EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN)
CERN-PH-EP/2010-067
2011/01/11
CMS-EXO-10-011
Sea ch o Hea y S able Cha ged Pa icles in pp Collisions
a √s=7 TeV
The CMS Collabo a ion∗
Abs ac
The esul o a sea ch a he LHC o hea y s able cha ged pa icles p oduced in pp
collisions a √s=7 TeV is desc ibed. The da a sample was collec ed wi h he CMS
de ec o and co esponds o an in eg a ed luminosi y o 3.1 pb−1. Momen um and
ioniza ion-ene gy-loss measu emen s in he inne acke de ec o a e used o iden-
i y acks compa ible wi h hea y slow-mo ing pa icles. Addi ionally, acks passing
muon iden i ica ion equi emen s a e also analyzed o he same signa u e. In each
case, no candida e passes he selec ion, wi h an expec ed backg ound o less han
0.1 e en s. A lowe limi a he 95% con idence le el on he mass o a s able gluino
is se a 398 GeV/c2, using a con en ional model o nuclea in e ac ions ha allows
cha ged had ons con aining his pa icle o each he muon de ec o s. A lowe limi
o 311 GeV/c2is also se o a s able gluino in a conse a i e scena io o comple e
cha ge supp ession, whe e any had on con aining his pa icle becomes neu al be-
o e eaching he muon de ec o s.
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 :1101.1645 1 [hep-ex] 9 Jan 2011
1
1 In oduc ion
Hea y s able (o quasi-s able) cha ged pa icles (HSCPs) appea in a ious ex ensions o he
s anda d model (SM) [1–8]. I he li e ime o an HSCP p oduced a he La ge Had on Collide
(LHC) is longe han a ew nanoseconds, he pa icle will a el o e dis ances ha a e compa-
able o la ge han he size o a ypical pa icle de ec o . In addi ion, i he HSCP mass is &100
GeV/c2, a signi ican ac ion o hese pa icles will ha e a eloci y, β≡ /c, smalle han 0.9.
These HSCPs will be di ec ly obse able h ough he dis inc i e signa u e o a high momen um
(p) pa icle wi h an anomalously la ge a e o ene gy loss h ough ioniza ion (dE/dx).
P e ious collide sea ches o HSCPs ha e o en been pe o med unde he assump ion ha
hese pa icles lose ene gy p ima ily h ough low-momen um- ans e in e ac ions, e en i hey
a e s ongly in e ac ing, and a e he e o e likely o each he ou e muon sys ems o he de ec-
o s and be iden i ied as muons [9–12]. The in e ac ions wi h ma e expe ienced by a s ongly-
in e ac ing HSCP, which is expec ed o o m a bound s a e (R-had on) [13] in he p ocess o
had oniza ion, can lead o i lipping he sign o i s elec ic cha ge o becoming neu al. A
ecen s udy [14] on he modeling o nuclea in e ac ions o HSCPs a eling h ough ma e ,
a ou s a scena io o cha ge supp ession. In his model he p obabili y is close o uni y o
an R-had on con aining a gluino, e
g ( he supe symme ic pa ne o he gluon), o a supe sym-
me ic bo om squa k, o eme ge as a neu al pa icle a e a e sing an amoun o ma e ial
ypical o he de ec o s ope a ing a LEP, he Te a on, o LHC. I his model is co ec , he ma-
jo i y o hese HSCPs would no be obse ed in he muon sys em o a ypical collide de ec o .
Expe imen al s a egies ha do no ely on he muon-like beha io o he HSCPs a e he e-
o e o g ea impo ance. Fo ins ance, sea ches ha e been pe o med o e y slow (β.0.4)
R-had ons con aining a gluino b ough o es in he de ec o [15, 16].
In his a icle we p esen a sea ch o HSCPs p oduced in pp collisions a √s=7 TeV a he
LHC wi h he Compac Muon Solenoid (CMS) de ec o [17]. The sea ch is based on he da a
sample collec ed be ween Ap il and Augus 2010 co esponding o an in eg a ed luminosi y
o 3.06 pb−1. We use igge s equi ing: a high- ans e se-momen um muon (pT>9 GeV/c);
o a dimuon pai (pT>3 GeV/c o each muon); o calo ime e -based missing ans e se
ene gy (Emiss
T>100 GeV), o sea ch o HSCPs ailing muon iden i ica ion o eme ging mainly
as neu al pa icles a e a e sing he calo ime e s; o a high- ans e se-ene gy je (ET>100
GeV) o sea ch o HSCPs accompanied by subs an ial had onic ac i i y. The analysis makes
use o wo app oaches. In a i s selec ion, e e ed o as “ acke -only”, he HSCP candida es a e
sea ched o as indi idual acks econs uc ed in he inne acke de ec o wi h la ge dE/dx
and pT. A second selec ion, e e ed o as “ acke -plus-muon”, addi ionally equi es ha he
ack is iden i ied as a muon in he ou e muon de ec o . Fo bo h selec ions, he mass o he
candida e is calcula ed om he measu ed pand dE/dx.
2 The CMS De ec o
The cen al ea u e o he CMS de ec o is a 3.8 T supe conduc ing solenoid o 6 m in e nal di-
ame e su ounding a silicon pixel and s ip acke , a c ys al elec omagne ic calo ime e , and
a b ass-scin illa o had onic calo ime e . Muons a e measu ed in gaseous de ec o s embedded
in he i on e u n yoke. Cen ally p oduced cha ged pa icles a e measu ed in he acke by
h ee laye s o silicon pixel de ec o s, ollowed by en mic os ip laye s. A pseudo apidi ies
(η≡ −ln an(θ/2), whe e θis he pola angle measu ed wi h espec o he beam di ec ion)
abo e ≈1.5, pa icles a e acked in wo pixel and wel e s ip laye s a anged in disks pe -
pendicula o he beam axis. In his analysis, he dE/dx measu emen is based only on he
23 Candida e Selec ion and Backg ound Es ima ion
in o ma ion om he silicon s ip de ec o s. The dE/dx measu emen p ecision is limi ed by
he silicon s ip analogue- o-digi al con e e (ADC) modules ha a e cha ac e ized by a max-
imum numbe o coun s pe channel co esponding o abou h ee imes he a e age cha ge
eleased by a minimum–ionizing pa icle (MIP) in 300 µm o silicon. This is he hickness o
he modules moun ed in he inne mos silicon s ip cen al laye s. The pT esolu ion o acks
measu ed in he cen al ( o wa d) egion o he silicon acke is 1% (2%) o pT alues up o
50 GeV/cand deg ades o 10% (20%) a pT alues o 1 TeV/c. The igge and econs uc ion
e iciencies o HSCPs in he muon de ec o s a e limi ed by he equi emen s on he a i al ime
o he pa icles a he muon sys em. These equi emen s a ec he e iciency o de ec ing slow
HSCPs. The dependence o he muon igge e iciency on he pa icle eloci y (β) is s udied
using da a and Mon e Ca lo (MC) simula ions and ound o dec ease, below β=0.7. The
muon igge becomes comple ely ine icien a β=0.5. A much mo e de ailed desc ip ion o
he CMS appa a us can be ound elsewhe e [17].
