. Wang,⁶V. Adler,⁷

K. Beernaert,⁷A. Cimmino,⁷S. Costantini,⁷G. Garcia,⁷M. Grunewald,⁷B. Klein,⁷J. Lellouch,⁷A. Marinov,⁷ J. Mccartin,⁷A. A. Ocampo Rios,⁷D. Ryckbosch,⁷N. Strobbe,⁷F. Thyssen,⁷M. Tytgat,⁷L. Vanelderen,⁷ P. Verwilligen,⁷S. Walsh,⁷E. Yazgan,⁷N. Zaganidis,⁷S. Basegmez,⁸G. Bruno,⁸R. Castello,⁸L. Ceard,⁸C. Delaere,⁸

T. du Pree,⁸D. Favart,⁸L. Forthomme,⁸A. Giammanco,^8,cJ. Hollar,⁸V. Lemaitre,⁸J. Liao,⁸O. Militaru,⁸ C. Nuttens,⁸D. Pagano,⁸A. Pin,⁸K. Piotrzkowski,⁸N. Schul,⁸J. M. Vizan Garcia,⁸N. Beliy,⁹T. Caebergs,⁹ E. Daubie,⁹G. H. Hammad,⁹G. A. Alves,¹⁰M. Correa Martins Junior,¹⁰D. De Jesus Damiao,¹⁰T. Martins,¹⁰

M. E. Pol,¹⁰M. H. G. Souza,¹⁰W. L. Alda´ Ju´nior,¹¹W. Carvalho,¹¹A. Custo´dio,¹¹E. M. Da Costa,¹¹ C. De Oliveira Martins,¹¹S. Fonseca De Souza,¹¹D. Matos Figueiredo,¹¹L. Mundim,¹¹H. Nogima,¹¹V. Oguri,¹¹

W. L. Prado Da Silva,¹¹A. Santoro,¹¹L. Soares Jorge,¹¹A. Sznajder,¹¹C. A. Bernardes,^12,dF. A. Dias,^12,e T. R. Fernandez Perez Tomei,¹²E. M. Gregores,^12,dC. Lagana,¹²F. Marinho,¹²P. G. Mercadante,^12,dS. F. Novaes,¹²

Sandra S. Padula,¹²V. Genchev,^13,fP. Iaydjiev,^13,fS. Piperov,¹³M. Rodozov,¹³S. Stoykova,¹³G. Sultanov,¹³ V. Tcholakov,¹³R. Trayanov,¹³M. Vutova,¹³A. Dimitrov,¹⁴R. Hadjiiska,¹⁴V. Kozhuharov,¹⁴L. Litov,¹⁴B. Pavlov,¹⁴

P. Petkov,¹⁴J. G. Bian,¹⁵G. M. Chen,¹⁵H. S. Chen,¹⁵C. H. Jiang,¹⁵D. Liang,¹⁵S. Liang,¹⁵X. Meng,¹⁵J. Tao,¹⁵ J. Wang,¹⁵X. Wang,¹⁵Z. Wang,¹⁵H. Xiao,¹⁵M. Xu,¹⁵J. Zang,¹⁵Z. Zhang,¹⁵C. Asawatangtrakuldee,¹⁶Y. Ban,¹⁶ S. Guo,¹⁶Y. Guo,¹⁶W. Li,¹⁶S. Liu,¹⁶Y. Mao,¹⁶S. J. Qian,¹⁶H. Teng,¹⁶S. Wang,¹⁶B. Zhu,¹⁶W. Zou,¹⁶C. Avila,¹⁷

J. P. Gomez,¹⁷B. Gomez Moreno,¹⁷A. F. Osorio Oliveros,¹⁷J. C. Sanabria,¹⁷N. Godinovic,¹⁸D. Lelas,¹⁸ R. Plestina,^18,gD. Polic,¹⁸I. Puljak,^18,fZ. Antunovic,¹⁹M. Kovac,¹⁹V. Brigljevic,²⁰S. Duric,²⁰K. Kadija,²⁰ J. Luetic,²⁰S. Morovic,²⁰A. Attikis,²¹M. Galanti,²¹G. Mavromanolakis,²¹J. Mousa,²¹C. Nicolaou,²¹F. Ptochos,²¹

