Search for decays of neutral beauty mesons into four muons

Abstract

(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image)

Abstract

A search for the non-resonant decays B [Stack ^sub s ^ ^sup 0^ ][arrow right][mu] ^sup +^ [mu] ^sup -^ [mu] ^sup +^ [mu] ^sup -^ and B ^sup 0^ [arrow right] [mu] ^sup +^ [mu] ^sup -^ [mu] ^sup +^ [mu] ^sup -^ is presented. The measurement is performed using the full Run 1 data set collected in proton-proton collisions by the LHCb experiment at the LHC. The data correspond to integrated luminosities of 1 and 2 fb^sup -1^ collected at centre-of-mass energies of 7 and 8 TeV, respectively. No signal is observed and upper limits on the branching fractions of the non-resonant decays at 95% confidence level are determined to be ...... ......[Figure not available: see fulltext.]

Published for SISSA by Springer

Received: November 24, 2016

Revised: February 2, 2017 Accepted: February 18, 2017

Published: March 1, 2017

Search for decays of neutral beauty mesons into four muons

JHEP03(2017)001

The LHCb collaboration

E-mail: mailto:[email protected]

Web End [email protected]

Abstract: A search for the non-resonant decays B0s ! [notdef]+[notdef][notdef]+[notdef] and B0 ! [notdef]+[notdef][notdef]+[notdef]

is presented. The measurement is performed using the full Run 1 data set collected in proton-proton collisions by the LHCb experiment at the LHC. The data correspond to integrated luminosities of 1 and 2 fb1 collected at centre-of-mass energies of 7 and 8 TeV, respectively. No signal is observed and upper limits on the branching fractions of the non-resonant decays at 95% con dence level are determined to be

B(B0s ! [notdef]+[notdef][notdef]+[notdef]) < 2.5 109,

B(B0 ! [notdef]+[notdef][notdef]+[notdef]) < 6.9 1010.

Keywords: B physics, Flavour Changing Neutral Currents, Hadron-Hadron scattering (experiments), Rare decay, Supersymmetry

ArXiv ePrint: 1611.07704

Open Access, Copyright CERN,for the bene t of the LHCb Collaboration. Article funded by SCOAP3.

doi:http://dx.doi.org/10.1007/JHEP03(2017)001

Web End =10.1007/JHEP03(2017)001

Contents

1 Introduction 1

2 Detector and simulation 3

3 Event selection 3

4 Selection e ciencies and systematic uncertainties 4

5 Normalisation 6

6 Results 8

7 Conclusion 9

The LHCb collaboration 14

1 Introduction

The rare decays B0(s) ! [notdef]+[notdef][notdef]+[notdef] proceed through b ! d(s) avour-changing neutral-

current processes, which are strongly suppressed in the Standard Model (SM).1 In the main non-resonant SM amplitude, one muon pair is produced via amplitudes described by electroweak loop diagrams and the other is created by a virtual photon as shown in gure 1(a). The branching fraction of the non-resonant B0s ! [notdef]+[notdef][notdef]+[notdef] decay is expected

to be 3.5 1011 [1].

Theories extending the SM can signi cantly enhance the B0(s) ! [notdef]+[notdef][notdef]+[notdef] decay rate by contributions of new particles. For example, in minimal supersymmetric models (MSSM), the decay can proceed via new scalar S and pseudoscalar P sgoldstino particles, which both decay into a dimuon nal state as shown in gure 1(b). There are two types of couplings between sgoldstinos and SM fermions. Type-I couplings describe interactions between a sgoldstino and two fermions, where the coupling strength is proportional to the fermion mass. Type-II couplings describe a four-particle vertex, where a scalar and a pseudoscalar sgoldstino interact with two fermions. Branching fractions up to B(B0s !

SP ) 104 and B(B0 ! SP ) 107 are possible [2]. Sgoldstinos can decay into a pair of

photons or a pair of charged leptons [3]. In this analysis the muonic decay is considered, as the coupling to electrons is smaller and the large -lepton mass limits the available phase space. The branching fractions of the sgoldstino decays strongly depend on the model parameters such as the sgoldstino mass and the supersymmetry breaking scale. In the search for + ! p[notdef]+[notdef] decays the HyperCP collaboration found an excess of events,

1The inclusion of charge-conjugate processes is implied throughout.

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+

+

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+

b

c

J/

b

P

W

b

d, s

Figure 1. Feynman diagrams for (a) the non-resonant B0(s) ! [notdef]+[notdef][notdef]+[notdef] decay, (b) a supersym-

metric B0(s) ! S(! [notdef]+[notdef])P (! [notdef]+[notdef]) decay and (c) the resonant B0s ! J/ (! [notdef]+[notdef])(! [notdef]+[notdef])

decay (see text).

which is consistent with the decay + ! P p with P ! [notdef]+[notdef] and a pseudoscalar mass of

m(P ) = 214.3 0.5 MeV [4].

So far only limits on the SM and MSSM branching fractions at 95% con dence level have been measured by LHCb based on the data recorded in 2011 [5] to be

B(B0s ! [notdef]+[notdef][notdef]+[notdef]) < 1.6 108,

B(B0 ! [notdef]+[notdef][notdef]+[notdef]) < 6.6 109,

B(B0s ! S(! [notdef]+[notdef])P (! [notdef]+[notdef])) < 1.6 108,

B(B0 ! S(! [notdef]+[notdef])P (! [notdef]+[notdef])) < 6.3 109.

These limits are based on assumed sgoldstino masses of m(S) = 2.5 GeV/c2, which is approximately the central value of the allowed mass range, and m(P ) = 214.3 MeV/c2.

The dominant SM decays of neutral B mesons into four muons proceed through resonances like , J/ and (2S). The most frequent of these decays is B0s ! J/ , where

both the J/ and the mesons decay into a pair of muons, as shown in gure 1(c). In the following, this decay is referred to as the resonant decay mode and treated as a background. From the product of the measured branching fractions of the underlying decays

B(B0s ! J/ ), B(J/ ! [notdef]+[notdef]), and B(! [notdef]+[notdef]) [6] its branching fraction is calculated

to be (1.83 0.18) 108.

In this paper a search for the non-resonant SM process, and for the MSSM-induced B0(s) ! [notdef]+[notdef][notdef]+[notdef] decays is presented, using pp collision data recorded by the LHCb detec

tor during LHC Run 1. Potentially contributing sgoldstinos are assumed to be short lived, such that they do not form a displaced vertex. The analysed data correspond to integrated luminosities of 1 and 2 fb1 collected at centre-of-mass energies of 7 and 8 TeV, respectively. The branching fraction is measured relative to the decay B+ ! J/ (! [notdef]+[notdef])K+,

which gives a clean signal with a precisely measured branching fraction [6]. This yields a signi cant improvement compared to the previous measurement, where the use of the B0 ! J/ K 0 decay as normalisation mode resulted in a large systematic uncertainty

originating from the S-wave fraction and the less precisely measured branching fraction. The advantage of normalising to a well-known B meson decay is that dominant systematic uncertainties originating mainly from the bb cross-section cancel in the ratio.

