JHEP04(2014)087
Published o SISSA by Sp inge
Recei ed:Feb ua y 5, 2014
Accep ed:Ma ch 14, 2014
Published:Ap il 11, 2014
Sea ches o Λ0
band Ξ0
bdecays o K0
Spπ−and
K0
SpK− inal s a es wi h i s obse a ion o he
Λ0
b→K0
Spπ−decay
The LHCb collabo a ion
E-mail: [email p o ec ed]
Abs ac : A sea ch o p e iously unobse ed decays o beau y ba yons o he inal s a es
K0
Spπ−and K0
SpK−is epo ed. The analysis is based on a da a sample co esponding o
an in eg a ed luminosi y o 1.0 b−1o pp collisions. The Λ0
b→K0pπ−decay is obse ed
wi h a signi icance o 8.6σ, wi h b anching ac ion
B(Λ0
b→K0pπ−) = (1.26 ±0.19 ±0.09 ±0.34 ±0.05) ×10−5,
whe e he unce ain ies a e s a is ical, sys ema ic, om he a io o agmen a ion ac ions
Λ0
b/ d, and om he b anching ac ion o he B0→K0π+π−no malisa ion channel,
espec i ely. A i s measu emen is made o he CP asymme y, gi ing
ACP (Λ0
b→K0pπ−) = 0.22 ±0.13 (s a ) ±0.03 (sys ) .
No signi ican signals a e seen o Λ0
b→K0
SpK−decays, Ξ0
bdecays o bo h he K0
Spπ−
and K0
SpK− inal s a es, and he Λ0
b→D−
s(→K0
SK−)pdecay, and uppe limi s on hei
b anching ac ions a e epo ed.
Keywo ds: Had on-Had on Sca e ing, B anching ac ion, B physics, Fla o physics
A Xi eP in : 1402.0770
Open Access, Copy igh CERN,
o he bene i o he LHCb Collabo a ion.
A icle unded by SCOAP3.
doi:10.1007/JHEP04(2014)087
JHEP04(2014)087
Con en s
1 In oduc ion 1
2 De ec o and da a se 2
3 Selec ion equi emen s, e iciency modelling and backg ound s udies 2
4 Fi model and esul s 6
5 Sys ema ic unce ain ies 7
6 B anching ac ion esul s 13
7 Di ec CP asymme y 14
8 Conclusions 15
The LHCb collabo a ion 19
1 In oduc ion
The s udy o beau y ba yon decays is s ill a an ea ly s age. Among he possible g ound
s a es wi h spin-pa i y JP=1
2
+[1], no had onic h ee-body decay o a cha mless inal
s a e has been obse ed. These channels p o ide in e es ing possibili ies o s udy had onic
decays and o sea ch o CP iola ion e ec s, which may a y signi ican ly ac oss he phase-
space [2,3], as ecen ly obse ed in cha ged Bmeson decays o cha mless h ee-body inal
s a es [4,5]. In con as o h ee-body neu al Bmeson decays o cha mless inal s a es
con aining K0
Smesons [6], conse a ion o ba yon numbe allows CP iola ion sea ches
wi hou he need o iden i y he la ou o he ini ial s a e.
In his pape , a sea ch is p esen ed o Λ0
band Ξ0
bba yon decays o inal s a es con-
aining a K0
Smeson, a p o on and ei he a kaon o a pion (deno ed Λ0
b(Ξ0
b)→K0
Sph−
whe e h=π, K).1No published heo e ical p edic ion o expe imen al limi exis s o
hei b anching ac ions. In e media e s a es con aining cha med had ons a e excluded
om he signal sample and s udied sepa a ely: he Λ0
b→Λ+
c(→pK0
S)π−decay is used as a
con ol channel, while he Λ0
b→Λ+
c(→pK0
S)K−and Λ0
b→D−
s(→K0
SK−)pdecays a e also
sea ched o . The Λ0
b→Λ+
c(→pK−π+)K−decay has ecen ly been obse ed [7], while
he Λ0
b→D−
spdecay has been sugges ed as a sou ce o backg ound o he B0
s→D∓
sK±
mode [8]. All b anching ac ions a e measu ed ela i e o ha o he well-known con ol
1The inclusion o cha ge-conjuga e p ocesses is implied h oughou his pape , excep whe e asymme ies
a e discussed.
– 1 –
JHEP04(2014)087
channel B0→K0π+π−[6,9,10], elying on exis ing measu emen s o he a io o ag-
men a ion ac ions Λ0
b/ d, including i s ans e se momen um (pT) dependence [11–13].
When quo ing absolu e b anching ac ions, he esul s a e exp essed in e ms o inal s a es
con aining ei he K0o K0mesons, acco ding o he expec a ion o each decay, ollowing
he con en ion in he li e a u e [1,14].
The pape is o ganised as ollows. A b ie desc ip ion o he LHCb de ec o and he
da a se used o he analysis is gi en in sec ion 2. The selec ion algo i hms, he me hod
o de e mine signal yields, and he sys ema ic unce ain ies on he esul s a e discussed
in sec ions 3–5. The measu ed b anching ac ions a e p esen ed in sec ion 6. Since a
signi ican signal is obse ed o he Λ0
b→K0
Spπ−channel, a measu emen o i s phase-
space in eg a ed CP asymme y is epo ed in sec ion 7. Conclusions a e gi en in sec ion 8.
2 De ec o and da a se
The LHCb de ec o [15] is a single-a m o wa d spec ome e co e ing he pseudo apidi y
ange 2 < η < 5, designed o he s udy o pa icles con aining bo cqua ks. The de ec o
includes a high p ecision acking sys em consis ing o a silicon-s ip e ex de ec o su -
ounding he pp in e ac ion egion, a la ge-a ea silicon-s ip de ec o loca ed ups eam o a
dipole magne wi h a bending powe o abou 4 Tm, and h ee s a ions o silicon-s ip de-
ec o s and s aw d i ubes placed downs eam. The combined acking sys em p o ides
momen um measu emen wi h ela i e unce ain y ha a ies om 0.4% a 5 GeV/c o 0.6%
a 100 GeV/c, and impac pa ame e (IP) esolu ion o 20 µm o acks wi h high ans e se
momen um. Cha ged had ons a e iden i ied using wo ing-imaging Che enko (RICH) de-
ec o s [16]. Pho on, elec on and had on candida es a e iden i ied by a calo ime e sys em
consis ing o scin illa ing-pad and p eshowe de ec o s, an elec omagne ic calo ime e and
a had onic calo ime e . Muons a e iden i ied by a sys em composed o al e na ing laye s
o i on and mul iwi e p opo ional chambe s [17]. The igge [18] consis s o a ha dwa e
s age, based on in o ma ion om he calo ime e and muon sys ems, ollowed by a so wa e
s age, which applies a ull e en econs uc ion.
