EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN)
CERN-PH-EP/2010-093
2011/02/22
CMS-BPH-10-010
Measu emen o BB Angula Co ela ions based on
Seconda y Ve ex Recons uc ion a √s=7 TeV
The CMS Collabo a ion∗
Abs ac
A measu emen o he angula co ela ions be ween beau y and an i-beau y had ons
(BB) p oduced in pp collisions a a cen e-o -mass ene gy o 7 TeV a he CERN LHC
is p esen ed, p obing o he i s ime he egion o small angula sepa a ion. The B
had ons a e iden i ied by he p esence o displaced seconda y e ices om hei de-
cays. The B had on angula sepa a ion is econs uc ed om he decay e ices and
he p ima y-in e ac ion e ex. The di e en ial BB p oduc ion c oss sec ion, mea-
su ed om a da a sample collec ed by CMS and co esponding o an in eg a ed lu-
minosi y o 3.1 pb−1, shows ha a sizable ac ion o he BB pai s a e p oduced wi h
small opening angles. These s udies p o ide a es o QCD and u he insigh in o
he dynamics o bb p oduc ion.
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 :1102.3194 2 [hep-ex] 21 Feb 2011
22 The CMS De ec o
1 In oduc ion
Beau y qua ks a e abundan ly p oduced h ough s ong in e ac ions in pp collisions a he
CERN La ge Had on Collide (LHC). The had op oduc ion o bb pai s is measu ed o ha e a
la ge c oss sec ion (o he o de o 100 µb) a a cen e-o -mass ene gy o 7 TeV [1–3]. De ailed
b qua k p oduc ion s udies p o ide subs an ial in o ma ion abou he dynamics o he unde -
lying ha d sca e ing subp ocesses wi hin pe u ba i e Quan um Ch omodynamics (pQCD).
In lowes o de pQCD, i.e. in 2 →2 pa on in e ac ion subp ocesses, momen um conse a ion
equi es he b and b qua ks o be emi ed in a back- o-back opology. Howe e , highe o de
2→2+n(n≥1) subp ocesses wi h addi ional pa ons (no ably gluons) emi ed, gi e ise o
di e en opologies o he inal s a e b qua ks. Consequen ly, measu emen s o bb angula and
momen um co ela ions p o ide in o ma ion abou he unde lying p oduc ion subp ocesses
and allow o a sensi i e es o pQCD leading-o de (LO) and nex - o-leading o de (NLO)
c oss sec ions and hei e olu ion wi h e en ene gy scales. S udies o b qua k p oduc ion a
he LHC may p o ide insigh in o he had onisa ion p ope ies o hea y qua ks a hese new
ene gy scales, as well as be e knowledge o he hea y qua k con en o he p o on. In ad-
di ion, iden i ica ion o b qua ks and p ecision measu emen s o hei p ope ies a e c ucial
ing edien s o new physics sea ches in which bb had op oduc ion is expec ed o be one o he
main backg ounds.
In his pape , angula co ela ions be ween pai s o beau y had ons, he ea e e e ed o as “B
had ons”, a e s udied wi h he Compac Muon Solenoid (CMS) de ec o , p obing o he i s
ime he egion o e y small angula sepa a ion a √s=7 TeV. Measu emen s o BB-pai
p oduc ion a e p esen ed di e en ially as a unc ion o he opening angle o di e en e en
scales, cha ac e ised by he leading je ans e se momen um. The ex apola ion back o he
angula sepa a ion o he b qua ks, which equi es modeling o hea y qua k agmen a ion and
had onisa ion, is no conside ed in his analysis. The esul s a e gi en o he isible kinema ic
ange de ined by he phase space a he had on le el.
Measu emen s o he ull ange o BB angula sepa a ion demand good angula esolu ion and
equi e he abili y o esol e small opening angles when he wo B had ons a e inside a single
econs uc ed je . The kinema ic p ope ies o B had ons can be econs uc ed using je s, lep ons
om semilep onic decays o B had ons o seconda y e ices (SV) o igina ing om he decay
o long-li ed B had ons. In his analysis, a me hod based on an i e a i e inclusi e seconda y
e ex inde ha exploi s he excellen acking capabili ies o he CMS de ec o is in oduced.