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2 Detector and simulation

The LHCb detector [7, 8] is a single-arm forward spectrometer covering the pseudorapidity range 2 < < 5, designed for the study of particles containing b or c quarks. The detector includes a high-precision tracking system consisting of a silicon-strip vertex detector surrounding the pp interaction region, a large-area silicon-strip detector located upstream of a dipole magnet with a bending power of about 4 Tm, and three stations of silicon-strip detectors and straw drift tubes placed downstream of the magnet. The tracking system provides a measurement of momentum, p, of charged particles with a relative uncertainty that varies from 0.5% at low momentum to 1.0% at 200 GeV/c. The minimum distance of a track to a primary vertex (PV), the impact parameter, is measured with a resolution of (15 + 29/pT) m, where pT is the component of the momentum transverse to the beam, in GeV/c. Di erent types of charged hadrons are distinguished using information from two ring-imaging Cherenkov (RICH) detectors. Photons, electrons and hadrons are identi ed by a calorimeter system consisting of scintillating-pad and preshower detectors, an electromagnetic calorimeter and a hadronic calorimeter. Muons are identi ed by a system composed of alternating layers of iron and multiwire proportional chambers.

In the simulation, pp collisions are generated using Pythia [9, 10] with a speci c LHCb con guration [11]. Decays of hadronic particles are described by EvtGen [12], in which nal-state radiation is generated using Photos [13]. The interaction of the generated particles with the detector, and its response, are implemented using the Geant4 toolkit [14, 15] as described in ref. [16].

3 Event selection

The online event selection is performed by a trigger, which consists of a hardware stage, based on information from the calorimeter and muon systems, followed by a software stage, which applies a full event reconstruction. In this analysis candidate events are rst required to pass the hardware trigger, which for 7 TeV (8 TeV) data selects events with at least one muon with a transverse momentum of pT > 1.48 GeV/c (pT > 1.76 GeV/c) or at least one pair of muons with the product of the transverse momenta larger than (1.296)2 GeV2/c2 ((1.6)2 GeV2/c2). In the subsequent software trigger, at least one of the nal-state particles is required to have pT > 1 GeV/c and an impact parameter larger than 100 m with respect to all PVs in the event.

In the o ine selection, the B0(s) decay vertex is constructed from four good quality muon candidates that form a common vertex and have a total charge of zero. The vertex is required to be signi cantly displaced from any PV. Among the four nal-state muons, there are four possible dimuon combinations with zero charge. In all four combinations, the mass windows corresponding to the (950{1090 MeV/c2), J/ (3000{3200 MeV/c2) and (2S) (3600{3800 MeV/c2) resonances are vetoed. This e ciently suppresses any background from any of the three mentioned resonances to a negligible level. Contributions of other charmonium states are found to be negligible.

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The MatrixNet (MN) [17], a multivariate classi er based on a Boosted Decision Tree [18, 19], is applied in order to remove combinatorial background, where a candidate B0(s) vertex is constructed from four muons that do not originate from a single B meson decay. The input variables are the following properties of the B0(s) candidate: the decay time, the vertex quality, the momentum and transverse momentum, the cosine of the direction angle (DIRA), and the smallest impact parameter chisquare ([notdef]2IP) with respect to any PV, where [notdef]2IP is de ned as the di erence between the vertex- t [notdef]2 of a PV reconstructed with and without the B0(s) candidate. The DIRA is de ned as the angle between the momentum of the reconstructed B0(s) candidate and the vector from the PV with the smallest [notdef]2IP to the B0(s) decay vertex. As training samples, simulated B0s ! [notdef]+[notdef][notdef]+[notdef]

and B0 ! [notdef]+[notdef][notdef]+[notdef] events, generated with a uniform probability across the decay phase

space, are used as a signal proxy. Before training, the signal simulation is weighted to correct for known discrepancies between data and simulation as described later. The background sample is taken from the far and the near sidebands in data as de ned in table 1. In order to verify that the classi cation of each event is unbiased, 10-fold cross-validation [20] is employed.

Background arising from misidentifying one or more particles is suppressed by applying particle identi cation (PID) requirements. Information from the RICH system, the calorimeters and the muon system is used to calculate the di erence in log-likelihood between the hypothesis of a nal-state particle being a pion or a muon, DLL.

Events in the signal region are not examined until the analysis is nalised. Events outside the signal region are split into the far sidebands, used to calculate the expected background yield, and the near sidebands, used to optimise the cuts on the MN response and the minimum DLL values of the four muon candidates in the nal state. The optimization of the cuts is performed on a two-dimensional grid maximising the gure of merit [21]

FoM = "signal /2 +

qNexpectedbkg "bkg.

The intended signi cance in terms of standard deviations () is set to three. Very similar selection criteria are found when using ve. The expected background yield before applying the MN and PID selection, Nexpectedbkg, is determined from a t to the events in the near sidebands using an exponential function. For each grid point the background e ciency,

"bkg, is measured using events from the near sidebands. The signal e ciency, "signal, is measured for each grid point using simulated B0(s) ! [notdef]+[notdef][notdef]+[notdef] decays. Lacking a model

for non-resonant B0(s) ! [notdef]+[notdef][notdef]+[notdef] simulation, the selection of the preceding measurement

was developed on B0s ! J/ (! [notdef]+[notdef])(! [notdef]+[notdef]) data. Now that a suitable simulation

model is available, signi cant improvements in terms of signal e ciency and background rejection are made by employing a multivariate classi er and being able to measure the selection e ciency from simulation.

4 Selection e ciencies and systematic uncertainties

The optimal working point corresponds to signal e ciencies of (0.580 0.003)% and

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Mass interval ( MeV/c2)

Near sidebands [5020, 5220] and [5426, 5626]

Far sidebands [4360, 5020] and [5626, 6360] Signal region [m(B0) 60, m(B0s) + 60]

B0s search region [m(B0s) 40, m(B0s) + 40]

B0 search region [m(B0) 40, m(B0) + 40]

Table 1. De nitions of intervals in the B0 and B0s reconstructed invariant mass distributions.