The analysis is based on a sample, co esponding o an in eg a ed luminosi y o 1.0 b−1
o pp collision da a a a cen e-o -mass ene gy o 7 TeV, collec ed wi h he LHCb de ec o
du ing 2011. Samples o simula ed e en s a e also used o de e mine he signal selec ion
e iciency, o model signal e en dis ibu ions and o in es iga e possible backg ound con i-
bu ions. In he simula ion, pp collisions a e gene a ed using Py hia 6.4 [19] wi h a speci ic
LHCb con igu a ion [20]. Decays o had onic pa icles a e desc ibed by E Gen [21], in
which inal-s a e adia ion is gene a ed using Pho os [22]. The in e ac ion o he gen-
e a ed pa icles wi h he de ec o and i s esponse a e implemen ed using he Gean 4
oolki [23,24] as desc ibed in e . [25].
3 Selec ion equi emen s, e iciency modelling and backg ound s udies
E en s a e igge ed and subsequen ly selec ed in a simila way o bo h Λ0
b(Ξ0
b)→K0
Sph−
signal modes and he B0→K0
Sπ+π−no malisa ion channel. E en s a e equi ed o be
– 2 –
JHEP04(2014)087
igge ed a ha dwa e le el ei he by a calo ime e signal wi h ans e se ene gy ET>
3.5 GeV associa ed wi h one o he pa icles in he signal decay chain, o by a pa icle in
he e en ha is independen o he signal decay. The so wa e igge equi es a wo-,
h ee- o ou - ack seconda y e ex wi h a la ge sum o he ans e se momen um o
he acks and signi ican displacemen om he p ima y pp in e ac ion e ices (PVs).
A leas one ack should ha e pT>1.7 GeV/c and χ2
IP wi h espec o any PV g ea e
han 16, whe e χ2
IP is de ined as he di e ence in χ2o a gi en PV econs uc ed wi h and
wi hou he conside ed pa icle. A mul i a ia e algo i hm [26] is used o he iden i ica ion
o seconda y e ices consis en wi h he decay o a bhad on.
An ini ial se o loose equi emen s is applied o il e he e en s selec ed by he igge .
Each bhad on (Λ0
b,Ξ0
bo B0) decay is econs uc ed by combining wo cha ged acks wi h
aK0
Scandida e. The K0
Scandida es a e econs uc ed in he π+π− inal s a e, and a e
classi ied in o wo ca ego ies. The i s includes candida es ha ha e hi s in he e ex
de ec o and he acking s a ions downs eam o he dipole magne , he ea e e e ed o
as “Long”. The second ca ego y includes hose decays in which ack segmen s o he wo
pions a e no ound in he e ex de ec o , and use only he acking s a ions downs eam
o he e ex de ec o (“Downs eam”). The pions a e equi ed o ha e momen um p >
2 GeV/c and o o m a e ex wi h χ2
x <12. In addi ion, o Downs eam (Long) K0
S
ype he pions mus ha e minimum χ2
IP wi h espec o any PV g ea e han 4 (9), and
he pai mus sa is y |m(π+π−)−mK0
S|<30 (20) MeV/c2, whe e mK0
Sis he known K0
S
mass [1]. The K0
Scandida e is associa ed o he PV ha minimises he χ2
IP, and he squa e
o he sepa a ion dis ance be ween he K0
S e ex and he associa ed PV di ided by i s
unce ain y (χ2
VS), mus be g ea e han 50 (90) o Downs eam (Long) candida es. Fo
Downs eam K0
Scandida es p > 6 GeV/c is also equi ed.
Fo bo h signal modes and he no malisa ion channel, he selec ion exploi s he opol-
ogy o he h ee-body decay and he bhad on kinema ic p ope ies. The scala sum o he
ans e se momen a o he daugh e s is equi ed o be g ea e han 3 GeV/c and a leas wo
o he daugh e s mus ha e pT>0.8 GeV/c. The IP o he cha ged daugh e wi h he la ges
pTis equi ed o be g ea e han 0.05 mm. The minimum o each pai o wo daugh e s o
he squa e o he dis ance o closes app oach di ided by i s unce ain y mus be less han 5.
Fu he mo e, i is equi ed ha he bhad on candida e has χ2
x <12, χ2
IP <4, χ2
VS >50,
ha i s e ex sepa a ion om he PV mus be g ea e han 1 mm, ha he cosine o he
“poin ing” angle be ween i s momen um ec o and he line joining i s p oduc ion and
decay e ices mus be g ea e han 0.9999, and ha i has pT>1.5 GeV/c. Addi ional e-
qui emen s a e imposed o educe backg ound: he sepa a ion be ween he K0
Sand bhad on
candida e e ices mus be posi i e in he zdi ec ion;2and he K0
S ligh dis ance mus be
g ea e han 15 mm. The bhad on candida es a e equi ed o ha e in a ian mass wi hin
he anges 5469 < m(K0
Sph−)<5938 MeV/c2, e alua ed o bo h h=K, π hypo heses, and
4779 < m(K0
Sπ+π−)<5866 MeV/c2. To a oid po en ial biases du ing he selec ion op i-
misa ion, egions o ±50 MeV/c2(c . he ypical esolu ion o 15 MeV/c2) a ound bo h he
Λ0
band Ξ0
bknown masses we e no examined un il he selec ion c i e ia we e es ablished.
2The zaxis poin s along he beam line om he in e ac ion egion h ough he LHCb de ec o .
– 3 –
JHEP04(2014)087
Fu he sepa a ion o signal om combina o ial backg ound candida es is achie ed wi h
a boos ed decision ee (BDT) mul i a ia e classi ie [27,28]. The BDT is ained using
he B0→K0
Sπ+π−con ol channel as a p oxy o he signal decays, wi h simula ed samples
used o he signal and da a om he sideband egion 5420 < m(K0
Sπ+π−)<5866 MeV/c2
o he backg ound. Po en ial ba yonic con ibu ions in he sidebands om Λ0
b→K0
Spπ−
and Λ+
c→K0
Spdecays a e educed by e oing he ele an in a ian masses in app op ia e
anges. In o de o a oid bias in he aining, he sample is spli andomly in o wo, and
wo sepa a e BDT ainings a e used. The se o inpu a iables is chosen o op imise he
pe o mance o he algo i hm, and o minimise e iciency a ia ion ac oss he phase-space.
The inpu a iables o he BDTs a e he pT,η,χ2
IP,χ2
VS, poin ing angle and χ2
x o he
bhad on candida e; he sum o he χ2
IP alues o he h+and h− acks (he e h=π, K, p);
and he χ2
IP,χ2
VS and χ2
x o he K0
Scandida e.
The choice o he op imal BDT cu alue is de e mined sepa a ely o each K0
Sca ego y,
and sepa a ely o he cha mless signal modes and o he channels con aining in e media e
Λ+
co D−
shad ons. An app op ia e igu e o me i o p e iously unobse ed modes is [29],
Q=sig
a/2 + √B,(3.1)
whe e a= 5 quan i ies he a ge le el o signi icance in uni s o s anda d de ia ions, sig is
he e iciency o he signal selec ion de e mined om he simula ion, and Bis he expec ed
numbe o backg ound e en s in he signal egion, which is es ima ed by ex apola ing he
esul o a i o he in a ian mass dis ibu ion o he da a sidebands. An al e na i e
op imisa ion app oach, which minimises he expec ed uppe limi [30], is also in es iga ed
and p o ides a simila esul .