P. A. Razis,²¹M. Finger,²²M. Finger, Jr.,²²Y. Assran,^23,hS. Elgammal,^23,iA. Ellithi Kamel,^23,jS. Khalil,^23,i M. A. Mahmoud,^23,kA. Radi,^23,lM. Kadastik,²⁴M. Mu¨ntel,²⁴M. Raidal,²⁴L. Rebane,²⁴A. Tiko,²⁴V. Azzolini,²⁵

P. Eerola,²⁵G. Fedi,²⁵M. Voutilainen,²⁵J. Ha¨rko¨nen,²⁶A. Heikkinen,²⁶V. Karima¨ki,²⁶R. Kinnunen,²⁶ M. J. Kortelainen,²⁶T. Lampe´n,²⁶K. Lassila-Perini,²⁶S. Lehti,²⁶T. Linde´n,²⁶P. Luukka,²⁶T. Ma¨enpa¨a¨,²⁶ T. Peltola,²⁶E. Tuominen,²⁶J. Tuominiemi,²⁶E. Tuovinen,²⁶D. Ungaro,²⁶L. Wendland,²⁶K. Banzuzi,²⁷ A. Karjalainen,²⁷A. Korpela,²⁷T. Tuuva,²⁷M. Besancon,²⁸S. Choudhury,²⁸M. Dejardin,²⁸D. Denegri,²⁸ B. Fabbro,²⁸J. L. Faure,²⁸F. Ferri,²⁸S. Ganjour,²⁸A. Givernaud,²⁸P. Gras,²⁸G. Hamel de Monchenault,²⁸P. Jarry,²⁸

E. Locci,²⁸J. Malcles,²⁸L. Millischer,²⁸A. Nayak,²⁸J. Rander,²⁸A. Rosowsky,²⁸I. Shreyber,²⁸M. Titov,²⁸ S. Baffioni,²⁹F. Beaudette,²⁹L. Benhabib,²⁹L. Bianchini,²⁹M. Bluj,^29,mC. Broutin,²⁹P. Busson,²⁹C. Charlot,²⁹ N. Daci,²⁹T. Dahms,²⁹L. Dobrzynski,²⁹R. Granier de Cassagnac,²⁹M. Haguenauer,²⁹P. Mine´,²⁹C. Mironov,²⁹

M. Nguyen,²⁹C. Ochando,²⁹P. Paganini,²⁹D. Sabes,²⁹R. Salerno,²⁹Y. Sirois,²⁹C. Veelken,²⁹A. Zabi,²⁹ J.-L. Agram,^30,nJ. Andrea,³⁰D. Bloch,³⁰D. Bodin,³⁰J.-M. Brom,³⁰M. Cardaci,³⁰E. C. Chabert,³⁰C. Collard,³⁰ E. Conte,^30,nF. Drouhin,^30,nC. Ferro,³⁰J.-C. Fontaine,^30,nD. Gele´,³⁰U. Goerlach,³⁰P. Juillot,³⁰A.-C. Le Bihan,³⁰

P. Van Hove,³⁰F. Fassi,³¹D. Mercier,³¹S. Beauceron,³²N. Beaupere,³²O. Bondu,³²G. Boudoul,³²H. Brun,³²

J. Chasserat,³²R. Chierici,^32,fD. Contardo,³²P. Depasse,³²H. El Mamouni,³²J. Fay,³²S. Gascon,³² M. Gouzevitch,³²B. Ille,³²T. Kurca,³²M. Lethuillier,³²L. Mirabito,³²S. Perries,³²V. Sordini,³²S. Tosi,³² Y. Tschudi,³²P. Verdier,³²S. Viret,³²Z. Tsamalaidze,³³G. Anagnostou,³⁴S. Beranek,³⁴M. Edelhoff,³⁴L. Feld,³⁴ N. Heracleous,³⁴O. Hindrichs,³⁴R. Jussen,³⁴K. Klein,³⁴J. Merz,³⁴A. Ostapchuk,³⁴A. Perieanu,³⁴F. Raupach,³⁴