(0.568 0.003)% for the B0s ! [notdef]+[notdef][notdef]+[notdef] and B0 ! [notdef]+[notdef][notdef]+[notdef] decay modes, respec

tively. Sources of peaking background such as B0 ! K 0[notdef]+[notdef], in which the kaon and the

pion originating from the K decay are misidenti ed as muons, are reduced to a negligible level by the optimised selection. The e ciencies for the MSSM processes are measured using simulated samples of the B0(s) ! S(! [notdef]+[notdef])P (! [notdef]+[notdef]) decays, where the B0(s) me

son decays into a pseudoscalar sgoldstino with a mass of 214.3 MeV/c2 [4] and a scalar sgoldstino with a mass of 2.5 GeV/c2. Both the P and S particles are simulated with a decay width of = 0.1 MeV/c2, which corresponds to a prompt decay. The measured e ciencies are the same for the B0s and the B0 decays and amount to (0.648 0.003)%.

The di erence between the SM and the MSSM e ciencies originates from the fact that in the case of the decay proceeding via P and S sgoldstinos, the decay products are more likely to be within the acceptance of the LHCb detector. In order to test the dependence of the measured B0(s) ! S(! [notdef]+[notdef])P (! [notdef]+[notdef]) branching fractions on the mass of the

scalar sgoldstino, the selection e ciency is measured in bins of dimuon invariant mass while requiring the corresponding other dimuon mass to be between 200 and 950 MeV/c2. An

e ciency variation of O(20%) is observed.

The selection applied to the normalisation mode B+ ! J/ (! [notdef]+[notdef])K+ di ers from

that applied to the signal modes in the PID criteria and that no multivariate analysis technique is applied. The total e ciency is (1.495 0.006)%. The uncertainties on the ef-

ciencies are driven by the limited number of simulated events and are treated as systematic uncertainties of 0.4{0.5%.

The total e ciency is calculated as the product of the e ciencies of the di erent stages of the selection. As an alternative to the trigger e ciency calculated on simulation, the value is calculated on B+ ! J/ (! [notdef]+[notdef])K+ data [22] and a systematic uncertainty of

3% is assigned corresponding to the relative di erence. The e ciency of the MN classi er to select the more frequent decay B0s ! J/ (! [notdef]+[notdef])(! K+K) is compared between

data and simulation. The relative di erence of 0.3% is assigned as a systematic uncertainty. Another source of systematic uncertainty arises from the track nding e ciency. Again, values obtained from data [23] and simulation are compared and the deviation is treated as a correction factor for the e ciency, while the uncertainty on the deviation, 1.7%, is assigned as a systematic uncertainty.

In general the agreement in the observables used in the selection between data and simulation is very good, although there are some distributions that are known to deviate.

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Therefore, the gradient boosting reweighting technique [24] is used to calculate weights that correct for di erences between data and simulation in B0s ! J/ (! [notdef]+[notdef])(! K+K).

The weighting is performed in the track multiplicity, the B transverse momentum, the [notdef]2 of

the decay vertex t and the [notdef]2IP. The rst two are chosen because they are correlated with the PID variables and the latter two dominate the feature ranking obtained from the MN training. These weights are applied to the B0(s) ! [notdef]+[notdef][notdef]+[notdef] and B+ ! J/ (! [notdef]+[notdef])K+

simulation samples, and are used to calculate the MN and the PID e ciencies. In order to account for inaccuracies of this method resulting from the kinematic and topological di erences between the decay modes, systematic uncertainties of 3.6% are assigned based on the di erence of the MN e ciency on B0(s) ! [notdef]+[notdef][notdef]+[notdef] and B0s ! J/ (! [notdef]+[notdef])(!

K+K). For the B+ ! J/ (! [notdef]+[notdef])K+ decay mode, the e ciencies are measured

with and without weights and the observed di erence of 2.3% is assigned as systematic uncertainty.

In order to determine accurate e ciencies of the applied PID requirements, calibration samples of muons from J/ ! [notdef]+[notdef] and ! [notdef]+[notdef] decays and of kaons from

D + ! D0(! K+)+ decays are used. The relative frequency for kaons and muons

to pass the PID criteria is calculated in bins of track multiplicity, particle momentum and pseudorapidity. Di erent binning schemes are tested and the observed di erences in the e ciencies of 1% for B+ ! J/ (! [notdef]+[notdef])K+ and 0.5% for B0(s) ! [notdef]+[notdef][notdef]+[notdef] are assigned

as systematic uncertainties. Additionally, 3% of the simulated B0(s) ! [notdef]+[notdef][notdef]+[notdef] decays contain muons with low transverse momentum outside the kinematic region covered by the calibration data. This fraction is assigned as a systematic uncertainty. Candidates that have a reconstructed invariant mass within 40 MeV/c2 around the known B0(s) mass,

which corresponds to 2 of the mass resolution, are treated as signal candidates. The ac

curacy of the e ciency of this cut is evaluated on B0s ! J/ (! [notdef]+[notdef])(! K+K) data.

A systematic uncertainty of 0.5% corresponding to the relative di erence of the e ciency measured on data and simulation is assigned. Systematic uncertainties of 0.9% and 0.5% in the case of B0(s) ! [notdef]+[notdef][notdef]+[notdef] and B+ ! J/ (! [notdef]+[notdef])K+ originate from the imper

fections of the e ciency of the event reconstruction due to soft photon radiation and 0.6% from mismatching of track segments between di erent tracking stations in the detector, which is measured using simulated events. All relevant sources of systematic uncertainty along with the total values are summarised in table 2. The most signi cant improvements with regard to the preceding measurement are the larger available data sample, and the choice of the B+ ! J/ (! [notdef]+[notdef])K+ decay as normalisation mode, which has the advan

tage of a precisely measured branching fraction and the absence of an additional systematic

uncertainty originating from the S-wave correction.

5 Normalisation

The B+ ! J/ (! [notdef]+[notdef])K+ signal yield is determined by performing an unbinned ex

tended maximum likelihood t to the K+[notdef]+[notdef] invariant mass distribution. In this t the J/ mass is constrained [25] to the world average [6]. The normalisation yield is found to be N(B+ ! J/ (! [notdef]+[notdef])K+) = 687890 920. The J/ K+ mass spectrum along

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Figure 2. Fit to the B+ ! J/ (! [notdef]+[notdef])K+ invariant mass distribution. The signal contribution

is modelled by a Hypatia2 [26] function (blue dotted line), the combinatorial background by an exponential function (green dash-dotted line). Partially reconstructed decays, such as B0 ! J/ K 0

where one pion is not reconstructed, are modelled by a Gaussian function with an exponential tail towards the lower mass side (red dashed line). Data are shown by black dots.

with the t result is shown in gure 2. A systematic uncertainty of 0.3% is assigned to the determined B+ ! J/ (! [notdef]+[notdef])K+ yield by using an alternative t model and performing

a binned extended maximum likelihood t.

