EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN)
CERN-PH-EP/2010-094
2011/05/30
CMS-QCD-10-007
S ange Pa icle P oduc ion in pp Collisions a √s= 0.9 and
7 TeV
The CMS Collabo a ion∗
Abs ac
The spec a o s ange had ons a e measu ed in p o on-p o on collisions, eco ded by
he CMS expe imen a he CERN LHC, a cen e-o -mass ene gies o 0.9 and 7 TeV.
The K0
S,Λ, and Ξ−pa icles and hei an ipa icles a e econs uc ed om hei decay
opologies and he p oduc ion a es a e measu ed as unc ions o apidi y and ans-
e se momen um, pT. The esul s a e compa ed o o he expe imen s and o p edic-
ions o he PYTHIA Mon e Ca lo p og am. The pTdis ibu ions a e ound o di e
subs an ially om he PYTHIA esul s and he p oduc ion a es exceed he p edic ions
by up o a ac o o h ee.
Submi ed o he Jou nal o High Ene gy Physics
∗See Appendix A o he lis o collabo a ion membe s
a Xi :1102.4282 2 [hep-ex] 27 May 2011
1
1 In oduc ion
Measu emen s o pa icle yields and spec a a e an essen ial s ep in unde s anding p o on-
p o on collisions a he La ge Had on Collide (LHC). The Compac Muon Solenoid (CMS)
Collabo a ion has published esul s on spec a o cha ged pa icles a cen e-o -mass ene -
gies o 0.9, 2.36, and 7 TeV [1, 2]. In his analysis he measu emen is ex ended o s ange
mesons and ba yons (K0
S,Λ,Ξ−)1a cen e-o -mass ene gies o 0.9 and 7 TeV. The in es i-
ga ion o s ange had on p oduc ion is an impo an ing edien in unde s anding he na u e
o he s ong o ce. The LHC expe imen s ALICE and LHCb ha e ecen ly epo ed esul s
on s ange had on p oduc ion a √s=0.9 TeV [3, 4]. In addi ion o esul s a √s=0.9 TeV,
we also p esen esul s a √s=7 TeV, opening up a new ene gy egime in which o s udy
he s ong in e ac ion. As he s ange qua k is hea ie han up and down qua ks, p oduc ion
o s ange had ons is gene ally supp essed ela i e o had ons con aining only up and down
qua ks. The amoun o s angeness supp ession is an impo an componen in Mon e Ca lo
(MC) models such as PYTHIA [5] and HIJING/BB [6]. Because he h eshold o s ange qua k
p oduc ion in a qua k-gluon plasma is much smalle han in a had on gas, an enhancemen
in s ange pa icle p oduc ion has equen ly been sugges ed as an indica ion o qua k-gluon
plasma o ma ion [7]. This e ec would be u he enhanced in ba yons wi h mul iple s ange
qua ks. While a qua k-gluon plasma is mo e likely o be ound in collisions o hea y nuclei,
he enhancemen o s ange qua k p oduc ion in high ene gy pp collisions would be a sign o a
collec i e e ec , acco ding o some models [8, 9]. In con as , ecen Regge- heo y calcula ions
indica e li le change in he a io o K0
S o cha ge pa icle p oduc ion wi h inc easing collision
ene gy [10, 11]. Thus, hese measu emen s can be used o cons ain heo ies, p o ide inpu o
uning o Mon e Ca lo models, and se e as a e e ence o he in e p e a ion o s angeness
p oduc ion esul s in hea y-ion collisions.
Minimum bias collisions a he LHC can be classi ied as elas ic sca e ing, inelas ic single-
di ac i e dissocia ion (SD), inelas ic double-di ac i e dissocia ion, and inelas ic non-di ac i e
sca e ing. The esul s p esen ed he e a e no malized o he sum o double-di ac i e and
non-di ac i e in e ac ions, e e ed o as non-single-di ac i e (NSD) in e ac ions [1, 2]. This
choice is made o mos closely ma ch he e en selec ion and o compa e wi h p e ious expe i-
men s, which o en used simila c i e ia. The K0
S,Λ, and Ξ−a e long-li ed pa icles (cτ>1 cm)
and can be iden i ied om hei decay p oduc s o igina ing om a displaced e ex. The pa -
icles a e econs uc ed om hei decays: K0
S→π+π−,Λ→pπ−, and Ξ−→Λπ−o e he
apidi y ange |y|<2, whe e he apidi y is de ined as y=1
2ln E+pL
E−pL,Eis he pa icle ene gy,
and pLis he pa icle momen um along he an iclockwise beam di ec ion. Fo each pa icle
species, we measu e he p oduc ion a e e sus apidi y and ans e se momen um pT, he
a e age pT, he cen al p oduc ion a e dN
dy |y≈0, and he in eg a ed yield o |y|<2 pe NSD
e en . We compa e ou measu emen s o esul s om Mon e Ca lo models and lowe ene gy
da a.
2 CMS expe imen and collec ed da a
CMS is a gene al pu pose expe imen a he LHC [12]. The silicon acke , lead- ungs a e c ys al
elec omagne ic calo ime e , and b ass-scin illa o had on calo ime e a e all imme sed in a
3.8 T axial magne ic ield while muon de ec o s a e in e spe sed wi h lux e u n s eel ou side o
he 6 m diame e supe conduc ing solenoid. The silicon acke is used o econs uc cha ged
pa icle ajec o ies wi h |η|<2.5, whe e he pseudo apidi y is de ined as η=−ln an θ
2,θ
1Pa icle-conjuga e s a es a e implied h oughou his pape .
23 S ange pa icle econs uc ion
being he pola angle wi h espec o he an iclockwise beam. The acke consis s o laye s
o 100×150 µm2pixel senso s a adii less han 15 cm and laye s o s ip senso s, wi h pi ch
anging om 80 o 183 µm, co e ing adii om 25 o 110 cm. In addi ion o ba el and endcap
de ec o s, CMS has ex ensi e o wa d calo ime y including a s eel and qua z- ib e had on
calo ime e (HF), which co e s 2.9 <|η|<5.2. The da a p esen ed in his pape we e collec ed
by he CMS expe imen in sp ing 2010 om p o on-p o on collisions a cen e-o -mass ene gies
o 0.9 and 7 TeV du ing a pe iod in which he p obabili y o wo collisions in he same bunch
c ossing was negligible and he bunch c ossings we e well sepa a ed.
The online selec ion o e en s equi ed ac i i y in he beam scin illa o coun e s a 3.23 <|η|<
4.65 in coincidence wi h colliding p o on bunches. The o line selec ion equi ed deposi s o
a leas 3 GeV o ene gy in each end o he HF [1], p e e en ially selec ing NSD e en s. A p i-
ma y e ex econs uc ed in he acke was equi ed and beam-halo and o he beam- ela ed
backg ound e en s we e ejec ed as desc ibed in Re . [1]. The da a selec ed wi h hese c i-
e ia con ain 9.08 and 23.86 million e en s a 0.9 and 7 TeV, co esponding o app oxima e
in eg a ed luminosi ies o 240 and 480 µb−1, espec i ely. To de e mine he accep ance and e -
iciency, minimum-bias Mon e Ca lo samples we e gene a ed a bo h cen e-o -mass ene gies
using PYTHIA 6.422 [5] wi h une D6T [13]. These e en s we e passed h ough a CMS de ec o
simula ion package based on GEANT 4 [14].
3 S ange pa icle econs uc ion
Ioniza ion deposi s eco ded by he silicon acke a e used o econs uc acks. To maxi-
mize econs uc ion e iciency, we use a combined ack collec ion o med om me ging acks
ound wi h he s anda d acking desc ibed in Re . [15] and he minimum bias acking de-
sc ibed in Re . [1]. Bo h acking collec ions use he same basic algo i hm; he di e ences a e in
he equi emen s o seeding, p opaga ing, and il e ing acks.
As desc ibed in Re . [15], he K0
Sand Λ(gene ically e e ed o as V0) econs uc ion combines
pai s o opposi ely cha ged acks; i he no malized χ2o he i o a common e ex is less han
7, he candida e is kep . The p ima y e ex is e i o each candida e, emo ing he wo acks
associa ed wi h he V0candida e. The nex wo pa ag aphs desc ibe he selec ion o candida es
o measu emen o V0and Ξ−p ope ies, espec i ely. Selec ion a iables a e measu ed in
uni s o σ, he calcula ed unce ain y including all co ela ions.
To emo e K0
Spa icles misiden i ied as Λpa icles and ice e sa, he K0
S(Λ)candida es mus
ha e a co esponding pπ−(π+π−)mass mo e han 2.5σaway om he wo ld-a e age Λ(K0
S)
mass. The p oduc ion c oss sec ions we measu e a e in ended o ep esen he p omp p oduc-
ion o K0
Sand Λ, including s ong and elec omagne ic decays. Howe e , V0pa icles can also
be p oduced om weak decays and om seconda y nuclea in e ac ions. These unwan ed con-
ibu ions a e educed by equi ing ha he V0momen um ec o poin s back o he p ima y
e ex. This is done by equi ing he 3D dis ance o closes app oach o he V0 o he p ima y
e ex o be less han 3σ. To emo e gene ic p omp backg ounds, he 3D V0 e ex sepa a ion
om he p ima y e ex mus be g ea e han 5σand bo h V0daugh e acks mus ha e a 3D
dis ance o closes app oach o he p ima y e ex g ea e han 3σ. Wi h he abo e selec ion,
he backg ound le el o low ans e se-momen um Λcandida es emains high. The e o e,
addi ional cu s a e applied o Λcandida es wi h pT<0.6 GeV/c:
•3D sepa a ion be ween he p ima y and Λ e ices >10σ(ins ead o >5σ),
• ans e se (2D) sepa a ion be ween he pp collision egion (beamspo ) and Λ e ex
>10σ(ins ead o no cu ), whe e he unce ain y is domina ed by he Λ e ex, and
3
•3D impac pa ame e o he pion and p o on acks wi h espec o he p ima y e -
ex >(7−2|y|)σ(ins ead o >3σ) whe e yis he apidi y o he Λcandida e. The
apidi y dependence is a consequence o he obse a ion ha , o he low ans e se
momen um candida es, la ge backg ounds domina e a small apidi y, while low
e iciency cha ac e izes he la ge apidi y beha iou .