One ad an age o his me hod is he unique capabili y o de ec BB pai s e en a small opening
angles, in which case he decay p oduc s o he B had ons end o be me ged in o a single je and
he s anda d B je agging echniques [4] a e no applicable. P e iously, s udies o azimu hal
bb co ela ions using e exing ha e been done a lowe ene gy in pp collisions [5, 6].
In Sec ion 2, a b ie o e iew o he subde ec o s ele an o his analysis is gi en. Sec ion
3 desc ibes he Mon e Ca lo (MC) simula ions and he p og ams used o QCD p edic ions.
The e en selec ion, he analysis de ails, and he de e mina ion o e iciencies and sys ema ic
unce ain ies a e desc ibed in Sec ion 4. In Sec ion 5 we p esen he esul s and compa e he
da a wi h heo e ical p edic ions.
2 The CMS De ec o
A de ailed desc ip ion o he CMS de ec o can be ound in Re . [7]. The cen al ea u e o
he CMS appa a us is a supe conduc ing solenoid o 6 m in e nal diame e , wi h a 3.8 T ax-
ial magne ic ield. The subde ec o s used in he p esen analysis a e acking de ec o s and
3
calo ime e s, loca ed wi hin he ield olume. The acke consis s o a silicon pixel and silicon
s ip acke co e ing he pseudo apidi y ange |η|<2.5. The pixel acke consis s o h ee
ba el laye s and wo endcap disks a each ba el end. The s ip acke has 10 ba el laye s and
12 endcap disks. The ba el and endcap calo ime e s (|η|<3) consis o a lead- ungs a e c ys al
elec omagne ic calo ime e (ECAL) and a b ass/scin illa o had on calo ime e (HCAL). The
ECAL and HCAL cells a e g ouped in o owe s, p ojec ing adially ou wa d om he in e ac-
ion egion, o igge ing pu poses and o acili a e je econs uc ion. The CMS expe imen
uses a igh -handed coo dina e sys em, wi h he o igin a he nominal p o on-p o on collision
poin , he x-axis poin ing owa ds he cen e o he LHC ing, he y-axis poin ing upwa ds (pe -
pendicula o he LHC plane), and he z-axis poin ing along he an iclockwise beam di ec ion.
The pola angle θis measu ed om he posi i e z-axis and he azimu hal angle φis measu ed
om he posi i e x-axis in he xy plane. The adius deno es he dis ance om he z-axis and
he pseudo apidi y is de ined by η=−ln( an(θ/2)).
3 Mon e Ca lo Simula ion and QCD P edic ions
Di e en simula ion p og ams a he LO and he NLO le el ha e been u ilized o desc ibe he
b p oduc ion p ocess wi hin pe u ba i e QCD. Wi hin he LO pic u e, h ee pa on le el p o-
duc ion subp ocesses can be de ined [8, 9], con en ionally deno ed by la ou c ea ion (FCR),
la ou exci a ion (FEX) and gluon spli ing (GSP), and a e implemen ed in Mon e Ca lo e en
gene a o s like PYTHIA [10] and HERWIG [11]. These subp ocesses a e ela ed o di e en inal
s a e opologies. No ably, in FCR p ocesses he bb pai s a e expec ed o be emi ed in a back-
o-back opology, which co esponds o a la ge angula sepa a ion be ween he b and b qua ks,
whe eas in GSP he pai emission ollows a mo e collinea opology, i.e. a small angula sepa-
a ion be ween he b and b qua ks. A highe o de s in QCD, he FCR, FEX and GSP sepa a ion
o p oduc ion subp ocesses becomes meaningless and only he combina ion o he 2 →2 and
2→2+n(n≥1) subp ocesses is ele an . Calcula ions o such p ocesses a e implemen ed
in MC@NLO [12–14] o FONLL [15]. The MADGRAPH/MADEVENT [16, 17] gene a o p o ides
he possibili y o simula e 2 →2, 3 subp ocesses a ee-le el, p o iding a hyb id solu ion be-
ween 2 →2 a LO and he NLO simula ions. We use also he CASCADE [18] gene a o , which
is based on o -shell LO ma ix elemen s using high-ene gy ac o iza ion [19] con ol ed wi h
unin eg a ed pa on dis ibu ions.