3 Candida e Selec ion and Backg ound Es ima ion
Candida e HSCPs a e p e-selec ed by equi ing a ack wi h |η|<2.5, pT>15 GeV/c, ela i e
unce ain y on he pTless han 15%, and ans e se (longi udinal) impac pa ame e wi h e-
spec o he econs uc ed p ima y collision e ex less han 0.25 (2.0) cm. Candida e acks a e
also equi ed o ha e a leas h ee measu emen s in he silicon-s ip de ec o . Fo he acke -
plus-muon selec ion, we addi ionally equi e he ack o be compa ible wi h ack segmen s e-
cons uc ed in he muon sys em. As an es ima o o he deg ee o compa ibili y o he obse ed
cha ge measu emen s wi h he MIP hypo hesis, a modi ied e sion o he Smi no -C ame -
on Mises [18, 19] disc iminan is used ( he modi ica ion applied o he o iginal o m o he
disc iminan elimina es he sensi i i y o incompa ibili y wi h he MIP hypo hesis due o low
ioniza ion):
Ias =3
N× 1
12N+
N
∑
i=1"Pi×Pi−2i−1
2N2#!, (1)
whe e Nis he numbe o cha ge measu emen s in he silicon-s ip de ec o s, Piis he p obabil-
i y o a MIP o p oduce a cha ge smalle o equal o he i– h cha ge measu emen o he ob-
se ed pa h leng h in he de ec o , and he sum is o e he ack measu emen s o de ed in e ms
o inc easing Pi. The cha ge p obabili y densi y unc ion used o calcula e Piis ob ained using
acks wi h p>5 GeV/cin e en s collec ed wi h a minimum bias igge . Non- ela i is ic
HSCP candida es will ha e he alue o he disc iminan Ias app oaching uni y. Figu e 1 shows
no malized dis ibu ions o pTand Ias in da a and wo MC samples, o candida es passing
he acke -only p e-selec ion. The i s MC sample con ains e en s om QCD p ocesses. The
second MC sample con ains signal e en s om pai -p oduc ion o s able e
g wi h a mass o 200
GeV/c2. Bo h samples a e gene a ed wi h he PYTHIA 6.422 [20] MC package. Mo e de ails on
he simula ion o he signal sample will be gi en below. The MC QCD simula ions a e ound
o ep oduce he da a, and he simula ed signal is clea ly sepa a ed. Because o he limi ed
numbe o a ailable simula ed e en s wi h low ans e se-momen um ans e s, he MC QCD
dis ibu ions display bin- o-bin a ia ions in he size o he s a is ical e o s.
The mos p obable alue o he pa icle dE/dx is de e mined using a ha monic es ima o Iho
g ade k=−2:
Ih=1
N∑
i
ck
i1/k
, (2)
whe e ciis he cha ge pe uni pa h leng h in he de ec o o he i- h measu emen o a gi en
3
(GeV/c)
T
p
0 500 1000
ac ion o acks/20 GeV/c
-6
10
-5
10
-4
10
-3
10
-2
10
-1
10
T acke - Only
200g
~
MC -
MC - QCD
Da a
-1
= 7 TeV 3.06 pb sCMS
as
I
0 0.2 0.4 0.6 0.8 1
ac ion o acks/0.02
-7
10
-6
10
-5
10
-4
10
-3
10
-2
10
-1
10
1T acke - Only
200g
~
MC -
MC - QCD
Da a
-1
= 7 TeV 3.06 pb sCMS
Figu e 1: No malized dis ibu ions o pT(le ) and Ias ( igh ) in da a and wo MC samples, o
candida es passing he acke -only p e-selec ion. The wo MC samples con ain e en s om
QCD p ocesses and om pai -p oduc ion o e
g wi h a mass o 200 GeV/c2, espec i ely.
ack. In o de o es ima e he mass (m) o highly ionizing pa icles, he ollowing ela ionship
be ween Ih,p, and mis assumed:
Ih=Km2
p2+C. (3)
Equa ion 3 ep oduces he Be he-Bloch o mula [21] wi h an accu acy o be e han 1% in he
ange 0.4 <β<0.9, which co esponds o 1.1 <(dE/dx)/(dE/dx)MIP <4.0. The empi ical
pa ame e s Kand Ca e de e mined om da a using a sample o low-momen um p o ons, o
which he i ed alues a e K=2.579 ±0.001 MeV cm−1c2and C=2.557 ±0.001 MeV cm−1,
and he mass esolu ion is 7%. The econs uc ed mass dis ibu ion o kaons and p o ons is in
e y good ag eemen wi h he one ob ained om MC ollowing his p ocedu e [22]. Fo masses
abo e 100 GeV/c2, he mass esolu ion is expec ed o wo sen because o he de e io a ion o he
momen um esolu ion and because o he limi on he maximum cha ge ha can be measu ed
by he silicon s ip acke ADCs, which also a ec s he mass scale. Fo a 300 GeV/c2HSCP,
he mass esolu ion is 12% and he econs uc ed peak posi ion is a 265 GeV/c2.
The sea ch is pe o med as a coun ing expe imen . Signal candida es a e equi ed o ha e Ias
and pTg ea e han h eshold alues and he mass o be in he ange o 75 o 2000 GeV/c2,
allowing sensi i i y o HSCP masses as low as 100 GeV/c2. The Ias dis ibu ion o he p e-
selec ed acks, and in pa icula i s ail, depends s ongly on he numbe o cha ge measu e-
men s on he ack. Thus, o inc ease he sensi i i y o he sea ch, p e-selec ed acks a e di-
ided in o subsamples acco ding o he numbe o silicon s ip measu emen s. The Ias (pT)
h eshold in each subsample is de e mined by equi ing a cons an e iciency on da a o all
subsamples, when he h eshold is applied sepa a ely. A me hod ha exploi s he absence
o co ela ion be ween he pTand dE/dx measu emen s in da a is used o es ima e he back-
g ound om MIPs. In a gi en subsample j, he numbe o acks ha a e expec ed o pass bo h
he inal pTand Ias h esholds se o he subsample is es ima ed as Dj=BjCj/Aj, whe e Ajis
he numbe o acks ha ail bo h he Ias and pTselec ions and Bj(Cj) is he numbe o acks
ha pass only he Ias (pT) selec ion. The Bjand Cj acks a e hen used o o m a binned p oba-
bili y densi y unc ion in Ih(p) o he Dj acks. Finally, using he mass de e mina ion (Eq. 3),
he ull mass spec um o he backg ound in he signal egion Dis p edic ed.

44 Resul s
By compa ing he p edic ed and obse ed numbe o acks o se e al e y loose selec ions in
a con ol egion o he mass spec um, co esponding o masses below 75 GeV/c2, he p edic-
ion is ound o unde es ima e sys ema ically he obse a ion by 12% (5%) o he acke -only
( acke -plus-muon) selec ion. A e co ec ing he p edic ed backg ound by his amoun , he
emaining backg ound sys ema ic unce ain y is conse a i ely es ima ed as wice he .m.s.
o he p edic ion- o-obse a ion a io dis ibu ion The esul ing unce ain y on he p edic ed
backg ound is 14% (17%).