The esul ing mass dis ibu ions o K0
Sand Λcandida es om he 0.9 and 7 TeV da a a e shown
in Figs. 1 and 2. The π+π−mass dis ibu ion is i wi h a double Gaussian (wi h a common
mean) signal unc ion plus a quad a ic backg ound. The pπ−mass dis ibu ion is i wi h
a double Gaussian (common mean) signal unc ion and a backg ound unc ion o he o m
AqB, whe e q=Mpπ−−(mp+mπ−),Mpπ−is he pπ−in a ian mass, and Aand Ba e ee
pa ame e s. The i ed K0
S(Λ)yields a √s=0.9 and 7 TeV a e 1.4×106(2.8×105)and 6.5×
106(1.5×106), espec i ely.
]
2
in a ian mass [MeV/c
−
π
+
π
450 500 550 600
2
Candida es / 1 MeV/c
0
20
40
60
80
100 3
10×
3
10×Yield: 1393 2
Mean: 497.8 MeV/c
2
: 8.4 MeV/cσA g
CMS
= 0.9 TeVs
]
2
in a ian mass [MeV/c
−
π
+
π
450 500 550 600
2
Candida es / 1 MeV/c
0
100
200
300
400
3
10×
3
10×Yield: 6534 2
Mean: 497.8 MeV/c
2
: 8.2 MeV/cσA g
CMS
= 7 TeVs
Figu e 1: The π+π−in a ian mass dis ibu ions om da a collec ed a √s=0.9 TeV (le ) and
7 TeV ( igh ). The solid cu es a e i s o a double Gaussian and quad a ic polynomial. The
dashed cu es show he quad a ic backg ound con ibu ion.
To econs uc he Ξ−, cha ged acks o he co ec sign a e combined wi h Λcandida es. The
χ2p obabili y o he i o a common e ex o he Λand he cha ged ack mus be g ea e
han 5%. In his i , he Λcandida e is cons ained o ha e he co ec wo ld-a e age mass [16].
The p ima y e ex is e i o each Ξ−candida e, emo ing all acks associa ed wi h he Ξ−.
The Ξ−candida es mus hen pass he ollowing selec ion c i e ia:
•3D impac pa ame e wi h espec o he p ima y e ex >2σ o he p o on ack
om he Λdecay, >3σ o he π− ack om he Λdecay, and >4σ o he π− ack
om he Ξ−decay,
•in a ian mass om he π+π−hypo hesis o he acks associa ed wi h he Λcan-
dida e a leas 20 MeV/c2away om he wo ld-a e age K0
Smass,
•3D impac pa ame e o he Ξ−candida e wi h espec o he p ima y e ex <3σ,
•3D sepa a ion be ween Λ e ex and p ima y e ex >10σ, and
•3D sepa a ion be ween Ξ− e ex and p ima y e ex >2σ.
The mass dis ibu ions o Ξ−candida es om he √s=0.9 and 7 TeV da a a e shown in Fig. 3.
The Λπ−mass is i wi h a double Gaussian (wi h a common mean) signal unc ion and a

44 E iciency co ec ion
]
2
in a ian mass [MeV/c
−
πp
1100 1120 1140
2
Candida es / 0.5 MeV/c
0
5
10
15
20
3
10×
3
10×Yield: 276 2
Mean: 1116.1 MeV/c
2
: 3.6 MeV/cσA g
CMS
= 0.9 TeVs
]
2
in a ian mass [MeV/c
−
πp
1100 1120 1140
2
Candida es / 0.5 MeV/c
0
20
40
60
80
100
120
3
10×
3
10×Yield: 1460 2
Mean: 1116.0 MeV/c
2
: 3.4 MeV/cσA g
CMS
= 7 TeVs
Figu e 2: The pπ−in a ian mass dis ibu ions om da a collec ed a √s=0.9 TeV (le ) and
7 TeV ( igh ). The solid cu es a e i s o a double Gaussian signal and a backg ound unc-
ion gi en by AqB, whe e q=Mpπ−−(mp+mπ−). The dashed cu es show he backg ound
con ibu ion.
backg ound unc ion o he o m Aq1/2 +Bq3/2, whe e q=MΛπ−−(mΛ+mπ−)and MΛπ−is
he Λπ−in a ian mass. The i ed Ξ−yields a √s=0.9 and 7 TeV a e 6.2×103and 3.4×104,
espec i ely.
4 E iciency co ec ion
The e iciency co ec ion is de e mined om a Mon e Ca lo simula ion which is used o mea-
su e he e ec s o accep ance and he e iciency o e en selec ion (including he igge ) and
pa icle econs uc ion. The Mon e Ca lo samples a e eweigh ed o ma ch he obse ed ack
mul iplici y in da a, as his has been shown o be an impo an componen o he igge e i-
ciency [1, 2]. This is e e ed o as ack weigh ing. The e iciency co ec ion also accoun s o
he o he decay channels o he s ange pa icles ha we do no a emp o econs uc , such as
K0
S→π0π0.
The e iciency is gi en by he numbe o econs uc ed pa icles di ided by he numbe o
gene a ed pa icles, subjec o wo modi ica ions. Fi s ly, he e iciency co ec ion is used o ac-
coun o candida es om SD e en s. As he esul s a e no malized o NSD e en s, candida es
om SD e en s which pass he e en selec ion mus be emo ed. This is done by de ining he
e iciency as he numbe o econs uc ed candida es in all e en s di ided by he numbe o
gene a ed candida es in NSD e en s. Secondly, he e iciency is modi ied o accoun o he
small con ibu ion o econs uc ed non-p omp s ange pa icles which pass he selec ion c i-
e ia. This is only an issue o he Λpa icles which ecei e con ibu ions om Ξand Ωdecays.
Since hese non-p omp Λpa icles a e p esen in bo h he MC and da a, we modi y he e i-
ciency o emo e his con ibu ion by calcula ing he nume a o using all o he econs uc ed
s ange pa icles and he denomina o wi h only he p omp gene a ed s ange pa icles. As
he MC ails o p oduce enough Ξpa icles (see Sec ion 6), he non-p omp Λ’s a e weigh ed
mo e han p omp Λ’s in he e iciency calcula ion.
The esul s o his analysis a e p esen ed in e ms o wo kinema ic dis ibu ions: ans e se
5
]
2
in a ian mass [MeV/c
−
πΛ
1300 1350 1400
2
Candida es / 2 MeV/c
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6 3
10×
3
10×Yield: 6.2 2
Mean: 1322.2 MeV/c
2
: 4.3 MeV/cσA g
CMS
= 0.9 TeVs
]
2
in a ian mass [MeV/c
−
πΛ
1300 1350 1400
2
Candida es / 2 MeV/c
0
2
4
6
8
3
10×
3
10×Yield: 34.4 2
Mean: 1322.1 MeV/c
2
: 4.1 MeV/cσA g
CMS
= 7 TeVs
Figu e 3: The Λπ−in a ian mass dis ibu ions om da a collec ed a √s=0.9 TeV (le ) 7 TeV
( igh ). The solid cu es a e i s o a double Gaussian signal and a backg ound unc ion gi en
by Aq1/2 +Bq3/2, whe e q=MΛπ−−(mΛ+mπ−). The dashed cu es show he backg ound
con ibu ion.
momen um and apidi y. Fo all modes, |y|is di ided in o 10 equal size bins om 0 o 2 and
pTis di ided in o 20 equal size bins om 0 o 4 GeV/cplus one bin each om 4 o 5 GeV/cand
5 o 6 GeV/c. In addi ion, he V0modes also ha e 6–8 GeV/cand 8–10 GeV/c pTbins. All esul s
a e o pa icles wi h |y|<2.
The e iciency co ec ion o he V0modes uses a wo-dimensional binning in pTand |y|. Thus,
he da a a e di ided in o 240 bins in he |y|,pTplane. The in a ian mass his og ams in each
bin a e i o a double Gaussian signal unc ion (wi h a common mean) and a backg ound
unc ion. In bins wi h ew en ies, a single Gaussian signal unc ion is used. Fo he Λsample,
some bins a e me ged due o spa se popula ions in |y|,pTspace. The me ging is pe o med
sepa a ely when measu ing |y|and pTsuch ha he me ging occu s ac oss pTand |y|bins,
espec i ely. The e iciency om MC is e alua ed in each bin and applied o he measu ed yield
o ob ain he co ec ed yield. The wo-dimensional binning used o he V0e iciency co ec ion
g ea ly educes p oblems a ising om emaining di e ences in p oduc ion dynamics be ween
he da a and he simula ion. The much smalle sample o Ξ−candida es p e en s he use
o 2D binning. Thus, he da a a e di ided in o |y|bins o measu e he |y|dis ibu ion and
in o pTbins o measu e he pTdis ibu ion. Howe e , he MC spec a do no ma ch he da a.
The e o e, each Mon e Ca lo Ξ−pa icle is weigh ed in pT(|y|) o ma ch he dis ibu ion in
da a when measu ing he e iciency e sus |y|(pT). Thus, he MC and da a dis ibu ions a e
o ced o ma ch in he a iable o e which we in eg a e o de e mine he e iciency. We e e
o his as kinema ic weigh ing. The e iciencies o all h ee pa icles a e shown e sus |y|
and pTin Fig. 4. The e iciencies ( o pa icles wi h |y|<2) include he accep ance, e en
selec ion, econs uc ion and selec ion, and also accoun o o he decay channels. The inc ease
in e iciency wi h pTis due o he imp o emen in acking e iciency as ack pTinc eases and
o he selec ion c i e ia designed o emo e p omp decays. The sligh dec ease a high pTis
due o pa icles decaying oo a ou o ha e econs uc ed acks. While he e is no cen e-o -
mass ene gy dependence on he e iciency e sus pT, pa icles p oduced a √s=7 TeV ha e a
highe a e age-pT, esul ing in a highe e iciency when plo ed e sus apidi y.