Po en ial sou ces o emaining backg ound a e supp essed wi h pa icle iden i ica ion
(PID) c i e ia. This is o pa icula impo ance o educing c oss eed be ween he signal
channels due o kaon/pion misiden i ica ion. Pa icle iden i ica ion in o ma ion is p o ided
by he RICH de ec o s [16], in e ms o he loga i hm o he likelihood a io be ween he
kaon/p o on and pion hypo heses (DLLKπ and DLLpπ). A igh DLLpπ c i e ion on he
p o on candida e supp esses mos possible backg ounds om misiden i ied bhad on de-
cays. An addi ional DLLKπ equi emen is imposed o educe c oss eed be ween K0
Spπ−
and K0
SpK−modes. In addi ion, candida es con aining acks wi h associa ed hi s in he
muon de ec o s a e ejec ed. The DLL equi emen s a e op imised using eq. (3.1), and
hei e iciencies a e de e mined using high-pu i y da a con ol samples o Λ→pπ−and
D0→K−π+decays, eweigh ed acco ding o he expec ed signal kinema ic (momen um
and pT) dis ibu ions om he simula ion.
The e iciency o he selec ion equi emen s is s udied wi h simula ion. A mul ibody
decay can in gene al p oceed h ough in e media e s a es and h ough a non esonan am-
pli ude. I is he e o e necessa y o model he a ia ion o he e iciency, and o accoun o
he dis ibu ion o signal e en s, o e he phase-space o he decay. The phase-space o he
decay o a spin-ze o pa icle o h ee spin-ze o pa icles can be comple ely desc ibed by he
Dali z plo [31] o any pai o he wo-body in a ian masses squa ed. The si ua ion o a
ba yon decay is mo e complica ed due o he spins o he ini ial and inal s a e e mions, bu
– 4 –
JHEP04(2014)087
he con en ional Dali z plo can s ill be used i spin e ec s a e neglec ed.3Fo h ee-body b
had on decays, bo h signal decays and he dominan combina o ial backg ounds popula e
egions close o he kinema ic bounda ies o he con en ional Dali z plo . Fo mo e accu a e
modelling o hose egions, i is con enien o ans o m o a ec angula space (he ea e
e e ed o as he squa e Dali z plo [33]) desc ibed by he a iables m0and θ0whe e
m0≡1
πa ccos 2m(K0
Sp)−mmin(K0
Sp)
mmax(K0
Sp)−mmin(K0
Sp)−1, θ0≡1
πθ(K0
Sp).(3.2)
He e m(K0
Sp) is he in a ian mass o he K0
Sand p o on, mmax(K0
Sp) = mΛ0
b−mh−and
mmin(K0
Sp) = mK0
S+mpa e he bounda ies o m(K0
Sp), θ(K0
Sp) is he angle be ween he
pand he h− ack in he K0
Sp es ame.
Simula ed e en s a e binned in he squa e Dali z plo a iables in o de o de e mine
he selec ion e iciencies. I no signi ican bhad on signal is seen, he e iciency co espond-
ing o a uni o m dis ibu ion ac oss he squa e Dali z plo is used as he nominal alue, and
a sys ema ic unce ain y is assigned due o he a ia ion ac oss he phase-space. When he
signal yield has signi icance (e alua ed as desc ibed in he nex sec ion) g ea e han 3 σ,
he signal dis ibu ion in he squa e Dali z plo is ob ained wi h he sPlo echnique [34]
(wi h he bhad on candida e in a ian mass used as he con ol a iable), and he e iciency
co esponding o he obse ed dis ibu ion is used.
The e is limi ed p io knowledge o he b anching ac ions o bba yon decays ha may
o m backg ounds o he cu en sea ch. Nume ous modes a e in es iga ed wi h simula ion,
and he only signi ican po en ial backg ound con ibu ion ha is ound o peak in he can-
dida e mass dis ibu ion is om Λ0
b→Λ+
c(→pK−π+)h−decays, whe e he kaon is misiden-
i ied as a pion, and he πK pai can o m a K0
Scandida e. To supp ess his backg ound,
candida es ha ha e pK−π+masses wi hin 30 MeV/c2o he known Λ+
cmass a e e oed.
The decays Λ0
b→Λ+
c(→pK0
S)h−and Λ0
b→D−
s(→K0
SK−)psha e he same inal s a e
as he cha mless signal modes and a e emo ed by e oing egions in m(K0
Sp) and m(K0
SK)
wi hin ±30 MeV/c2o he known Λ+
cand D−
smasses. These e oes a e e e sed o selec
and s udy he decay modes wi h in e media e cha med s a es. The addi ional equi emen
o he cha med modes educes he combina o ial backg ound. The e o e he op imal BDT
equi emen is ob ained sepa a ely o each channel.
The backg ounds o he no malisa ion channel a e ea ed as in e . [6]. The main
con ibu ions a e conside ed o be cha mless decays wi h an un econs uc ed pho on in he
inal s a e (e.g. B0→K0
Sπ+π−γo B0→η0(→ρ0γ)K0
S), cha mless decays o B0o B+
mesons in o wo ec o pa icles (e.g. B0→K∗0(→K0
Sπ0)ρ0and B+→K∗+(→K0
Sπ+)ρ0)
whe e a so pion is no econs uc ed, and cha med decays (e.g. B−→D0(→K0
Sπ+π−)π−)
whe e a pion is no econs uc ed.
3No e ha Λ0
bba yons p oduced in pp collisions a √s= 7 TeV ha e been measu ed o ha e only a small
deg ee o pola isa ion [32].
– 5 –
JHEP04(2014)087
4 Fi model and esul s
All signal and backg ound yields a e de e mined simul aneously by pe o ming an unbinned
ex ended maximum likelihood i o he bhad on candida e in a ian mass dis ibu ion
o each inal s a e and K0
Sca ego y. The p obabili y densi y unc ion (PDF) in each
in a ian mass dis ibu ion is de ined as he sum o se e al componen s (signal, c oss- eed
con ibu ions, combina o ial and o he backg ounds), wi h shapes de i ed om simula ion.
Signal PDFs a e known o ha e asymme ic ails ha esul om a combina ion o he
e ec s o inal s a e adia ion and s ochas ic acking impe ec ions. The Λ0
b(Ξ0
b)→K0
Sph−
signal mass dis ibu ions a e modelled by he sum o a “co e” Gaussian and a bi u ca ed
Gaussian unc ion, ha sha e he same mean alue. The co e esolu ion is allowed o be
di e en o each K0
Sca ego y, whils he wo wid hs o he bi u ca ed Gaussian a e com-
mon o Downs eam and Long ypes. Al e na i e shapes a e s udied using simula ion, and
his choice is ound o p o ide he mos s able and accu a e desc ip ion o a gi en numbe
o pa ame e s.