The B0(s) ! [notdef]+[notdef][notdef]+[notdef] branching fraction is calculated as

B(B0(s) ! [notdef]+[notdef][notdef]+[notdef]) = N(B0(s) ! [notdef]+[notdef][notdef]+[notdef]) d,s,

with

d,s = "(B+ ! J/ (! [notdef]+[notdef])K+) B(B+ ! J/ (! [notdef]+[notdef])K+)

"(B0(s) ! [notdef]+[notdef][notdef]+[notdef]) N(B+ ! J/ (! [notdef]+[notdef])K+)

where N(B+ ! J/ (! [notdef]+[notdef])K+) and N(B0(s) ! [notdef]+[notdef][notdef]+[notdef]) are the observed yields of

the normalisation and the signal channel, respectively. The ratio between the production rates of B0s and B0 was measured by LHCb to be fs/fd = 0.259 0.015 [27]. The measure

ment was performed using pp collision data at ps = 7 TeV, but found to be stable between ps = 7 TeV and 8 TeV by a previous LHCb measurement [28]. The ratio between the B+ and B0 production rates is assumed to be unity. As a consequence fs/fu is equal to fs/fd.

The single event sensitivities, d,s, amount

SMs = (8.65 0.80) 1010, SMd = (2.29 0.16) 1010, MSSMs = (7.75 0.72) 1010, MSSMd = (2.01 0.14) 1010,

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fu fd,s ,

for the B0s and the B0 decay modes in the SM and in the MSSM scenario. Here, the uncertainties are the combined values of the statistical uncertainty on the

B+ ! J/ (! [notdef]+[notdef])K+ yield and the systematic uncertainty. In the case of s the

systematic uncertainty is dominated by the ratio of fu/fs and in the case of d by the weighting procedure applied to correct for the di erence between data and simulation.

The individual sources of systematic uncertainties given in table 2 are assumed to be uncorrelated and are combined quadratically. The total systematic uncertainty is 9.2% for the B0s decay and 7.2% for the B0 decay. These values are small compared to the statistical uncertainty on the expected number of background events in the B0 and B0s search regions.

The whole analysis strategy is cross-checked by measuring the B0s ! J/ (! [notdef]+[notdef])(!

[notdef]+[notdef]) branching fraction. The obtained value has a precision of 20% and is compatible with the product of the branching fractions of the underlying decays taken from ref. [6].

The number of expected background events is determined by tting an exponential function to the far sidebands of m([notdef]+[notdef][notdef]+[notdef]). Extrapolating and integrating the tted function in 40 MeV/c2 wide windows around the B0(s) meson masses yields the number of

expected background events,

Nexpectedbkg(B0) = 0.55+0.240.19 (stat) 0.20 (syst) and Nexpectedbkg(B0s) = 0.47+0.230.18 (stat) 0.18 (syst).

The statistical uncertainty is the combination of the Poissonian uncertainty originating from the limited size of the data sample and the uncertainty on the t parameters. As an alternative t model a second-order polynomial is used and the di erence between these background expectations is assigned as a systematic uncertainty.

6 Results

The nal distribution of the reconstructed mass of the four muon system is shown in gure 3. No candidates are observed in either the B0 or the B0s search region, which is consistent with the expected background yield.

The Hybrid CLs procedure [29{31], with log-normal priors to account for uncertainties of both background and e ciency estimations, is used to convert the observations into upper limits on the corresponding branching fractions. The exclusion at 95% con dence level assuming the SM single event sensitivities is shown in gure 4. The result for the corresponding MSSM values is presented in gure 5. The limits on the branching fractions of the B0s and B0 decays are anti-correlated. Replacing the log-normal priors by gamma distributions yields the same results.

Assuming negligible cross-feed between the B0s and the B0 search regions, the observed upper limits on the branching fractions at 95% con dence level are found to be

B(B0s ! [notdef]+[notdef][notdef]+[notdef]) < 2.5 109,

B(B0 ! [notdef]+[notdef][notdef]+[notdef]) < 6.9 1010,

B(B0s ! S(! [notdef]+[notdef])P (! [notdef]+[notdef])) < 2.2 109,

B(B0 ! S(! [notdef]+[notdef])P (! [notdef]+[notdef])) < 6.0 1010.

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Source Value [%] Selection e ciency 0.4 0.5

Trigger e ciency 3.0

MN e ciency 0.3 Track nding e ciency 1.7 Weighting B0(s) ! [notdef]+[notdef][notdef]+[notdef] 3.6

Weighting B+ ! J/ (! [notdef]+[notdef])K+ 2.3

PID binning B+ ! J/ (! [notdef]+[notdef])K+ 1.0

PID binning B0(s) ! [notdef]+[notdef][notdef]+[notdef] 0.5

Kinematic coverage of PID calibration data 3.0

40 MeV/c2 search region e ciency 0.5

Soft photon radiation B0(s) ! [notdef]+[notdef][notdef]+[notdef] 0.9

Soft photon radiation B+ ! J/ (! [notdef]+[notdef])K+ 0.5

Track segments mismatching 0.6

Normalisation t 0.3 fu/fs 5.8

B(B+ ! J/ K+) 3.0 B(J/ ! [notdef]+[notdef]) 0.1

Combined s SM 9.2

Combined d SM 7.2

Combined s MSSM 9.2 Combined d MSSM 7.2

Table 2. Summary of systematic uncertainties a ecting the single event sensitivities along with the total systematic uncertainty calculated by adding up the individual components in quadrature. The dominating uncertainty arising from fu/fs only contributes to s. The uncertainty of the stated selection e ciencies arising from the limited number of simulated events is 0.5% for B0 !

[notdef]+[notdef][notdef]+[notdef] and 0.4% for all other considered decay modes.

7 Conclusion

In summary, a search for non-resonant B0(s) ! [notdef]+[notdef][notdef]+[notdef] decays has been presented.

In addition, the sensitivity to a speci c MSSM scenario has been probed. The applied selection focuses on nding four muon tracks that form a common vertex. For the SM scenario and the MSSM decay through short-lived scalar and pseudoscalar new particles, the limits set by the previous measurement performed by LHCb on a subset of the present data, are improved by a factor of 6.4 (7.3) for the SM (MSSM) mode in the case of the B0s decay and by a factor of 9.5 (10.5) in the case of the B0 decay.

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Figure 3. Mass distribution of selected B0(s) ! [notdef]+[notdef][notdef]+[notdef] events observed in 3 fb1 of data in all

considered B mass regions. Background (red line) is modelled by an exponential function. Signal subregions for B0 and B0s searches are also shown. The error bars on the individual points with n entries are pn.