As a check on he abili y o he Mon e Ca lo simula ion o ep oduce he e iciency, he (well-
64 E iciency co ec ion
|y|
0 0.5 1 1.5 2
E iciency
0
0.05
0.1
0.15
0.2
0.25
0.3
0
S
= 7 TeV: Ks 0
S
= 0.9 TeV: Ks
Λ = 7 TeV: s
Λ = 0.9 TeV: s
−
Ξ = 7 TeV: s −
Ξ = 0.9 TeV: s
CMS
[GeV/c]
T
p
0 2 4 6 8 10
E iciency
0
0.1
0.2
0.3
0.4
0
S
= 7 TeV: Ks 0
S
= 0.9 TeV: Ks
Λ = 7 TeV: s
Λ = 0.9 TeV: s
−
Ξ = 7 TeV: s −
Ξ = 0.9 TeV: s
CMS
Figu e 4: To al e iciencies, including accep ance, igge and e en selec ion, econs uc ion
and pa icle selec ion, and o he decay modes, as a unc ion o |y|(le ) and pT( igh ) o K0
S,
Λ, and Ξ−p oduced p omp ly in he ange |y|<2. E o ba s come om MC s a is ics.
known) K0
S,Λ, and Ξ−li e imes a e measu ed. Fo he K0
Smeasu emen , he da a a e di ided
in o bins o pTand c , whe e c is calcula ed as c =cmL/pwhe e m,L, and pa e, espec i ely,
he mass, decay leng h, and momen um o he pa icle. In each bin he da a is co ec ed by
he MC e iciency and he co ec ed yields summed in pT o ob ain he c dis ibu ion. Due o
smalle sample sizes, he Λand Ξ−yields a e only measu ed in bins o c . Using he kinema ic
weigh ing echnique, he MC e iciency in each bin o c is calcula ed wi h he pTspec um
co ec ly weigh ed o ma ch da a. The co ec ed li e ime dis ibu ions, shown in Fig. 5, display
exponen ial beha iou . The e ex sepa a ion equi emen s esul in e y low e iciencies and
low yields in he i s li e ime bin and a e hus expec ed o ha e some disc epancies. An ac ual
measu emen o he li e ime would emo e his issue by using he educed p ope ime, whe e
one measu es he li e ime ela i e o he poin a which he pa icle had a chance o be econ-
s uc ed. The measu ed alues o he li e imes a e also easonably consis en wi h he wo ld
a e ages [16] (shown in Fig. 5) conside ing ha only s a is ical unce ain ies a e epo ed and
ha his is no he op imal me hod o a li e ime measu emen .
To con e he e iciency co ec ed yields o pe e en yields equi es he ue numbe o NSD
e en s, which is ob ained by co ec ing he numbe o selec ed e en s o he e en selec ion
ine iciency. The e en selec ion includes bo h he online igge and o line selec ion desc ibed
in Sec ion 2. The e en selec ion e iciency is de e mined in wo ways. In he de aul me hod,
i is calcula ed di ec ly om he Mon e Ca lo simula ion (app op ia ely weigh ed by he ack
mul iplici y o ep oduce he da a). In he al e na i e me hod, he e en selec ion e iciency e -
sus ack mul iplici y is de i ed om he Mon e Ca lo. Then, each measu ed e en is weigh ed
by he in e se o he e en selec ion e iciency based on i s numbe o acks. The numbe o
e en s di ided by he numbe o weigh ed e en s gi es he e en selec ion e iciency. How-
e e , since he e en selec ion equi es a p ima y e ex, no e en s will ha e ewe han wo
acks. The e o e, he Mon e Ca lo is also used o de e mine he ac ion o NSD e en s which
ha e ewe han wo acks and he e en selec ion e iciency is adjus ed o include his e ec .
In bo h me hods, he e en selec ion e iciency accoun s o unwan ed SD e en s which pass
he e en selec ion. The nume a o in he e iciency a io con ains all selec ed e en s, including
7
c [cm]
0
S
K
0 2 4 6 8 10 12
-1
) dN / dc (cm)
NSD
(1/N
-2
10
-1
10
0.1 ps± = 89.0 τ = 7 TeV: s 0.2 ps± = 89.3 τ = 0.9 TeV: s
CMS
0.05 ps± = 89.53
PDG
τ
S a is ical
unce ain ies
only
c [cm]Λ
0 2 4 6 8 10 12 14 16 18 20
-1
) dN / dc (cm)
NSD
(1/N
-2
10
-1
10 1.1 ps± = 261.4 τ = 7 TeV: s 3.1 ps± = 264.6 τ = 0.9 TeV: s
CMS
2.0 ps± = 263.1
PDG
τ
S a is ical
unce ain ies
only
c [cm]
−
Ξ
0 1 2 3 4 5 6 7 8 9 10
-1
) dN / dc (cm)
NSD
(1/N
-3
10
-2
10
5 ps± = 167 τ = 7 TeV: s 8 ps± = 178 τ = 0.9 TeV: s
CMS
1.5 ps± = 163.9
PDG
τ
S a is ical
unce ain ies
only
Figu e 5: K0
S(le ), Λ(middle), and Ξ−( igh ) co ec ed decay ime dis ibu ions a √s=0.9 and
7 TeV. The alues o he li e imes, de i ed om a i wi h an exponen ial unc ion (solid line),
a e shown in he legend along wi h he wo ld-a e age alue. The e o ba s and unce ain ies
on he li e imes e e o he s a is ical unce ain y only.
single-di ac i e e en s, while he denomina o con ains all NSD e en s.
5 Sys ema ic unce ain ies
The sys ema ic unce ain ies, epo ed in Table 1, a e di ided in o wo ca ego ies: no maliza-
ion unce ain ies, which only a ec he o e all no maliza ion, and poin - o-poin unce ain-
ies, which may also a ec he shape o he pTand |y|dis ibu ions.
The lis below summa izes he sou ce and e alua ion o he poin - o-poin sys ema ic unce -
ain ies.
•Kinema ic weigh ing e sus 2D binning: The e iciency co ec ions using he 1D kine-
ma ic weigh ing echnique (used o he Ξ−analysis) and he 2D binning echnique
(used o he V0analysis) we e compa ed by measu ing he e iciency wi h bo h
me hods on he highes s a is ics channel (K0
Sa 7 TeV).
•Non-p omp Λ: The con ibu ion o non-p omp Λdecays is a ied by a ac o o
wo in he simula ion.
•MC une: The nominal e iciency calcula ed om he de aul PYTHIA 6 D6T une [13]
is compa ed o he e iciency ob ained om he PYTHIA 6 Pe ugia0 (P0) une [17] and
PYTHIA 8 [18].
•Va ia ion o econs uc ion cu s: The ollowing cu s a e a ied o all h ee modes:
V0 e ex sepa a ion signi icance (±2σ), 3D impac pa ame e o V0and Ξ−(±2σ),
3D impac pa ame e o acks (±2σ), cu on K0
S(Λ)mass o Λ(K0
S)candida es
(±1.5σ), and inc ease o numbe o hi s equi ed on each ack om 3 o 5. Fo he
Ξ−, addi ional cu s we e a ied: he Ξ− e ex sepa a ion signi icance (±1σ) and Ξ−
e ex i p obabili y (±3%).
•De ached pa icle econs uc ion: Finding ha he co ec ed li e ime dis ibu ions
a e exponen ial wi h he co ec li e ime is a e i ica ion o ou unde s anding o he
econs uc ion e iciency e sus decay leng h. The sys ema ic unce ain y is aken
as he di e ence be ween he i ed li e imes and he wo ld-a e age li e imes [16].
While he K0
Sand Λli e imes a e wi hin 1% o he wo ld-a e age, a 2% sys ema ic
unce ain y is conse a i ely assigned.
14 6 Resul s
[GeV/c]
T
p
0 2 4 6 8 10
)
0
S
) / N(KΛN(
0
0.2
0.4
0.6
0.8
1
= 7 TeVs
PYTHIA6 D6T
PYTHIA6 P0
PYTHIA8
= 0.9 TeVs
PYTHIA6 D6T
PYTHIA6 P0
PYTHIA8
CMS
[GeV/c]
T
p
0 1 2 3 4 5 6
)Λ) / N(
−
ΞN(
0
0.05
0.1
0.15
0.2
0.25
= 7 TeVs
PYTHIA6 D6T
PYTHIA6 P0
PYTHIA8
= 0.9 TeVs
PYTHIA6 D6T
PYTHIA6 P0
PYTHIA8
CMS
Figu e 8: N(Λ)/N(K0
S)(le ) and N(Ξ−)/N(Λ)( igh ) in NSD e en s e sus pT. The inne
e ical e o ba s (when isible) show he s a is ical unce ain ies, he ou e he s a is ical and
all sys ema ic unce ain ies summed in quad a u e. Resul s a e shown o h ee PYTHIA p e-
dic ions a each cen e-o -mass ene gy.
om STAR [24] and a √s=0.9 TeV esul s om ALICE [3]. These h ee esul s show a ema k-
able consis ency ac oss a wide a ie y o collision ene gies. In con as , he CDF alues o
N(Λ)/N(K0
S)[26] a e signi ican ly highe han he CMS esul s while he CDF measu emen s
o N(Ξ−)/N(Λ)[25] a e lowe , albei wi h less signi icance.
Reducing he pTdis ibu ions o a single alue, he a e age pT, we compa e he CMS esul s
wi h ea lie esul s a lowe ene gies in Fig. 11 [3, 24, 26–32]. The CMS esul s a e in excellen
ag eemen wi h he ecen ALICE measu emen s a 0.9 TeV. The CMS esul s con inue he
o e all end o inc easing a e age pTwi h inc easing pa icle mass and inc easing cen e-o -
mass ene gy.
6.3 Analysis o p oduc ion a e
As a measu e o he o e all p oduc ion a e in NSD e en s, dN
dy |y≈0and he o al yield o |y|<2
we e ex ac ed and abula ed in Table 4. The quan i y dN
dy |y≈0is he a e age alue o dN
dy o e
he egion |y|<0.2. The in eg a ed yields o |y|<2 a e ob ained by in eg a ing he pTspec a,
using he Tsallis unc ion i o accoun o pa icles abo e he measu ed pT ange.