J. Sammet,³⁴S. Schael,³⁴D. Sprenger,³⁴H. Weber,³⁴B. Wittmer,³⁴V. Zhukov,^34,oM. Ata,³⁵J. Caudron,³⁵ E. Dietz-Laursonn,³⁵M. Erdmann,³⁵A. Gu¨th,³⁵T. Hebbeker,³⁵C. Heidemann,³⁵K. Hoepfner,³⁵D. Klingebiel,³⁵

P. Kreuzer,³⁵J. Lingemann,³⁵C. Magass,³⁵M. Merschmeyer,³⁵A. Meyer,³⁵M. Olschewski,³⁵P. Papacz,³⁵ H. Pieta,³⁵H. Reithler,³⁵S. A. Schmitz,³⁵L. Sonnenschein,³⁵J. Steggemann,³⁵D. Teyssier,³⁵M. Weber,³⁵ M. Bontenackels,³⁶V. Cherepanov,³⁶G. Flu¨gge,³⁶H. Geenen,³⁶M. Geisler,³⁶W. Haj Ahmad,³⁶F. Hoehle,³⁶ B. Kargoll,³⁶T. Kress,³⁶Y. Kuessel,³⁶A. Nowack,³⁶L. Perchalla,³⁶O. Pooth,³⁶J. Rennefeld,³⁶P. Sauerland,³⁶

A. Stahl,³⁶M. Aldaya Martin,³⁷J. Behr,³⁷W. Behrenhoff,³⁷U. Behrens,³⁷M. Bergholz,^37,pA. Bethani,³⁷ K. Borras,³⁷A. Burgmeier,³⁷A. Cakir,³⁷L. Calligaris,³⁷A. Campbell,³⁷E. Castro,³⁷F. Costanza,³⁷D. Dammann,³⁷ G. Eckerlin,³⁷D. Eckstein,³⁷D. Fischer,³⁷G. Flucke,³⁷A. Geiser,³⁷I. Glushkov,³⁷S. Habib,³⁷J. Hauk,³⁷H. Jung,^37,f

M. Kasemann,³⁷P. Katsas,³⁷C. Kleinwort,³⁷H. Kluge,³⁷A. Knutsson,³⁷M. Kra¨mer,³⁷D. Kru¨cker,³⁷ E. Kuznetsova,³⁷W. Lange,³⁷W. Lohmann,^37,pB. Lutz,³⁷R. Mankel,³⁷I. Marfin,³⁷M. Marienfeld,³⁷ I.-A. Melzer-Pellmann,³⁷A. B. Meyer,³⁷J. Mnich,³⁷A. Mussgiller,³⁷S. Naumann-Emme,³⁷J. Olzem,³⁷H. Perrey,³⁷

A. Petrukhin,³⁷D. Pitzl,³⁷A. Raspereza,³⁷P. M. Ribeiro Cipriano,³⁷C. Riedl,³⁷M. Rosin,³⁷J. Salfeld-Nebgen,³⁷ R. Schmidt,^37,pT. Schoerner-Sadenius,³⁷N. Sen,³⁷A. Spiridonov,³⁷M. Stein,³⁷R. Walsh,³⁷C. Wissing,³⁷ C. Autermann,³⁸V. Blobel,³⁸S. Bobrovskyi,³⁸J. Draeger,³⁸H. Enderle,³⁸J. Erfle,³⁸U. Gebbert,³⁸M. Go¨rner,³⁸