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[notdef]+[notdef][notdef]+[notdef]) parameters plane.

Acknowledgments

We express our gratitude to our colleagues in the CERN accelerator departments for the excellent performance of the LHC. We thank the technical and administrative sta at the LHCb institutes. We acknowledge support from CERN and from the national

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+

)

(P

B

+ ) [

10

9

]

Figure 5. Expected and observed 95% CL exclusion in B(B0 ! S(! [notdef]+[notdef])P (! [notdef]+[notdef])) vs. B(B0s ! S(! [notdef]+[notdef])P (! [notdef]+[notdef])) parameters plane with scalar and pseudoscalar S and P

as described in section 3.

agencies: CAPES, CNPq, FAPERJ and FINEP (Brazil); NSFC (China); CNRS/IN2P3 (France); BMBF, DFG and MPG (Germany); INFN (Italy); FOM and NWO (The Netherlands); MNiSW and NCN (Poland); MEN/IFA (Romania); MinES and FASO (Russia); MinECo (Spain); SNSF and SER (Switzerland); NASU (Ukraine); STFC (United Kingdom); NSF (U.S.A.). We acknowledge the computing resources that are provided by CERN, IN2P3 (France), KIT and DESY (Germany), INFN (Italy), SURF (The Netherlands), PIC (Spain), GridPP (United Kingdom), RRCKI and Yandex LLC (Russia), CSCS (Switzerland), IFIN-HH (Romania), CBPF (Brazil), PL-GRID (Poland) and OSC (U.S.A.). We are indebted to the communities behind the multiple open source software packages on which we depend. Individual groups or members have received support from AvH Foundation (Germany), EPLANET, Marie Sk lodowska-Curie Actions and ERC (European Union), Conseil G en eral de Haute-Savoie, Labex ENIGMASS and OCEVU, R egion Auvergne (France), RFBR and Yandex LLC (Russia), GVA, XuntaGal and GENCAT (Spain), Herchel Smith Fund, The Royal Society, Royal Commission for the Exhibition of 1851 and the Leverhulme Trust (United Kingdom).

Open Access. This article is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/

Web End =CC-BY 4.0 ), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.

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The LHCb collaboration

R. Aaij40, B. Adeva39, M. Adinol 48, Z. Ajaltouni5, S. Akar6, J. Albrecht10, F. Alessio40,M. Alexander53, S. Ali43, G. Alkhazov31, P. Alvarez Cartelle55, A.A. Alves Jr59, S. Amato2,S. Amerio23, Y. Amhis7, L. An41, L. Anderlini18, G. Andreassi41, M. Andreotti17;g,J.E. Andrews60, R.B. Appleby56, F. Archilli43, P. dArgent12, J. Arnau Romeu6, A. Artamonov37,M. Artuso61, E. Aslanides6, G. Auriemma26, M. Baalouch5, I. Babuschkin56, S. Bachmann12, J.J. Back50, A. Badalov38, C. Baesso62, S. Baker55, W. Baldini17, A. Baranov35, R.J. Barlow56,C. Barschel40, S. Barsuk7, W. Barter40, M. Baszczyk27, V. Batozskaya29, B. Batsukh61,V. Battista41, A. Bay41, L. Beaucourt4, J. Beddow53, F. Bedeschi24, I. Bediaga1, L.J. Bel43,V. Bellee41, N. Belloli21;i, K. Belous37, I. Belyaev32, E. Ben-Haim8, G. Bencivenni19, S. Benson43,J. Benton48, A. Berezhnoy33, R. Bernet42, A. Bertolin23, C. Betancourt42, F. Betti15,M.-O. Bettler40, M. van Beuzekom43, Ia. Bezshyiko42, S. Bifani47, P. Billoir8, T. Bird56,A. Birnkraut10, A. Bitadze56, A. Bizzeti18;u, T. Blake50, F. Blanc41, J. Blouw11;, S. Blusk61,V. Bocci26, T. Boettcher58, A. Bondar36;w, N. Bondar31;40, W. Bonivento16, I. Bordyuzhin32,A. Borgheresi21;i, S. Borghi56, M. Borisyak35, M. Borsato39, F. Bossu7, M. Boubdir9, T.J.V. Bowcock54, E. Bowen42, C. Bozzi17;40, S. Braun12, M. Britsch12, T. Britton61,J. Brodzicka56, E. Buchanan48, C. Burr56, A. Bursche2, J. Buytaert40, S. Cadeddu16,R. Calabrese17;g, M. Calvi21;i, M. Calvo Gomez38;m, A. Camboni38, P. Campana19, D.H. Campora Perez40, L. Capriotti56, A. Carbone15;e, G. Carboni25;j, R. Cardinale20;h,A. Cardini16, P. Carniti21;i, L. Carson52, K. Carvalho Akiba2, G. Casse54, L. Cassina21;i,L. Castillo Garcia41, M. Cattaneo40, Ch. Cauet10, G. Cavallero20, R. Cenci24;t, D. Chamont7,M. Charles8, Ph. Charpentier40, G. Chatzikonstantinidis47, M. Chefdeville4, S. Chen56,S.-F. Cheung57, V. Chobanova39, M. Chrzaszcz42;27, X. Cid Vidal39, G. Ciezarek43,P.E.L. Clarke52, M. Clemencic40, H.V. Cli 49, J. Closier40, V. Coco59, J. Cogan6, E. Cogneras5,V. Cogoni16;40;f, L. Cojocariu30, G. Collazuol23;o, P. Collins40, A. Comerma-Montells12,A. Contu40, A. Cook48, G. Coombs40, S. Coquereau38, G. Corti40, M. Corvo17;g, C.M. Costa Sobral50, B. Couturier40, G.A. Cowan52, D.C. Craik52, A. Crocombe50,M. Cruz Torres62, S. Cunli e55, R. Currie55, C. DAmbrosio40, F. Da Cunha Marinho2,E. DallOcco43, J. Dalseno48, P.N.Y. David43, A. Davis59, O. De Aguiar Francisco2,K. De Bruyn6, S. De Capua56, M. De Cian12, J.M. De Miranda1, L. De Paula2, M. De Serio14;d,P. De Simone19, C.-T. Dean53, D. Decamp4, M. Deckenho 10, L. Del Buono8, M. Demmer10,A. Dendek28, D. Derkach35, O. Deschamps5, F. Dettori40, B. Dey22, A. Di Canto40, H. Dijkstra40,F. Dordei40, M. Dorigo41, A. Dosil Su arez39, A. Dovbnya45, K. Dreimanis54, L. Dufour43,G. Dujany56, K. Dungs40, P. Durante40, R. Dzhelyadin37, A. Dziurda40, A. Dzyuba31,N. D el eage4, S. Easo51, M. Ebert52, U. Egede55, V. Egorychev32, S. Eidelman36;w,S. Eisenhardt52, U. Eitschberger10, R. Ekelhof10, L. Eklund53, S. Ely61, S. Esen12, H.M. Evans49,T. Evans57, A. Falabella15, N. Farley47, S. Farry54, R. Fay54, D. Fazzini21;i, D. Ferguson52,A. Fernandez Prieto39, F. Ferrari15;40, F. Ferreira Rodrigues2, M. Ferro-Luzzi40, S. Filippov34, R.A. Fini14, M. Fiore17;g, M. Fiorini17;g, M. Firlej28, C. Fitzpatrick41, T. Fiutowski28,F. Fleuret7;b, K. Fohl40, M. Fontana16;40, F. Fontanelli20;h, D.C. Forshaw61, R. Forty40,V. Franco Lima54, M. Frank40, C. Frei40, J. Fu22;q, E. Furfaro25;j, C. Farber40,A. Gallas Torreira39, D. Galli15;e, S. Gallorini23, S. Gambetta52, M. Gandelman2, P. Gandini57,Y. Gao3, L.M. Garcia Martin69, J. Garc a Pardias39, J. Garra Tico49, L. Garrido38,P.J. Garsed49, D. Gascon38, C. Gaspar40, L. Gavardi10, G. Gazzoni5, D. Gerick12, E. Gersabeck12,M. Gersabeck56, T. Gershon50, Ph. Ghez4, S. Gian 41, V. Gibson49, O.G. Girard41, L. Giubega30,K. Gizdov52, V.V. Gligorov8, D. Golubkov32, A. Golutvin55;40, A. Gomes1;a, I.V. Gorelov33,C. Gotti21;i, M. Grabalosa G andara5, R. Graciani Diaz38, L.A. Granado Cardoso40, E. Graug es38,