The cen al p oduc ion a es o K0
S,Λ, and Ξ−a e compa ed o p e ious esul s in Fig. 12.
The esul s show he expec ed inc ease in p oduc ion wi h cen e-o -mass ene gy wi h li le
e idence o a di e ence due o beam pa icles. As he ALICE esul s a e no malized o all
inelas ic collisions, hey a e expec ed o be somewha lowe han he CMS esul s.
The p oduc ion a ios N(K0
S)/N(Λ)and N(Ξ−)/N(Λ) e sus |y|a e shown in Fig. 13. The
apidi y dis ibu ions a e e y la and, as obse ed in he pTdis ibu ions o Fig. 8, show no
dependence on cen e-o -mass ene gy. Th ee PYTHIA p edic ions a each cen e-o -mass ene gy
a e also shown in Fig. 13. These esul s con i m wha can al eady be seen in he compa isons
shown in he le panes o Fig. 6; PYTHIA unde es ima es he p oduc ion o s ange pa icles
and he disc epancy g ows wi h pa icle mass.

6.3 Analysis o p oduc ion a e 15
[GeV/c]
T
p
0 1 2 3 4 5 6
-1
(GeV/c)
T
/dp
−
Ξ
) dN
NSD
(1/N
-5
10
-4
10
-3
10
-2
10
CMS: pp @ 7 TeV
CMS: pp @ 0.9 TeV
@ 1.96 TeVpCDF: p
ALICE: pp @ 0.9 TeV
STAR: pp @ 0.2 TeV
0 1 2 3 4 5 6
-1
(GeV/c)
T
/dp
Λ
) dN
NSD
(1/N
-4
10
-3
10
-2
10
-1
10
0 1 2 3 4 5 6
-1
(GeV/c)
T
/dp
0
S
K
) dN
NSD
(1/N
-4
10
-3
10
-2
10
-1
10
1CMS
Figu e 9: K0
S( op), Λ(middle), and Ξ−(bo om) p oduc ion pe e en e sus pT. The e o ba s
on he CMS esul s show he combined s a is ical, poin - o-poin sys ema ic, and no maliza ion
sys ema ic unce ain ies. The e o ba s on he CDF [25], ALICE [3], and STAR [24] esul s show
he combined s a is ical and sys ema ic unce ain ies. The CMS, CDF, and STAR esul s a e
no malized o NSD e en s while he ALICE esul s a e no malized o all inelas ic e en s.
Table 4: dN
dy |y≈0and in eg a ed yields (|y|<2.0)pe NSD e en om da a. In each da a
column, he i s unce ain y is s a is ical and he second is sys ema ic.
√s=0.9 TeV √s=7 TeV
Pa icle dN
dy |y≈0NdN
dy |y≈0N
K0
S0.205±0.001±0.015 0.784±0.002±0.056 0.346±0.001±0.025 1.341±0.001±0.097
Λ0.108±0.001±0.012 0.404±0.004±0.046 0.189±0.001±0.022 0.717±0.005±0.082
Ξ−0.011±0.001±0.001 0.043±0.001±0.006 0.021±0.001±0.003 0.080±0.001±0.011
16 6 Resul s
[GeV/c]
T
p
0 1 2 3 4 5 6
)Λ
) / N(
−
ΞN(
0
0.1
0.2
0.3
@ 1.96 TeVpCDF: p @ 1.8 TeVpCDF: p @ 0.63 TeVpCDF: p
ALICE: pp @ 0.9 TeV
STAR: pp @ 0.2 TeV
CMS: pp @ 7 TeV
CMS: pp @ 0.9 TeV
0 1 2 3 4 5 6
)
0
S
) / N(KΛN(
0.5
1
1.5
CMS
Figu e 10: Ra io o Λ o K0
Sp oduc ion ( op) and Ξ− o Λp oduc ion (bo om) e sus pT. The
CMS, ALICE [3], and STAR [24] e o ba s include he s a is ical and sys ema ic unce ain ies.
The CDF e o ba s include he s a is ical unce ain ies o N(Λ)/N(K0
S)[26] and he s a is i-
cal and sys ema ic unce ain ies o N(Ξ−)/N(Λ)[25]. The CDF N(Λ)/N(K0
S)bin sizes a e
doubled o educed luc ua ions. Fo expe imen s in which he binning o Λand Ξ−is di e -
en (ALICE and STAR), bins a e me ged o p o ide common bin anges in he N(Ξ−)/N(Λ)
dis ibu ion.
6.3 Analysis o p oduc ion a e 17
[TeV] s
-1
10 1 10
[GeV/c]
−
Ξ
〉
T
p〈
0.6
0.8
1
1.2 −
Ξ
CMS (pp))pE735 (p
ALICE (pp)
)pUA5 (p
STAR (pp)
[GeV/c]
Λ
〉
T
p〈
0.6
0.7
0.8
0.9
1
1.1 Λ
CMS (pp)
)pCDF (p )pE735 (p
ALICE (pp)
)pUA5 (p
STAR (pp)
[GeV/c]
0
S
K
〉
T
p〈
0.5
0.6
0.7
0.8 0
S
K
CMS (pp)
)pCDF (p
ALICE (pp)
)pUA5 (p
STAR (pp)
CMS
Figu e 11: A e age pT o K0
S( op), Λ(middle), and Ξ−(bo om), as a unc ion o he cen e-o -
mass ene gy. The CMS measu emen s a e o |y|<2. The o he esul s a e om UA5 [27–31]
(p¯
p collisions co e ing |y|<2.5, |y|<2, and |y|<3 o K0
S,Λ, and Ξ−, espec i ely), E735 [32]
(p¯
p collisions using acks wi h −0.36 <η<1.0), CDF [26] (p¯
p collisions co e ing |η|<1.0),
STAR [24] (pp collisions co e ing |y|<0.5), and ALICE [3] (pp collisions co e ing |y|<0.75 o
K0
Sand Λand |y|<0.8 o Ξ−). Some poin s ha e been sligh ly o se om he ue ene gy o
imp o e isibili y. The e ical ba s indica e he s a is ical and sys ema ic unce ain ies (when
a ailable) summed in quad a u e.
18 6 Resul s
[TeV] s
-1
10 1 10
0≈y
/dy
−
Ξ
) dN
e
(1/N
0
0.005
0.01
0.015
0.02
0.025 −
Ξ
CMS NSD (pp)
ALICE INEL (pp)
STAR NSD (pp)
0≈y
/dy
Λ
) dN
e
(1/N
0.1
0.15
0.2 Λ
CMS NSD (pp)
ALICE INEL (pp)
STAR NSD (pp)
0≈y
/dy
0
S
K
) dN
e
(1/N
0.1
0.15
0.2
0.25
0.3
0.35 S
0
K
CMS NSD (pp)
)pCDF MB (p
ALICE INEL (pp)
)pUA5 NSD (p
STAR NSD (pp)
CMS
Figu e 12: The cen al apidi y p oduc ion a e o K0
S( op), Λ(middle), and Ξ−(bo om), as a
unc ion o he cen e-o -mass ene gy. The p e ious esul s a e om UA5 [29, 30] (p¯
p), CDF [33]
(p¯
p), STAR [24] (pp), and ALICE [3] (pp). The CMS, UA5, and STAR esul s a e no malized o
NSD e en s. The CDF esul s a e no malized o e en s passing hei igge and e en selec ion
de ined chie ly by ac i i y in bo h sides o he de ec o , a leas ou acks, and a p ima y e -
ex. The ALICE esul s a e no malized o all inelas ic e en s. Some poin s ha e been sligh ly
o se om he ue ene gy o imp o e isibili y. The e ical ba s indica e he s a is ical unce -
ain ies o he UA5 and CDF esul s and he combined s a is ical and sys ema ic unce ain ies
o he CMS, ALICE, and STAR esul s.
19
|y|
0 0.5 1 1.5 2
)
0
S
) / N(KΛN(
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
= 7 TeVs
PYTHIA6 D6T
PYTHIA6 P0
PYTHIA8
= 0.9 TeVs
PYTHIA6 D6T
PYTHIA6 P0
PYTHIA8
CMS
|y|
0 0.5 1 1.5 2
)Λ) / N(
−
ΞN(
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
= 7 TeVs
PYTHIA6 D6T
PYTHIA6 P0
PYTHIA8
= 0.9 TeVs
PYTHIA6 D6T
PYTHIA6 P0
PYTHIA8
CMS
Figu e 13: The p oduc ion a ios N(Λ)/N(K0
S)(le ) and N(Ξ−)/N(Λ)( igh ) in NSD e en s
e sus |y|. The inne e ical e o ba s (when isible) show he s a is ical unce ain ies, he
ou e he s a is ical and all sys ema ic unce ain ies summed in quad a u e. Resul s a e shown
o h ee PYTHIA p edic ions a each cen e-o -mass ene gy.
Table 5 shows a compa ison o he p oduc ion a e o da a o PYTHIA 6 wi h he D6T une.
The le column shows a la ge inc ease in he s ange pa icle p oduc ion c oss sec ion as he
cen e-o -mass ene gy inc eases om 0.9 o 7 TeV. The sys ema ic unce ain ies o his a io
a e educed as he same unce ain y a ec s bo h samples nea ly equally. The esul s o K0
S
and Λa e consis en wi h he inc ease obse ed in inclusi e cha ged pa icle p oduc ion [1, 2]
(5.82
3.48 =1.67)while he Ξ− esul s show a sligh ly g ea e inc ease. The inc ease in pa icle
p oduc ion om 0.9 o 7 TeV is no well modelled by PYTHIA 6. Ano he ea u e, seen in he
igh column, is he de ici o s ange pa icles p oduced by PYTHIA 6. The de ici o K0
Spa icles
in he MC, 15% (28%) low a 0.9 (7) TeV, is consis en wi h he esul s ound in he p oduc ion
o cha ged pa icles [1, 2]. Howe e , he de ici is much wo se as he mass inc eases, esul ing
in a 63% educ ion in Ξ−pa icles in MC compa ed o da a a √s=7 TeV. While alues a e
only p esen ed o PYTHIA 6 wi h he D6T une, he same ea u es a e also e iden o he o he
wo PYTHIA compa isons in he apidi y dis ibu ion plo s in Fig. 6.