The signi ican yield o Λ0
b→Λ+
c(→pK0
S)π−decays allows a subse o i pa ame e s
common o he unobse ed bba yon decays o be de e mined om da a. The co e wid h
and he ela i e ac ion be ween he Gaussian and bi u ca ed Gaussian componen a e
he e o e exp essed in e ms o he pa ame e s ob ained om he i o Λ0
b→Λ+
c(→pK0
S)π−
candida es, wi h de ia ions om hose alues allowed wi hin anges as seen in he simula-
ion. Explici ly, he unc ion used o each unobse ed channel jand K0
S ype cis
PDF(m;µ, σc
co e, σR, σL) = sc,j
cG(m;µ, sc,j
σσc
co e) + (1 −sc,j
c)B(m;µ, σL, σR),(4.1)
whe e mis he in a ian mass o he bhad on candida e and Gand B ep esen he
Gaussian and bi u ca ed Gaussian dis ibu ions espec i ely. The pa ame e s σLand σR
a e espec i ely he le and igh wid hs o he bi u ca ed Gaussian unc ion, σc
co e and
ca e he wid h and he ac ion o he co e Gaussian o Λ0
b→Λ+
c(→pK0
S)π−can-
dida es, while sc,j
σand sc,j
a e he co esponding scale ac o s o he channel j, de e -
mined om simula ion. The peak posi ion µ o Λ0
bdecays is sha ed among all modes,
while ha o Ξ0
bdecays is ixed acco ding o he measu ed Λ0
band Ξ0
bmass di e ence,
mΞ0
b−mΛ0
b= 168.6±5.0 MeV/c2[1]. The scale ac o s o Λ0
band Ξ0
bsignal shapes a e
allowed o di e bu a e ound o be consis en . The i model and i s s abili y a e alida ed
wi h ensembles o pseudo-expe imen s, and no signi ican bias is ound.
The no malisa ion channel is pa ame ised ollowing e . [6]. The signal dis ibu ion
o he Bcandida e in a ian mass is modelled by he sum o wo C ys al Ball (CB) unc-
ions [35], whe e he powe law ails a e on opposi e sides o he peak. The wo CB unc ions
a e cons ained o ha e he same peak posi ion and esolu ion, which a e loa ed in he
i . The ail pa ame e s and he ela i e no malisa ion o he wo CB unc ions a e aken
om he simula ion and ixed in he i o da a. To accoun o B0
s→K0
Sπ+π−decays [6]
an addi ional componen , pa ame ised in he same way as he B0channel, is included.
I s peak posi ion is ixed acco ding o he known B0
s−B0mass di e ence [1], i s wid h is
cons ained o be he same as ha seen o he B0mode o wi hin he di e ence ound in
simula ion, and i s yield is allowed o a y independen ly.
– 6 –
JHEP04(2014)087
An exponen ial shape is used o desc ibe he combina o ial backg ound, which is
ea ed as independen o each decay mode and K0
S ype. C oss- eed con ibu ions a e also
conside ed o each K0
Sph− inal s a e. Fo he no malisa ion channel, a con ibu ion om
B0
s→K0
SK±π∓decays is included, while yields o o he possible misiden i ied backg ounds
a e ound o be negligible [6]. C oss- eed and misiden i ied B0
s→K0
SK±π∓shapes a e mod-
elled by double CB unc ions, wi h independen peak posi ions and esolu ions. The yields
o hese componen s a e cons ained o be consis en wi h he numbe o signal candida es
in he co esponding co ec ly iden i ied spec um, mul iplied by he ele an misiden i i-
ca ion p obabili y. The peaking backg ounds o he no malisa ion channel epo ed in sec-
ion 3a e modelled by a gene alised ARGUS unc ion [36] con ol ed wi h a Gaussian unc-
ion wi h wid h de e mined om simula ion. The yield o each con ibu ion is cons ained
wi hin unce ain y acco ding o he co esponding e iciency and b anching ac ion.
The esul s o he i o da a a e shown in igu e 1 o Λ0
b(Ξ0
b)→K0
Sph−candida es,
igu e 2 o Λ0
b→Λ+
c(→pK0
S)h−and Λ0
b→D−
spcandida es and igu e 3 o he B0→
K0
Sπ+π−no malisa ion channel, sepa a ed by K0
S ype. The i ed yields and ele an
e iciencies a e ga he ed in able 1. The s a is ical signi icance o each signal is compu ed
as p2 ln(Lsig/L0), whe e Lsig and L0a e he likelihoods om he nominal i and om
he i omi ing he signal componen , espec i ely. These s a is ical likelihood cu es o
each K0
Sca ego y a e con ol ed wi h a Gaussian unc ion o wid h gi en by he sys ema ic
unce ain y on he i yield. The o al signi icance, o Downs eam and Long K0
S ypes
combined, is ound o be 8.6σand 2.1σ o Λ0
b→K0
Spπ−and Λ0
b→K0
SpK−decays,
espec i ely. Mo eo e , he s a is ical signi icance o he Λ0
b→Λ+
c(→pK0
S)K−decay is
ound o be 9.4σand 8.0σ o Downs eam and Long ca ego ies espec i ely, con i ming he
ecen obse a ion o his channel [7]. The signi icances o all o he channels a e below 2 σ.
The Dali z plo dis ibu ion o Λ0
b→K0
Spπ−decays, shown in igu e 4, is ob ained using
he sPlo echnique and applying e en -by-e en e iciency co ec ions based on he posi ion
o he decay in he squa e Dali z plo . A s uc u e a low pπ−in a ian mass, which may
o igina e om exci ed nucleon s a es, is appa en bu he e a e no clea s uc u es in he
o he wo in a ian mass combina ions.
5 Sys ema ic unce ain ies
The choice o no malisa ion channel is designed o minimise sys ema ic unce ain ies in he
b anching ac ion de e mina ion. Since no bba yon decay has been p e iously measu ed
wi h su icien p ecision o se e as a no malisa ion channel, he B0→K0
Sπ+π−channel
is used. The emaining sys ema ic unce ain ies a e summa ised in able 2sepa a ely o
each signal mode and K0
S ype.
The e iciency de e mina ion p ocedu es ely on he accu acy o he simula ion. Unce -
ain ies on he e iciencies a ise due o he limi ed size o he simula ion samples, di e ences
be ween da a and he simula ion and, o he h ee-body modes, he a ia ion o he e i-
ciency o e he phase-space.