{ 14 {

JHEP03(2017)001

E. Graverini42, G. Graziani18, A. Grecu30, P. Gri th47, L. Grillo21;40;i, B.R. Gruberg Cazon57,O. Grunberg67, E. Gushchin34, Yu. Guz37, T. Gys40, C. Gobel62, T. Hadavizadeh57,C. Hadjivasiliou5, G. Haefeli41, C. Haen40, S.C. Haines49, S. Hall55, B. Hamilton60, X. Han12,S. Hansmann-Menzemer12, N. Harnew57, S.T. Harnew48, J. Harrison56, M. Hatch40, J. He63,T. Head41, A. Heister9, K. Hennessy54, P. Henrard5, L. Henry8, J.A. Hernando Morata39,E. van Herwijnen40, M. He67, A. Hicheur2, D. Hill57, C. Hombach56, H. Hopchev41,W. Hulsbergen43, T. Humair55, M. Hushchyn35, N. Hussain57, D. Hutchcroft54, M. Idzik28,P. Ilten58, R. Jacobsson40, A. Jaeger12, J. Jalocha57, E. Jans43, A. Jawahery60, F. Jiang3,M. John57, D. Johnson40, C.R. Jones49, C. Joram40, B. Jost40, N. Jurik61, S. Kandybei45,W. Kanso6, M. Karacson40, J.M. Kariuki48, S. Karodia53, M. Kecke12, M. Kelsey61,I.R. Kenyon47, M. Kenzie49, T. Ketel44, E. Khairullin35, B. Khanji12, C. Khurewathanakul41,T. Kirn9, S. Klaver56, K. Klimaszewski29, S. Koliiev46, M. Kolpin12, I. Komarov41, R.F. Koopman44, P. Koppenburg43, A. Kosmyntseva32, A. Kozachuk33, M. Kozeiha5,L. Kravchuk34, K. Kreplin12, M. Kreps50, P. Krokovny36;w, F. Kruse10, W. Krzemien29,W. Kucewicz27;l, M. Kucharczyk27, V. Kudryavtsev36;w, A.K. Kuonen41, K. Kurek29,T. Kvaratskheliya32;40, D. Lacarrere40, G. La erty56, A. Lai16, G. Lanfranchi19, C. Langenbruch9,T. Latham50, C. Lazzeroni47, R. Le Gac6, J. van Leerdam43, J.-P. Lees4, A. Le at33;40,J. Lefrancois7, R. Lef evre5, F. Lemaitre40, E. Lemos Cid39, O. Leroy6, T. Lesiak27,B. Leverington12, Y. Li7, T. Likhomanenko35;68, R. Lindner40, C. Linn40, F. Lionetto42, B. Liu16,X. Liu3, D. Loh50, I. Longsta 53, J.H. Lopes2, D. Lucchesi23;o, M. Lucio Martinez39, H. Luo52,A. Lupato23, E. Luppi17;g, O. Lupton57, A. Lusiani24, X. Lyu63, F. Machefert7, F. Maciuc30,O. Maev31, K. Maguire56, S. Malde57, A. Malinin68, T. Maltsev36, G. Manca7, G. Mancinelli6,P. Manning61, J. Maratas5;v, J.F. Marchand4, U. Marconi15, C. Marin Benito38, P. Marino24;t,J. Marks12, G. Martellotti26, M. Martin6, M. Martinelli41, D. Martinez Santos39,F. Martinez Vidal69, D. Martins Tostes2, L.M. Massacrier7, A. Massa erri1, R. Matev40,A. Mathad50, Z. Mathe40, C. Matteuzzi21, A. Mauri42, B. Maurin41, A. Mazurov47,M. McCann55, J. McCarthy47, A. McNab56, R. McNulty13, B. Meadows59, F. Meier10,M. Meissner12, D. Melnychuk29, M. Merk43, A. Merli22;q, E. Michielin23, D.A. Milanes66,M.-N. Minard4, D.S. Mitzel12, A. Mogini8, J. Molina Rodriguez1, I.A. Monroy66, S. Monteil5,M. Morandin23, P. Morawski28, A. Mord a6, M.J. Morello24;t, J. Moron28, A.B. Morris52,R. Mountain61, F. Muheim52, M. Mulder43, M. Mussini15, D. Muller56, J. Muller10, K. Muller42,V. Muller10, P. Naik48, T. Nakada41, R. Nandakumar51, A. Nandi57, I. Nasteva2, M. Needham52,N. Neri22, S. Neubert12, N. Neufeld40, M. Neuner12, A.D. Nguyen41, T.D. Nguyen41,C. Nguyen-Mau41;n, S. Nieswand9, R. Niet10, N. Nikitin33, T. Nikodem12, A. Novoselov37, D.P. OHanlon50, A. Oblakowska-Mucha28, V. Obraztsov37, S. Ogilvy19, R. Oldeman49, C.J.G. Onderwater70, J.M. Otalora Goicochea2, A. Otto40, P. Owen42, A. Oyanguren69;40, P.R. Pais41, A. Palano14;d, F. Palombo22;q, M. Palutan19, J. Panman40, A. Papanestis51,M. Pappagallo14;d, L.L. Pappalardo17;g, W. Parker60, C. Parkes56, G. Passaleva18, A. Pastore14;d, G.D. Patel54, M. Patel55, C. Patrignani15;e, A. Pearce56;51, A. Pellegrino43, G. Penso26,M. Pepe Altarelli40, S. Perazzini40, P. Perret5, L. Pescatore47, K. Petridis48, A. Petrolini20;h,A. Petrov68, M. Petruzzo22;q, E. Picatoste Olloqui38, B. Pietrzyk4, M. Pikies27, D. Pinci26,A. Pistone20, A. Piucci12, S. Playfer52, M. Plo Casasus39, T. Poikela40, F. Polci8,A. Poluektov50;36, I. Polyakov61, E. Polycarpo2, G.J. Pomery48, A. Popov37, D. Popov11;40,B. Popovici30, S. Poslavskii37, C. Potterat2, E. Price48, J.D. Price54, J. Prisciandaro39,A. Pritchard54, C. Prouve48, V. Pugatch46, A. Puig Navarro41, G. Punzi24;p, W. Qian57,R. Quagliani7;48, B. Rachwal27, J.H. Rademacker48, M. Rama24, M. Ramos Pernas39,M.S. Rangel2, I. Raniuk45, F. Ratnikov35, G. Raven44, F. Redi55, S. Reichert10, A.C. dos Reis1,C. Remon Alepuz69, V. Renaudin7, S. Ricciardi51, S. Richards48, M. Rihl40, K. Rinnert54,