Table 5: Compa ison o s angeness p oduc ion a es be ween PYTHIA 6 Mon e Ca lo (D6T)
and da a. In each column, he i s unce ain y is s a is ical and he second is sys ema ic.
Pa icle "dN
dy |y≈0(7 TeV)
dN
dy |y≈0(0.9 TeV)# "dN
dy |y≈0(MCD6T)
dN
dy |y≈0(Da a)#
Da a MC (D6T) √s=0.9 TeV √s=7 TeV
K0
S1.69 ±0.01 ±0.06 1.42 0.852 ±0.005 ±0.061 0.717 ±0.001 ±0.052
Λ1.75 ±0.02 ±0.08 1.48 0.606 ±0.007 ±0.070 0.514 ±0.003 ±0.059
Ξ−1.93 ±0.10 ±0.09 1.51 0.477 ±0.021 ±0.064 0.373 ±0.010 ±0.050
7 Conclusions
This a icle p esen s a s udy o he p oduc ion o K0
S,Λ, and Ξ−pa icles in p o on-p o on col-
lisions a cen e-o -mass ene gies 0.9 and 7 TeV. By ully exploi ing he low-momen um ack

20 7 Conclusions
econs uc ion capabili ies o CMS, we ha e measu ed he ans e se-momen um dis ibu ion
o hese s ange pa icles down o ze o. F om his sample o 10 million s ange pa icles, he
ans e se momen um dis ibu ions we e measu ed ou o 10 GeV/c o K0
Sand Λand ou
o 6 GeV/c o Ξ−. We i hese dis ibu ions wi h a Tsallis unc ion o ob ain in o ma ion on
he exponen ial decay a low pTand he powe -law beha iou a high pT. All species show a
la ening o he exponen ial decay as he cen e-o -mass ene gy inc eases. While he ba yons
show li le change in he high-pT egion, he K0
Spowe -law pa ame e dec eases om 7.8 o 6.9.
The a e age pT alues, calcula ed di ec ly om he da a, a e ound o inc ease wi h pa icle
mass and cen e-o -mass ene gy, in ag eemen wi h p edic ions and o he expe imen al esul s.
While he PYTHIA pTdis ibu ions used in his analysis show signi ican a ia ion based on
une and e sion, hey a e all b oade han he da a dis ibu ions.
We ha e also measu ed he p oduc ion e sus apidi y and ex ac ed he alue o dN/dy in
he cen al apidi y egion. The inc ease in p oduc ion o s ange pa icles as he cen e-o -
mass ene gy inc eases om 0.9 o 7 TeV is app oxima ely consis en wi h he esul s o in-
clusi e cha ged pa icles. Howe e , as in he inclusi e cha ged pa icle case, PYTHIA ails o
ma ch his inc ease. Fo K0
Sp oduc ion, he disc epancy is simila o wha has been ound in
cha ged pa icles. Howe e , he de ici be ween PYTHIA and da a is signi ican ly la ge o
he wo hype ons a bo h ene gies, eaching a ac o o h ee disc epancy o Ξ−p oduc ion
a √s=7 TeV. I a qua k-gluon plasma o o he collec i e e ec s we e p esen , we migh ex-
pec an enhancemen o double-s ange ba yons o single-s ange ba yons and/o an enhance-
men o s ange ba yons o s ange mesons. Howe e , he p oduc ion a ios N(Λ)/N(K0
S)and
N(Ξ−)/N(Λ) e sus apidi y and ans e se momen um show no change wi h cen e-o -mass
ene gy. Thus, he de iciency in PYTHIA is likely o igina ing om pa ame e s egula ing he
equency o s ange qua ks appea ing in colou s ings. The a ie y o measu emen s p e-
sen ed he e can be used o une PYTHIA and o he models as well as a baseline o unde s and
measu emen s o s angeness p oduc ion in hea y-ion collisions.
Acknowledgemen s
We wish o cong a ula e ou colleagues in he CERN accele a o depa men s o he excellen
pe o mance o he LHC machine. We hank he echnical and adminis a i e s a a CERN and
o he CMS ins i u es, and acknowledge suppo om: FMSR (Aus ia); FNRS and FWO (Bel-
gium); CNPq, CAPES, FAPERJ, and FAPESP (B azil); MES (Bulga ia); CERN; CAS, MoST, and
NSFC (China); COLCIENCIAS (Colombia); MSES (C oa ia); RPF (Cyp us); Academy o Sci-
ences and NICPB (Es onia); Academy o Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3
(F ance); BMBF, DFG, and HGF (Ge many); GSRT (G eece); OTKA and NKTH (Hunga y);
DAE and DST (India); IPM (I an); SFI (I eland); INFN (I aly); NRF and WCU (Ko ea); LAS
(Li huania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); PAEC (Pakis an); SCSR
(Poland); FCT (Po ugal); JINR (A menia, Bela us, Geo gia, Uk aine, Uzbekis an); MST and
MAE (Russia); MSTD (Se bia); MICINN and CPAN (Spain); Swiss Funding Agencies (Swi ze -
land); NSC (Taipei); TUBITAK and TAEK (Tu key); STFC (Uni ed Kingdom); DOE and NSF
(USA). Indi iduals ha e ecei ed suppo om he Ma ie-Cu ie p og amme and he Eu opean
Resea ch Council (Eu opean Union); he Le en is Founda ion; he A. P. Sloan Founda ion; he
Alexande on Humbold Founda ion; he Associazione pe lo S iluppo Scien i ico e Tecno-
logico del Piemon e (I aly); he Belgian Fede al Science Policy O ice; he Fonds pou la Fo ma-
ion `
a la Reche che dans l’´
ındus ie e dans l’ ´
Ag icul u e (FRIA-Belgium); and he Agen schap
oo Inno a ie doo We enschap en Technologie (IWT-Belgium).
21
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23
A The CMS Collabo a ion
Ye e an Physics Ins i u e, Ye e an, A menia
V. Khacha yan, A.M. Si unyan, A. Tumasyan
Ins i u ¨u Hochene giephysik de OeAW, Wien, Aus ia
W. Adam, T. Be gaue , M. D agice ic, J. E ¨
o, C. Fabjan, M. F iedl, R. F ¨
uhwi h, V.M. Ghe e,
J. Hamme 1, S. H¨
ansel, C. Ha l, M. Hoch, N. H¨
o mann, J. H ubec, M. Jei le , G. Kasieczka,
W. Kiesenho e , M. K amme , D. Liko, I. Mikulec, M. Pe nicka, H. Roh inge , R. Sch¨
o beck,
J. S auss, A. Tau ok, F. Teischinge , P. Wagne , W. Wal enbe ge , G. Walzel, E. Widl, C.-E. Wulz
Na ional Cen e o Pa icle and High Ene gy Physics, Minsk, Bela us
V. Mossolo , N. Shumeiko, J. Sua ez Gonzalez
Uni e si ei An we pen, An we pen, Belgium
L. Benucci, K. Ce ny, E.A. De Wol , X. Janssen, T. Maes, L. Mucibello, S. Ochesanu, B. Roland,
R. Rougny, M. Sel aggi, H. Van Hae e mae , P. Van Mechelen, N. Van Remo el
V ije Uni e si ei B ussel, B ussel, Belgium
S. Beauce on, F. Blekman, S. Blywee , J. D’Hond , O. De oede, R. Gonzalez Sua ez,
A. Kaloge opoulos, J. Maes, M. Maes, S. Ta e nie , W. Van Doninck, P. Van Mulde s, G.P. Van
Onsem, I. Villella
Uni e si ´e Lib e de B uxelles, B uxelles, Belgium
O. Cha a , B. Cle baux, G. De Len decke , V. De o, A.P.R. Gay, G.H. Hammad, T. H eus,
P.E. Ma age, L. Thomas, C. Vande Velde, P. Vanlae , J. Wickens
Ghen Uni e si y, Ghen , Belgium
V. Adle , S. Cos an ini, M. G unewald, B. Klein, A. Ma ino , J. Mcca in, D. Ryckbosch,
F. Thyssen, M. Ty ga , L. Vanelde en, P. Ve willigen, S. Walsh, N. Zaganidis
Uni e si ´e Ca holique de Lou ain, Lou ain-la-Neu e, Belgium
S. Basegmez, G. B uno, J. Caud on, L. Cea d, J. De Fa e eau De Jene e , C. Delae e, P. Demin,
D. Fa a , A. Giammanco, G. G ´
egoi e, J. Holla , V. Lemai e, J. Liao, O. Mili a u, S. O yn,
D. Pagano, A. Pin, K. Pio zkowski, N. Schul
Uni e si ´e de Mons, Mons, Belgium
N. Beliy, T. Caebe gs, E. Daubie
Cen o B asilei o de Pesquisas Fisicas, Rio de Janei o, B azil
G.A. Al es, D. De Jesus Damiao, M.E. Pol, M.H.G. Souza
Uni e sidade do Es ado do Rio de Janei o, Rio de Janei o, B azil
W. Ca alho, E.M. Da Cos a, C. De Oli ei a Ma ins, S. Fonseca De Souza, L. Mundim,
H. Nogima, V. Ogu i, W.L. P ado Da Sil a, A. San o o, S.M. Sil a Do Ama al, A. Sznajde ,