The selec ion algo i hms exploi he di e ence be ween signal and backg ound in se -
e al a iables. Fo he pTand decay leng h a iables, he dis ibu ions in da a and simula-
– 7 –
JHEP04(2014)087
]
2
c) [MeV/
−
π
p
S
0
K(m
5500 5600 5700 5800 5900
)
2
cCandida es / ( 16.75 MeV/
0
20
40
60
80
100 LHCb
S
0
KDowns eam
]
2
c) [MeV/
−
π
p
S
0
K(m
5500 5600 5700 5800 5900
)
2
cCandida es / ( 16.75 MeV/
0
10
20
30
40
50
60
LHCb
S
0
KLong
]
2
c) [MeV/
−
pK
S
0
K(m
5500 5600 5700 5800 5900
)
2
cCandida es / ( 16.75 MeV/
0
5
10
15
20
25
30
35
40
LHCb
S
0
KDowns eam
]
2
c) [MeV/
−
pK
S
0
K(m
5500 5600 5700 5800 5900
)
2
cCandida es / ( 16.75 MeV/
0
2
4
6
8
10
12
14
16
18
20
22 LHCb
S
0
KLong
Figu e 1. In a ian mass dis ibu ion o ( op) K0
Spπ−and (bo om) K0
SpK−candida es o he
(le ) Downs eam and ( igh ) Long K0
Sca ego ies a e he inal selec ion in he ull da a sample.
Each signi ican componen o he i model is displayed: Λ0
bsignal ( iole do -dashed), Ξ0
bsignal
(g een dashed) and combina o ial backg ound ( ed do ed). The o e all i is gi en by he solid
blue line. Con ibu ions wi h e y small yields a e no shown.
ion a e known o di e , which can lead o a bias in he es ima ed e iciency. The pTdis i-
bu ion o Λ0
b→Λ+
cπ−decays in da a is ob ained wi h he sPlo echnique, and compa ed o
ha in he simula ion. The co esponding possible bias in he e iciency is assigned as sys-
ema ic unce ain y o each decay. The alue o he Λ0
bli e ime used in he simula ion di e s
om he mos ecen measu emen [37]. A simila eweigh ing o he e iciency as done o
he pTdis ibu ion esul s in an es ima e o he associa ed sys ema ic unce ain y o he
Λ0
bmodes. The Ξ0
bli e ime is no ye measu ed, and no unce ain y is assigned o he alue
used in he simula ion (1.42 ps) — unless he ue li e ime is d ama ically di e en om his
alue, he co esponding bias will in any case be negligible compa ed o o he unce ain ies.
The unce ain ies due o simula ion, including also he small e ec o limi ed simula ion
samples sizes, a e combined in quad a u e and lis ed as a single con ibu ion in able 2.
Fo modes wi hou signi ican signals, he e ec o e iciency a ia ion ac oss he phase-
space (labelled ∆PHSP in able 2) is e alua ed om he sp ead o he pe -bin e iciency
a e di iding he squa e Dali z plo in a coa se binning scheme. The la ge sys ema ic un-
ce ain ies e lec he unknown dis ibu ion o signal e en s ac oss he phase-space and
he la ge e iciency a ia ion. Con e sely, he unce ain ies on he no malisa ion and
– 8 –
JHEP04(2014)087
whe e N¯
/ is he obse ed yield o Λ0
b/¯
Λ0
bdecays. To ob ain he physical CP asymme-
y, his has o be co ec ed o small de ec ion (AD) and p oduc ion (AP) asymme ies,
ACP =ARAW
CP −AP−AD. This can be con enien ly achie ed wi h Λ0
b→Λ+
c(→pK0
S)π−de-
cays, which sha e he same inal s a e as he mode o in e es , and ha e negligible expec ed
CP iola ion.
The measu ed inclusi e aw asymme y o Λ0
b→Λ+
c(→pK0
S)π−decays is ound
o be ARAW
CP =−0.047 ±0.027, indica ing ha he combined de ec ion and p oduc ion
asymme y is a he ew pe cen le el. The i ed aw asymme y o Λ0
b→K0
Spπ−decays
is ARAW
CP = 0.17 ±0.13, whe e he unce ain y is s a is ical only. The aw asymme y o
each o he backg ound componen s is ound o be consis en wi h ze o, as expec ed.
Se e al sou ces o sys ema ic unce ain ies a e conside ed. The unce ain y on AP+AD
comes di ec ly om he esul o he i o Λ0
b→Λ+
c(→pK0
S)π−decays. The e ec o a ia-
ions o he de ec ion asymme y wi h he decay kinema ics, which can be sligh ly di e en
o econs uc ed Λ0
b→K0
Spπ−and Λ0
b→Λ+
c(→pK0
S)π−decays, is negligible. The pos-
sible a ia ion o he CP asymme y ac oss he phase-space o he Λ0
b→K0
Spπ−decay,
and he non-uni o m e iciency esul s in a sys ema ic unce ain y ha is e alua ed by
weigh ing e en s using he sPlo echnique and ob aining an e iciency-co ec ed alue o
ARAW
CP . The 0.003 di e ence wi h espec o he nominal alue is assigned as unce ain y.
E ec s ela ed o he choices o signal and backg ound models, and possible in insic i
biases, a e e alua ed in a simila way as o he b anching ac ion measu emen s, leading
o an unce ain y o 0.001. These unce ain ies a e summed in quad a u e o yield he
o al sys ema ic unce ain y.
The phase-space in eg a ed CP asymme y is ound o be
ACP (Λ0
b→K0
Spπ−)=0.22 ±0.13 (s a ) ±0.03 (sys ) ,
which is consis en wi h ze o.
8 Conclusions
Using a da a sample collec ed by he LHCb expe imen co esponding o an in eg a ed
luminosi y o 1.0 b−1o pp collisions a √s= 7 TeV, sea ches o he h ee-body cha m-
less decay modes Λ0
b(Ξ0
b)→K0
Spπ−and Λ0
b(Ξ0
b)→K0
SpK−a e pe o med. Decays wi h
in e media e cha med had ons gi ing he same inal s a e a e also in es iga ed. The decay
channel Λ0
b→K0
Spπ−is obse ed o he i s ime, wi h a signi icance o 8.6σ, allowing
a measu emen o i s phase-space in eg a ed CP asymme y, which shows no signi ican
de ia ion om ze o. All p esen ed esul s, excep o hose o he b anching ac ions o
Λ0
b→Λ+
cπ−and Λ0
b→Λ+
cK−, a e he i s o da e. The i s obse a ion o a cha mless
h ee-body decay o a bba yon opens a new ield o possible ampli ude analyses and CP
iola ion measu emen s ha will be o g ea in e es o s udy wi h la ge da a samples.
Acknowledgmen s
We exp ess ou g a i ude o ou colleagues in he CERN accele a o depa men s o
he excellen pe o mance o he LHC. We hank he echnical and adminis a i e s a
– 15 –
JHEP04(2014)087
a he LHCb ins i u es. We acknowledge suppo om CERN and om he na ional
agencies: CAPES, CNPq, FAPERJ and FINEP (B azil); NSFC (China); CNRS/IN2P3
and Region Au e gne (F ance); BMBF, DFG, HGF and MPG (Ge many); SFI (I eland);
INFN (I aly); FOM and NWO (The Ne he lands); SCSR (Poland); MEN/IFA (Romania);
MinES, Rosa om, RFBR and NRC “Ku cha o Ins i u e” (Russia); MinECo, Xun aGal
and GENCAT (Spain); SNSF and SER (Swi ze land); NAS Uk aine (Uk aine); STFC
(Uni ed Kingdom); NSF (U.S.A.). We also acknowledge he suppo ecei ed om he
ERC unde FP7. The Tie 1 compu ing cen es a e suppo ed by IN2P3 (F ance), KIT
and BMBF (Ge many), INFN (I aly), NWO and SURF (The Ne he lands), PIC (Spain),
G idPP (Uni ed Kingdom). We a e indeb ed o he communi ies behind he mul iple open
sou ce so wa e packages we depend on. We a e also hank ul o he compu ing esou ces
and he access o so wa e R&D ools p o ided by Yandex LLC (Russia).
