Physics Le e s B 759 (2016) 282–292
Con en s lis s a ailable a ScienceDi ec
Physics Le e s B
www.else ie .com/loca e/physle b
Obse a ion o he Λ0
b→Λφ decay
.The LHCb Collabo a ion
a i c l e i n o a b s a c
A icle his o y:
Recei ed 10 Ma ch 2016
Recei ed in e ised o m 13 May 2016
Accep ed 24 May 2016
A ailable online 26 May 2016
Edi o : W.-D. Schla e
The Λ0
b→Λφ decay is obse ed using da a co esponding o an in eg a ed luminosi y o 3.0 b
−1
eco ded by he LHCb expe imen . The decay p oceeds a leading o de ia a b →sss loop ansi ion and
is he e o e sensi i e o he possible p esence o pa icles beyond he S anda d Model. A fi s obse a ion
is epo ed wi h a significance o 5.9s anda d de ia ions. The alue o he b anching ac ion is measu ed
o be (5.18 ±1.04 ±0.35+0.67
−0.62) ×10−6, whe e he fi s unce ain y is s a is ical, he second is sys ema ic,
and he hi d is ela ed o ex e nal inpu s. T iple-p oduc asymme ies a e measu ed o be consis en
wi h ze o.
©2016 The Au ho . Published by Else ie B.V. This is an open access a icle unde he CC BY license
(h p://c ea i ecommons.o g/licenses/by/4.0/). Funded by SCOAP3.
1. In oduc ion
In he S anda d Model (SM), he fla ou -changing neu al cu -
en decay Λ0
b→Λφ p oceeds ia a b →sss loop (penguin) p o-
cess. A Feynman diag am o he gluonic penguin ha con ibu es
o his decay a leading o de is displayed in Fig. 1. This ansi-
ion has been he subjec o heo e ical and expe imen al in e es
in B0
sand B0decays, since possible beyond he SM pa icles in he
loop could induce non-SM CP iola ion [1–3]. The p ocess has been
p obed wi h decay- ime-dependen me hods in he B0
s→φφ and
B0→K0
Sφdecay modes [4–7], which es o CP iola ion in he in-
e e ence be ween mixing and decay. In addi ion, measu emen s
o CP iola ion in he decay ha e been pe o med wi h he fla ou -
specific B0→K∗0φchannel [8]. The esul s o da e a e consis en
wi h CP conse a ion in he b →sss p ocess. Model-independen ly,
non-SM physics con ibu ions could appea di e en ly in hese de-
cay modes, hough many models con ain s ong co ela ions [9].
Measu emen s wi h Λ0
bba yons o e he possibili y o look o
CP iola ion in he decay, bo h by s udying CP asymme ies and by
means o T-odd obse ables. These obse ables ha e been s ud-
ied in g ea e de ail o B0
sand B0meson decays han hose o
Λ0
bba yons [4,8,10,11]. P oposed me hods o s udy T-odd asym-
me ies o Λ0
bba yons [12] exploi he pola isa ion s uc u e o
Λ0
b→ΛVdecays, whe e Vdeno es a ec o esonance [12], and
can be a ec ed by he ini ial Λ0
bpola isa ion i non-ze o. An
LHCb measu emen o he ini ial pola isa ion in Λ0
b→J/ ψΛ de-
cays has yielded a alue consis en wi h ze o, hough pola isa ion
a he le el o 10% is possible gi en s a is ical unce ain ies [13].
No SM p edic ion exis s specifically o he T-odd asymme ies in
Λ0
b→Λφ decays, hough no la ge asymme ies a e expec ed gi en
he p edic ion o CP conse a ion in he decays o beau y mesons
o he same ansi ion. Measu emen s o CP asymme ies ha e
Fig. 1. Feynman diag am con ibu ing o he Λ0
b→Λφ decay.
been pe o med by LHCb in an inclusi e analysis o Λ0
b→Λhhde-
cays [14], whe e h(h) e e s o a kaon o pion, wi h co esponding
CP asymme ies measu ed o be consis en wi h ze o.
In his pape , a measu emen o he Λ0
b→Λφ b anching ac-
ion is p esen ed using he B0→K0
Sφdecay as a no malisa ion
channel, which has a measu ed b anching ac ion o (7.3+0.7
−0.6) ×
10−6[15]. The selec ion equi emen s used o isola e he Λ0
b→
Λφ decay wi h well-unde s ood efficiencies ejec sui able con ol
channels o a ACP measu emen . The Λ0
b→Λφ sample is hen
used o pe o m measu emen s o he T-odd iple-p oduc asym-
me ies, which do no equi e a con ol channel. The esul s a e
based on pp collision da a co esponding o an in eg a ed lumi-
nosi y o 1.0 b
−1and 2.0 b
−1collec ed by he LHCb expe imen
a cen e-o -mass ene gies o √s=7TeV in 2011 and 8TeVin
2012, espec i ely.
2. De ec o and simula ion
The LHCb de ec o [16,17] 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
h p://dx.doi.o g/10.1016/j.physle b.2016.05.077
0370-2693/©2016 The Au ho . Published by Else ie B.V. This is an open access a icle unde he CC BY license (h p://c ea i ecommons.o g/licenses/by/4.0/). Funded by
SCOAP3.
The LHCb Collabo a ion / Physics Le e s B 759 (2016) 282–292 283
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 4Tm, and h ee s a ions o silicon-
s ip de ec o s and s aw d i ubes placed downs eam o he
magne . The acking sys em p o ides a measu emen o momen-
um, p, o cha ged pa icles wi h a ela i e unce ain y ha a ies
om 0.5% a low momen um o 1.0% a 200 GeV/c. The minimum
dis ance o a ack o a p ima y e ex, he impac pa ame e , is
measu ed wi h a esolu ion o (15 +29/pT)μm, whe e pTis he
componen o he momen um ans e se o he beam, in GeV/c.
Di e en ypes o cha ged had ons a e dis inguished using in o -
ma ion om wo ing-imaging Che enko de ec o s. Pho ons, elec-
ons and had ons a e iden ified 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 . The online e en selec-
ion is pe o med by a igge , which consis s o a ha dwa e s age,
based on in o ma ion om he calo ime e and muon sys ems, ol-
lowed by a so wa e s age, which applies a ull e en econs uc-
ion. A he ha dwa e igge s age, e en s a e equi ed o ha e
a muon wi h high pTo a had on, pho on o elec on wi h high
ans e se ene gy in he calo ime e s. Fo had ons, he ans e se
ene gy h eshold is 3.5 GeV. In he subsequen so wa e igge ,
a leas one cha ged pa icle mus ha e a ans e se momen um
pT>1.7GeV/cand be inconsis en wi h o igina ing om a PV.
Finally, he acks o wo o mo e o he final-s a e pa icles a e
equi ed o o m a e ex ha is significan ly displaced om he
PVs. The final s a e pa icles ha a e iden ified as kaons a e e-
qui ed o ha e a combined in a ian mass consis en wi h ha o
he φmeson.
In he simula ion, pp collisions a e gene a ed using Py hia8 [18]
wi h a specific LHCb configu a ion [19]. Decays o had onic pa i-
cles a e desc ibed by E Gen [20], in which final-s a e adia ion
is gene a ed using Pho os [21]. The in e ac ion o he gene a ed
pa icles wi h he de ec o , and i s esponse, a e implemen ed us-
ing he Gean 4 oolki [22] as desc ibed in Re . [23]. The decays o
Λ0
bba yons a e modelled acco ding o a phase-space desc ip ion.