F. To es Da Sil a De A aujo
Ins i u o de Fisica Teo ica, Uni e sidade Es adual Paulis a, Sao Paulo, B azil
F.A. Dias, M.A.F. Dias, T.R. Fe nandez Pe ez Tomei, E. M. G ego es2, F. Ma inho, S.F. No aes,
Sand a S. Padula
Ins i u e o Nuclea Resea ch and Nuclea Ene gy, So ia, Bulga ia
N. Da meno 1, L. Dimi o , V. Genche 1, P. Iaydjie 1, S. Pipe o , M. Rodozo , S. S oyko a,
G. Sul ano , V. Tcholako , R. T ayano , I. Vanko
30 A The CMS Collabo a ion
S. Goy Lopez, J.M. He nandez, M.I. Josa, G. Me ino, J. Pue a Pelayo, I. Redondo, L. Rome o,
J. San aolalla, C. Willmo
Uni e sidad Au ´onoma de Mad id, Mad id, Spain
C. Albaja , G. Codispo i, J.F. de T oc´
oniz
Uni e sidad de O iedo, O iedo, Spain
J. Cue as, J. Fe nandez Menendez, S. Folgue as, I. Gonzalez Caballe o, L. Llo e Iglesias,
J.M. Vizan Ga cia
Ins i u o de F´ısica de Can ab ia (IFCA), CSIC-Uni e sidad de Can ab ia, San ande , Spain
J.A. B oche o Ci uen es, I.J. Cab illo, A. Calde on, M. Chamizo Lla as, S.H. Chuang, J. Dua e
Campde os, M. Felcini21, M. Fe nandez, G. Gomez, J. Gonzalez Sanchez, C. Jo da, P. Lobelle
Pa do, A. Lopez Vi o, J. Ma co, R. Ma co, C. Ma inez Ri e o, F. Ma o as, F.J. Munoz Sanchez,
J. Pied a Gomez22, T. Rod igo, A. Ruiz-Jimeno, L. Scodella o, M. Sob on Sanudo, I. Vila, R. Vila
Co abi a e
CERN, Eu opean O ganiza ion o Nuclea Resea ch, Gene a, Swi ze land
D. Abbaneo, E. Au ay, G. Auzinge , P. Baillon, A.H. Ball, D. Ba ney, A.J. Bell23, D. Benede i,
C. Be ne 3, W. Bialas, P. Bloch, A. Bocci, S. Bolognesi, H. B euke , G. B ona, K. Bunkowski,
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D. D’En e ia, A. De Roeck, S. Di Guida, F. Dua e Ramos, A. Ellio -Peise , B. F isch, W. Funk,
A. Gaddi, S. Gennai, G. Geo giou, H. Ge wig, D. Gigi, K. Gill, D. Gio dano, F. Glege, R. Gomez-
Reino Ga ido, M. Gouze i ch, P. Go oni, S. Gowdy, L. Guiducci, M. Hansen, J. Ha ey,
J. Hegeman, B. Hegne , C. Hende son, G. Heske h, H.F. Ho mann, A. Honma, V. Innocen e,
P. Jano , K. Kaadze, E. Ka a akis, P. Lecoq, C. Lou enc¸o, A. Macphe son, T. M¨
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M. Mannelli, L. Mase i, F. Meije s, S. Me si, E. Meschi, R. Mose , M.U. Moze , M. Mulde s,
E. Nes old1, M. Nguyen, T. O imo o, L. O sini, E. Pe ez, A. Pe illi, A. P ei e , M. Pie ini,
M. Pimi¨
a, G. Polese, A. Racz, J. Rod igues An unes, G. Rolandi24, T. Romme ski chen,
C. Ro elli25, M. Ro e e, H. Sakulin, C. Sch¨
a e , C. Schwick, I. Segoni, A. Sha ma, P. Sieg is ,
M. Simon, P. Sphicas26, D. Spiga, M. Spi opulu19, F. S ¨
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A. Tsygano , G.I. Ve es12, P. Vichoudis, M. Vou ilainen, W.D. Zeune
Paul Sche e Ins i u , Villigen, Swi ze land
W. Be l, K. Dei e s, W. E dmann, K. Gaba hule , R. Ho isbe ge , Q. Ing am, H.C. Kaes li,
S. K¨
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A. S a odumo 28
Ins i u e o Pa icle Physics, ETH Zu ich, Zu ich, Swi ze land
P. Bo ignon, L. Caminada29, Z. Chen, S. Ci olin, G. Disse o i, M. Di ma , J. Eugs e ,
K. F euden eich, C. G ab, A. He ´
e, W. Hin z, P. Lecom e, W. Lus e mann, C. Ma chica29,
P. Ma inez Ruiz del A bol, P. Me idiani, P. Mileno ic30, F. Moo ga , P. Ne , F. Nessi-Tedaldi,
L. Pape, F. Pauss, T. Punz, A. Rizzi, F.J. Ronga, M. Rossini, L. Sala, A.K. Sanchez, M.-C. Sawley,
B. S iege , L. Tausche †, A. Thea, K. Theo ila os, D. T eille, C. U schele , R. Wallny, M. Webe ,
L. Weh li, J. Weng
Uni e si ¨a Z¨u ich, Zu ich, Swi ze land
E. Aguil´
o, C. Amsle , V. Chiochia, S. De Vissche , C. Fa a o, M. I o a Riko a, B. Millan Mejias,
C. Regen us, P. Robmann, A. Schmid , H. Snoek
Na ional Cen al Uni e si y, Chung-Li, Taiwan
Y.H. Chang, K.H. Chen, W.T. Chen, S. Du a, A. Go, C.M. Kuo, S.W. Li, W. Lin, M.H. Liu,
Z.K. Liu, Y.J. Lu, D. Mek e o ic, J.H. Wu, S.S. Yu

31
Na ional Taiwan Uni e si y (NTU), Taipei, Taiwan
P. Ba alini, P. Chang, Y.H. Chang, Y.W. Chang, Y. Chao, K.F. Chen, W.-S. Hou, Y. Hsiung,
K.Y. Kao, Y.J. Lei, R.-S. Lu, J.G. Shiu, Y.M. Tzeng, M. Wang
Cuku o a Uni e si y, Adana, Tu key
A. Adiguzel, M.N. Baki ci31, S. Ce ci32, Z. Demi , C. Dozen, I. Dumanoglu, E. Esku , S. Gi gis,
G. Gokbulu , Y. Gule , E. Gu pina , I. Hos, E.E. Kangal, T. Ka aman, A. Kayis Topaksu, A. Na ,
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L.N. Ve gili, M. Ve gili, C. Zo bilmez
Middle Eas Technical Uni e si y, Physics Depa men , Anka a, Tu key
I.V. Akin, T. Alie , S. Bilmis, M. Deniz, H. Gamsizkan, A.M. Gule , K. Ocalan, A. Ozpineci,
M. Se in, R. Se e , U.E. Su a , E. Yildi im, M. Zey ek
Bogazici Uni e si y, Is anbul, Tu key
M. Deliome oglu, D. Demi 34, E. G¨
ulmez, A. Halu, B. Isildak, M. Kaya35, O. Kaya35,
S. Ozko ucuklu36, N. Sonmez37
Na ional Scien i ic Cen e , Kha ko Ins i u e o Physics and Technology, Kha ko , Uk aine
L. Le chuk
Uni e si y o B is ol, B is ol, Uni ed Kingdom
P. Bell, F. Bos ock, J.J. B ooke, T.L. Cheng, E. Clemen , D. Cussans, R. F azie , J. Golds ein,
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S. Me son, D.M. Newbold38, K. Ni unpong, A. Poll, S. Senkin, V.J. Smi h, S. Wa d
Ru he o d Apple on Labo a o y, Didco , Uni ed Kingdom
L. Basso39, K.W. Bell, A. Belyae 39, C. B ew, R.M. B own, B. Camanzi, D.J.A. Cocke ill,
J.A. Coughlan, K. Ha de , S. Ha pe , B.W. Kennedy, E. Olaiya, D. Pe y , B.C. Radbu n-Smi h,
C.H. Shephe d-Themis ocleous, I.R. Tomalin, W.J. Wome sley, S.D. Wo m
Impe ial College, London, Uni ed Kingdom
R. Bainb idge, G. Ball, J. Ballin, R. Beuselinck, O. Buchmulle , D. Colling, N. C ipps, M. Cu aja ,
G. Da ies, M. Della Neg a, J. Fulche , D. Fu yan, A. Gune a ne B ye , G. Hall, Z. Ha he ell,
J. Hays, G. Iles, G. Ka apos oli, L. Lyons, A.-M. Magnan, J. Ma ouche, R. Nandi, J. Nash,
A. Niki enko28, A. Papageo giou, M. Pesa esi, K. Pe idis, M. Pioppi40, D.M. Raymond,
N. Rompo is, A. Rose, M.J. Ryan, C. Seez, P. Sha p, A. Spa ow, A. Tappe , S. Tou neu ,
M. Vazquez Acos a, T. Vi dee, S. Wake ield, D. Wa d ope, T. Whyn ie
B unel Uni e si y, Uxb idge, Uni ed Kingdom
M. Ba e , M. Chadwick, J.E. Cole, P.R. Hobson, A. Khan, P. Kybe d, D. Leslie, W. Ma in,
I.D. Reid, L. Teodo escu
Baylo Uni e si y, Waco, USA
K. Ha akeyama
Bos on Uni e si y, Bos on, USA
T. Bose, E. Ca e a Ja in, C. Fan asia, A. Heis e , J. S . John, P. Lawson, D. Lazic, J. Rohl ,
D. Spe ka, L. Sulak
B own Uni e si y, P o idence, USA
A. A e isyan, S. Bha acha ya, J.P. Chou, D. Cu s, A. Fe apon o , U. Hein z, S. Jabeen,
G. Kuka se , G. Landsbe g, M. Na ain, D. Nguyen, M. Segala, T. Spee , K.V. Tsang
32 A The CMS Collabo a ion
Uni e si y o Cali o nia, Da is, Da is, USA
M.A. Bo gia, R. B eedon, M. Calde on De La Ba ca Sanchez, D. Ceb a, S. Chauhan, M. Che ok,