The basic Mon e Ca lo e en gene a o applied in his analysis is he LO PYTHIA p og am ( e -
sion 6.422 [10]), which is used o de e mine selec ion e iciencies and o op imise he e exing
algo i hm o B had on econs uc ion. The e en samples a e gene a ed applying he s anda d
PYTHIA se ings [10] wi h une D6T [20] o he unde lying e en and wi h he CTEQ6L1 [21]
p o on pa on dis ibu ion unc ions (PDF). All e en s gene a ed by he PYTHIA p og am a e
p ocessed wi h a de ailed simula ion o he CMS de ec o esponse based on he GEANT4 pack-
age [22].
Fo compa ison wi h heo e ical p edic ions, e en s wi h wo and h ee pa ons in he inal
s a e a e gene a ed by means o he MADGRAPH/MADEVENT4 p og am, whe e he showe -
ing is pe o med wi h PYTHIA, and he je ma ching scheme used is “kT-MLM” [23]. The
CTEQ6L1 [21] pa on dis ibu ion unc ions a e used, and he mass o he b qua k is se o
mb=4.75 GeV.
Fo he e en s p oduced wi h he CASCADE gene a o , he CCFM se A [24] o pa on dis ibu-
ions is used. The calcula ions include he p ocesses g∗g∗→b¯
band g∗q→gq →b¯
bX. The
ma ix elemen o g∗g∗→b¯
bal eady includes a la ge ac ion o he p ocess g∗g→gg →
b¯
bX [19, 25], he e o e g∗g→gg →b¯
bX is no added o a oid double coun ing.
44 E en Selec ion and Da a Analysis
A u he se o QCD e en s is p oduced by means o he MC@NLO gene a o ( e sion 3.4 [14]
wi h s anda d scale se ings and b-qua k mass mb=4.75 GeV), which ma ches NLO QCD
ma ix elemen calcula ions wi h pa on showe simula ions as implemen ed in HERWIG ( e -
sion 6.510) [11]. The p o on PDF se used is CTEQ6M [21]. Fo he NLO gene a ed e en s, no
ull CMS de ec o simula ion is done. Subsequen o he pa on showe ing and had onisa ion
p ocess, he gene a ed s able pa icles in he e en s a e clus e ed in o je s wi h he an i-kTje
algo i hm [26].
4 E en Selec ion and Da a Analysis
The da a sample used in his analysis was collec ed by he CMS expe imen du ing 2010 a a
cen e-o -mass ene gy o √s=7 TeV and co esponds o an in eg a ed luminosi y o 3.1 ±
0.3 pb−1. Only da a om uns when he CMS de ec o componen s ele an o his analysis
we e ully unc ional and when s able beam condi ions we e p esen a e used. E en s om
non-collision p ocesses a e ejec ed by equi ing a p ima y (“collision”) e ex (PV) [27, 28]
wi h a leas ou well econs uc ed acks. Backg ound om beam-wall and beam halo e en s,
and e en s aking high ene gy deposi s in he HCAL, a e il e ed ou based on pulse shape, hi
mul iplici y and iming c i e ia.
4.1 Analysis O e iew
The analysis elies on he single-je igge in bo h he ha dwa e-le el (L1) and he so wa e
high-le el (HLT) componen s o he CMS igge sys em [7]. We equi e a leas one HLT
je wi h unco ec ed ans e se calo ime ic ene gy EU
Tabo e a igge h eshold o 15, 30 o
50 GeV. Figu e 1 shows he leading je ans e se momen um (pT) spec a wi h pa icle low
je s [29] and he co esponding igge e iciency dependence on pT. The e iciencies, also
shown in Figu e 1, a e de e mined using e en s selec ed wi h a lowe EU
T(p escaled) igge .