T. Hermanns,³⁸R. S. Ho¨ing,³⁸K. Kaschube,³⁸G. Kaussen,³⁸H. Kirschenmann,³⁸R. Klanner,³⁸J. Lange,³⁸ B. Mura,³⁸F. Nowak,³⁸T. Peiffer,³⁸N. Pietsch,³⁸C. Sander,³⁸H. Schettler,³⁸P. Schleper,³⁸E. Schlieckau,³⁸ A. Schmidt,³⁸M. Schro¨der,³⁸T. Schum,³⁸H. Stadie,³⁸G. Steinbru¨ck,³⁸J. Thomsen,³⁸C. Barth,³⁹J. Berger,³⁹

T. Chwalek,³⁹W. De Boer,³⁹A. Dierlamm,³⁹M. Feindt,³⁹M. Guthoff,^39,fC. Hackstein,³⁹F. Hartmann,³⁹ M. Heinrich,³⁹H. Held,³⁹K. H. Hoffmann,³⁹S. Honc,³⁹I. Katkov,^39,oJ. R. Komaragiri,³⁹D. Martschei,³⁹ S. Mueller,³⁹Th. Mu¨ller,³⁹M. Niegel,³⁹A. Nu¨rnberg,³⁹O. Oberst,³⁹A. Oehler,³⁹J. Ott,³⁹G. Quast,³⁹K. Rabbertz,³⁹

F. Ratnikov,³⁹N. Ratnikova,³⁹S. Ro¨cker,³⁹A. Scheurer,³⁹F.-P. Schilling,³⁹G. Schott,³⁹H. J. Simonis,³⁹ F. M. Stober,³⁹D. Troendle,³⁹R. Ulrich,³⁹J. Wagner-Kuhr,³⁹T. Weiler,³⁹M. Zeise,³⁹G. Daskalakis,⁴⁰T. Geralis,⁴⁰

S. Kesisoglou,⁴⁰A. Kyriakis,⁴⁰D. Loukas,⁴⁰I. Manolakos,⁴⁰A. Markou,⁴⁰C. Markou,⁴⁰C. Mavrommatis,⁴⁰ E. Ntomari,⁴⁰L. Gouskos,⁴¹T. J. Mertzimekis,⁴¹A. Panagiotou,⁴¹N. Saoulidou,⁴¹I. Evangelou,⁴²C. Foudas,^42,f P. Kokkas,⁴²N. Manthos,⁴²I. Papadopoulos,⁴²V. Patras,⁴²G. Bencze,⁴³C. Hajdu,^43,fP. Hidas,⁴³D. Horvath,^43,q B. Radics,⁴³F. Sikler,⁴³V. Veszpremi,⁴³G. Vesztergombi,^43,rN. Beni,⁴⁴S. Czellar,⁴⁴J. Molnar,⁴⁴J. Palinkas,⁴⁴ Z. Szillasi,⁴⁴J. Karancsi,⁴⁵P. Raics,⁴⁵Z. L. Trocsanyi,⁴⁵B. Ujvari,⁴⁵S. B. Beri,⁴⁶V. Bhatnagar,⁴⁶N. Dhingra,⁴⁶ R. Gupta,⁴⁶M. Jindal,⁴⁶M. Kaur,⁴⁶M. Z. Mehta,⁴⁶N. Nishu,⁴⁶L. K. Saini,⁴⁶A. Sharma,⁴⁶J. Singh,⁴⁶S. Ahuja,⁴⁷

A. Bhardwaj,⁴⁷B. C. Choudhary,⁴⁷A. Kumar,⁴⁷A. Kumar,⁴⁷S. Malhotra,⁴⁷M. Naimuddin,⁴⁷K. Ranjan,⁴⁷ V. Sharma,⁴⁷R. K. Shivpuri,⁴⁷S. Banerjee,⁴⁸S. Bhattacharya,⁴⁸S. Dutta,⁴⁸B. Gomber,⁴⁸Sa. Jain,⁴⁸Sh. Jain,⁴⁸ R. Khurana,⁴⁸S. Sarkar,⁴⁸M. Sharan,⁴⁸A. Abdulsalam,⁴⁹R. K. Choudhury,⁴⁹D. Dutta,⁴⁹S. Kailas,⁴⁹V. Kumar,⁴⁹