As signi ican backg ound ejec ion can be ob ained wi hou a sizable e ec on he signal e i-
ciency, he inal selec ion is op imized by equi ing he o al expec ed backg ound in he sea ch
egion o be ∼0.05 e en s. This low-backg ound choice op imizes he disco e y po en ial e en
i jus a hand ul o e en s a e obse ed, and a he same ime main ains signi ican exclusion
sensi i i y in he case ha no e en s a e obse ed.
4 Resul s
In addi ion o he inal “ igh ” selec ion, he esul o a “loose” selec ion is epo ed in Table 1.
The loose selec ion e ains a ela i ely la ge numbe o backg ound candida es and allows us
o compa e he backg ound p edic ion wi h he obse ed da a. Figu e 2 shows good ag eemen
be ween he obse ed and p edic ed mass spec um ob ained using he loose selec ion o he
acke -plus-muon and acke -only candida es.
)
2
Mass (GeV/c
0 500 1000
2
T acks / 50 GeV/c
-1
10
1
10
2
10
3
10 T acke + Muon
Da a-based p edic ion
Da a
400g
~
MC -
-1
= 7 TeV 3.06 pb sCMS
)
2
Mass (GeV/c
0 500 1000
2
T acks / 50 GeV/c
-1
10
1
10
2
10
T acke - Only
Da a-based p edic ion
Da a
300g
~
MC -
-1
= 7 TeV 3.06 pb sCMS
Figu e 2: Mass spec um o he loose selec ion de ined in Table 1 o he acke -plus-muon
(le ) and acke -only ( igh ) candida es. Shown a e: obse ed spec um (black do s wi h
he e o ba s), da a-based p edic ed backg ound spec um ( ed iangles) wi h i s unce ain y
(g een band) and he spec um p edic ed by MC o a signal o pai -p oduced s able e
g wi h a
mass o 400 (le ) and 300 ( igh ) GeV/c2(blue his og am).
The esul s o he sea ch wi h he inal selec ion a e also p esen ed in Table 1. No candida e
HSCP ack is obse ed in ei he he acke -only o acke -plus-muon analysis.
Gi en he null esul , c oss sec ion uppe limi s a he 95% C.L. a e se on he HSCP p oduc ion
o wo benchma k scena ios: di ec p oduc ion o e
g pai s and ˜
1pai s. Fo a gi en mass, he
c oss sec ion o e
g p oduc ion is expec ed o be much la ge han ha o ˜
1p oduc ion a bo h
he Te a on and he LHC. Thus highe mass limi s can be se o he o me a bo h machines.
5
Table 1: Selec ions used in he analysis and esul s o he sea ch. The acke -plus-muon and
acke -only selec ions a e labeled as “Mu” and “Tk”, espec i ely. As explained in he ex ,
he ac ual Ias (pT) h esholds a e de e mined in he a ious subsamples by he equi emen o a
cons an e iciency o candida e selec ion, eI(epT). These h esholds, indica ed by Imin
as (pmin
T),
a e he e o e epo ed as a ange o alues. Expec ed and obse ed numbe o candida es in
he signal egion a e epo ed in he “Expec ed” and “Obse ed” ows, espec i ely. Top: loose
selec ion. Bo om: igh selec ion.
LOOSE Mu Tk
eI3.2 ×10−21.0 ×10−2
Imin
as 0.049 - 0.162 0.007 - 0.278
epT1.0 ×10−13.2 ×10−2
pmin
T(GeV/c) 34 - 36 59 - 62
Expec ed 281 ±2(s a .)±49(sys .)426 ±1(s a .)±62(sys .)
Obse ed 307 452
TIGHT Mu Tk
eI1.0 ×10−41.0 ×10−4
Imin
as 0.184 - 0.782 0.186 - 0.784
epT1.0 ×10−33.2 ×10−4
pmin
T(GeV/c) 115 - 118 154 - 210
Expec ed 0.025 ±0.002(s a .)±0.004(sys .)0.074 ±0.002(s a .)±0.011(sys .)
Obse ed 0 0
Howe e , as he mass o a p oduced pa icle inc eases, he a io o he p oduc ion c oss sec ion
a he LHC o ha a he Te a on inc eases. Fo e
g masses in he egion o 350 GeV/c2, he
inc ease in ela i e c oss sec ion ou weighs he di e ence in in eg a ed luminosi y be ween he
cu en Te a on and LHC da a se s, enabling he LHC o se he mos sensi i e limi s on he
sea ch o e
g.
E en s wi h pai p oduc ion o e
g and ˜
1, wi h mass alues in he ange 130-900 GeV/c2, a e gen-
e a ed wi h PYTHIA in o de o compu e he e iciency o ou selec ion on hese signals. The ˜
1
and e
g a e ea ed as s able in all hese samples and hei had oniza ion is pe o med by PYTHIA.
A pa ame e ele an o he e
g pai p oduc ion, and no o he ˜
1pai p oduc ion, is he ac ion,
, o p oduced e
g had onizing in o a e
g-gluon s a e (R-gluonball). This ac ion is an unknown
pa ame e o he had oniza ion model and a ec s he ac ion o R-had ons ha a e neu al a
p oduc ion, which in u n a ec s he de ec ion e iciency. In his s udy, esul s a e ob ained o
wo di e en alues o , 0.1 and 0.5, o show he e ec o he had oniza ion model unce ain y
on he sensi i i y o he sea ch. The in e ac ions o he HSCPs wi h he CMS appa a us and he
de ec o esponse a e simula ed in de ail wi h he GEANT4 9.2 [23, 24] oolki . The R-had on
s ong in e ac ions wi h ma e a e modeled as in Re . [25, 26]. This model, like a numbe o
o he s [14, 27–29], assumes ha he p obabili y o an in e ac ion be ween he hea y pa on and
a qua k in he a ge nucleon is low since he c oss sec ion a ies wi h he in e se squa e o he
pa on mass acco ding o pe u ba i e QCD. The adop ed model chooses a p agma ic app oach
based on analogy wi h obse ed low ene gy had on sca e ing. Howe e , gi en he e y la ge
unce ain ies on he dynamics unde lying R-had on in e ac ions, an ex emely pessimis ic sce-
na io o comple e cha ge supp ession, whe e each nuclea in e ac ion su e ed by he R-had on
causes i o become neu al, is also conside ed. The acke -only selec ion is expec ed o ha e
sensi i i y e en in such a scena io. The o al signal e iciency is epo ed in Table 2 o some
combina ions o models and selec ions. Rela i ely small di e ences a e ound be ween he
64 Resul s
Table 2: To al signal selec ion e iciency and c oss sec ion uppe limi s o di e en combina-
ions o models and selec ions: pai p oduc ion o supe symme ic s op and gluinos; acke -
plus-muon (Mu) and acke -only (Tk) selec ions; di e en ac ions, , o R-gluonball s a es
p oduced a e had oniza ion and cha ge supp ession (ch. supp .) scena io.
gluino mass (GeV/c2) 200 300 400 500 600 900
Theo e ical c oss sec ion (pb) 606 57.2 8.98 1.87 0.470 0.0130
Mu; =0.1
To al e iciency (%) 7.17 10.4 13.1 15.1 14.5 9.18
Expec ed 95% C.L. limi (pb) 15.1 10.4 8.25 7.16 7.47 11.8
Obse ed 95% C.L. limi (pb) 14.5 9.98 7.92 6.88 7.17 11.3
Mu; =0.5;
To al e iciency (%) 3.84 5.46 7.03 8.23 8.10 4.98
Expec ed 95% C.L. limi (pb) 28.2 19.8 15.4 13.1 13.3 21.7
Obse ed 95% C.L. limi (pb) 27.1 19.0 14.8 12.6 12.8 20.9
Tk; =0.1; ch. supp .