The e en sample is hen di ided in o h ee ene gy scale bins co esponding o he pT anges
whe e he di e en je igge s a e o e 99% e icien . These co espond o samples whe e
he ans e se momen a o he leading je , using co ec ed je ene gies [30], exceed 56, 84
and 120 GeV, espec i ely. The e ec i e in eg a ed luminosi y, aking in o accoun he igge
p escale ac o s, co esponds o 0.031, 0.313 and 3.069 pb−1, espec i ely, o he h ee samples,
including some o e lap.
The isible kinema ic ange o he measu emen s is de ined a he B had on le el by he e-
qui emen s |η(B)|<2.0 and pT(B)>15 GeV o bo h o he B had ons. The leading je used o
de ine he minimum ene gy scale is equi ed o be wi hin |η(je )|<3.0.
In his analysis, he HLT igge ed e en s a e equi ed o ha e a leas one econs uc ed je
wi h a minimum co ec ed pT, a econs uc ed PV, and in addi ion a leas wo econs uc ed
seconda y e ices (SV). Fo he o line je econs uc ion, pa icle low objec s [29] a e clus-
e ed wi h he an i-kTje algo i hm [26, 31] wi h a dis ance pa ame e RkT=0.5. Fo u he
BB angula analysis, hese gene ic seconda y e ices a e equi ed o o igina e om B had on
decays, as desc ibed in he ollowing pa ag aphs.
The ligh di ec ion o he o iginal B had on is app oxima ed by he ec o −→
SV, joining he PV
(posi ion o B had on p oduc ion) and he SV (posi ion o he B had on decay). The leng h
|−→
SV|is he h ee-dimensional ligh dis ance (D3D) and i s signi icance is gi en by S3D=
D3D/σ(D3D), whe e σ(D3D)is he unce ain y o D3D.
In an e en wi h wo SVs, which a e conside ed o o igina e om a bb pai , he angula co ela-

4.2 Ve ex Recons uc ion and BCandida e Iden i ica ion 5
(GeV)
T
leading je p
50 100 150 200 250 300 350 400 450 500
numbe o e en s
1
10
2
10
3
10
4
10
5
10
6
10
7
10
8
10 > 15 GeV
U
T
E
> 30 GeV
U
T
E
> 50 GeV
U
T
E
-1
= 7 TeV, L = 3.1 pbsCMS
(GeV)
T
leading je p
50 100 150 200 250 300 350 400 450 500
numbe o e en s
1
10
2
10
3
10
4
10
5
10
6
10
7
10
8
10
(GeV)
T
leading je p
0 20 40 60 80 100 120 140
e iciency
0
0.2
0.4
0.6
0.8
1
(GeV)
T
leading je p
0 20 40 60 80 100 120 140
e iciency
0
0.2
0.4
0.6
0.8
1
> 15 GeV
U
T
E
> 30 GeV
U
T
E
> 50 GeV
U
T
E
-1
= 7 TeV, L = 3.1 pbsCMS
(GeV)
T
leading je p
0 20 40 60 80 100 120 140
e iciency
0
0.2
0.4
0.6
0.8
1
Figu e 1: The measu ed ans e se momen um dis ibu ions o he leading je in he e en
(le ) and measu ed e iciency o igge an e en on he high-le el igge as a unc ion o je
pT( igh ), o h ee di e en igge h esholds.
ion a iables be ween he B and B had ons a e calcula ed using hei ligh di ec ions. Typical
a iables used o he cha ac e iza ion o he angula co ela ions be ween he wo had ons a e
he di e ence in azimu hal angles (∆φ) and he di e ence in pola angles, usually exp essed in
e ms o pseudo apidi y (∆η), o he combined sepa a ion a iable ∆R=p∆η2+∆φ2.
The kinema ic egions wi h ∆R<0.8 and wi h ∆R>2.4 a e used o compa isons o no mali-
sa ions o he simula ion. The c oss sec ions in eg a ed o e hese wo egions will be deno ed
by σ∆R<0.8 and by σ∆R>2.4, and he a io by ρ∆R=σ∆R<0.8/σ∆R>2.4. This is inspi ed by he heo-
e ical p edic ions, since a low ∆R alues he gluon spli ing p ocess is expec ed o con ibu e
signi ican ly, whe eas a high ∆R alues la ou c ea ion p e ails.