Open Access. This a icle is dis ibu ed unde he e ms o he C ea i e Commons
A ibu ion License (CC-BY 4.0), which pe mi s any use, dis ibu ion and ep oduc ion in
any medium, p o ided he o iginal au ho (s) and sou ce a e c edi ed.
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S. Eisenha d 49, U. Ei schbe ge 9, R. Ekelho 9, L. Eklund50,37, I. El Ri ai5, Ch. Elsasse 39,
A. Falabella16, , C. F¨a be 11, C. Fa inelli40, S. Fa y51, D. Fe guson49, V. Fe nandez Albo 36,
F. Fe ei a Rod igues1, M. Fe o-Luzzi37, S. Filippo 32, M. Fio e16, , M. Fio ini16, ,
C. Fi zpa ick37, M. Fon ana10, F. Fon anelli19,j, R. Fo y37, O. F ancisco2, M. F ank37, C. F ei37,
M. F osini17,37,g, E. Fu a o23,l, A. Gallas To ei a36, D. Galli14,d, M. Gandelman2, P. Gandini58,
Y. Gao3, J. Ga o oli58, P. Ga osi53, J. Ga a Tico46, L. Ga ido35, C. Gaspa 37, R. Gauld54,
E. Ge sabeck11, M. Ge sabeck53, T. Ge shon47, Ph. Ghez4, A. Gianelle21, V. Gibson46,
L. Giubega28, V.V. Gligo o 37, C. G¨obel59, D. Golubko 30, A. Golu in52,30,37, A. Gomes1,a,
H. Go don37, M. G abalosa G´anda a5, R. G aciani Diaz35, L.A. G anado Ca doso37,
E. G aug´es35, G. G aziani17, A. G ecu28, E. G eening54, S. G egson46, P. G i i h44, L. G illo11,
O. G ¨unbe g60, B. Gui58, E. Gushchin32, Yu. Guz34,37, T. Gys37, C. Hadji asiliou58, G. Hae eli38,
C. Haen37, T.W. Ha kenscheid62, S.C. Haines46, S. Hall52, B. Hamil on57, T. Hampson45,
S. Hansmann-Menzeme 11, N. Ha new54, S.T. Ha new45, J. Ha ison53, T. Ha mann60, J. He37,
T. Head37, V. Heijne40, K. Hennessy51, P. Hen a d5, J.A. He nando Mo a a36,
E. an He wijnen37, M. Heß60, A. Hicheu 1, D. Hill54, M. Hoballah5, C. Hombach53,
W. Hulsbe gen40, P. Hun 54, T. Huse51, N. Hussain54, D. Hu chc o 51, D. Hynds50,
V. Iako enko43, M. Idzik26, P. Il en55, R. Jacobsson37, A. Jaege 11, E. Jans40, P. Ja on38,
A. Jawahe y57, F. Jing3, M. John54, D. Johnson54, C.R. Jones46, C. Jo am37, B. Jos 37,
– 19 –
JHEP04(2014)087
N. Ju ik58, M. Kaballo9, S. Kandybei42, W. Kanso6, M. Ka acson37, T.M. Ka bach37,
I.R. Kenyon44, T. Ke el41, B. Khanji20, S. Kla e 53, O. Kochebina7, I. Koma o 38,
R.F. Koopman41, P. Koppenbu g40, M. Ko ole 31, A. Kozlinskiy40, L. K a chuk32, K. K eplin11,
M. K eps47, G. K ocke 11, P. K oko ny33, F. K use9, M. Kucha czyk20,25,37,k, V. Kud ya se 33,
K. Ku ek27, T. K a a skheliya30,37, V.N. La Thi38, D. Laca e e37, G. La e y53, A. Lai15,
D. Lambe 49, R.W. Lambe 41, E. Lancio i37, G. Lan anchi18, C. Langenb uch37, T. La ham47,
C. Lazze oni44, R. Le Gac6, J. an Lee dam40, J.-P. Lees4, R. Le `e e5, A. Le la 31, J. Le an¸cois7,
S. Leo22, O. Le oy6, T. Lesiak25, B. Le e ing on11, Y. Li3, M. Liles51, R. Lindne 37, C. Linn11,
F. Lione o39, B. Liu15, G. Liu37, S. Lohn37, I. Longs a 50, J.H. Lopes2, N. Lopez-Ma ch38,
P. Lowdon39, H. Lu3, D. Lucchesi21, , J. Luisie 38, H. Luo49, E. Luppi16, , O. Lup on54,
F. Mache e 7, I.V. Machikhiliyan30, F. Maciuc28, O. Mae 29,37, S. Malde54, G. Manca15,e,
G. Mancinelli6, J. Ma a as5, U. Ma coni14, P. Ma ino22, , R. M¨a ki38, J. Ma ks11,
G. Ma ello i24, A. Ma ens8, A. Ma ´ın S´anchez7, M. Ma inelli40, D. Ma inez San os41,
D. Ma ins Tos es2, A. Massa e i1, R. Ma e 37, Z. Ma he37, C. Ma euzzi20, A. Mazu o 16,37, ,
M. McCann52, J. McCa hy44, A. McNab53, R. McNul y12, B. McSkelly51, B. Meadows56,54,
F. Meie 9, M. Meissne 11, M. Me k40, D.A. Milanes8, M.-N. Mina d4, J. Molina Rod iguez59,
S. Mon eil5, D. Mo an53, M. Mo andin21, P. Mo awski25, A. Mo d`a6, M.J. Mo ello22, ,
R. Moun ain58, I. Mous40, F. Muheim49, K. M¨ulle 39, R. Mu esan28, B. Mu yn26, B. Mus e 38,
P. Naik45, T. Nakada38, R. Nandakuma 48, I. Nas e a1, M. Needham49, S. Neube 37,
N. Neu eld37, A.D. Nguyen38, T.D. Nguyen38, C. Nguyen-Mau38,q, M. Nicol7, V. Niess5, R. Nie 9,