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V. Rives Molina38, P. Robbe7;40, A.B. Rodrigues1, E. Rodrigues59, J.A. Rodriguez Lopez66,P. Rodriguez Perez56;, A. Rogozhnikov35, S. Roiser40, A. Rollings57, V. Romanovskiy37,A. Romero Vidal39, J.W. Ronayne13, M. Rotondo19, M.S. Rudolph61, T. Ruf40, P. Ruiz Valls69, J.J. Saborido Silva39, E. Sadykhov32, N. Sagidova31, B. Saitta16;f, V. Salustino Guimaraes2,C. Sanchez Mayordomo69, B. Sanmartin Sedes39, R. Santacesaria26, C. Santamarina Rios39,M. Santimaria19, E. Santovetti25;j, A. Sarti19;k, C. Satriano26;s, A. Satta25, D.M. Saunders48,D. Savrina32;33, S. Schael9, M. Schellenberg10, M. Schiller40, H. Schindler40, M. Schlupp10,M. Schmelling11, T. Schmelzer10, B. Schmidt40, O. Schneider41, A. Schopper40, K. Schubert10,M. Schubiger41, M.-H. Schune7, R. Schwemmer40, B. Sciascia19, A. Sciubba26;k, A. Semennikov32,A. Sergi47, N. Serra42, J. Serrano6, L. Sestini23, P. Seyfert21, M. Shapkin37, I. Shapoval45,Y. Shcheglov31, T. Shears54, L. Shekhtman36;w, V. Shevchenko68, B.G. Siddi17;40,R. Silva Coutinho42, L. Silva de Oliveira2, G. Simi23;o, S. Simone14;d, M. Sirendi49, N. Skidmore48,T. Skwarnicki61, E. Smith55, I.T. Smith52, J. Smith49, M. Smith55, H. Snoek43, M.D. Sokolo 59, F.J.P. Soler53, B. Souza De Paula2, B. Spaan10, P. Spradlin53, S. Sridharan40, F. Stagni40,M. Stahl12, S. Stahl40, P. Stefko41, S. Stefkova55, O. Steinkamp42, S. Stemmle12, O. Stenyakin37,S. Stevenson57, S. Stoica30, S. Stone61, B. Storaci42, S. Stracka24;p, M. Straticiuc30,U. Straumann42, L. Sun64, W. Sutcli e55, K. Swientek28, V. Syropoulos44, M. Szczekowski29,T. Szumlak28, S. TJampens4, A. Tayduganov6, T. Tekampe10, M. Teklishyn7, G. Tellarini17;g,F. Teubert40, E. Thomas40, J. van Tilburg43, M.J. Tilley55, V. Tisserand4, M. Tobin41, S. Tolk49,L. Tomassetti17;g, D. Tonelli40, S. Topp-Joergensen57, F. Toriello61, E. Tourne er4, S. Tourneur41,K. Trabelsi41, M. Traill53, M.T. Tran41, M. Tresch42, A. Trisovic40, A. Tsaregorodtsev6,P. Tsopelas43, A. Tully49, N. Tuning43, A. Ukleja29, A. Ustyuzhanin35;x, U. Uwer12, C. Vacca16;f,V. Vagnoni15;40, A. Valassi40, S. Valat40, G. Valenti15, A. Vallier7, R. Vazquez Gomez19,P. Vazquez Regueiro39, S. Vecchi17, M. van Veghel43, J.J. Velthuis48, M. Veltri18;r,G. Veneziano57, A. Venkateswaran61, M. Vernet5, M. Vesterinen12, B. Viaud7, D. Vieira1,M. Vieites Diaz39, H. Viemann67, X. Vilasis-Cardona38;m, M. Vitti49, V. Volkov33, A. Vollhardt42,B. Voneki40, A. Vorobyev31, V. Vorobyev36;w, C. Vo67, J.A. de Vries43, C. V azquez Sierra39,R. Waldi67, C. Wallace50, R. Wallace13, J. Walsh24, J. Wang61, D.R. Ward49, H.M. Wark54, N.K. Watson47, D. Websdale55, A. Weiden42, M. Whitehead40, J. Wicht50, G. Wilkinson57;40,M. Wilkinson61, M. Williams40, M.P. Williams47, M. Williams58, T. Williams47, F.F. Wilson51,J. Wimberley60, J. Wishahi10, W. Wislicki29, M. Witek27, G. Wormser7, S.A. Wotton49,K. Wraight53, K. Wyllie40, Y. Xie65, Z. Xing61, Z. Xu41, Z. Yang3, Y. Yao61, H. Yin65, J. Yu65,X. Yuan36;w, O. Yushchenko37, K.A. Zarebski47, M. Zavertyaev11;c, L. Zhang3, Y. Zhang7,Y. Zhang63, A. Zhelezov12, Y. Zheng63, A. Zhokhov32, X. Zhu3, V. Zhukov9, S. Zucchelli15