Di e ences in he efficiencies o p o ons and an i-p o ons, a he
sub-pe cen le el, a e accoun ed o wi h he Gean 4 implemen a-
ion o he de ec o desc ip ion.
3. Selec ion
The Λ0
b→Λφ and B0→K0
Sφdecays a e econs uc ed h ough
he Λ →pπ−, K0
S→π+π−and φ→K+K−final s a es, whe e
he inclusion o cha ge conjuga e p ocesses is implied h ough-
ou he pape . Decays o Λ →pπ−and K0
S→π+π−a e econ-
s uc ed in wo di e en ca ego ies. The fi s ca ego y con ains Λ
(K0
S) had ons ha decay inside he e ex de ec o accep ance and
he second con ains Λ(K0
S) had ons ha decay ou side. These ca -
ego ies a e e e ed o as long and downs eam, espec i ely. The
high esolu ion o he e ex de ec o leads o enhanced momen-
um, e ex, and mass esolu ions o candida es in he long ca e-
go y ela i e o downs eam candida es.
Boos ed decision ees (BDTs) [24,25] a e used o sepa a e sig-
nal om backg ound. Di e en BDTs a e ained o decays whe e
he daugh e acks o he Λ(K0
S) had on a e classified as long o
downs eam and acco ding o whe he he da a was collec ed in
2011 (7 TeV) o 2012 (8 TeV), yielding eigh sepa a e BDTs in o al.
The se o inpu a iables used o ain he Λ0
b→Λφ (B0→K0
Sφ)
BDTs consis s o he Λ0
b(B0) e ex fi quali y, pT, η, he di e -
ence in χ2o he PV econs uc ed wi h and wi hou he candida e
(χ2
IP), he fligh dis ance squa ed di ided by he associa ed a iance
(χ2
FD), he angle be ween he momen um ec o and he ec o
om he PV o he decay e ex, he Λ(K0
S) e ex fi quali y, and
he pTand ηo he φand he Λ(K0
S) had ons. The minimum and
maximum alues o he pTand ηassocia ed o he final s a e pa -
icles a e also included. In addi ion, he BDT ained on he long
ca ego y uses he χ2
IP and χ2
FD o he Λ(K0
S) wi h espec o he
associa ed PV. A PV is econs uc ed by equi ing a minimum o
fi e good quali y acks ha a e consis en wi h o igina ing om
he same loca ion wi hin he luminous egion. Be o e he BDTs
a e ained, ini ial loose equi emen s a e imposed on he inpu
a iables. The BDTs a e ained using simula ed candida es o he
signal and da a sidebands o he backg ound. Fo he aining
samples, he signal egion is defined as being wi hin 150 MeV/c2
o he known Λ0
b(B0) mass [26]. In addi ion, he K+K−in a ian
mass is equi ed o be wi hin 20 MeV/c2o he known φmass
and he pπ−in a ian mass is equi ed o be wi hin 15 MeV/c2
o he known Λmass [26]. The sidebands a e defined o be wi hin
500 MeV/c2o he known Λ0
b(B0) mass excluding he signal e-
gion.
The figu e o me i used o de e mine he equi emen imposed
on he Λ0
b→Λφ BDT ou pu is defined as ε/(3/2 +Nbkg)[27],
whe e εis he signal efficiency, and Nbkg is he numbe o back-
g ound e en s. This figu e o me i is op imised o de ec ion a
h ee s anda d de ia ions o decay modes no p e iously obse ed.
The signal efficiency is ob ained om simula ed signal candida es
and he numbe o backg ound e en s is calcula ed om fi s o he
da a sidebands in e pola ed o he signal egion. This op imisa ion
p ocedu e is pe o med sepa a ely o each BDT.
In con as o he Λ0
b→Λφ BDTs, he op imum esponse e-
qui emen o he B0→K0
SφBDTs is chosen based on a figu e
o me i defined as Nsig/Nsig +Nbkg, whe e Nsig is he numbe
o signal e en s, es ima ed om he BDT efficiency on simula ed
da ase s no malised using he known b anching ac ion o he
B0→K0
Sφdecay [15], and Nbkg is he expec ed numbe o back-
g ound candida es in he signal egion, ex apola ed om he B0
sidebands. This figu e o me i is chosen as he B0→K0
Sφb anch-
ing ac ion is well measu ed and is op imised sepa a ely o each
classifie .
4. Mass fi model
Fo bo h he Λ0
b→Λφ and B0→K0
Sφdecay modes, a h ee-
dimensional fi is employed o de e mine he signal candida e
yields. In he Λ0
b→Λφ case, he h ee dimensions a e he
pπ−K+K−, pπ−, and K+K−in a ian masses, while in he fi
o de e mine he B0→K0
Sφcandida e yield, he h ee dimensions
a e he π+π−K+K−, π+π−, and K+K−in a ian masses.
Fou componen s a e p esen in he B0→K0
Sφmass fi : he
signal B0→K0
Sφcomponen , he B0→K0
SK+K−non- esonan
con ibu ion, a π+π−K+K−combina o ial componen , along wi h
a ue K0
Scomponen combined wi h wo andom kaons. The
B0→K0
SK+K−non- esonan componen has been obse ed by
he BaBa [28], Belle [6] and LHCb [29] Collabo a ions. This is
sepa a ed om he signal decay h ough he di e en K+K−in-
a ian mass line shapes. No significan pa ially econs uc ed
backg ound, in which one o mo e o he final s a e pa icles a e
missed, is ound in he B0mass egion. Peaking backg ounds, om
decays in which a leas one o he final s a e pa icles has been
misiden ified, a e supp essed by he na ow K+K−mass window
a ound he φmeson and a e ea ed as sys ema ic unce ain ies.
The B0signal is modelled wi h he same modified Gaussian
unc ion as used in Re . [30]. The modified Gaussian gi es ex a
deg ees o eedom o accommoda e ex ended ails a om he
mean. The φsignal is modelled wi h a ela i is ic B ei –Wigne
284 The LHCb Collabo a ion / Physics Le e s B 759 (2016) 282–292
shape [31] con ol ed wi h a Gaussian esolu ion unc ion. The K0
S
signal is pa ame ised by he sum o wo Gaussian unc ions wi h a
common mean. Decays om eal B0mesons o he K0
SK+K−final
s a e in which he K+K−pai is non- esonan a e desc ibed by he
same B0and K0
Sline shapes as he signal, bu wi h a phase-space
ac o o desc ibe he non- esonan kaon pai s. The phase-space
ac o is gi en by he exp ession (m2−(2mK)2)/m2, whe e mis he
K+K−in a ian mass and mKis fixed o he alue o he cha ged
kaon mass. The use o a Fla é unc ion [32] a he han a phase-
space ac o o desc ibe a possible scala componen unde he φ
esonance is ound o ha e a negligible e ec on he esul s and is
he e o e no included. The combina o ial backg ound is modelled
by exponen ial unc ions in all h ee mass dimensions.
A simul aneous fi o he long and downs eam da ase s is pe -
o med. The B0 esolu ion, modified Gaussian ail pa ame e s and
esolu ions and ac ions o he K0
SGaussian unc ions a e con-
s ained o alues ob ained om a fi o simula ed da a, pe o med
sepa a ely o long and downs eam da ase s. The o al yield and
ac ion in he downs eam da ase a e le as ee pa ame e s o
each componen .