N. Niki in31, T. Nikodem11, A. No oselo 34, A. Oblakowska-Mucha26, V. Ob az so 34,
S. Ogge o40, S. Ogil y50, O. Okh imenko43, R. Oldeman15,e, G. Onde wa e 62, M. O landea28,
J.M. O alo a Goicochea2, P. Owen52, A. Oyangu en35, B.K. Pal58, A. Palano13,c, M. Palu an18,
J. Panman37, A. Papanes is48,37, M. Pappagallo50, L. Pappala do16, C. Pa kes53, C.J. Pa kinson9,
G. Passale a17, G.D. Pa el51, M. Pa el52, C. Pa ignani19,j, C. Pa el-Nico escu28,
A. Pazos Al a ez36, A. Pea ce53, A. Pelleg ino40, G. Penso24,m, M. Pepe Al a elli37,
S. Pe azzini14,d, E. Pe ez T igo36, P. Pe e 5, M. Pe in-Te in6, L. Pesca o e44, E. Pesen63,
G. Pessina20, K. Pe idis52, A. Pe olini19,j, E. Pica os e Olloqui35, B. Pie zyk4, T. Pilaˇ 47,
D. Pinci24, A. Pis one19, S. Play e 49, M. Plo Casasus36, F. Polci8, G. Polok25, A. Poluek o 47,33,
E. Polyca po2, A. Popo 34, D. Popo 10, B. Popo ici28, C. Po e a 35, A. Powell54,
J. P iscianda o38, A. P i cha d51, C. P ou e45, V. Puga ch43, A. Puig Na a o38, G. Punzi22,s,
W. Qian4, B. Rachwal25, J.H. Rademacke 45, B. Rako omia amanana38, M. Rama18,
M.S. Rangel2, I. Raniuk42, N. Rauschmay 37, G. Ra en41, S. Red o d54, S. Reiche 53,
M.M. Reid47, A.C. dos Reis1, S. Riccia di48, A. Richa ds52, K. Rinne 51, V. Ri es Molina35,
D.A. Roa Rome o5, P. Robbe7, D.A. Robe s57, A.B. Rod igues1, E. Rod igues53,
P. Rod iguez Pe ez36, S. Roise 37, V. Romano sky34, A. Rome o Vidal36, M. Ro ondo21,
J. Rou ine 38, T. Ru 37, F. Ru ini22, H. Ruiz35, P. Ruiz Valls35, G. Saba ino24,l,
J.J. Sabo ido Sil a36, N. Sagido a29, P. Sail50, B. Sai a15,e, V. Salus ino Guima aes2,
B. Sanma in Sedes36, R. San acesa ia24, C. San ama ina Rios36, E. San o e i23,l, M. Sapuno 6,
A. Sa i18, C. Sa iano24,n, A. Sa a23, M. Sa ie16, , D. Sa ina30,31, M. Schille 41,
H. Schindle 37, M. Schlupp9, M. Schmelling10, B. Schmid 37, O. Schneide 38, A. Schoppe 37,
M.-H. Schune7, R. Schwemme 37, B. Sciascia18, A. Sciubba24, M. Seco36, A. Semenniko 30,
K. Sende owska26, I. Sepp52, N. Se a39, J. Se ano6, P. Sey e 11, M. Shapkin34,
I. Shapo al16,42, , Y. Shcheglo 29, T. Shea s51, L. Shekh man33, O. She chenko42,
V. She chenko61, A. Shi es9, R. Sil a Cou inho47, G. Simi21, M. Si endi46, N. Skidmo e45,
T. Skwa nicki58, N.A. Smi h51, E. Smi h54,48, E. Smi h52, J. Smi h46, M. Smi h53, H. Snoek40,
M.D. Sokolo 56, F.J.P. Sole 50, F. Soom o38, D. Souza45, B. Souza De Paula2, B. Spaan9,
A. Spa kes49, P. Sp adlin50, F. S agni37, S. S ahl11, O. S einkamp39, S. S e enson54, S. S oica28,
– 20 –
JHEP04(2014)087
S. S one58, B. S o aci39, S. S acka22,37, M. S a iciuc28, U. S aumann39, R. S oili21,
V.K. Subbiah37, L. Sun56, W. Su cli e52, S. Swien ek9, V. Sy opoulos41, M. Szczekowski27,
P. Szczypka38,37, D. Szila d2, T. Szumlak26, S. T’Jampens4, M. Teklishyn7, G. Tella ini16, ,
E. Teodo escu28, F. Teube 37, C. Thomas54, E. Thomas37, J. an Tilbu g11, V. Tisse and4,
M. Tobin38, S. Tolk41, L. Tomasse i16, , D. Tonelli37, S. Topp-Joe gensen54, N. To 54,
E. Tou ne ie 4,52, S. Tou neu 38, M.T. T an38, M. T esch39, A. Tsa ego od se 6, P. Tsopelas40,
N. Tuning40, M. Ubeda Ga cia37, A. Ukleja27, A. Us yuzhanin61, U. Uwe 11, V. Vagnoni14,
G. Valen i14, A. Vallie 7, R. Vazquez Gomez18, P. Vazquez Reguei o36, C. V´azquez Sie a36,
S. Vecchi16, J.J. Vel huis45, M. Vel i17,h, G. Veneziano38, M. Ves e inen11, B. Viaud7, D. Viei a2,
X. Vilasis-Ca dona35,p, A. Vollha d 39, D. Volyanskyy10, D. Voong45, A. Vo obye 29,
V. Vo obye 33, C. Voß60, H. Voss10, J.A. de V ies40, R. Waldi60, C. Wallace47, R. Wallace12,
S. Wande no h11, J. Wang58, D.R. Wa d46, N.K. Wa son44, A.D. Webbe 53, D. Websdale52,
M. Whi ehead47, J. Wich 37, J. Wiechczynski25, D. Wiedne 11, L. Wigge s40, G. Wilkinson54,
M.P. Williams47,48, M. Williams55, F.F. Wilson48, J. Wimbe ley57, J. Wishahi9, W. Wislicki27,