To al e iciency (%) 0.59 2.44 4.16 6.39 8.60 7.66
Expec ed 95% C.L. limi (pb) 188 45.5 26.7 17.4 12.9 14.5
Obse ed 95% C.L. limi (pb) 176 42.6 25.0 16.2 12.1 13.6
s op mass (GeV/c2) 130 200 300 500 800
Theo e ical c oss sec ion (pb) 120 13.0 1.31 0.0480 0.00110
Mu;
To al e iciency (%) 2.99 9.50 14.7 19.6 14.0
Expec ed 95% C.L. limi (pb) 36.1 11.4 7.35 5.52 7.71
Obse ed 95% C.L. limi (pb) 34.7 10.9 7.06 5.30 7.39
Tk; ch. supp .
To al e iciency (%) 0.02 1.19 3.55 7.27 7.68
Expec ed 95% C.L. limi (pb) 5540 93.2 31.3 15.3 14.5
Obse ed 95% C.L. limi (pb) 5180 87.2 29.2 14.3 13.5
7
Table 3: Sou ces o sys ema ic e o s and co esponding ela i e unce ain ies.
Sou ce o Sys ema ic E o Rela i e Unce ain y (%)
Theo e ical c oss sec ion 10 - 25
In eg a ed luminosi y 11
T igge e iciency 12
Muon econs uc ion e iciency 5
T ack econs uc ion e iciency <5
Momen um scale <5
Ioniza ion ene gy loss scale <3
To al unce ain y on signal accep ance 15
acke -plus-muon and acke -only selec ion excep in he cha ge supp ession scena io, whe e
he acke -plus-muon selec ion is comple ely ine icien .
This analysis is ound o be complemen a y o he sea ch o long-li ed s opped pa icles p e-
sen ed in [16]. Indeed, o he case o e
g wi h =0.1 and mass alues below 500 GeV/c2, he
ac ion o HSCPs ha ha e β<0.4 and pass he inal selec ion is less han 0.5%. The e o e he
wo analyses explo e di e en anges o p oduced pa icle eloci ies wi h no o e lap.
The main sou ces o sys ema ic unce ain y a ec ing he esul s p esen ed in he ollowing
a e summa ized in Table 3. The unce ain y on he signal selec ion e iciency is es ima ed o
be 15% o all conside ed combina ions o models and selec ions. The main sou ce o his
unce ain y is an assumed 10% unce ain y on he je ene gy scale [30], which a ec s bo h he
je and Emiss
T igge e iciency by abou 10%. In a mo e ecen s udy [31], he es ima e o he
unce ain y on he je ene gy scale has been educed by a ac o o wo. Howe e , in his
analysis we ha e conse a i ely chosen o e ain he ea lie es ima e o 10%. The unce ain y
on he muon igge e iciency and he impac o an impe ec simula ion o he synch oniza ion
o he muon igge and eadou elec onics a e s udied wi h da a and MC. They esul in an
o e all unce ain y on he signal selec ion e iciency o less han 5%. The unce ain y on he
o line ack econs uc ion e iciency [32, 33], ack momen um scale [34] and ioniza ion ene gy
loss scale [22] is also ound o yield no mo e han 5% unce ain y on he o e all signal selec ion
e iciency. The unce ain y on he absolu e alue o he in eg a ed luminosi y is es ima ed o be
11% [35].
The uppe limi on he c oss sec ion is compu ed a 95% C.L. using a Bayesian me hod wi h a
la signal p io and a log-no mal p io used o in eg a ion o e he nuisance pa ame e s [18,
19, 21]. In o de o ob ain a conse a i e uppe limi we se he expec ed backg ound o ze o.
The acke -plus-muon selec ion p o ides be e limi s han he acke -only o all scena ios
bu he one wi h comple e cha ge supp ession. Fo each conside ed scena io, he c oss sec ion
uppe limi ob ained wi h he mos sensi i e selec ion is epo ed in Table 2 and Fig. 3, along
wi h he heo e ical p edic ions o e
g and ˜
1pai p oduc ion compu ed a nex - o-leading o de
(NLO) + nex - o-leading log (NLL) [36–39] using he PROSPINO 2 p og am [40]. The e
g heo-
e ical p edic ions e e o he case whe e he squa ks and gluino a e degene a e in mass. In
he hea y squa k limi hese c oss sec ions a e abou 10% highe . Fo he case o ˜
1, beyond
LO, he c oss sec ion does no only depend on he ˜
1mass, bu also, hough o a much lesse
ex en [41], on he e
g mass, he a e age mass o he i s and second gene a ion squa ks and he
s op mixing angle. Fo his eason, he ˜
1 heo e ical p edic ions epo ed in Table 2 and Fig. 3
e e o he SPS1a’ benchma k scena io [42]. All sys ema ic unce ain ies discussed abo e a e
included in he c oss sec ion uppe limi s epo ed in Table 2 and Fig. 3. F om he in e sec ion
14 A The CMS Collabo a ion
Uni e si y o So ia, So ia, Bulga ia
M. Dyulenda o a, R. Hadjiiska, V. Kozhuha o , L. Li o , E. Ma ino a, M. Ma ee , B. Pa lo ,
P. Pe ko
Ins i u e o High Ene gy Physics, Beijing, China
J.G. Bian, G.M. Chen, H.S. Chen, C.H. Jiang, D. Liang, S. Liang, J. Wang, J. Wang, X. Wang,
Z. Wang, M. Xu, M. Yang, J. Zang, Z. Zhang
S a e Key Lab. o Nucl. Phys. and Tech., Peking Uni e si y, Beijing, China
Y. Ban, S. Guo, W. Li, Y. Mao, S.J. Qian, H. Teng, L. Zhang, B. Zhu
Uni e sidad de Los Andes, Bogo a, Colombia
A. Cab e a, B. Gomez Mo eno, A.A. Ocampo Rios, A.F. Oso io Oli e os, J.C. Sanab ia
Technical Uni e si y o Spli , Spli , C oa ia
N. Godino ic, D. Lelas, K. Lelas, R. Ples ina3, D. Polic, I. Puljak
Uni e si y o Spli , Spli , C oa ia
Z. An uno ic, M. Dzelalija
Ins i u e Rudje Bosko ic, Zag eb, C oa ia