4.2 Ve ex Recons uc ion and BCandida e Iden i ica ion
The p ima y e ex is econs uc ed om acks o low impac pa ame e wi h espec o he
nominal in e ac ion egion. In cases o mul iple in e ac ions in he same bunch c ossing (pile-
up e en s), he p ima y in e ac ion e ex is chosen o be he one wi h he la ges squa ed
ans e se momen um sum ST=∑p2
Ti, whe e he sum uns o e all acks associa ed wi h he
e ex. Residual e ec s om pile-up e en s a e ound o be negligible.
Nex , he e en s a e equi ed o ha e a leas wo econs uc ed seconda y e ices. An inclu-
si e seconda y e ex inding (IVF) echnique, comple ely independen o je econs uc ion, is
applied o his pu pose. This echnique econs uc s seconda y e ices by clus e ing acks
a ound he so-called seeding acks cha ac e ized by high h ee-dimensional impac pa ame e
signi icance Sd=d/σ(d), whe e dand σ(d)a e he impac pa ame e and i s unce ain y a
he PV, espec i ely. The acks a e clus e ed o a seed ack based on hei compa ibili y gi en
hei sepa a ion dis ance in h ee dimensions, he sepa a ion dis ance signi icance (dis ance
no malised o i s unce ain y), and he angula sepa a ion. The clus e ed acks a e hen i -
ed o a common e ex wi h an ou lie - esis an i e [32, 33]. The e ices sha ing mo e han
70% o he acks compa ible wi hin he unce ain ies a e me ged. As a inal s ep, all acks a e
assigned o ei he he p ima y o he seconda y e ices on he basis o he signi icance o he
ack o e ex dis ance.
In his analysis, a SV is equi ed o be made up o a leas h ee acks, o ha e a maximal wo-
64 E en Selec ion and Da a Analysis
dimensional ligh dis ance Dxy =|−→
SVxy|<2.5 cm, a minimal wo-dimensional ligh dis ance
signi icance S2D=Dxy/σ(Dxy)>3, and o possess a e ex mass mSV <6.5 GeV. He e, σ(Dxy)
is he unce ain y on Dxy. The ou -momen um o he e ex pSV = (ESV,~
pSV)is calcula ed
as he sum pSV =∑pio e all acks i ed o ha e ex, wi h pi= (Ei,~
pi), using he pion
mass hypo hesis o e e y ack o ob ain i s ene gy Ei. The e ex mass mSV is calcula ed
as m2
SV =E2
SV −~
p2
SV. The ou -momen um o he econs uc ed B had on candida e is hen
iden i ied wi h he SV ou –momen um, and hus he a iables pT(B),η(B) o he B had on
candida es a e eadily calcula ed om pSV.
E en s wi h a leas wo seconda y e ices may o igina e om any o he ollowing p ocesses:
a) ue ’signal’ BB e en s; b) ue BB e en s whe e a leas one B had on is no co ec ly econ-
s uc ed (SV om o he sou ces); c) QCD e en s wi h ligh qua k and gluon je s, which en e
h ough misiden i ica ion o e ices no o igina ing om B decay; d) di ec cc p oduc ion wi h
long li ed D had ons; e) sequen ial B→D→Xdecay chains, whe e B had ons decay o long
li ed D had ons, and bo h B and D e ices a e econs uc ed. The BB signal e en s con ain a
ac ion om op qua k pai p oduc ion o less han 1% [34, 35].
O en, bo h he B and D decay e ices a e econs uc ed by he IVF. Such opologies need o
be dis inguished om e en s wi h wo quasi-collinea B had ons. To achie e his, an i e a i e
me ging p ocedu e is applied o e ices wi h ∆R<0.4. The p ocedu e is op imised o yield
a single B candida e associa ed wi h a decay chain B→D→X, while success ully e aining
wo B candida es also in e en s whe e wo eal B had ons a e emi ed nea ly collinea ly. The
e ices a e me ged in o a single B candida e i he in a ian mass o he sum o e all acks
is below 5.5 GeV and cos β>0.99, whe e βis he angle be ween he line connec ing he wo
e ices and he sum o he momen a o he acks associa ed o he e ex a la ges dis ance
om he PV.