M. Wi ek25, G. Wo mse 7, S.A. Wo on46, S. W igh 46, S. Wu3, K. Wyllie37, Y. Xie49,37,
Z. Xing58, Z. Yang3, X. Yuan3, O. Yushchenko34, M. Zangoli14, M. Za e yae 10,b, F. Zhang3,
L. Zhang58, W.C. Zhang12, Y. Zhang3, A. Zhelezo 11, A. Zhokho 30, L. Zhong3and A. Z yagin37.
1Cen o B asilei o de Pesquisas F´ısicas (CBPF), Rio de Janei o, B azil
2Uni e sidade Fede al do Rio de Janei o (UFRJ), Rio de Janei o, B azil
3Cen e o High Ene gy Physics, Tsinghua Uni e si y, Beijing, China
4LAPP, Uni e si ´e de Sa oie, CNRS/IN2P3, Annecy-Le-Vieux, F ance
5Cle mon Uni e si ´e, Uni e si ´e Blaise Pascal, CNRS/IN2P3, LPC, Cle mon -Fe and, F ance
6CPPM, Aix-Ma seille Uni e si ´e, CNRS/IN2P3, Ma seille, F ance
7LAL, Uni e si ´e Pa is-Sud, CNRS/IN2P3, O say, F ance
8LPNHE, Uni e si ´e Pie e e Ma ie Cu ie, Uni e si ´e Pa is Dide o , CNRS/IN2P3, Pa is, F ance
9Fakul ¨a Physik, Technische Uni e si ¨a Do mund, Do mund, Ge many
10 Max-Planck-Ins i u ¨u Ke nphysik (MPIK), Heidelbe g, Ge many
11 Physikalisches Ins i u , Rup ech -Ka ls-Uni e si ¨a Heidelbe g, Heidelbe g, Ge many
12 School o Physics, Uni e si y College Dublin, Dublin, I eland
13 Sezione INFN di Ba i, Ba i, I aly
14 Sezione INFN di Bologna, Bologna, I aly
15 Sezione INFN di Caglia i, Caglia i, I aly
16 Sezione INFN di Fe a a, Fe a a, I aly
17 Sezione INFN di Fi enze, Fi enze, I aly
18 Labo a o i Nazionali dell’INFN di F asca i, F asca i, I aly
19 Sezione INFN di Geno a, Geno a, I aly
20 Sezione INFN di Milano Bicocca, Milano, I aly
21 Sezione INFN di Pado a, Pado a, I aly
22 Sezione INFN di Pisa, Pisa, I aly
23 Sezione INFN di Roma To Ve ga a, Roma, I aly
24 Sezione INFN di Roma La Sapienza, Roma, I aly
25 Hen yk Niewodniczanski Ins i u e o Nuclea Physics Polish Academy o Sciences, K ak´ow, Poland
26 AGH - Uni e si y o Science and Technology, Facul y o Physics and Applied Compu e Science,
K ak´ow, Poland
27 Na ional Cen e o Nuclea Resea ch (NCBJ), Wa saw, Poland
28 Ho ia Hulubei Na ional Ins i u e o Physics and Nuclea Enginee ing, Bucha es -Magu ele,
Romania
29 Pe e sbu g Nuclea Physics Ins i u e (PNPI), Ga china, Russia
30 Ins i u e o Theo e ical and Expe imen al Physics (ITEP), Moscow, Russia
31 Ins i u e o Nuclea Physics, Moscow S a e Uni e si y (SINP MSU), Moscow, Russia
– 21 –
JHEP04(2014)087
32 Ins i u e o Nuclea Resea ch o he Russian Academy o Sciences (INR RAN), Moscow, Russia
33 Budke Ins i u e o Nuclea Physics (SB RAS) and No osibi sk S a e Uni e si y, No osibi sk,
Russia
34 Ins i u e o High Ene gy Physics (IHEP), P o ino, Russia
35 Uni e si a de Ba celona, Ba celona, Spain
36 Uni e sidad de San iago de Compos ela, San iago de Compos ela, Spain
37 Eu opean O ganiza ion o Nuclea Resea ch (CERN), Gene a, Swi ze land
38 Ecole Poly echnique F´ed´e ale de Lausanne (EPFL), Lausanne, Swi ze land
39 Physik-Ins i u , Uni e si ¨a Z¨u ich, Z¨u ich, Swi ze land
40 Nikhe Na ional Ins i u e o Suba omic Physics, Ams e dam, The Ne he lands
41 Nikhe Na ional Ins i u e o Suba omic Physics and VU Uni e si y Ams e dam, Ams e dam, The
Ne he lands
42 NSC Kha ki Ins i u e o Physics and Technology (NSC KIPT), Kha ki , Uk aine
43 Ins i u e o Nuclea Resea ch o he Na ional Academy o Sciences (KINR), Kyi , Uk aine
44 Uni e si y o Bi mingham, Bi mingham, Uni ed Kingdom
45 H.H. Wills Physics Labo a o y, Uni e si y o B is ol, B is ol, Uni ed Kingdom
46 Ca endish Labo a o y, Uni e si y o Camb idge, Camb idge, Uni ed Kingdom
47 Depa men o Physics, Uni e si y o Wa wick, Co en y, Uni ed Kingdom
48 STFC Ru he o d Apple on Labo a o y, Didco , Uni ed Kingdom
49 School o Physics and As onomy, Uni e si y o Edinbu gh, Edinbu gh, Uni ed Kingdom
50 School o Physics and As onomy, Uni e si y o Glasgow, Glasgow, Uni ed Kingdom
51 Oli e Lodge Labo a o y, Uni e si y o Li e pool, Li e pool, Uni ed Kingdom
52 Impe ial College London, London, Uni ed Kingdom
53 School o Physics and As onomy, Uni e si y o Manches e , Manches e , Uni ed Kingdom
54 Depa men o Physics, Uni e si y o Ox o d, Ox o d, Uni ed Kingdom
55 Massachuse s Ins i u e o Technology, Camb idge, MA, Uni ed S a es
56 Uni e si y o Cincinna i, Cincinna i, OH, Uni ed S a es
57 Uni e si y o Ma yland, College Pa k, MD, Uni ed S a es
58 Sy acuse Uni e si y, Sy acuse, NY, Uni ed S a es
59 Pon i ´ıcia Uni e sidade Ca ´olica do Rio de Janei o (PUC-Rio), Rio de Janei o, B azil, associa ed
o 2
60 Ins i u ¨u Physik, Uni e si ¨a Ros ock, Ros ock, Ge many, associa ed o 11
61 Na ional Resea ch Cen e Ku cha o Ins i u e, Moscow, Russia, associa ed o 30
62 KVI - Uni e si y o G oningen, G oningen, The Ne he lands, associa ed o 40
63 Celal Baya Uni e si y, Manisa, Tu key, associa ed o 37
aUni e sidade Fede al do T iˆangulo Minei o (UFTM), Ube aba-MG, B azil
bP.N. Lebede Physical Ins i u e, Russian Academy o Science (LPI RAS), Moscow, Russia
cUni e si `a di Ba i, Ba i, I aly
dUni e si `a di Bologna, Bologna, I aly
eUni e si `a di Caglia i, Caglia i, I aly
Uni e si `a di Fe a a, Fe a a, I aly
gUni e si `a di Fi enze, Fi enze, I aly
hUni e si `a di U bino, U bino, I aly
iUni e si `a di Modena e Reggio Emilia, Modena, I aly
jUni e si `a di Geno a, Geno a, I aly
kUni e si `a di Milano Bicocca, Milano, I aly
lUni e si `a di Roma To Ve ga a, Roma, I aly
mUni e si `a di Roma La Sapienza, Roma, I aly
nUni e si `a della Basilica a, Po enza, I aly
oAGH - Uni e si y o Science and Technology, Facul y o Compu e Science, Elec onics and
Telecommunica ions, K ak´ow, Poland
pLIFAELS, La Salle, Uni e si a Ramon Llull, Ba celona, Spain
– 22 –
JHEP04(2014)087
qHanoi Uni e si y o Science, Hanoi, Vie Nam
Uni e si `a di Pado a, Pado a, I aly
sUni e si `a di Pisa, Pisa, I aly
Scuola No male Supe io e, Pisa, I aly
– 23 –