V. B iglje ic, S. Du ic, K. Kadija, S. Mo o ic
Uni e si y o Cyp us, Nicosia, Cyp us
A. A ikis, M. Galan i, J. Mousa, C. Nicolaou, F. P ochos, P.A. Razis, H. Rykaczewski
Academy o Scien i ic Resea ch and Technology o he A ab Republic o Egyp , Egyp ian
Ne wo k o High Ene gy Physics, Cai o, Egyp
Y. Ass an4, M.A. Mahmoud5
Na ional Ins i u e o Chemical Physics and Biophysics, Tallinn, Es onia
A. Hek o , M. Kadas ik, K. Kannike, M. M¨
un el, M. Raidal, L. Rebane
Depa men o Physics, Uni e si y o Helsinki, Helsinki, Finland
V. Azzolini, P. Ee ola
Helsinki Ins i u e o Physics, Helsinki, Finland
S. Czella , J. H¨
a k¨
onen, A. Heikkinen, V. Ka im¨
aki, R. Kinnunen, J. Klem, M.J. Ko elainen,
T. Lamp´
en, K. Lassila-Pe ini, S. Leh i, T. Lind´
en, P. Luukka, T. M¨
aenp¨
a¨
a, E. Tuominen,
J. Tuominiemi, E. Tuo inen, D. Unga o, L. Wendland
Lappeen an a Uni e si y o Technology, Lappeen an a, Finland
K. Banzuzi, A. Ko pela, T. Tuu a
Labo a oi e d’Annecy-le-Vieux de Physique des Pa icules, IN2P3-CNRS, Annecy-le-Vieux,
F ance
D. Sillou
DSM/IRFU, CEA/Saclay, Gi -su -Y e e, F ance
M. Besancon, S. Choudhu y, M. Deja din, D. Deneg i, B. Fabb o, J.L. Fau e, F. Fe i, S. Ganjou ,
F.X. Gen i , A. Gi e naud, P. G as, G. Hamel de Monchenaul , P. Ja y, E. Locci, J. Malcles,
M. Ma ionneau, L. Millische , J. Rande , A. Rosowsky, I. Sh eybe , M. Ti o , P. Ve ecchia
Labo a oi e Lep ince-Ringue , Ecole Poly echnique, IN2P3-CNRS, Palaiseau, F ance
S. Ba ioni, F. Beaude e, L. Bianchini, M. Bluj6, C. B ou in, P. Busson, C. Cha lo , T. Dahms,
L. Dob zynski, R. G anie de Cassagnac, M. Haguenaue , P. Min´
e, C. Mi ono , C. Ochando,
P. Paganini, D. Sabes, R. Sale no, Y. Si ois, C. Thiebaux, B. Wyslouch7, A. Zabi

15
Ins i u Plu idisciplinai e Hube Cu ien, Uni e si ´e de S asbou g, Uni e si ´e de Hau e
Alsace Mulhouse, CNRS/IN2P3, S asbou g, F ance
J.-L. Ag am8, J. And ea, A. Besson, D. Bloch, D. Bodin, J.-M. B om, M. Ca daci, E.C. Chabe ,
C. Colla d, E. Con e8, F. D ouhin8, C. Fe o, J.-C. Fon aine8, D. Gel´
e, U. Goe lach, S. G ede ,
P. Juillo , M. Ka im8, A.-C. Le Bihan, Y. Mikami, P. Van Ho e
Cen e de Calcul de l’Ins i u Na ional de Physique Nucleai e e de Physique des
Pa icules (IN2P3), Villeu banne, F ance
F. Fassi, D. Me cie
Uni e si ´e de Lyon, Uni e si ´e Claude Be na d Lyon 1, CNRS-IN2P3, Ins i u de Physique
Nucl´eai e de Lyon, Villeu banne, F ance
C. Ba y, N. Beaupe e, M. Bedjidian, O. Bondu, G. Boudoul, D. Boumediene, H. B un,
N. Chanon, R. Chie ici, D. Con a do, P. Depasse, H. El Mamouni, A. Falkiewicz, J. Fay,
S. Gascon, B. Ille, T. Ku ca, T. Le G and, M. Le huillie , L. Mi abi o, S. Pe ies, V. So dini, S. Tosi,
Y. Tschudi, P. Ve die , H. Xiao
E. And onikash ili Ins i u e o Physics, Academy o Science, Tbilisi, Geo gia
V. Roinish ili
RWTH Aachen Uni e si y, I. Physikalisches Ins i u , Aachen, Ge many
G. Anagnos ou, M. Edelho , L. Feld, N. He acleous, O. Hind ichs, R. Jussen, K. Klein, J. Me z,
N. Moh , A. Os apchuk, A. Pe ieanu, F. Raupach, J. Samme , S. Schael, D. Sp enge , H. Webe ,
M. Webe , B. Wi me
RWTH Aachen Uni e si y, III. Physikalisches Ins i u A, Aachen, Ge many
M. A a, W. Bende , M. E dmann, J. F angenheim, T. Hebbeke , A. Hinzmann, K. Hoep ne ,
C. Ho , T. Klimko ich, D. Klingebiel, P. K euze , D. Lanske†, C. Magass, G. Mase i,
M. Me schmeye , A. Meye , P. Papacz, H. Pie a, H. Rei hle , S.A. Schmi z, L. Sonnenschein,
J. S eggemann, D. Teyssie
RWTH Aachen Uni e si y, III. Physikalisches Ins i u B, Aachen, Ge many
M. Bon enackels, M. Da ids, M. Duda, G. Fl¨
ugge, H. Geenen, M. Gi els, W. Haj Ahmad,
D. Heydhausen, T. K ess, Y. Kuessel, A. Linn, A. Nowack, L. Pe challa, O. Poo h, J. Renne eld,
P. Saue land, A. S ahl, M. Thomas, D. To nie , M.H. Zoelle
Deu sches Elek onen-Synch o on, Hambu g, Ge many
M. Aldaya Ma in, W. Beh enho , U. Beh ens, M. Be gholz9, K. Bo as, A. Caki , A. Campbell,
E. Cas o, D. Dammann, G. Ecke lin, D. Ecks ein, A. Flossdo , G. Flucke, A. Geise , I. Glushko ,
J. Hauk, H. Jung, M. Kasemann, I. Ka ko , P. Ka sas, C. Kleinwo , H. Kluge, A. Knu sson,
D. K ¨
ucke , E. Kuzne so a, W. Lange, W. Lohmann9, R. Mankel, M. Ma ien eld, I.-A. Melze -
Pellmann, A.B. Meye , J. Mnich, A. Mussgille , J. Olzem, A. Pa en i, A. Raspe eza, A. Ra al,
R. Schmid 9, T. Schoe ne -Sadenius, N. Sen, M. S ein, J. Tomaszewska, D. Volyanskyy, R. Walsh,
C. Wissing
Uni e si y o Hambu g, Hambu g, Ge many
C. Au e mann, S. Bob o skyi, J. D aege , H. Ende le, U. Gebbe , K. Kaschube, G. Kaussen,
R. Klanne , J. Lange, B. Mu a, S. Naumann-Emme, F. Nowak, N. Pie sch, C. Sande , H. Sche le ,
P. Schlepe , M. Sch ¨
ode , T. Schum, J. Schwand , A.K. S i as a a, H. S adie, G. S einb ¨
uck,
J. Thomsen, R. Wol
Ins i u ¨u Expe imen elle Ke nphysik, Ka ls uhe, Ge many