All B candida es a e e ained i hey ha e a minimal 3D ligh dis ance signi icance S3D>5,
a pseudo apidi y |η(SV)|<2, a ans e se momen um pT(SV)>8 GeV, and a e ex mass
mSV >1.4 GeV. The quali y o he B candida e econs uc ion echnique is illus a ed in Fig. 2
o e en s wi h a leading je ha ing pT>84 GeV (all selec ion cu s apa om hose on he
shown quan i ies a e applied). The simula ion desc ibes he da a e y well in e ms o e ex
mass and 3D decay leng h signi icance dis ibu ion.
Only hose e en s which ha e exac ly wo B had on candida es and which ha e a e ex mass
sum m1+m2>4.5 GeV a e e ained. A o al o 160, 380 and 1038 e en s pass all hese equi e-
men s o he h ee leading je pTbins, espec i ely om he lowes o he highes . The o e all
con ibu ions om e en s wi h h ee o mo e B candida es is ound o be negligible (less han
1%).
4.3 E iciency and Resolu ion
This analysis uses selec ion e iciency co ec ions as a unc ion o he leading je pTand he
∆Rbe ween he wo SVs. The co ec ions a e de e mined om he simula ed PYTHIA e en
samples. They ex apola e om he measu ed e ex momen a o he isible phase space o
ue B had ons, de ined by |η(B)|<2.0, and pT(B)>15 GeV. The momen um measu ed
by he e ex candida e ep esen s o he o de o 50% o he ue B had on momen um. The
o e all e en econs uc ion e iciencies (including bo h B had on decays) a e ound o be 7.4%,
9.3% and 10.7%, on a e age, o he h ee je pTbins, espec i ely om he lowes o he highes .
The alidi y o he ∆R-dependence o he e iciencies ob ained om simula ion is checked using
a da a d i en me hod based on e en mixing, as illus a ed below. I is ound ha he ∆R-
4.4 Sys ema ic Unce ain ies 7
e ex mass (GeV)
0 1 2 3 4 5 6 7 8
numbe o B candida es
-1
10
1
10
2
10
3
10
4
10 Da a
B
D
Ligh
-1
= 7 TeV, L = 3.1 pbsCMS
e ex mass (GeV)
0 1 2 3 4 5 6 7 8
numbe o B candida es
-1
10
1
10
2
10
3
10
4
10
3D ligh dis ance signi icance
0 50 100 150 200 250
numbe o B candida es
-1
10
1
10
2
10
3
10
Da a
B
D
Ligh
-1
= 7 TeV, L = 3.1 pbsCMS
10 20
0
200
400
600
800
3D ligh dis ance signi icance
0 50 100 150 200 250
numbe o B candida es
-1
10
1
10
2
10
3
10
Figu e 2: P ope ies o he econs uc ed B candida es: e ex mass dis ibu ion (le ) and ligh
dis ance signi icance dis ibu ion ( igh ). The inse in he igh plo shows a zoom o he ligh
dis ance signi icance dis ibu ion wi h na owe bins and linea scale. The da a a e shown by
he solid poin s. The decomposi ion in o he di e en sou ces, beau y, cha m and ligh qua ks,
is shown o he PYTHIA Mon e Ca lo simula ion. The simula ed dis ibu ions a e no malised
o he o al numbe o da a e en s. All selec ion cu s apa om hose on he shown quan i ies
a e applied.
dependence is well desc ibed by he simula ion, jus i ying his app oach. The di e ences a e
used o es ima e he sys ema ic unce ain ies.