The fi o he Λ0
b→Λφ channel uses he same fi model as
he B0→K0
Sφcon ol channel: a modified Gaussian unc ion is
used o desc ibe he Λ0
bmass shape, a double Gaussian model o
desc ibe he Λshape, and a ela i is ic B ei –Wigne con ol ed
wi h a Gaussian esolu ion unc ion o desc ibe ha o he φ es-
onance. Due o he ela i ely unexplo ed mass spec a p esen
in he Λ0
b→Λφ decay, he backg ound con ibu ions ha e been
iden ified using he da a sidebands. In he final fi , ou com-
ponen s a e p esen . These a e he signal Λ0
b→Λφ componen ,
he Λ0
b→ΛK+K−non- esonan componen in which he K+K−
dimension is desc ibed using he phase-space ac o defined p e i-
ously, combina o ial componen s wi h ue φo Λ esonances, and
a componen ha has a combina o ial o igin in all h ee mass di-
mensions. Combina o ial backg ounds a e modelled by exponen ial
unc ions in each fi dimension. As o he case o he B0→K0
Sφ
fi , he o al yield and ac ion in he downs eam da ase a e le
as ee pa ame e s o each componen . In addi ion, he same pa-
ame e s a e cons ained o simula ed da a as in he B0→K0
Sφfi .
5. B anching ac ion measu emen
The Λ0
b→Λφ b anching ac ion is ob ained om he ela ion
B(Λ0
b→Λφ) =
o
B0→K0
Sφ
o
Λ0
b→Λφ · d
Λ0
b·
NΛ0
b→Λφ
NB0→K0
Sφ·B(B0→K0φ)
2
·B(K0
S→π+π−)
B(Λ →pπ−),(1)
whe e o deno es he combined efficiency o he candida e e-
cons uc ion, he offline selec ion, he igge equi emen s, and
he efficiency o de ec o accep ance; d(Λ0
b)deno es he ac ion
o bqua ks ha had onise o B0(Λ0
b) had ons. The a io is aken
om he LHCb measu ed alue Λ0
b/ d=0.387 ±0.033 [33]. The
ex a ac o 1/2in Eq. (1) accoun s o he ac ha only hal o
K0mesons will decay as K0
Smesons. The alue o he B0→K0φ
b anching ac ion is aken o be (7.3+0.7
−0.6) ×10−6[15], while he
PDG alues o he Λand K0
Sb anching ac ions a e used [26].
The econs uc ion, selec ion and so wa e igge efficien-
cies, as well as he accep ance o he LHCb de ec o , a e de e -
mined om simula ed samples, using da a-d i en co ec ion ac-
o s whe e necessa y. The di e en in e ac ion c oss-sec ions o
he final-s a e pa icles wi h he de ec o ma e ial a e accoun ed
o using simula ed da ase s.
Fo he case o he ha dwa e igge , he efficiency o e en s
igge ed by he signal candida e is de e mined om con ol sam-
ples o D0→K−π+and Λ →pπ−decays. The efficiency o e en s
igge ed independen ly o he signal candida e is de e mined om
simula ion. The ag eemen be ween da a and simula ion o he
dis ibu ions o he a iables used in he BDT is e ified wi h he
B0→K0
Sφda a.
Da a-d i en co ec ions o he econs uc ion efficiency o
acks co esponding o he long ca ego y a e ob ained om J/ ψ
samples using a ag-and-p obe me hod [34]. This is applied a e
a sepa a e weigh ing o ensu e ag eemen in de ec o occupancy
be ween da a and simula ion. Fo measu emen s o he ela i e
b anching ac ion o Λ0
b→Λφ o B0→K0
Sφ, he final s a e di -
e s by subs i u ing he p o on om he decay o he Λwi h a
pion. Howe e , due o he di e ences in he kinema ics o he pi-
ons om he Λand he K0
Sdecays, he dis inc co ec ion ac o s
o bo h daugh e s o he Λand K0
Sa e conside ed. In addi ion o
he ack econs uc ion efficiency, he e exing efficiency o long-
li ed pa icles con ains disag eemen be ween da a and simula ion.
The co esponding co ec ion ac o s o he long and downs eam
da ase s a e de e mined sepa a ely om D0→φK0
Sdecays.
The yields o he Λ0
b→Λφ signal and B0→K0
Sφcon ol mode
a e de e mined om simul aneous ex ended unbinned maximum
likelihood fi s o he espec i e da ase s di ided acco ding o he
da a- aking pe iod and also acco ding o whe he he Λ (K0
S)decay
p oduc s a e econs uc ed as long o downs eam acks. Efficien-
cies a e applied o each da ase indi idually. The p ojec ions o he
fi esul o Λ0
b→Λφ da a a e shown in Fig. 2. The fi ed yields
a e 350 ±24 and 89 ±13 o he B0→K0
Sφand Λ0
b→Λφ de-
cay modes, espec i ely. The s a is ical significance o he Λ0
b→Λφ
decay, de e mined acco ding o Wilks’ heo em [35] om he di -
e ence in he likelihood alue o he fi s wi h and wi hou he
Λ0
b→Λφ componen , is ound o be 6.5 s anda d de ia ions. Wi h
he sys ema ic unce ain ies discussed below included, he signi -
icance o he obse ed Λ0
b→Λφ decay yield is calcula ed o be
5.9 s anda d de ia ions. The p ojec ions o he fi esul o he
B0→K0
Sφda a a e shown in Fig. 3. The fi is ound o desc ibe
he da a well in all h ee dimensions and a clea peak om he
con ol mode is seen.
The sys ema ic con ibu ions o he b anching ac ion unce -
ain y budge a e summa ised in Table 1. The la ges con ibu ions
o he sys ema ic unce ain ies esul om da a-d i en co ec ions
applied o simula ed da a along wi h he mass model used o de-
e mine he signal yields.
Signal mismodelling is accoun ed o using a one-dimensional
ke nel es ima e o he desc ip ion o he simula ed mass dis ibu-
ions [36]. Backg ound mismodelling is accoun ed o using a linea
unc ion. The ke nel es ima e is used in bo h he signal and con ol
channels o desc ibe he Λ0
b, B0, K0
S, and Λline shapes. In o de o
de e mine he sys ema ic unce ain ies, 1000 pseudoexpe imen s
a e gene a ed wi h he al e na i e model and a e subsequen ly fi -
ed wi h he nominal model. The a e age di e ence be ween he
gene a ed and fi ed yield alues is aken as he sys ema ic unce -
ain y. This leads o unce ain ies o 3.0% and 0.6% o he signal
and con ol mode yields, espec i ely.
Sys ema ic unce ain ies associa ed wi h he efficiency co ec-
ions om simula ed da ase s a e conside ed. The limi ed size o
he simula ed sample gi es ise o an unce ain y o 2.2%. The
main unce ain ies in he acking and e exing co ec ion ac-
o s a ise om he limi ed size o he con ol sample, which leads
o unce ain ies o 0.5% and 2.6%, espec i ely. Fo he case o he
igge efficiency, unce ain ies ela ed o he so wa e igge can-
cel be ween he signal and con ol modes, as he so wa e igge
decision is made only on he decay p oduc s o he φmeson. Un-
The LHCb Collabo a ion / Physics Le e s B 759 (2016) 282–292 285
Fig. 2. Fi p ojec ions o he pπ−K+K−in a ian mass in he (a) long and (b) downs eam da ase s, he K+K−in a ian mass in he (c) long and (d) downs eam da ase s,
and he pπ−in a ian mass in he (e) long and ( ) downs eam da ase s. The o al fi p ojec ion is gi en by he blue solid line. The blue and g een do ed lines ep esen
he φ+Λand pu e combina o ial fi componen s, espec i ely. The ed and magen a dashed lines ep esen he Λ0
b→Λφ signal and he Λ0
b→ΛK+K−non- esonan
componen s, espec i ely. Black poin s ep esen he da a. Da a unce ain ies a e Poisson 68% confidence in e als. (Fo in e p e a ion o he e e ences o colou in his figu e
legend, he eade is e e ed o he web e sion o his a icle.)
ce ain ies in he efficiency o he ha dwa e igge selec ions a e
es ima ed using da a-d i en me hods, o which an unce ain y o
2.8% is applied. The BDTs used o selec signal and con ol modes
use he same inpu a iables. Biases could exis i he simula ion
mismodels hese a iables di e en ly o signal and con ol modes.