C. Ba h, J. Baue , V. Buege, T. Chwalek, W. De Boe , A. Die lamm, G. Di kes, M. Feind ,
J. G uschke, C. Hacks ein, F. Ha mann, S.M. Heindl, M. Hein ich, H. Held, K.H. Ho mann,
16 A The CMS Collabo a ion
S. Honc, T. Kuh , D. Ma schei, S. Muelle , Th. M¨
ulle , M. Niegel, O. Obe s , A. Oehle , J. O ,
T. Pei e , D. Pipa o, G. Quas , K. Rabbe z, F. Ra niko , M. Renz, C. Saou , A. Scheu e ,
P. Schie e decke , F.-P. Schilling, G. Scho , H.J. Simonis, F.M. S obe , D. T oendle, J. Wagne -
Kuh , M. Zeise, V. Zhuko 10, E.B. Zieba h
Ins i u e o Nuclea Physics ”Demok i os”, Aghia Pa aske i, G eece
G. Daskalakis, T. Ge alis, S. Kesisoglou, A. Ky iakis, D. Loukas, I. Manolakos, A. Ma kou,
C. Ma kou, C. Ma omma is, E. Pe akou
Uni e si y o A hens, A hens, G eece
L. Gouskos, T.J. Me zimekis, A. Panagio ou1
Uni e si y o Io´annina, Io´annina, G eece
I. E angelou, C. Foudas, P. Kokkas, N. Man hos, I. Papadopoulos, V. Pa as, F.A. T ian is
KFKI Resea ch Ins i u e o Pa icle and Nuclea Physics, Budapes , Hunga y
A. A anyi, G. Bencze, L. Boldizsa , G. Deb eczeni, C. Hajdu1, D. Ho a h11, A. Kapusi,
K. K ajcza 12, A. Laszlo, F. Sikle , G. Vesz e gombi12
Ins i u e o Nuclea Resea ch ATOMKI, Deb ecen, Hunga y
N. Beni, J. Molna , J. Palinkas, Z. Szillasi, V. Veszp emi
Uni e si y o Deb ecen, Deb ecen, Hunga y
P. Raics, Z.L. T ocsanyi, B. Uj a i
Panjab Uni e si y, Chandiga h, India
S. Bansal, S.B. Be i, V. Bha naga , N. Dhing a, M. Jindal, M. Kau , J.M. Kohli, M.Z. Meh a,
N. Nishu, L.K. Saini, A. Sha ma, A.P. Singh, J.B. Singh, S.P. Singh
Uni e si y o Delhi, Delhi, India
S. Ahuja, S. Bha acha ya, B.C. Choudha y, P. Gup a, S. Jain, S. Jain, A. Kuma , R.K. Shi pu i
Bhabha A omic Resea ch Cen e, Mumbai, India
R.K. Choudhu y, D. Du a, S. Kailas, S.K. Ka a ia, A.K. Mohan y1, L.M. Pan , P. Shukla
Ta a Ins i u e o Fundamen al Resea ch - EHEP, Mumbai, India
T. Aziz, M. Guchai 13, A. Gu u, M. Mai y14, D. Majumde , G. Majumde , K. Mazumda ,
G.B. Mohan y, A. Saha, K. Sudhaka , N. Wick amage
Ta a Ins i u e o Fundamen al Resea ch - HECR, Mumbai, India
S. Bane jee, S. Dugad, N.K. Mondal
Ins i u e o S udies in Theo e ical Physics & Ma hema ics (IPM), Teh an, I an
H. A aei, H. Bakhshiansohi, S.M. E esami, A. Fahim, M. Hashemi, A. Ja a i, M. Khakzad,
A. Mohammadi, M. Mohammadi Naja abadi, S. Pak ina Mehdiabadi, B. Sa a zadeh,
M. Zeinali
INFN Sezione di Ba i a, Uni e si `a di Ba i b, Poli ecnico di Ba i c, Ba i, I aly
M. Abb esciaa,b, L. Ba bonea,b, C. Calab iaa,b, A. Colaleoa, D. C eanzaa,c, N. De Filippisa,c,
M. De Palmaa,b, A. Dimi o a, L. Fio ea, G. Iasellia,c, L. Lusi oa,b,1, G. Maggia,c, M. Maggia,
N. Mannaa,b, B. Ma angellia,b, S. Mya,c, S. Nuzzoa,b, N. Paci icoa,b, G.A. Pie oa, A. Pompilia,b,
G. Pugliesea,c, F. Romanoa,c, G. Rosellia,b, G. Sel aggia,b, L. Sil es isa, R. T en aduea,
S. Tuppu ia,b, G. Zi oa
INFN Sezione di Bologna a, Uni e si `a di Bologna b, Bologna, I aly
G. Abbiendia, A.C. Ben enu ia, D. Bonaco sia, S. B aiban -Giacomellia,b, L. B igliado ia,
17
P. Capiluppia,b, A. Cas oa,b, F.R. Ca alloa, M. Cu iania,b, G.M. Dalla allea, F. Fabb ia,
A. Fan ania,b, D. Fasanellaa, P. Giacomellia, M. Giun aa, S. Ma cellinia, M. Meneghellia,b,
A. Mon ana ia, F.L. Na a iaa,b, F. Odo icia, A. Pe o aa, F. P ima e aa, A.M. Rossia,b,
T. Ro ellia,b, G. Si olia,b, R. T a aglinia,b
INFN Sezione di Ca ania a, Uni e si `a di Ca ania b, Ca ania, I aly
S. Albe goa,b, G. Cappelloa,b, M. Chio bolia,b,1, S. Cos aa,b, A. T icomia,b, C. Tu ea
INFN Sezione di Fi enze a, Uni e si `a di Fi enze b, Fi enze, I aly
G. Ba baglia, V. Ciullia,b, C. Ci ininia, R. D’Alessand oa,b, E. Foca dia,b, S. F osalia,b, E. Galloa,
C. Gen aa, P. Lenzia,b, M. Meschinia, S. Paole ia, G. Sguazzonia, A. T opianoa,1
INFN Labo a o i Nazionali di F asca i, F asca i, I aly
L. Benussi, S. Bianco, S. Cola anceschi15, F. Fabb i, D. Piccolo
INFN Sezione di Geno a, Geno a, I aly
P. Fabb ica o e, R. Musenich
INFN Sezione di Milano-Biccoca a, Uni e si `a di Milano-Bicocca b, Milano, I aly
A. Benagliaa,b, F. De Guioa,b,1, L. Di Ma eoa,b, A. Ghezzia,b,1, M. Malbe ia,b, S. Mal ezzia,
A. Ma ellia,b, A. Massi onia,b, D. Menascea, L. Mo onia, M. Paganonia,b, D. Ped inia,
S. Ragazzia,b, N. Redaellia, S. Salaa, T. Taba elli de Fa isa,b, V. Tancinia,b
INFN Sezione di Napoli a, Uni e si `a di Napoli ”Fede ico II” b, Napoli, I aly
S. Buon empoa, C.A. Ca illo Mon oyaa, A. Cimminoa,b, A. De Cosaa,b, M. De G u olaa,b,
F. Fabozzia,16, A.O.M. Io ioa, L. Lis aa, M. Me olaa,b, P. Nolia,b, P. Paoluccia
INFN Sezione di Pado a a, Uni e si `a di Pado a b, Uni e si `a di T en o (T en o) c, Pado a,
I aly
P. Azzia, N. Bacche aa, P. Bellana,b, D. Biselloa,b, A. B ancaa, R. Ca lina,b, E. Con ia, M. De
Ma iaa,b, T. Do igoa, F. Fanzagoa, F. Gaspa inia,b, P. Giubila oa,b, F. Gonellaa, A. G eselea,c,