P. Mehta,⁴⁹A. K. Mohanty,^49,fL. M. Pant,⁴⁹P. Shukla,⁴⁹T. Aziz,⁵⁰S. Ganguly,⁵⁰M. Guchait,^50,sM. Maity,^50,t G. Majumder,⁵⁰K. Mazumdar,⁵⁰G. B. Mohanty,⁵⁰B. Parida,⁵⁰K. Sudhakar,⁵⁰N. Wickramage,⁵⁰S. Banerjee,⁵¹

S. Dugad,⁵¹H. Arfaei,⁵²H. Bakhshiansohi,^52,uS. M. Etesami,^52,vA. Fahim,^52,uM. Hashemi,⁵²A. Jafari,^52,u M. Khakzad,⁵²A. Mohammadi,^52,wM. Mohammadi Najafabadi,⁵²S. Paktinat Mehdiabadi,⁵²B. Safarzadeh,^52,x

M. Zeinali,^52,vM. Abbrescia,^53a,53bL. Barbone,^53a,53bC. Calabria,^53a,53b,fS. S. Chhibra,^53a,53bA. Colaleo,^53a D. Creanza,^53a,53cN. De Filippis,^53a,53c,fM. De Palma,^53a,53bL. Fiore,^53aG. Iaselli,^53a,53cL. Lusito,^53a,53b G. Maggi,^53a,53cM. Maggi,^53aB. Marangelli,^53a,53bS. My,^53a,53cS. Nuzzo,^53a,53bN. Pacifico,^53a,53bA. Pompili,^53a,53b G. Pugliese,^53a,53cG. Selvaggi,^53a,53bL. Silvestris,^53aG. Singh,^53a,53bG. Zito,^53aG. Abbiendi,^54aA. C. Benvenuti,^54a

D. Bonacorsi,^54a,54bS. Braibant-Giacomelli,^54a,54bL. Brigliadori,^54a,54bP. Capiluppi,^54a,54bA. Castro,^54a,54b F. R. Cavallo,^54aM. Cuffiani,^54a,54bG. M. Dallavalle,^54aF. Fabbri,^54aA. Fanfani,^54a,54bD. Fasanella,^54a,54b,f P. Giacomelli,^54aC. Grandi,^54aL. Guiducci,^54a,54bS. Marcellini,^54aG. Masetti,^54aM. Meneghelli,^54a,54b,f A. Montanari,^54aF. L. Navarria,^54a,54bF. Odorici,^54aA. Perrotta,^54aF. Primavera,^54a,54bA. M. Rossi,^54a,54b T. Rovelli,^54a,54bG. Siroli,^54a,54bR. Travaglini,^54a,54bS. Albergo,^55a,55bG. Cappello,^55a,55bM. Chiorboli,^55a,55b S. Costa,^55a,55bR. Potenza,^55a,55bA. Tricomi,^55a,55bC. Tuve,^55a,55bG. Barbagli,^56aV. Ciulli,^56a,56bC. Civinini,^56a R. D’Alessandro,^56a,56bE. Focardi,^56a,56bS. Frosali,^56a,56bE. Gallo,^56aS. Gonzi,^56a,56bM. Meschini,^56aS. Paoletti,^56a PRL108, 252002 (2012) P H Y S I C A L R E V I E W L E T T E R S 22 JUNE 2012

G. Sguazzoni,^56aA. Tropiano,^56a,fL. Benussi,⁵⁷S. Bianco,⁵⁷S. Colafranceschi,^57,yF. Fabbri,⁵⁷D. Piccolo,⁵⁷ P. Fabbricatore,⁵⁸R. Musenich,⁵⁸A. Benaglia,^59a,59b,fF. De Guio,^59a,59bL. Di Matteo,^59a,59b,fS. Fiorendi,^59a,59b