In o de o quan i y his e ec , he con ol mode is selec ed wi h
he same classifie as he signal decay. The di e ence in he mea-
su ed b anching ac ion is ound o be 4.1%.
The Λ0
b→Σ0(→Λγ)K+K−and Λ0
b→pK−φdecay modes
a e ound o be he only significan peaking backg ound con i-
bu ions. Howe e , o he case o he Λ0
b→pK−φdecay, he
esul ing candida es a e econs uc ed in he long da ase only.
Wi h he assump ion ha he b anching ac ion o his decay
is he same size as o he signal, he con ibu ion is <1% com-
pa ed o he Λ0
b→Λφ decay and a om he Λ0
bsignal e-
gion, and is he e o e igno ed. In o de o de e mine he shape
in he pπ−K+K−spec um o he Λ0
b→Σ0K+K−decay, a sam-
ple o Λ0
b→Σ0K+K−simula ed e en s is used wi h a equi e-
men ha he K+K−in a ian mass is wi hin 30 MeV/c2o he
nominal φmass. The inclusion o an addi ional fi componen
using he shape om simula ion is ound o ha e a small e -
ec on he signal yield a he le el o 0.1%, which is assigned
as a sys ema ic unce ain y. Fo he case o he B0→K0
Sφcon-
ol mode, no peaking backg ound con ibu ions ha e been iden i-
fied.
The b anching ac ion a io is measu ed o be
B(Λ0
b→Λφ)
B(B0→K0
Sφ)
Λ0
b
B0=0.55 ±0.11 (s a ) ±0.04 (sys ).
The use o he wo ld a e age alue o B(B0→K0
Sφ) =(3.65 +0.35
−0.30) ×
10−6[15] gi es he final esul o
B(Λ0
b→Λφ)/10−6=5.18 ±1.04 (s a )
±0.35 (sys ) +0.50
−0.43 (B(B0→K0
Sφ))
±0.44( d/ Λ0
b).
6. T iple-p oduc asymme ies
The Λ0
b→Λφ decay is a spin-1/2 o spin-1/2plus ec o an-
si ion. Fi e angles a e needed o desc ibe his decay since Λ0
b
ba yons may po en ially be p oduced wi h a ans e se pola isa-
ion in p o on–p o on collisions [13], as shown in Fig. 4. The angle
θis defined as he pola angle o he Λba yon in he Λ0
b es
ame wi h espec o he no mal ec o defined h ough
ˆ
n=
p1×
pΛ0
b
|
p1×
pΛ0
b|,(2)
whe e
p1is he momen um o an incoming p o on and
pΛ0
bis he
momen um o he Λ0
bba yon. The angles θΛand Λa e defined
as he pola and azimu hal angles o he p o on om he decay
o he Λba yon in he Λ es ame. The angles θφand φa e
defined as he pola and azimu hal angles o he K+meson in he
es ame o he φmeson.
T iple-p oduc asymme ies, which a e odd unde ime- e e sal,
ha e been p oposed by Lei ne and Ajal ouni using he azimu hal
angles ni, i ∈{Λ, φ}, defined as [12]
286 The LHCb Collabo a ion / Physics Le e s B 759 (2016) 282–292
Fig. 3. Fi p ojec ions o he π+π−K+K−in a ian mass in he (a) long and (b) downs eam da ase s, he K+K−in a ian mass in he (c) long and (d) downs eam
da ase s, and he π+π−in a ian mass in he (e) long and ( ) downs eam da ase s. The o al fi p ojec ion is gi en by he blue solid line. The g een and blue do ed lines
ep esen he combina o ial and K0
S+ andom K+K−fi componen s, espec i ely. The ed and magen a dashed lines ep esen he B0→K0
Sφsignal and he B0→K0
SK+K−
non- esonan componen s, espec i ely. Black poin s ep esen he da a. Da a unce ain ies a e Poisson 68% confidence in e als. (Fo in e p e a ion o he e e ences o colou
in his figu e legend, he eade is e e ed o he web e sion o his a icle.)
Table 1
Sys ema ic unce ain y con ibu ions o he b anch-
ing ac ion a io.
Sou ce Unce ain y (%)
Mass model 3.0
Simula ion sample size 2.2
T acking efficiency 0.5
Ve ex efficiency 2.6
Ha dwa e igge 2.8
Selec ion efficiency 4.1
Peaking backg ound 0.1
To al 6.7
cosni=
eY·
ui,(3)
sinni=
eZ·(
eY×
ui), (4)
whe e
ui=
eZ׈
ni
|
eZ׈
ni|.(5)
The basis {
eX,
eY,
eZ}is defined in he Λ0
b es ame, in which
eZ
is pa allel o ˆ
n,
eXis chosen o be pa allel o he momen um o
he incoming p o on, and ˆ
nΛ(φ) is he no mal ec o o he Λ(φ)
decay plane, defined h ough
ˆ
nΛ=
pp×
pπ
|
pp×
pπ|,(6)
ˆ
nφ=
pK+×
pK−
|
pK+×
pK−|.(7)
Asymme ies in cosniand sinni, whe e i ∈{Λ, φ}, a e defined
as
Ac
i=N+,c
i−N−,c
i
N+,c
i+N−,c
i
,(8)
As
i=N+,s
i−N−,s
i
N+,s
i+N−,s
i
,(9)
whe e N+(−),c
iand N+(−),s
ideno e he numbe o candida es o
which he cosniand sinniobse ables a e posi i e (nega i e),
espec i ely.
The asymme ies Ac,s
Λand Ac,s
φa e de e mined expe imen-
ally h ough a simul aneous unbinned maximum likelihood fi o
da ase s in which he ele an obse ables a e posi i e and nega-
i e. The fi cons uc ion and obse ables a e iden ical o ha used
o he b anching ac ion measu emen . Howe e , he yields o
each da ase a e pa ame ised in e ms o he o al yield, Nj, and
he asymme y, Aj, o fi componen jas
N+
j=Nj
2(1+Aj), (10)
N−
j=Nj
2(1−Aj). (11)
Dis ibu ions o he sin n(Λ,φ) and cos n(Λ,φ) obse ables om
Λ0
b→Λφ da a ha e been ex ac ed using he sPlo me hod [37]
and a e p o ided in Fig. 5. The nume ical alues o he fi ed asym-
me ies a e gi en in Table 2.
Mismodelling o he mass componen s could lead o back-
g ound con amina ion in he de e mina ion o he asymme ies. In
The LHCb Collabo a ion / Physics Le e s B 759 (2016) 282–292 287
Fig. 4. Decay angles o he Λ0
b→Λφ decay, whe e he angles a e defined in he ex .
Fig. 5. Dis ibu ions o he angula obse ables: (a) sin nΛ,(b)cosnΛ,(c)sinnφ,(d)cosnφ om weigh ed Λ0
b→Λφ da a.
Table 2
Asymme ies measu ed om Λ0
b→
Λφ da a e en s.