The esolu ion achie ed in he ∆R econs uc ion is es ima ed om simula ion. The compa i-
son o he ∆R alues econs uc ed be ween he wo e ices ∆RVV wi h he alues calcula ed
be ween he o iginal ue B had ons ∆RBB, de e mines he esolu ion. This is illus a ed in
Fig. 3, which shows he wo-dimensional dis ibu ion ∆RVV e sus ∆RBB and i s p ojec ion
on o he diagonal (∆RVV −∆RBB). A i o his p ojec ion di ec ly yields an a e age esolu ion
be e han 0.02 in ∆R o he co e egion, a alue much smalle han he ∆Rbin wid h o 0.4.
In o de o calcula e di e en ial c oss sec ions, a ∆R-dependen pu i y co ec ion is applied.
The con ibu ions o pu i y due o mig a ion a e illus a ed in Fig. 3a. The o al numbe o
e en en ies o he diagonal is ound o be abou 3%. The la ges impu i y occu s close o
∆RVV ≈3 as can be seen in he 2D plo . These e en s a e due o mis econs uc ed collinea
e en s whe e only one B had on is econs uc ed, while a ake e ex is ound in he ecoiling
ligh qua k je . The la ges e ec on a single bin is below 10% and his is aken in o accoun in
he pu i y co ec ion. The unce ain y a ising om his co ec ion is included in he sys ema ic
unce ain ies. The a e age BB pu i y is ound o be 84%, wi h a a ia ion wi hin abou ±10%
o e he ull ∆R ange in he isible egion o he h ee leading je pTbins.
4.4 Sys ema ic Unce ain ies
Unce ain ies ele an o he shape o he di e en ial dis ibu ions a e c ucial o his pape .
The consis ency in shape be ween he da a and he simula ion is assessed and he sys ema ic
unce ain ies a e es ima ed by da a d i en me hods. The sys ema ic unce ain ies ela ed o he
absolu e no malisa ion a e much la ge han he shape dependen ones. They sum up o a o al
o 47%, bu do no a ec he shape analysis (see below). The dominan con ibu ion o igina es
om he B had on econs uc ion e iciency (±20%, es ima ed in [4]), which amoun s o a o al
84 E en Selec ion and Da a Analysis
BB
R∆
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
VV
R∆
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
1
10
2
10
637 23 5 1
11 388 8
7 183 2
7 109 1
5 107 2
5 2 135 1
4 2 252 6
5 6 1 1 1 7 471 3
4 1 1 5 2 206 4
4 1 60
4 20
= 7 TeV, Simula ionsCMS
BB
R∆
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
VV
R∆
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
BB
R∆ -
VV
R∆
-0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 0.2
numbe o e en s
0
50
100
150
200
250
300
350
400
= 7 TeV, Simula ionsCMS
BB
R∆ -
VV
R∆
-0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 0.2
numbe o e en s
0
50
100
150
200
250
300
350
400
Figu e 3: Resolu ion o he ∆R econs uc ion, ob ained using simula ion o he leading je
pT>84 GeV sample. Le : ∆R alues econs uc ed be ween he wo seconda y e ices ∆RVV
e sus he alues be ween he o iginal B had ons ∆RBB, in he isible B had on phase space (see
ex ). Righ : p ojec ion on o he diagonal (∆RVV −∆RBB). The numbe s in he boxes ep esen
he numbe o e en s econs uc ed in ha pa icula bin.
o 44% o econs uc ing wo B had ons.
In he ollowing he shape dependen sys ema ic unce ain ies o he ∆Rdis ibu ions a e dis-
cussed. The alues a e quo ed in e ms o he ela i e change o he in eg a ed c oss sec ion
a io ρ∆R=σ∆R<0.8/σ∆R>2.4. Ve y simila sys ema ic unce ain ies a ise o he ∆φdis ibu-
ions and, hence, hey a e no quo ed sepa a ely.