S. Gennai,^59a,fA. Ghezzi,^59a,59bS. Malvezzi,^59aR. A. Manzoni,^59a,59bA. Martelli,^59a,59bA. Massironi,^59a,59b,f D. Menasce,^59aL. Moroni,^59aM. Paganoni,^59a,59bD. Pedrini,^59aS. Ragazzi,^59a,59bN. Redaelli,^59aS. Sala,^59a T. Tabarelli de Fatis,^59a,59bS. Buontempo,^60aC. A. Carrillo Montoya,^60a,fN. Cavallo,^60a,zA. De Cosa,^60a,60b,f O. Dogangun,^60a,60bF. Fabozzi,^60a,zA. O. M. Iorio,^60aL. Lista,^60aS. Meola,^60a,aaM. Merola,^60a,60bP. Paolucci,^60a,f

P. Azzi,^61aN. Bacchetta,^61a,fP. Bellan,^61a,61bD. Bisello,^61a,61bA. Branca,^61a,fR. Carlin,^61a,61bP. Checchia,^61a T. Dorigo,^61aF. Gasparini,^61a,61bU. Gasparini,^61a,61bA. Gozzelino,^61aK. Kanishchev,^61a,61cS. Lacaprara,^61a

I. Lazzizzera,^61a,61cM. Margoni,^61a,61bA. T. Meneguzzo,^61a,61bN. Pozzobon,^61a,61bP. Ronchese,^61a,61b F. Simonetto,^61a,61bE. Torassa,^61aM. Tosi,^61a,61b,fS. Vanini,^61a,61bP. Zotto,^61a,61bG. Zumerle,^61a,61b M. Gabusi,^62a,62bS. P. Ratti,^62a,62bC. Riccardi,^62a,62bP. Torre,^62a,62bP. Vitulo,^62a,62bM. Biasini,^63a,63bG. M. Bilei,^63a

L. Fano`,<sup>63a,63b</sup>P. Lariccia,<sup>63a,63b</sup>A. Lucaroni,<sup>63a,63b,f</sup>G. Mantovani,<sup>63a,63b</sup>M. Menichelli,<sup>63a</sup>A. Nappi,<sup>63a,63b</sup> F. Romeo,<sup>63a,63b</sup>A. Saha,<sup>63a</sup>A. Santocchia,<sup>63a,63b</sup>S. Taroni,<sup>63a,63b,f</sup>P. Azzurri,<sup>64a,64c</sup>G. Bagliesi,<sup>64a</sup>T. Boccali,<sup>64a</sup> G. Broccolo,<sup>64a,64c</sup>R. Castaldi,<sup>64a</sup>R. T. D’Agnolo,<sup>64a,64c</sup>R. Dell’Orso,<sup>64a</sup>F. Fiori,<sup>64a,64b,f</sup>L. Foa`,^64a,64cA. Giassi,^64a

A. Kraan,^64aF. Ligabue,^64a,64cT. Lomtadze,^64aL. Martini,^64a,bbA. Messineo,^64a,64bF. Palla,^64aA. Rizzi,^64a,64b A. T. Serban,^64a,ccP. Spagnolo,^64aP. Squillacioti,^64a,fR. Tenchini,^64aG. Tonelli,^64a,64b,fA. Venturi,^64a,f P. G. Verdini,^64aL. Barone,^65a,65bF. Cavallari,^65aD. Del Re,^65a,65b,fM. Diemoz,^65aM. Grassi,^65a,65b,fE. Longo,^65a,65b

P. Meridiani,^65a,fF. Micheli,^65a,65bS. Nourbakhsh,^65a,65bG. Organtini,^65a,65bR. Paramatti,^65aS. Rahatlou,^65a,65b M. Sigamani,^65aL. Soffi,^65a,65bN. Amapane,^66a,66bR. Arcidiacono,^66a,66cS. Argiro,^66a,66bM. Arneodo,^66a,66c C. Biino,^66aC. Botta,^66a,66bN. Cartiglia,^66aM. Costa,^66a,66bN. Demaria,^66aA. Graziano,^66a,66bC. Mariotti,^66a,f