Asymme y Fi alue
Ac
Λ−0.22 ±0.12
As
Λ0.13 ±0.12
Ac
φ−0.01 ±0.12
As
φ−0.07 ±0.12
he de e mina ion o he unce ain y ela ed o he mass model,
wo con ibu ions a e conside ed. These a e he line shape models
and he backg ound asymme ies. The e ec s o he line shapes a e
quan ified using he same me hod as he b anching ac ion mea-
su emen , i.e. he gene a ion o da ase s wi h a one-dimensional
ke nel es ima e o he simula ion mass dis ibu ions in addi ion
o modifica ion o he backg ound desc ip ion. In he nominal fi ,
componen s ha a e no om he Λ0
b→Λφ signal ha e ze o
asymme ies. Fo backg ound componen s his is jus ified due o
he unco ela ed kinema ics o he K+K−and pπ−sys ems. How-
e e , he non- esonan Λ0
b→ΛK+K−con ibu ion could ha e
non-ze o asymme ies. The sys ema ic unce ain y due o he as-
sump ion o ze o backg ound asymme ies is de e mined h ough
compa ing he nominal fi agains he fi wi h all possible asym-
me ies allowed o a y eely.
Efficiencies a e ound o be independen o he sinniand
cosniobse ables. The sys ema ic unce ain y due o he angu-
la accep ance is hen aken om he s a is ical unce ain y in fi s
o he simula ed da ase s, a e he applica ion o an app op ia e
weigh ing o accoun o he di e ences be ween da a and simu-
la ion. The esolu ions o he angula obse ables a e ound om
simula ed e en s o be 32.3 m ad and 22.1 m ad o he nΛand
nφangles, espec i ely. The unce ain y due o bin mig a ion is
hen assigned assuming maximal asymme y and leads o mino
unce ain ies o 0.007 o he nφangle and 0.010 o he nΛ
288 The LHCb Collabo a ion / Physics Le e s B 759 (2016) 282–292
Table 3
Sys ema ic unce ain y con ibu ions o he iple-p oduc asymme ies.
Sou ce Ac
ΛAs
ΛAc
φAs
φ
Mass model 0.061 0.051 0.026 0.009
Angula accep ance 0.010 0.010 0.010 0.010
Angula esolu ion 0.008 0.008 0.005 0.005
To al 0.062 0.053 0.028 0.014
angle. Sys ema ic con ibu ions o he iple-p oduc unce ain y
budge a e summa ised in Table 3.
7. Summa y
A sea ch o he Λ0
b→Λφ decay is p esen ed based on a
da ase o 3.0 b
−1collec ed by he LHCb expe imen in 2011 and
2012. The decay is obse ed o he fi s ime wi h a significance
o 5.9 s anda d de ia ions including sys ema ic unce ain ies. The
b anching ac ion is ound o be
B(Λ0
b→Λφ)/10−6=5.18 ±1.04 (s a )
±0.35 (sys ) +0.50
−0.43 (B(B0→K0
Sφ))
±0.44( d/ Λ0
b).
T iple-p oduc asymme ies a e measu ed o be
Ac
Λ=−0.22 ±0.12 (s a ) ±0.06 (sys ),
As
Λ=0.13 ±0.12 (s a ) ±0.05 (sys ),
Ac
φ=−0.01 ±0.12 (s a ) ±0.03 (sys ),
As
φ=−0.07 ±0.12 (s a ) ±0.01 (sys ),
and a e consis en wi h ze o. Da a collec ed by he LHCb expe -
imen in he o hcoming yea s will imp o e he s a is ical p e-
cision o hese measu emen s and enable he dynamics o b →s
ansi ions in beau y ba yons o be p obed in g ea e de ail, which
will g ea ly enhance he each o sea ches o physics beyond he
SM.
Acknowledgemen s
We exp ess ou g a i ude o ou colleagues in he CERN ac-
cele 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 a he LHCb in-
s 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 (F ance); BMBF, DFG and MPG (Ge many);
INFN (I aly); FOM and NWO (The Ne he lands); MNiSW and NCN
(Poland); MEN/IFA (Romania); MinES and FANO (Russia); MinECo
(Spain); SNSF and SER (Swi ze land); NASU (Uk aine); STFC (Uni ed
Kingdom); NSF (USA). We acknowledge he compu ing esou ces
ha a e p o ided by CERN, IN2P3 (F ance), KIT and DESY (Ge -
many), INFN (I aly), SURF (The Ne he lands), PIC (Spain), G idPP
(Uni ed Kingdom), RRCKI and Yandex LLC (Russia), CSCS (Swi ze -
land), IFIN-HH (Romania), CBPF (B azil), PL-GRID (Poland) and OSC
(USA). We a e indeb ed o he communi ies behind he mul i-
ple open sou ce so wa e packages on which we depend. Indi id-
ual g oups o membe s ha e ecei ed suppo om A H Founda-
ion (Ge many), EPLANET, Ma ie Skłodowska-Cu ie Ac ions and ERC
(Eu opean Union), Conseil Géné al de Hau e-Sa oie, Labex ENIG-
MASS and OCEVU, Région Au e gne (F ance), RFBR and Yandex LLC
(Russia), GVA, Xun aGal and GENCAT (Spain), He chel Smi h Fund,
The Royal Socie y, Royal Commission o he Exhibi ion o 1851
and he Le e hulme T us (Uni ed Kingdom).
Re e ences
[1] Y. Shimizu, M. Tanimo o, K. Yamamo o, Supe symme y con ibu ions o CP
iola ions in b →sand b →d ansi ions aking accoun o new da a, Phys.
Re . D 87 (2013) 056004, a Xi :1212.6486.
[2] A. Da a, M. Imbeaul , D. London, B →φK∗, B →φKSand new physics, Phys.
Le . B 671 (2009) 256, a Xi :0811.2957.
[3] T. Mo oi, CP iola ion in B0→φKSin SUSY GUT wi h igh -handed neu inos,
Phys. Le . B 493 (2000) 366, a Xi :hep-ph/0007328.
[4] LHCb Collabo a ion, R. Aaij, e al., Measu emen o CP iola ion in B0
s→φφ
decays, Phys. Re . D 90 (2014) 052011, a Xi :1407.2222.
[5] LHCb Collabo a ion, R. Aaij, e al., Fi s measu emen o he CP- iola ing phase
in B0
s→φφ decays, Phys. Re . Le . 110 (2013) 241802, a Xi :1303.7125.
[6] Belle Collabo a ion, K. Abe, e al., Measu emen o ime-dependen CP- iola ing
asymme ies in B0→φK0
S, K+K−K0
S, and ηK0
Sdecays, Phys. Re . Le . 91
(2003) 261602, a Xi :hep-ex/0308035.
[7] BaBa Collabo a ion, J.P. Lees, e al., S udy o CP iola ion in Dali z-plo analy-
ses o B0→K+K−K0
S, B+→K+K−K+, and B+→K0
SK0
SK+, Phys. Re . D 85
(2012) 112010, a Xi :1201.5897.
[8] LHCb Collabo a ion, R. Aaij, e al., Measu emen o pola iza ion ampli udes
and CP asymme ies in B0→φK∗(892)0, J. High Ene gy Phys. 05 (2014) 069,
a Xi :1403.2888.
[9] M. Raidal, CP asymme y in B →φKSdecays in le - igh models and i s impli-
ca ions on Bsdecays, Phys. Re . Le . 89 (2002) 231803, a Xi :hep-ph/0208091.
[10] M. G onau, J.L. Rosne , T iple p oduc asymme ies in K, D(s)and B(s)decays,
Phys. Re . D 84 (2011) 096013, a Xi :1107.1232.
[11] S.K. Pa a, A. Kundu, CPT iola ion and iple-p oduc co ela ions in B decays,
Phys. Re . D 87 (11) (2013) 116005, a Xi :1305.1417.