•Algo i hmic e ec s. The shape o he ∆Rdependence o he e iciency α(∆R)is checked
by means o an e en mixing me hod. This e en mixing echnique mimics an e en
wi h wo genuine SVs by me ging wo independen e en s, whe e each has a leas
one econs uc ed SV. The posi ions o he wo PVs a e equi ed o be wi hin 20 µm
in h ee-dimensional space. This mixed e en is hen analysed and he ac ion o
cases whe e bo h o iginal SVs a e again p ope ly econs uc ed is used o de e mine
he ∆Rdependence o he e iciency o ind wo genuine SVs in an e en which had
he SVs al eady econs uc ed. The shape o his e iciency α(∆R)is de e mined o
he da a and o he simula ed samples independen ly in bins o ∆R. The e ex
econs uc ion e iciency as a unc ion o ∆R o da a and o simula ion, and hei
a io a e shown in Fig. 4. Since in his analysis he shape is he mos ele an p op-
e y, he alues in Fig. 4b ha e been escaled o he mean alue. This a io exhibi s
good consis ency in shape be ween simula ion and da a o e he ull ∆R ange, in-
cluding he egion o small ∆R. The di e ences a e ound o be wi hin 2% and a e
aken as sys ema ic unce ain ies.
•Bhad on momen a. The mean econs uc ion e iciency o an obse ed ∆R alue
s ongly depends on he kinema ic p ope ies o he B had on pai . I depends on
he pTo each B had on and p edominan ly on he so e o he wo. Since all e i-
ciency co ec ions a e aken om he MC simula ion, i is impo an o e i y ha
he kinema ic beha iou o he BB pai s is also p ope ly modelled by he simula ion.
Con idence in he Mon e Ca lo modelling is p o ided by compa ing he ans e se
momen um dis ibu ions o he econs uc ed B candida es de i ed om da a and
om Mon e Ca lo simula ion. The dis ibu ions o he econs uc ed pTo he ha de
15
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19
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
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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
20 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, Y. Guo, W. Li, Y. Mao, S.J. Qian, H. Teng, L. Zhang, B. Zhu, W. Zou
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
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Cha les Uni e si y, P ague, Czech Republic
M. Finge , M. Finge J .
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

21
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
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
L. Meg elidze, V. Roinish ili
Ins i u e o High Ene gy Physics and In o ma iza ion, Tbilisi S a e Uni e si y, Tbilisi,
Geo gia
D. Lomidze
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
22 A The CMS Collabo a ion
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,
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. N oma i, E. Pe akou
Uni e si y o A hens, A hens, G eece
L. Gouskos, T.J. Me zimekis, A. Panagio ou
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, R. Gup 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 Resea ch and Fundamen al Sciences (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
23
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,
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, C. G andia, 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,
S. Gonzia,b, 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, A. B ancaa, R. Ca lina,b, P. Checchiaa, M. De
Ma iaa,b, T. Do igoa, U. Dossellia, F. Gaspa inia,b, U. Gaspa inia,b, P. Giubila oa,b,
A. G eselea,c, A. Kaminskiya,b, S. Lacap a aa,17, I. Lazzizze aa,c, M. Ma gonia,b, M. Mazzuca oa,
A.T. Meneguzzoa,b, M. Nespoloa,1, M. Passaseoa, L. Pe ozzia,1, N. Pozzobona,b, P. Ronchesea,b,
F. Simone oa,b, E. To assaa, M. Tosia,b, A. T iossia, S. Vaninia,b, G. Zume lea,b
INFN Sezione di Pa ia a, Uni e si `a di Pa ia b, Pa ia, I aly
U. Be zanoa, C. Ricca dia,b, P. To ea,b, P. Vi uloa,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,
24 A The CMS Collabo a ion
T. Lom adzea, L. Ma inia,18, 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, S. Nou bakhsha, G. O gan inia,b, A. Palmaa,b, F. Pandol ia,b,1, R. Pa ama ia,
S. Raha loua,b
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
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
31
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

32 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 INFN Sezione di Pe ugia; Uni e si `
a di Pe ugia, Pe ugia, I aly
40: Also a Ins i u e o Nuclea Resea ch, Moscow, Russia
41: Also a Ho ia Hulubei Na ional Ins i u e o Physics and Nuclea Enginee ing (IFIN-HH),
Bucha es , Romania
42: Also a Is anbul Technical Uni e si y, Is anbul, Tu key