S. Maselli,^66aE. Migliore,^66a,66bV. Monaco,^66a,66bM. Musich,^66a,fM. M. Obertino,^66a,66cN. Pastrone,^66a M. Pelliccioni,^66aA. Potenza,^66a,66bA. Romero,^66a,66bM. Ruspa,^66a,66cR. Sacchi,^66a,66bV. Sola,^66a,66b

A. Solano,^66a,66bA. Staiano,^66aA. Vilela Pereira,^66aS. Belforte,^67aV. Candelise,^67a,67bF. Cossutti,^67a G. Della Ricca,^67a,67bB. Gobbo,^67aM. Marone,^67a,67b,fD. Montanino,^67a,67b,fA. Penzo,^67aA. Schizzi,^67a,67b S. G. Heo,⁶⁸T. Y. Kim,⁶⁸S. K. Nam,⁶⁸S. Chang,⁶⁹J. Chung,⁶⁹D. H. Kim,⁶⁹G. N. Kim,⁶⁹D. J. Kong,⁶⁹H. Park,⁶⁹ S. R. Ro,⁶⁹D. C. Son,⁶⁹T. Son,⁶⁹J. Y. Kim,⁷⁰Zero J. Kim,⁷⁰S. Song,⁷⁰H. Y. Jo,⁷¹S. Choi,⁷²D. Gyun,⁷²B. Hong,⁷² M. Jo,⁷²H. Kim,⁷²T. J. Kim,⁷²K. S. Lee,⁷²D. H. Moon,⁷²S. K. Park,⁷²M. Choi,⁷³S. Kang,⁷³J. H. Kim,⁷³C. Park,⁷³ I. C. Park,⁷³S. Park,⁷³G. Ryu,⁷³Y. Cho,⁷⁴Y. Choi,⁷⁴Y. K. Choi,⁷⁴J. Goh,⁷⁴M. S. Kim,⁷⁴E. Kwon,⁷⁴B. Lee,⁷⁴

J. Lee,⁷⁴S. Lee,⁷⁴H. Seo,⁷⁴I. Yu,⁷⁴M. J. Bilinskas,⁷⁵I. Grigelionis,⁷⁵M. Janulis,⁷⁵A. Juodagalvis,⁷⁵ H. Castilla-Valdez,⁷⁶E. De La Cruz-Burelo,⁷⁶I. Heredia-de La Cruz,⁷⁶R. Lopez-Fernandez,⁷⁶R. Magan˜a Villalba,⁷⁶

J. Martı´nez-Ortega,⁷⁶A. Sa´nchez-Herna´ndez,⁷⁶L. M. Villasenor-Cendejas,⁷⁶S. Carrillo Moreno,⁷⁷ F. Vazquez Valencia,⁷⁷H. A. Salazar Ibarguen,⁷⁸E. Casimiro Linares,⁷⁹A. Morelos Pineda,⁷⁹M. A. Reyes-Santos,⁷⁹

D. Krofcheck,⁸⁰A. J. Bell,⁸¹P. H. Butler,⁸¹R. Doesburg,⁸¹S. Reucroft,⁸¹H. Silverwood,⁸¹M. Ahmad,⁸² M. I. Asghar,⁸²H. R. Hoorani,⁸²S. Khalid,⁸²W. A. Khan,⁸²T. Khurshid,⁸²S. Qazi,⁸²M. A. Shah,⁸²M. Shoaib,⁸²

G. Brona,⁸³K. Bunkowski,⁸³M. Cwiok,⁸³W. Dominik,⁸³K. Doroba,⁸³A. Kalinowski,⁸³M. Konecki,⁸³ J. Krolikowski,⁸³H. Bialkowska,⁸⁴B. Boimska,⁸⁴T. Frueboes,⁸⁴R. Gokieli,⁸⁴M. Go´rski,⁸⁴M. Kazana,⁸⁴