S. Lacap a aa,17, I. Lazzizze aa,c, M. Ma gonia,b, M. Mazzuca oa, A.T. Meneguzzoa,b,
M. Nespoloa, M. Pego a oa, L. Pe ozzia,1, N. Pozzobona,b, P. Ronchesea,b, E. To assaa,
M. Tosia,b, A. T iossia, S. Vaninia,b, S. Ven u aa, G. Zume lea,b
INFN Sezione di Pa ia a, Uni e si `a di Pa ia b, Pa ia, I aly
P. Baessoa,b, U. Be zanoa, C. Ricca dia,b, P. To ea,b, P. Vi uloa,b, C. Vi iania,b
INFN Sezione di Pe ugia a, Uni e si `a di Pe ugia b, Pe ugia, I aly
M. Biasinia,b, G.M. Bileia, B. Capone ia,b, L. Fan`
oa,b, P. La icciaa,b, A. Luca onia,b,1,
G. Man o ania,b, M. Menichellia, A. Nappia,b, A. San occhiaa,b, L. Se olia, S. Ta onia,b,
M. Valda aa,b, R. Volpea,b,1
INFN Sezione di Pisa a, Uni e si `a di Pisa b, Scuola No male Supe io e di Pisa c, Pisa, I aly
P. Azzu ia,c, G. Bagliesia, J. Be na dinia,b, T. Boccalia,1, G. B occoloa,c, R. Cas aldia,
R.T. D’Agnoloa,c, R. Dell’O soa, F. Fio ia,b, L. Fo`
aa,c, A. Giassia, A. K aana, F. Ligabuea,c,
T. Lom adzea, L. Ma inia, A. Messineoa,b, F. Pallaa, F. Palmona ia, S. Sa ka a,c, G. Segne ia,
A.T. Se bana, P. Spagnoloa, R. Tenchinia, G. Tonellia,b,1, A. Ven u ia,1, P.G. Ve dinia
INFN Sezione di Roma a, Uni e si `a di Roma ”La Sapienza” b, Roma, I aly
L. Ba onea,b, F. Ca alla ia, D. Del Rea,b, E. Di Ma coa,b, M. Diemoza, D. F ancia,b, M. G assia,
E. Longoa,b, G. O gan inia,b, A. Palmaa,b, F. Pandol ia,b,1, R. Pa ama ia, S. Raha loua,b
18 A The CMS Collabo a ion
INFN Sezione di To ino a, Uni e si `a di To ino b, Uni e si `a del Piemon e O ien ale (No-
a a) c, To ino, I aly
N. Amapanea,b, R. A cidiaconoa,c, S. A gi oa,b, M. A neodoa,c, C. Biinoa, C. Bo aa,b,1,
N. Ca igliaa, R. Cas elloa,b, M. Cos aa,b, N. Dema iaa, A. G azianoa,b,1, C. Ma io ia,
M. Ma onea,b, S. Masellia, E. Miglio ea,b, G. Milaa,b, V. Monacoa,b, M. Musicha,b,
M.M. Obe inoa,c, N. Pas onea, M. Pelliccionia,b,1, A. Rome oa,b, M. Ruspaa,c, R. Sacchia,b,
V. Solaa,b, A. Solanoa,b, A. S aianoa, D. T ocinoa,b, A. Vilela Pe ei aa,b,1
INFN Sezione di T ies e a, Uni e si `a di T ies e b, T ies e, I aly
F. Amb oglinia,b, S. Bel o ea, F. Cossu ia, G. Della Riccaa,b, B. Gobboa, D. Mon aninoa,b,
A. Penzoa
Kangwon Na ional Uni e si y, Chunchon, Ko ea
S.G. Heo
Kyungpook Na ional Uni e si y, Daegu, Ko ea
S. Chang, J. Chung, D.H. Kim, G.N. Kim, J.E. Kim, D.J. Kong, H. Pa k, D. Son, D.C. Son
Chonnam Na ional Uni e si y, Ins i u e o Uni e se and Elemen a y Pa icles, Kwangju,
Ko ea
Ze o Kim, J.Y. Kim, S. Song
Ko ea Uni e si y, Seoul, Ko ea
S. Choi, B. Hong, M. Jo, H. Kim, J.H. Kim, T.J. Kim, K.S. Lee, D.H. Moon, S.K. Pa k, H.B. Rhee,
E. Seo, S. Shin, K.S. Sim
Uni e si y o Seoul, Seoul, Ko ea
M. Choi, S. Kang, H. Kim, C. Pa k, I.C. Pa k, S. Pa k, G. Ryu
Sungkyunkwan Uni e si y, Suwon, Ko ea
Y. Choi, Y.K. Choi, J. Goh, J. Lee, S. Lee, H. Seo, I. Yu
Vilnius Uni e si y, Vilnius, Li huania
M.J. Bilinskas, I. G igelionis, M. Janulis, D. Ma isiu e, P. Pe o , T. Sabonis
Cen o de In es igacion y de Es udios A anzados del IPN, Mexico Ci y, Mexico
H. Cas illa Valdez, E. De La C uz Bu elo, R. Lopez-Fe nandez, A. S´
anchez He n´
andez,
L.M. Villaseno -Cendejas
Uni e sidad Ibe oame icana, Mexico Ci y, Mexico
S. Ca illo Mo eno, F. Vazquez Valencia
Beneme i a Uni e sidad Au onoma de Puebla, Puebla, Mexico
H.A. Salaza Iba guen
Uni e sidad Au ´onoma de San Luis Po os´ı, San Luis Po os´ı, Mexico
E. Casimi o Lina es, A. Mo elos Pineda, M.A. Reyes-San os
Uni e si y o Auckland, Auckland, New Zealand
P. All ey, D. K o check
Uni e si y o Can e bu y, Ch is chu ch, New Zealand
P.H. Bu le , R. Doesbu g, H. Sil e wood
Na ional Cen e o Physics, Quaid-I-Azam Uni e si y, Islamabad, Pakis an
M. Ahmad, I. Ahmed, M.I. Asgha , H.R. Hoo ani, W.A. Khan, T. Khu shid, S. Qazi
19
Ins i u e o Expe imen al Physics, Facul y o Physics, Uni e si y o Wa saw, Wa saw, Poland
M. Cwiok, W. Dominik, K. Do oba, A. Kalinowski, M. Konecki, J. K olikowski
Sol an Ins i u e o Nuclea S udies, Wa saw, Poland
T. F ueboes, R. Gokieli, M. G´
o ski, M. Kazana, K. Naw ocki, K. Romanowska-Rybinska,
M. Szlepe , G. W ochna, P. Zalewski
Labo a ´o io de Ins umen a¸c˜ao e F´ısica Expe imen al de Pa ´ıculas, Lisboa, Po ugal
N. Almeida, A. Da id, P. Faccioli, P.G. Fe ei a Pa acho, M. Gallina o, P. Ma ins, P. Musella,
A. Nayak, P.Q. Ribei o, J. Seixas, P. Sil a, J. Va ela1, H.K. W¨
oh i
Join Ins i u e o Nuclea Resea ch, Dubna, Russia
I. Belo elo , P. Bunin, M. Finge , M. Finge J ., I. Golu in, A. Kamene , V. Ka ja in, G. Kozlo ,
A. Lane , P. Moisenz, V. Palichik, V. Pe elygin, S. Shma o , V. Smi no , A. Volodko, A. Za ubin
Pe e sbu g Nuclea Physics Ins i u e, Ga china (S Pe e sbu g), Russia
N. Bonda , V. Golo so , Y. I ano , V. Kim, P. Le chenko, V. Mu zin, V. O eshkin, I. Smi no ,