[12] O. Lei ne , Z.J. Ajal ouni, Tes ing CP and ime e e sal symme ies wi h Λb→
ΛV(1−)decays, Nucl. Phys. B, P oc. Suppl. 174 (2007) 169, a Xi :hep-ph/
0610189.
[13] LHCb Collabo a ion, R. Aaij, e al., Measu emen s o he 0
b→J/ψ decay
ampli udes and he 0
bpola isa ion in pp collisions a
√s=7TeV, Phys. Le . B
724 (2013) 27, a Xi :1302.5578.
[14] LHCb Collabo a ion, R. Aaij, e al., Obse a ions o Λ0
b→ΛK+π−and Λ0
b→
ΛK+K−decays and sea ches o o he Λ0
band 0
bdecays o Λh+h−final
s a es, J. High Ene gy Phys. (2016), h p://dx.doi.o g/10.1007/JHEP05(2016)081,
a Xi :1603.00413.
[15] Hea y Fla o A e aging G oup, Y. Amhis, e al., A e ages o b-had on, c-had on,
and τ-lep on p ope ies as o summe 2014, a Xi :1412.7515, upda ed esul s
and plo s a ailable a h p://www.slac.s an o d.edu/xo g/h ag/.
[16] LHCb Collabo a ion, A.A. Al es J ., e al., The LHCb de ec o a he LHC, J. In-
s um. 3 (2008) S08005.
[17] LHCb Collabo a ion, R. Aaij, e al., LHCb de ec o pe o mance, In . J. Mod.
Phys. A 30 (2015) 1530022, a Xi :1412.6352.
[18] T. Sjös and, S. M enna, P. Skands, PYTHIA 6.4 physics and manual, J. High En-
e gy Phys. 05 (2006) 026, a Xi :hep-ph/0603175;
T. Sjös and, S. M enna, P. Skands, A b ie in oduc ion o PYTHIA 8.1, Compu .
Phys. Commun. 178 (2008) 852, a Xi :0710.3820.
[19] I. Belyae , e al., Handling o he gene a ion o p ima y e en s in Gauss, he
LHCb simula ion amewo k, J. Phys. Con . Se . 331 (2011) 032047.
[20] D.J. Lange, The E Gen pa icle decay simula ion package, Nucl. Ins um. Me h-
ods Phys. Res., Sec . A 462 (2001) 152.
[21] P. Golonka, Z. Was, PHOTOS Mon e Ca lo: a p ecision ool o QED co ec ions
in Zand Wdecays, Eu . Phys. J. C 45 (2006) 97, a Xi :hep-ph/0506026.
[22] Gean 4 Collabo a ion, J. Allison, e al., Gean 4 de elopmen s and applica ions,
IEEE T ans. Nucl. Sci. 53 (2006) 270;
Gean 4 Collabo a ion, S. Agos inelli, e al., Gean 4: a simula ion oolki , Nucl.
Ins um. Me hods Phys. Res., Sec . A 506 (2003) 250.
[23] M. Clemencic, e al., The LHCb simula ion applica ion, Gauss: design, e olu ion
and expe ience, J. Phys. Con . Se . 331 (2011) 032023.
[24] L. B eiman, J.H. F iedman, R.A. Olshen, C.J. S one, Classifica ion and Reg ession
T ees, Wadswo h in e na ional g oup, Belmon , Cali o nia, USA, 1984.
[25] R.E. Schapi e, Y. F eund, A decision- heo e ic gene aliza ion o on-line lea ning
and an applica ion o boos ing, J. Compu . Sys . Sci. 55 (1997) 119.
[26] Pa icle Da a G oup, K.A. Oli e, e al., Re iew o pa icle physics, Chin. Phys. C
38 (2014) 090001.
[27] G. Punzi, Sensi i i y o sea ches o new signals and i s op imiza ion, in:
L. Lyons, R. Moun , R. Rei meye (Eds.), S a is ical P oblems in Pa icle Physics,
As ophysics, and Cosmology, 2003, p. 79, a Xi :physics/0308063.
[28] BaBa Collabo a ion, B. Aube , e al., Measu emen o CP asymme ies in B0→
φK0and B0→K+K−K0
Sdecays, Phys. Re . D 71 (2005) 091102, a Xi :hep-ex/
0502019.
[29] LHCb Collabo a ion, R. Aaij, e al., S udy o B0
(s)→K0
Sh+h− decays wi h fi s
obse a ion o B0
s→K0
SK±π∓and B0
s→K0
Sπ+π−, J. High Ene gy Phys. 10
(2013) 143, a Xi :1307.7648.
[30] LHCb Collabo a ion, R. Aaij, e al., Obse a ion o CP iola ion in B±→DK±
decays, Phys. Le . B 712 (2012) 203;
The LHCb Collabo a ion / Physics Le e s B 759 (2016) 282–292 289
LHCb Collabo a ion, R. Aaij, e al., Obse a ion o CP iola ion in B±→DK±
decays, Phys. Le . B 713 (2012) 351, a Xi :1203.3662 (E a um).
[31] HERA-B Collabo a ion, I. Ab , e al., K∗0and φmeson p oduc ion in p o on–
nucleus in e ac ions a √s=41.6GeV, Eu . Phys. J. C 50 (2007) 315, a Xi :
hep-ex/0606049.
[32] S.M. Fla é, On he na u e o 0+mesons, Phys. Le . B 63 (1976) 228.
[33] LHCb Collabo a ion, R. Aaij, e al., S udy o he kinema ic dependences o 0
b
p oduc ion in pp collisions and a measu emen o he 0
b→+
cπ−b anching
ac ion, J. High Ene gy Phys. 08 (2014) 143, a Xi :1405.6842.
[34] LHCb Collabo a ion, R. Aaij, e al., Measu emen o he ack econs uc ion e -
ficiency a LHCb, J. Ins um. 10 (2015) P02007, a Xi :1408.1251.
[35] S.S. Wilks, The la ge-sample dis ibu ion o he likelihood a io o es ing com-
posi e hypo heses, Ann. Ma h. S a . 9 (1938) 60.
[36] K.S. C anme , Ke nel es ima ion in high-ene gy physics, Compu . Phys. Com-
mun. 136 (2001) 198, a Xi :hep-ex/0011057.
[37] M. Pi k, F.R. Le Dibe de , sPlo : a s a is ical ool o un old da a dis ibu-
ions, Nucl. Ins um. Me hods Phys. Res., Sec . A 555 (2005) 356, a Xi :
physics/0402083.