K. Nawrocki,⁸⁴K. Romanowska-Rybinska,⁸⁴M. Szleper,⁸⁴G. Wrochna,⁸⁴P. Zalewski,⁸⁴N. Almeida,⁸⁵ P. Bargassa,⁸⁵A. David,⁸⁵P. Faccioli,⁸⁵P. G. Ferreira Parracho,⁸⁵M. Gallinaro,⁸⁵J. Seixas,⁸⁵J. Varela,⁸⁵ P. Vischia,⁸⁵I. Belotelov,⁸⁶P. Bunin,⁸⁶M. Gavrilenko,⁸⁶I. Golutvin,⁸⁶I. Gorbunov,⁸⁶A. Kamenev,⁸⁶V. Karjavin,⁸⁶

G. Kozlov,⁸⁶A. Lanev,⁸⁶A. Malakhov,⁸⁶P. Moisenz,⁸⁶V. Palichik,⁸⁶V. Perelygin,⁸⁶S. Shmatov,⁸⁶V. Smirnov,⁸⁶ A. Volodko,⁸⁶A. Zarubin,⁸⁶S. Evstyukhin,⁸⁷V. Golovtsov,⁸⁷Y. Ivanov,⁸⁷V. Kim,⁸⁷P. Levchenko,⁸⁷V. Murzin,⁸⁷ V. Oreshkin,⁸⁷I. Smirnov,⁸⁷V. Sulimov,⁸⁷L. Uvarov,⁸⁷S. Vavilov,⁸⁷A. Vorobyev,⁸⁷An. Vorobyev,⁸⁷Yu. Andreev,⁸⁸

A. Dermenev,⁸⁸S. Gninenko,⁸⁸N. Golubev,⁸⁸M. Kirsanov,⁸⁸N. Krasnikov,⁸⁸V. Matveev,⁸⁸A. Pashenkov,⁸⁸ D. Tlisov,⁸⁸A. Toropin,⁸⁸V. Epshteyn,⁸⁹M. Erofeeva,⁸⁹V. Gavrilov,⁸⁹M. Kossov,^89,fN. Lychkovskaya,⁸⁹

V. Popov,⁸⁹G. Safronov,⁸⁹S. Semenov,⁸⁹V. Stolin,⁸⁹E. Vlasov,⁸⁹A. Zhokin,⁸⁹A. Belyaev,⁹⁰E. Boos,⁹⁰ M. Dubinin,^90,eL. Dudko,⁹⁰A. Ershov,⁹⁰A. Gribushin,⁹⁰V. Klyukhin,⁹⁰O. Kodolova,⁹⁰I. Lokhtin,⁹⁰A. Markina,⁹⁰

S. Obraztsov,⁹⁰M. Perfilov,⁹⁰S. Petrushanko,⁹⁰A. Popov,⁹⁰L. Sarycheva,^90,aV. Savrin,⁹⁰A. Snigirev,⁹⁰ V. Andreev,⁹¹M. Azarkin,⁹¹I. Dremin,⁹¹M. Kirakosyan,⁹¹A. Leonidov,⁹¹G. Mesyats,⁹¹S. V. Rusakov,⁹¹ A. Vinogradov,⁹¹I. Azhgirey,⁹²I. Bayshev,⁹²S. Bitioukov,⁹²V. Grishin,^92,fV. Kachanov,⁹²D. Konstantinov,⁹² A. Korablev,⁹²V. Krychkine,⁹²V. Petrov,⁹²R. Ryutin,⁹²A. Sobol,⁹²L. Tourtchanovitch,⁹²S. Troshin,⁹²N. Tyurin,⁹²

A. Uzunian,⁹²A. Volkov,⁹²P. Adzic,^93,ddM. Djordjevic,⁹³M. Ekmedzic,⁹³D. Krpic,^93,ddJ. Milosevic,⁹³