J. Conway, P.T. Cox, J. Dolen, R. E bache , E. F iis, W. Ko, A. Kopecky, R. Lande , H. Liu,
S. Ma uyama, T. Miceli, M. Nikolic, D. Pelle , J. Robles, S. Salu , T. Schwa z, M. Sea le, J. Smi h,
M. Squi es, M. T ipa hi, R. Vasquez Sie a, C. Veelken
Uni e si y o Cali o nia, Los Angeles, Los Angeles, USA
V. And ee , K. A isaka, D. Cline, R. Cousins, A. Deishe , J. Du is, S. E han, C. Fa ell, J. Hause ,
M. Igna enko, C. Ja is, C. Plage , G. Rakness, P. Schlein†, J. Tucke , V. Value
Uni e si y o Cali o nia, Ri e side, Ri e side, USA
J. Babb, R. Cla e, J. Ellison, J.W. Ga y, F. Gio dano, G. Hanson, G.Y. Jeng, S.C. Kao, F. Liu,
H. Liu, A. Lu h a, H. Nguyen, B.C. Shen†, R. S inge , J. S u dy, S. Sumowidagdo, R. Wilken,
S. Wimpenny
Uni e si y o Cali o nia, San Diego, La Jolla, USA
W. And ews, J.G. B anson, G.B. Ce a i, E. Dusinbe e, D. E ans, F. Gol , A. Holzne , R. Kelley,
M. Lebou geois, J. Le s, B. Mangano, J. Muelmens aed , S. Padhi, C. Palme , G. Pe ucciani,
H. Pi, M. Pie i, R. Ranie i, M. Sani, V. Sha ma1, S. Simon, Y. Tu, A. Va ak, F. W¨
u hwein,
A. Yagil
Uni e si y o Cali o nia, San a Ba ba a, San a Ba ba a, USA
D. Ba ge, R. Bellan, C. Campagna i, M. D’Al onso, T. Danielson, K. Flowe s, P. Ge e ,
J. Incandela, C. Jus us, P. Kala ase, S.A. Koay, D. Ko alskyi, V. K u elyo , S. Lowe e, N. Mccoll,
V. Pa lunin, F. Rebassoo, J. Ribnik, J. Richman, R. Rossin, D. S ua , W. To, J.R. Vliman
Cali o nia Ins i u e o Technology, Pasadena, USA
A. Bo nheim, J. Bunn, Y. Chen, M. Ga aullin, D. Kci a, V. Li ine, Y. Ma, A. Mo , H.B. Newman,
C. Rogan, V. Timciuc, P. T aczyk, J. Ve e ka, R. Wilkinson, Y. Yang, R.Y. Zhu
Ca negie Mellon Uni e si y, Pi sbu gh, USA
B. Akgun, R. Ca oll, T. Fe guson, Y. Iiyama, D.W. Jang, S.Y. Jun, Y.F. Liu, M. Paulini, J. Russ,
N. Te en ye , H. Vogel, I. Vo obie
Uni e si y o Colo ado a Boulde , Boulde , USA
J.P. Cumala , M.E. Dina do, B.R. D ell, C.J. Edelmaie , W.T. Fo d, A. Gaz, B. Heybu n, E. Luiggi
Lopez, U. Nauenbe g, J.G. Smi h, K. S enson, K.A. Ulme , S.R. Wagne , S.L. Zang
Co nell Uni e si y, I haca, USA
L. Agos ino, J. Alexande , A. Cha e jee, S. Das, N. Egge , L.J. Fields, L.K. Gibbons, B. Hel sley,
W. Hopkins, A. Khukhunaish ili, B. K eis, V. Kuzne so , G. Nicolas Kau man, J.R. Pa e son,
D. Puigh, D. Riley, A. Ryd, X. Shi, W. Sun, W.D. Teo, J. Thom, J. Thompson, J. Vaughan, Y. Weng,
L. Wins om, P. Wi ich
Fai ield Uni e si y, Fai ield, USA
A. Biselli, G. Ci ino, D. Winn
Fe mi Na ional Accele a o Labo a o y, Ba a ia, USA
S. Abdullin, M. Alb ow, J. Ande son, G. Apollina i, M. A ac, J.A. Bakken, S. Bane jee,
L.A.T. Baue dick, A. Be e as, J. Be yhill, P.C. Bha , I. Bloch, F. Bo che ding, K. Bu ke ,
J.N. Bu le , V. Che lu u, H.W.K. Cheung, F. Chlebana, S. Cihangi , M. Dema eau, D.P. Ea ly,
V.D. El i a, S. Esen, I. Fisk, J. F eeman, Y. Gao, E. Go schalk, D. G een, K. Gun ho i,
O. Gu sche, A. Hahn, J. Hanlon, R.M. Ha is, J. Hi schaue , B. Hoobe man, E. James, H. Jensen,
M. Johnson, U. Joshi, R. Kha iwada, B. Kilmins e , B. Klima, K. Kousou is, S. Kuno i, S. Kwan,
33
C. Leonidopoulos, P. Limon, R. Lip on, J. Lykken, K. Maeshima, J.M. Ma a ino, D. Mason,
P. McB ide, T. McCauley, T. Miao, K. Mish a, S. M enna, Y. Musienko41, C. Newman-Holmes,
V. O’Dell, S. Popescu42, R. Po des, O. P oko ye , N. Saoulidou, E. Sex on-Kennedy, S. Sha ma,
A. Soha, W.J. Spalding, L. Spiegel, P. Tan, L. Taylo , S. Tkaczyk, L. Uplegge , E.W. Vaande ing,
R. Vidal, J. Whi mo e, W. Wu, F. Yang, F. Yumice a, J.C. Yun
Uni e si y o Flo ida, Gaines ille, USA
D. Acos a, P. A e y, D. Bou ilko , M. Chen, G.P. Di Gio anni, D. Dobu , A. D ozde skiy,
R.D. Field, M. Fishe , Y. Fu, I.K. Fu ic, J. Ga ne , S. Goldbe g, B. Kim, S. Klimenko,
J. Konigsbe g, A. Ko y o , A. K opi ni skaya, T. Kyp eos, K. Ma che , G. Mi selmakhe ,
L. Muniz, Y. Pakho in, C. P esco , R. Reming on, M. Schmi , B. Scu lock, P. Selle s,
N. Skhi ladze, D. Wang, J. Yel on, M. Zaka ia
Flo ida In e na ional Uni e si y, Miami, USA
C. Ce on, V. Gaul ney, L. K ame , L.M. Lebolo, S. Linn, P. Ma kowi z, G. Ma inez,
J.L. Rod iguez
Flo ida S a e Uni e si y, Tallahassee, USA
T. Adams, A. Askew, D. Bandu in, J. Bochenek, J. Chen, B. Diamond, S.V. Gleyze , J. Haas,
S. Hagopian, V. Hagopian, M. Jenkins, K.F. Johnson, H. P ospe , L. Que enmon , S. Sekmen,
V. Vee a agha an
Flo ida Ins i u e o Technology, Melbou ne, USA
M.M. Baa mand, B. Do ney, S. Gu again, M. Hohlmann, H. Kalakhe y, R. Ralich,
I. Vodopiyano
Uni e si y o Illinois a Chicago (UIC), Chicago, USA
M.R. Adams, I.M. Anghel, L. Apanase ich, Y. Bai, V.E. Baz e a, R.R. Be s, J. Callne ,
R. Ca anaugh, C. D agoiu, E.J. Ga cia-Solis, L. Gau hie , C.E. Ge be , D.J. Ho man,
S. Khala yan, F. Lac oix, M. Malek, C. O’B ien, C. Sil es e, A. Smo on, D. S om, N. Va elas
The Uni e si y o Iowa, Iowa Ci y, USA
U. Akgun, E.A. Albay ak, B. Bilki, K. Cankocak43, W. Cla ida, F. Du u, C.K. Lae, E. McClimen ,
J.-P. Me lo, H. Me me kaya, A. Mes i ish ili, A. Moelle , J. Nach man, C.R. Newsom,
E. No beck, J. Olson, Y. Onel, F. Ozok, S. Sen, J. We zel, T. Ye kin, K. Yi
Johns Hopkins Uni e si y, Bal imo e, USA
B.A. Ba ne , B. Blumen eld, A. Bona o, C. Eskew, D. Fehling, G. Giu giu, A.V. G i san, Z.J. Guo,
G. Hu, P. Maksimo ic, S. Rappoccio, M. Swa z, N.V. T an, A. Whi beck
The Uni e si y o Kansas, Law ence, USA
P. Ba inge , A. Bean, G. Benelli, O. G acho , M. Mu ay, D. Noonan, V. Radicci, S. Sande s,
J.S. Wood, V. Zhuko a
Kansas S a e Uni e si y, Manha an, USA
T. Bol on, I. Chakabe ia, A. I ano , M. Makouski, Y. Ma a in, S. Sh es ha, I. S in adze, Z. Wan
Law ence Li e mo e Na ional Labo a o y, Li e mo e, USA
J. G onbe g, D. Lange, D. W igh
Uni e si y o Ma yland, College Pa k, USA
A. Baden, M. Bou emeu , S.C. Eno, D. Fe encek, J.A. Gomez, N.J. Hadley, R.G. Kellogg, M. Ki n,
Y. Lu, A.C. Migne ey, K. Rossa o, P. Rume io, F. San anas asio, A. Skuja, J. Temple, M.B. Tonjes,
S.C. Tonwa , E. Twed
34 A The CMS Collabo a ion
Massachuse s Ins i u e o Technology, Camb idge, USA
B. Al e , G. Baue , J. Benda id, W. Busza, E. Bu z, I.A. Cali, M. Chan, V. Du a, P. E e ae s,
G. Gomez Ceballos, M. Goncha o , K.A. Hahn, P. Ha is, Y. Kim, M. Klu e, Y.-J. Lee, W. Li,
C. Loizides, P.D. Luckey, T. Ma, S. Nahn, C. Paus, D. Ralph, C. Roland, G. Roland, M. Rudolph,
G.S.F. S ephans, K. Sumo ok, K. Sung, E.A. Wenge , S. Xie, M. Yang, Y. Yilmaz, A.S. Yoon,
M. Zane i
Uni e si y o Minneso a, Minneapolis, USA
P. Cole, S.I. Coope , P. Cushman, B. Dahmes, A. De Benede i, P.R. Dude o, G. F anzoni,
J. Haup , K. Klapoe ke, Y. Kubo a, J. Mans, V. Reko ic, R. Rusack, M. Sasse ille, A. Singo sky
Uni e si y o Mississippi, Uni e si y, USA
L.M. C emaldi, R. Godang, R. K oege , L. Pe e a, R. Rahma , D.A. Sande s, D. Summe s