LHCb Collabo a ion
R. Aaij 39, C. Abellán Be e a 41, B. Ade a 38, M. Adinolfi 47, Z. Ajal ouni 5, S. Aka 6, J. Alb ech 10,
F. Alessio 39, M. Alexande 52, S. Ali 42, G. Alkhazo 31, P. Al a ez Ca elle 54, A.A. Al es J 58, S. Ama o 2,
S. Ame io 23, Y. Amhis 7, L. An 3,40, L. Ande lini 18, G. And eassi 40, M. And eo i 17,g, J.E. And ews 59,
R.B. Appleby 55, O. Aquines Gu ie ez 11, F. A chilli 39, P. d’A gen 12, A. A amono 36, M. A uso 60,
E. Aslanides 6, G. Au iemma 26,n, M. Baalouch 5, S. Bachmann 12, J.J. Back 49, A. Badalo 37, C. Baesso 61,
S. Bake 54, W. Baldini 17, R.J. Ba low 55, C. Ba schel 39, S. Ba suk 7, W. Ba e 39, V. Ba ozskaya 29,
V. Ba is a 40, A. Bay40, L. Beaucou 4, J. Beddow 52, F. Bedeschi 24, I. Bediaga 1, L.J. Bel 42, V. Bellee 40,
N. Belloli 21,k, I. Belyae 32, E. Ben-Haim 8, G. Benci enni 19, S. Benson 39,∗, J. Ben on 47, A. Be ezhnoy 33,
R. Be ne 41, A. Be olin23, F. Be i 15, M.-O. Be le 39, M. an Beuzekom 42, S. Bi ani 46, P. Billoi 8,
T. Bi d 55, A. Bi nk au 10, A. Bizze i 18,i, T. Blake 49, F. Blanc 40, J. Blouw 11, S. Blusk 60, V. Bocci 26,
A. Bonda 35, N. Bonda 31,39, W. Boni en o 16, A. Bo ghe esi 21,k, S. Bo ghi 55, M. Bo isyak 67,
M. Bo sa o 38, M. Boubdi 9, T.J.V. Bowcock 53, E. Bowen 41, C. Bozzi 17,39, S. B aun 12, M. B i sch 12,
T. B i on 60, J. B odzicka 55, E. Buchanan 47, C. Bu 55, A. Bu sche2, J. Buy ae 39, S. Cadeddu 16,
R. Calab ese 17,g, M. Cal i 21,k, M. Cal o Gomez 37,p, P. Campana 19, D. Campo a Pe ez 39, L. Cap io i 55,
A. Ca bone15,e, G. Ca boni 25,l, R. Ca dinale 20,j, A. Ca dini 16, P. Ca ni i 21,k, L. Ca son 51,
K. Ca alho Akiba 2, G. Casse 53, L. Cassina 21,k, L. Cas illo Ga cia 40, M. Ca aneo 39, Ch. Caue 10,
G. Ca alle o 20, R. Cenci 24, , M. Cha les 8, Ph. Cha pen ie 39, G. Cha zikons an inidis 46, M. Che de ille 4,
S. Chen 55, S.-F. Cheung 56, M. Ch zaszcz 41,27, X. Cid Vidal 39, G. Cieza ek 42, P.E.L. Cla ke 51,
M. Clemencic 39, H.V. Cli 48, J. Closie 39, V. Coco 58, J. Cogan 6, E. Cogne as 5, V. Cogoni 16, ,
L. Cojoca iu 30, G. Collazuol 23, , P. Collins 39, A. Come ma-Mon ells 12, A. Con u39, A. Cook 47,
M. Coombes 47, S. Coque eau 8, G. Co i 39, M. Co o 17,g, B. Cou u ie 39, G.A. Cowan 51, D.C. C aik 51,
A. C ocombe 49, M. C uz To es 61, S. Cunli e 54, R. Cu ie 54, C. D’Amb osio 39, E. Dall’Occo 42,
J. Dalseno 47, P.N.Y. Da id 42, A. Da is 58, O. De Aguia F ancisco 2, K. De B uyn 6, S. De Capua 55,
M. De Cian 12, J.M. De Mi anda 1, L. De Paula 2, P. De Simone 19, C.-T. Dean 52, D. Decamp 4,
M. Deckenho 10, L. Del Buono 8, N. Déléage 4, M. Demme 10, D. De kach 67, O. Deschamps 5,
F. De o i 39, B. Dey 22, A. Di Can o 39, F. Di Ruscio 25, H. Dijks a 39, F. Do dei 39, M. Do igo 40,
A. Dosil Suá ez 38, A. Do bnya 44, K. D eimanis 53, L. Du ou 42, G. Dujany 55, K. Dungs 39, P. Du an e 39,
R. Dzhelyadin 36, A. Dziu da 27, A. Dzyuba31, S. Easo 50,39, U. Egede 54, V. Ego yche 32, S. Eidelman 35,
S. Eisenha d 51, U. Ei schbe ge 10, R. Ekelho 10, L. Eklund 52, I. El Ri ai 5, Ch. Elsasse 41, S. Ely 60,
S. Esen 12, H.M. E ans 48, T. E ans 56, A. Falabella 15, C. Fä be 39, N. Fa ley 46, S. Fa y 53, R. Fay 53,
D. Fazzini 21,k, D. Fe guson 51, V. Fe nandez Albo 38, F. Fe a i 15, F. Fe ei a Rod igues 1,
M. Fe o-Luzzi 39, S. Filippo 34, M. Fio e 17,g, M. Fio ini 17,g, M. Fi lej 28, C. Fi zpa ick 40, T. Fiu owski 28,
F. Fleu e 7,b, K. Fohl 39, M. Fon ana 16, F. Fon anelli 20,j, D.C. Fo shaw 60, R. Fo y 39, M. F ank 39, C. F ei 39,
M. F osini 18, J. Fu 22, E. Fu a o 25,l, A. Gallas To ei a 38, D. Galli 15,e, S. Gallo ini 23, S. Gambe a 51,
M. Gandelman 2, P. Gandini 56, Y. Gao 3, J. Ga cía Pa diñas 38, J. Ga a Tico 48, L. Ga ido 37, P.J. Ga sed 48,
D. Gascon 37, C. Gaspa 39, L. Ga a di 10, G. Gazzoni 5, D. Ge ick 12, E. Ge sabeck 12, M. Ge sabeck 55,
T. Ge shon 49, Ph. Ghez 4, S. Gianì 40, V. Gibson 48, O.G. Gi a d 40, L. Giubega 30, V.V. Gligo o 39,
C. Göbel 61, D. Golubko 32, A. Golu in 54,39, A. Gomes1,a, C. Go i 21,k, M. G abalosa Gánda a 5,
R. G aciani Diaz 37, L.A. G anado Ca doso 39, E. G augés 37, E. G a e ini 41, G. G aziani 18, A. G ecu30,
P. G iffi h 46, L. G illo 12, O. G ünbe g 65, B. Gui 60, E. Gushchin 34, Yu. Guz 36,39, T. Gys 39,
T. Hada izadeh 56, C. Hadji asiliou 60, G. Hae eli 40, C. Haen 39, S.C. Haines 48, S. Hall 54, B. Hamil on 59,
X. Han 12, S. Hansmann-Menzeme 12, N. Ha new 56, S.T. Ha new 47, J. Ha ison 55, J. He 39, T. Head 40,
A. Heis e 9, K. Hennessy 53, P. Hen a d 5, L. Hen y 8, J.A. He nando Mo a a 38, E. an He wijnen 39,
290 The LHCb Collabo a ion / Physics Le e s B 759 (2016) 282–292
M. Heß 65, A. Hicheu 2, D. Hill 56, M. Hoballah 5, C. Hombach 55, L. Hongming 40, W. Hulsbe gen 42,
T. Humai 54, M. Hushchyn 67, N. Hussain 56, D. Hu chc o 53, M. Idzik 28, P. Il en 57, R. Jacobsson 39,
A. Jaege 12, J. Jalocha 56, E. Jans 42, A. Jawahe y59, M. John 56, D. Johnson 39, C.R. Jones 48, C. Jo am 39,
B. Jos 39, N. Ju ik 60, S. Kandybei 44, W. Kanso 6, M. Ka acson 39, T.M. Ka bach 39,†, S. Ka odia 52,