V. Sulimo , L. U a o , S. Va ilo , A. Vo obye
Ins i u e o Nuclea Resea ch, Moscow, Russia
Yu. And ee , S. Gninenko, N. Golube , M. Ki sano , N. K asniko , V. Ma ee , A. Pashenko ,
A. To opin, S. T oi sky
Ins i u e o Theo e ical and Expe imen al Physics, Moscow, Russia
V. Epsh eyn, V. Ga ilo , V. Ka ano †, M. Kosso 1, A. K okho in, N. Lychko skaya,
G. Sa ono , S. Semeno , V. S olin, E. Vlaso , A. Zhokin
Moscow S a e Uni e si y, Moscow, Russia
E. Boos, M. Dubinin18, L. Dudko, A. E sho , A. G ibushin, O. Kodolo a, I. Lokh in,
S. Ob az so , S. Pe ushanko, L. Sa yche a, V. Sa in, A. Snigi e
P.N. Lebede Physical Ins i u e, Moscow, Russia
V. And ee , M. Aza kin, I. D emin, M. Ki akosyan, S.V. Rusako , A. Vinog ado
S a e Resea ch Cen e o Russian Fede a ion, Ins i u e o High Ene gy Physics, P o ino,
Russia
I. Azhgi ey, S. Bi iouko , V. G ishin1, V. Kachano , D. Kons an ino , A. Ko able , V. K ychkine,
V. Pe o , R. Ryu in, S. Slabospi sky, A. Sobol, L. Tou chano i ch, S. T oshin, N. Tyu in,
A. Uzunian, A. Volko
Uni e si y o Belg ade, Facul y o Physics and Vinca Ins i u e o Nuclea Sciences, Belg ade,
Se bia
P. Adzic19, M. Djo dje ic, D. K pic19, J. Milose ic
Cen o de In es igaciones Ene g´e icas Medioambien ales y Tecnol´ogicas (CIEMAT),
Mad id, Spain
M. Aguila -Beni ez, J. Alca az Maes e, P. A ce, C. Ba ilana, E. Cal o, M. Cepeda, M. Ce ada,
N. Colino, B. De La C uz, C. Diez Pa dos, D. Dom´
ınguez V´
azquez, C. Fe nandez Bedoya,
J.P. Fe n´
andez Ramos, A. Fe ando, J. Flix, M.C. Fouz, P. Ga cia-Abia, O. Gonzalez Lopez,
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

20 A The CMS Collabo a ion
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. Felcini20, 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 Gomez21, 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. Bell22, D. Benede i,
C. Be ne 3, W. Bialas, P. Bloch, A. Bocci, S. Bolognesi, H. B euke , G. B ona, K. Bunkowski,
T. Campo esi, E. Cano, G. Ce mina a, T. Ch is iansen, J.A. Coa asa Pe ez, B. Cu ´
e,
D. D’En e ia, A. De Roeck, 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 ,
E. Ka a akis, P. Lecoq, C. Leonidopoulos, C. Lou enc¸o, A. Macphe son, T. M¨
aki, L. Malge i,
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, G. Rolandi23, T. Romme ski chen, C. Ro elli24, M. Ro e e,
H. Sakulin, C. Sch¨
a e , C. Schwick, I. Segoni, A. Sha ma, P. Sieg is , M. Simon, P. Sphicas25,
D. Spiga, M. Spi opulu18, F. S ¨
ockli, M. S oye, P. T opea, A. Tsi ou, 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¨
onig, D. Ko linski, U. Langenegge , F. Meie , D. Renke , T. Rohe, J. Sibille26,
A. S a odumo 27
Ins i u e o Pa icle Physics, ETH Zu ich, Zu ich, Swi ze land
P. Bo ignon, L. Caminada28, 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 chica28,
P. Ma inez Ruiz del A bol, P. Me idiani, P. Mileno ic29, 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. Wallny20, 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, L. Wilke
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, J.H. Wu, S.S. Yu
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
21
Cuku o a Uni e si y, Adana, Tu key
A. Adiguzel, M.N. Baki ci30, S. Ce ci31, 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 ,
G. Onengu , K. Ozdemi , S. Oz u k, A. Pola oz, K. Sogu 32, B. Tali, H. Topakli30, D. Uzun,
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 33, E. G¨
ulmez, A. Halu, B. Isildak, M. Kaya34, O. Kaya34,
S. Ozko ucuklu35, N. Sonmez36
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,
M. G imes, M. Hansen, D. Ha ley, G.P. Hea h, H.F. Hea h, B. Huck ale, J. Jackson, L. K eczko,
S. Me son, D.M. Newbold37, 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. Basso, K.W. Bell, A. Belyae , 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 enko27, A. Papageo giou, M. Pesa esi, K. Pe idis, M. Pioppi38, 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, A. Clough, 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
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
22 A The CMS Collabo a ion
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, G. Pasz o 39, A. Sa pa hy, 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, 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, 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. Musienko40, C. Newman-Holmes, V. O’Dell, S. Popescu41,
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
23
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 , 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, C.E. Ge be , D.J. Ho man, S. Khala yan, F. Lac oix,
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. Cankocak42, 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
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