Uni e si y o Neb aska-Lincoln, Lincoln, USA
K. Bloom, S. Bose, J. Bu , D.R. Claes, A. Dominguez, M. Eads, J. Kelle , T. Kelly, I. K a chenko,
J. Lazo-Flo es, C. Lunds ed , H. Malbouisson, S. Malik, G.R. Snow
S a e Uni e si y o New Yo k a Bu alo, Bu alo, USA
U. Bau , A. Godshalk, I. Iash ili, S. Jain, A. Kha chila a, A. Kuma , S.P. Shipkowski, K. Smi h
No heas e n Uni e si y, Bos on, USA
G. Al e son, E. Ba be is, D. Baumga el, O. Boe iu, M. Chasco, S. Reuc o , J. Swain, D. Wood,
J. Zhang
No hwes e n Uni e si y, E ans on, USA
A. Anas asso , A. Kubik, N. Odell, R.A. O ie zynski, B. Pollack, A. Pozdnyako , M. Schmi ,
S. S oyne , M. Velasco, S. Won
Uni e si y o No e Dame, No e Dame, USA
L. An onelli, D. Be y, M. Hild e h, C. Jessop, D.J. Ka mga d, J. Kolb, T. Kolbe g, K. Lannon,
W. Luo, S. Lynch, N. Ma inelli, D.M. Mo se, T. Pea son, R. Ruch i, J. Slaunwhi e, N. Valls,
J. Wa chol, M. Wayne, J. Ziegle
The Ohio S a e Uni e si y, Columbus, USA
B. Bylsma, L.S. Du kin, J. Gu, C. Hill, P. Killewald, K. Ko o , T.Y. Ling, M. Rodenbu g,
G. Williams
P ince on Uni e si y, P ince on, USA
N. Adam, E. Be y, P. Elme , D. Ge baudo, V. Halyo, P. Hebda, A. Hun , J. Jones, E. Lai d,
D. Lopes Pegna, D. Ma low, T. Med ede a, M. Mooney, J. Olsen, P. Pi ou´
e, X. Quan, H. Saka,
D. S ickland, C. Tully, J.S. We ne , A. Zu anski
Uni e si y o Pue o Rico, Mayaguez, USA
J.G. Acos a, X.T. Huang, A. Lopez, H. Mendez, S. Oli e os, J.E. Rami ez Va gas,
A. Za se klyaniy
Pu due Uni e si y, Wes La aye e, USA
E. Alagoz, V.E. Ba nes, G. Bolla, L. Bo ello, D. Bo ole o, A. E e e , A.F. Ga inkel, Z. Gecse,
L. Gu ay, Z. Hu, M. Jones, O. Koybasi, M. K ess, A.T. Laasanen, N. Leona do, C. Liu,
V. Ma ousso , P. Me kel, D.H. Mille , N. Neumeis e , I. Shipsey, D. Sil e s, A. S ya ko skiy,
H.D. Yoo, J. Zablocki, Y. Zheng
Pu due Uni e si y Calume , Hammond, USA
P. Jindal, N. Pa asha
35
Rice Uni e si y, Hous on, USA
C. Boulahouache, V. Cuplo , K.M. Ecklund, F.J.M. Geu s, J.H. Liu, B.P. Padley, R. Redjimi,
J. Robe s, J. Zabel
Uni e si y o Roches e , Roches e , USA
B. Be cha , A. Bodek, Y.S. Chung, R. Co a elli, P. de Ba ba o, R. Demina, Y. Eshaq, H. Flache ,
A. Ga cia-Bellido, P. Goldenzweig, Y. Go a, J. Han, A. Ha el, D.C. Mine , D. O bake ,
G. Pe illo, D. Vishne skiy, M. Zielinski
The Rocke elle Uni e si y, New Yo k, USA
A. Bha i, R. Ciesielski, L. Demo ie , K. Goulianos, G. Lungu, C. Mes opian, M. Yan
Ru ge s, he S a e Uni e si y o New Je sey, Pisca away, USA
O. A amen o , A. Ba ke , D. Duggan, Y. Ge sh ein, R. G ay, E. Halkiadakis, D. Hidas, D. Hi s,
A. La h, S. Panwalka , R. Pa el, A. Richa ds, K. Rose, S. Schne ze , S. Somalwa , R. S one,
S. Thomas
Uni e si y o Tennessee, Knox ille, USA
G. Ce izza, M. Hollingswo h, S. Spanie , Z.C. Yang, A. Yo k
Texas A&M Uni e si y, College S a ion, USA
J. Asaadi, R. Eusebi, J. Gilmo e, A. Gu ola, T. Kamon, V. Kho ilo ich, R. Mon al o,
C.N. Nguyen, I. Osipenko , J. Pi a ski, A. Sa ono , S. Sengup a, A. Ta a ino , D. Toback,
M. Weinbe ge
Texas Tech Uni e si y, Lubbock, USA
N. Akchu in, J. Damgo , C. Jeong, K. Ko i anggoon, S.W. Lee, Y. Roh, A. Sill, I. Voloboue ,
R. Wigmans, E. Yazgan
Vande bil Uni e si y, Nash ille, USA
E. Appel , E. B ownson, D. Engh, C. Flo ez, W. Gabella, W. Johns, P. Ku , C. Magui e, A. Melo,
P. Sheldon, S. Tuo, J. Velko ska
Uni e si y o Vi ginia, Cha lo es ille, USA
M.W. A en on, M. Balazs, S. Bou le, M. Buehle , S. Cone i, B. Cox, B. F ancis, R. Hi osky,
A. Ledo skoy, C. Lin, C. Neu, R. Yohay
Wayne S a e Uni e si y, De oi , USA
S. Gollapinni, R. Ha , P.E. Ka chin, P. Lamichhane, M. Ma son, C. Mils `
ene, A. Sakha o
Uni e si y o Wisconsin, Madison, USA
M. Ande son, M. Bach is, J.N. Bellinge , D. Ca lsmi h, S. Dasu, J. E on, L. G ay, K.S. G ogg,
M. G o he, R. Hall-Wil on1, M. He ndon, P. Klabbe s, J. Klukas, A. Lana o, C. Laza idis,
J. Leona d, R. Lo eless, A. Mohapa a, D. Reede , I. Ross, A. Sa in, W.H. Smi h, J. Swanson,
M. Weinbe g
†: Deceased
1: Also a CERN, Eu opean O ganiza ion o Nuclea Resea ch, Gene a, Swi ze land
2: Also a Uni e sidade Fede al do ABC, San o And e, B azil
3: Also a Labo a oi e Lep ince-Ringue , Ecole Poly echnique, IN2P3-CNRS, Palaiseau, F ance
4: Also a Suez Canal Uni e si y, Suez, Egyp
5: Also a Fayoum Uni e si y, El-Fayoum, Egyp
6: Also a Sol an Ins i u e o Nuclea S udies, Wa saw, Poland
7: Also a Massachuse s Ins i u e o Technology, Camb idge, USA
8: Also a Uni e si ´
e de Hau e-Alsace, Mulhouse, F ance

36 A The CMS Collabo a ion
9: Also a B andenbu g Uni e si y o Technology, Co bus, Ge many
10: Also a Moscow S a e Uni e si y, Moscow, Russia
11: Also a Ins i u e o Nuclea Resea ch ATOMKI, Deb ecen, Hunga y
12: Also a E¨
o ¨
os Lo ´
and Uni e si y, Budapes , Hunga y
13: Also a Ta a Ins i u e o Fundamen al Resea ch - HECR, Mumbai, India
14: Also a Uni e si y o Vis a-Bha a i, San inike an, India
15: Also a Facol `
a Ingegne ia Uni e si `
a di Roma ”La Sapienza”, Roma, I aly
16: Also a Uni e si `
a della Basilica a, Po enza, I aly
17: Also a Labo a o i Nazionali di Legna o dell’ INFN, Legna o, I aly
18: Also a Uni e si `
a degli s udi di Siena, Siena, I aly
19: Also a Cali o nia Ins i u e o Technology, Pasadena, USA
20: Also a Facul y o Physics o Uni e si y o Belg ade, Belg ade, Se bia
21: Also a Uni e si y o Cali o nia, Los Angeles, Los Angeles, USA
22: Also a Uni e si y o Flo ida, Gaines ille, USA
23: Also a Uni e si ´
e de Gen`
e e, Gene a, Swi ze land
24: Also a Scuola No male e Sezione dell’ INFN, Pisa, I aly
25: Also a INFN Sezione di Roma; Uni e si `
a di Roma ”La Sapienza”, Roma, I aly
26: Also a Uni e si y o A hens, A hens, G eece
27: Also a The Uni e si y o Kansas, Law ence, USA
28: Also a Ins i u e o Theo e ical and Expe imen al Physics, Moscow, Russia
29: Also a Paul Sche e Ins i u , Villigen, Swi ze land
30: Also a Uni e si y o Belg ade, Facul y o Physics and Vinca Ins i u e o Nuclea Sciences,
Belg ade, Se bia
31: Also a Gaziosmanpasa Uni e si y, Toka , Tu key
32: Also a Adiyaman Uni e si y, Adiyaman, Tu key
33: Also a Me sin Uni e si y, Me sin, Tu key
34: Also a Izmi Ins i u e o Technology, Izmi , Tu key
35: Also a Ka kas Uni e si y, Ka s, Tu key
36: Also a Suleyman Demi el Uni e si y, Ispa a, Tu key
37: Also a Ege Uni e si y, Izmi , Tu key
38: Also a Ru he o d Apple on Labo a o y, Didco , Uni ed Kingdom
39: Also a School o Physics and As onomy, Uni e si y o Sou hamp on, Sou hamp on,
Uni ed Kingdom
40: Also a INFN Sezione di Pe ugia; Uni e si `
a di Pe ugia, Pe ugia, I aly
41: Also a Ins i u e o Nuclea Resea ch, Moscow, Russia
42: Also a Ho ia Hulubei Na ional Ins i u e o Physics and Nuclea Enginee ing (IFIN-HH),
Bucha es , Romania
43: Also a Is anbul Technical Uni e si y, Is anbul, Tu key