M. Kecke 12, M. Kelsey 60, I.R. Kenyon 46, M. Kenzie 39, T. Ke el 43, E. Khai ullin 67, B. Khanji 21,39,k,
C. Khu ewa hanakul 40, T. Ki n 9, S. Kla e 55, K. Klimaszewski 29, M. Kolpin 12, I. Koma o 40,
R.F. Koopman 43, P. Koppenbu g 42,39, M. Kozeiha 5, L. K a chuk 34, K. K eplin 12, M. K eps 49,
P. K oko ny 35, F. K use 10, W. K zemien 29, W. Kucewicz 27,o, M. Kucha czyk 27, V. Kud ya se 35,
A.K. Kuonen40, K. Ku ek 29, T. K a a skheliya 32, D. Laca e e 39, G. La e y 55,39, A. Lai 16, D. Lambe 51,
G. Lan anchi 19, C. Langenb uch 49, B. Langhans 39, T. La ham 49, C. Lazze oni 46, R. Le Gac 6,
J. an Lee dam42, J.-P. Lees 4, R. Le è e 5, A. Lefla 33,39, J. Le ançois 7, E. Lemos Cid 38, O. Le oy 6,
T. Lesiak 27, B. Le e ing on 12, Y. Li 7, T. Likhomanenko 67,66, R. Lindne 39, C. Linn 39, F. Lione o 41,
B. Liu 16, X. Liu 3, D. Loh 49, I. Longs a 52, J.H. Lopes 2, D. Lucchesi 23, , M. Lucio Ma inez 38, H. Luo 51,
A. Lupa o 23, E. Luppi 17,g, O. Lup on 56, N. Lusa di 22, A. Lusiani24, X. Lyu 62, F. Mache e 7, F. Maciuc 30,
O. Mae 31, K. Magui e 55, S. Malde 56, A. Malinin 66, G. Manca 7, G. Mancinelli 6, P. Manning 60,
A. Mapelli 39, J. Ma a as 5, J.F. Ma chand 4, U. Ma coni 15, C. Ma in Beni o 37, P. Ma ino 24, , J. Ma ks 12,
G. Ma ello i 26, M. Ma in 6, M. Ma inelli 40, D. Ma inez San os 38, F. Ma inez Vidal 68,
D. Ma ins Tos es 2, L.M. Massac ie 7, A. Massa e i 1, R. Ma e 39, A. Ma had49, Z. Ma he 39,
C. Ma euzzi 21, A. Mau i 41, B. Mau in 40, A. Mazu o 46, M. McCann 54, J. McCa hy 46, A. McNab 55,
R. McNul y 13, B. Meadows 58, F. Meie 10, M. Meissne 12, D. Melnychuk 29, M. Me k 42, A. Me li 22,u,
E. Michielin 23, D.A. Milanes 64, M.-N. Mina d 4, D.S. Mi zel 12, J. Molina Rod iguez 61, I.A. Mon oy 64,
S. Mon eil 5, M. Mo andin 23, P. Mo awski 28, A. Mo dà 6, M.J. Mo ello 24, , J. Mo on 28, A.B. Mo is 51,
R. Moun ain 60, F. Muheim 51, D. Mülle 55, J. Mülle 10, K. Mülle 41, V. Mülle 10, M. Mussini 15,
B. Mus e 40, P. Naik 47, T. Nakada 40, R. Nandakuma 50, A. Nandi56, I. Nas e a 2, M. Needham 51,
N. Ne i 22, S. Neube 12, N. Neu eld 39, M. Neune 12, A.D. Nguyen 40, C. Nguyen-Mau 40,q, V. Niess 5,
S. Nieswand 9, R. Nie 10, N. Niki in 33, T. Nikodem 12, A. No oselo 36, D.P. O’Hanlon 49,
A. Oblakowska-Mucha28, V. Ob az so 36, S. Ogil y 52, O. Okh imenko 45, R. Oldeman 16,48, ,
C.J.G. Onde wa e 69, B. Oso io Rod igues 1, J.M. O alo a Goicochea 2, A. O o 39, P. Owen 54,
A. Oyangu en 68, A. Palano14,d, F. Palombo 22,u, M. Palu an 19, J. Panman 39, A. Papanes is 50,
M. Pappagallo 52, L.L. Pappala do 17,g, C. Pappenheime 58, W. Pa ke 59, C. Pa kes 55, G. Passale a 18,
G.D. Pa el 53, M. Pa el 54, C. Pa ignani 20,j, A. Pea ce55,50, A. Pelleg ino 42, G. Penso 26,m,
M. Pepe Al a elli 39, S. Pe azzini 15,e, P. Pe e 5, L. Pesca o e 46, K. Pe idis 47, A. Pe olini 20,j,
M. Pe uzzo 22, E. Pica os e Olloqui 37, B. Pie zyk 4, M. Pikies 27, D. Pinci 26, A. Pis one20, A. Piucci 12,
S. Play e 51, M. Plo Casasus 38, T. Poikela 39, F. Polci 8, A. Poluek o 49,35, I. Polyako 32, E. Polyca po 2,
A. Popo 36, D. Popo 11,39, B. Popo ici 30, C. Po e a 2, E. P ice 47, J.D. P ice 53, J. P iscianda o 38,
A. P i cha d 53, C. P ou e 47, V. Puga ch 45, A. Puig Na a o 40, G. Punzi 24,s, W. Qian 56, R. Quagliani 7,47,
B. Rachwal 27, J.H. Rademacke 47, M. Rama 24, M. Ramos Pe nas 38, M.S. Rangel 2, I. Raniuk 44,
G. Ra en 43, F. Redi 54, S. Reiche 55, A.C. dos Reis1, V. Renaudin 7, S. Riccia di 50, S. Richa ds 47,
M. Rihl 39, K. Rinne 53,39, V. Ri es Molina 37, P. Robbe 7, A.B. Rod igues 1, E. Rod igues 55,
J.A. Rod iguez Lopez 64, P. Rod iguez Pe ez 55, A. Rogozhniko 67, S. Roise 39, V. Romano sky 36,
A. Rome o Vidal38, J.W. Ronayne 13, M. Ro ondo 23, T. Ru 39, P. Ruiz Valls 68, J.J. Sabo ido Sil a 38,
N. Sagido a 31, B. Sai a 16, , V. Salus ino Guima aes 2, C. Sanchez Mayo domo 68, B. Sanma in Sedes 38,
R. San acesa ia 26, C. San ama ina Rios 38, M. San ima ia 19, E. San o e i 25,l, A. Sa i19,m, C. Sa iano 26,n,
A. Sa a25, D.M. Saunde s 47, D. Sa ina 32,33, S. Schael 9, M. Schille 39, H. Schindle 39, M. Schlupp 10,
M. Schmelling 11, T. Schmelze 10, B. Schmid 39, O. Schneide 40, A. Schoppe 39, M. Schubige 40,
M.-H. Schune 7, R. Schwemme 39, B. Sciascia 19, A. Sciubba 26,m, A. Semenniko 32, A. Se gi 46, N. Se a 41,
J. Se ano 6, L. Ses ini 23, P. Sey e 21, M. Shapkin 36, I. Shapo al 17,44,g, Y. Shcheglo 31, T. Shea s 53,
L. Shekh man 35, V. She chenko 66, A. Shi es 10, B.G. Siddi 17, R. Sil a Cou inho 41, L. Sil a de Oli ei a 2,
G. Simi 23,s, M. Si endi 48, N. Skidmo e 47, T. Skwa nicki 60, E. Smi h 54, I.T. Smi h 51, J. Smi h 48,
M. Smi h 55, H. Snoek 42, M.D. Sokolo 58, F.J.P. Sole 52, F. Soom o 40, D. Souza 47, B. Souza De Paula 2,
B. Spaan 10, P. Sp adlin 52, S. S idha an 39, F. S agni 39, M. S ahl 12, S. S ahl 39, S. S e ko a 54,
O. S einkamp 41, O. S enyakin 36, S. S e enson 56, S. S oica 30, S. S one 60, B. S o aci 41, S. S acka 24, ,