1 Centro Brasileiro de Pesquisas F sicas (CBPF), Rio de Janeiro, Brazil

2 Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil

3 Center for High Energy Physics, Tsinghua University, Beijing, China

4 LAPP, Universit e Savoie Mont-Blanc, CNRS/IN2P3, Annecy-Le-Vieux, France

5 Clermont Universit e, Universit e Blaise Pascal, CNRS/IN2P3, LPC, Clermont-Ferrand, France

6 CPPM, Aix-Marseille Universit e, CNRS/IN2P3, Marseille, France

7 LAL, Universit e Paris-Sud, CNRS/IN2P3, Orsay, France

8 LPNHE, Universit e Pierre et Marie Curie, Universit e Paris Diderot, CNRS/IN2P3, Paris, France

9 I. Physikalisches Institut, RWTH Aachen University, Aachen, Germany

10 Fakultat Physik, Technische Universitat Dortmund, Dortmund, Germany

11 Max-Planck-Institut fur Kernphysik (MPIK), Heidelberg, Germany

12 Physikalisches Institut, Ruprecht-Karls-Universitat Heidelberg, Heidelberg, Germany

13 School of Physics, University College Dublin, Dublin, Ireland

14 Sezione INFN di Bari, Bari, Italy

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JHEP03(2017)001

15 Sezione INFN di Bologna, Bologna, Italy

16 Sezione INFN di Cagliari, Cagliari, Italy

17 Sezione INFN di Ferrara, Ferrara, Italy

18 Sezione INFN di Firenze, Firenze, Italy

19 Laboratori Nazionali dellINFN di Frascati, Frascati, Italy

20 Sezione INFN di Genova, Genova, Italy

21 Sezione INFN di Milano Bicocca, Milano, Italy

22 Sezione INFN di Milano, Milano, Italy

23 Sezione INFN di Padova, Padova, Italy

24 Sezione INFN di Pisa, Pisa, Italy

25 Sezione INFN di Roma Tor Vergata, Roma, Italy

26 Sezione INFN di Roma La Sapienza, Roma, Italy

27 Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences, Krak ow, Poland

28 AGH | University of Science and Technology, Faculty of Physics and Applied Computer Science, Krak ow, Poland

29 National Center for Nuclear Research (NCBJ), Warsaw, Poland

30 Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest-Magurele, Romania

31 Petersburg Nuclear Physics Institute (PNPI), Gatchina, Russia

32 Institute of Theoretical and Experimental Physics (ITEP), Moscow, Russia

33 Institute of Nuclear Physics, Moscow State University (SINP MSU), Moscow, Russia

34 Institute for Nuclear Research of the Russian Academy of Sciences (INR RAN), Moscow, Russia

35 Yandex School of Data Analysis, Moscow, Russia

36 Budker Institute of Nuclear Physics (SB RAS), Novosibirsk, Russia

37 Institute for High Energy Physics (IHEP), Protvino, Russia

38 ICCUB, Universitat de Barcelona, Barcelona, Spain

39 Universidad de Santiago de Compostela, Santiago de Compostela, Spain

40 European Organization for Nuclear Research (CERN), Geneva, Switzerland

41 Insitute of Physics, Ecole Polytechnique F ed erale de Lausanne (EPFL), Lausanne, Switzerland

42 Physik-Institut, Universitat Zurich, Zurich, Switzerland

43 Nikhef National Institute for Subatomic Physics, Amsterdam, The Netherlands

44 Nikhef National Institute for Subatomic Physics and VU University Amsterdam, Amsterdam, The Netherlands

45 NSC Kharkiv Institute of Physics and Technology (NSC KIPT), Kharkiv, Ukraine

46 Institute for Nuclear Research of the National Academy of Sciences (KINR), Kyiv, Ukraine

47 University of Birmingham, Birmingham, United Kingdom

48 H.H. Wills Physics Laboratory, University of Bristol, Bristol, United Kingdom

49 Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom

50 Department of Physics, University of Warwick, Coventry, United Kingdom

51 STFC Rutherford Appleton Laboratory, Didcot, United Kingdom

52 School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom

53 School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom

54 Oliver Lodge Laboratory, University of Liverpool, Liverpool, United Kingdom

55 Imperial College London, London, United Kingdom

56 School of Physics and Astronomy, University of Manchester, Manchester, United Kingdom

57 Department of Physics, University of Oxford, Oxford, United Kingdom

58 Massachusetts Institute of Technology, Cambridge, MA, United States

59 University of Cincinnati, Cincinnati, OH, United States

60 University of Maryland, College Park, MD, United States

61 Syracuse University, Syracuse, NY, United States

62 Pontif cia Universidade Cat olica do Rio de Janeiro (PUC-Rio), Rio de Janeiro, Brazil, associated to2

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JHEP03(2017)001

63 University of Chinese Academy of Sciences, Beijing, China, associated to3

64 School of Physics and Technology, Wuhan University, Wuhan, China, associated to3

65 Institute of Particle Physics, Central China Normal University, Wuhan, Hubei, China, associated to3

66 Departamento de Fisica , Universidad Nacional de Colombia, Bogota, Colombia, associated to8

67 Institut fur Physik, Universitat Rostock, Rostock, Germany, associated to12

68 National Research Centre Kurchatov Institute, Moscow, Russia, associated to32

69 Instituto de Fisica Corpuscular (IFIC), Universitat de Valencia-CSIC, Valencia, Spain, associated to38

70 Van Swinderen Institute, University of Groningen, Groningen, The Netherlands, associated to43

a Universidade Federal do Tri^angulo Mineiro (UFTM), Uberaba-MG, Brazil

b Laboratoire Leprince-Ringuet, Palaiseau, France

c P.N. Lebedev Physical Institute, Russian Academy of Science (LPI RAS), Moscow, Russia

d Universit a di Bari, Bari, Italy

e Universit a di Bologna, Bologna, Italy

f Universit a di Cagliari, Cagliari, Italy

g Universit a di Ferrara, Ferrara, Italy

h Universit a di Genova, Genova, Italy

i Universit a di Milano Bicocca, Milano, Italy

j Universit a di Roma Tor Vergata, Roma, Italy

k Universit a di Roma La Sapienza, Roma, Italy

l AGH | University of Science and Technology, Faculty of Computer Science, Electronics andTelecommunications, Krak ow, Poland

m LIFAELS, La Salle, Universitat Ramon Llull, Barcelona, Spain

n Hanoi University of Science, Hanoi, Viet Nam

o Universit a di Padova, Padova, Italy

p Universit a di Pisa, Pisa, Italy

q Universit a degli Studi di Milano, Milano, Italy

r Universit a di Urbino, Urbino, Italy

s Universit a della Basilicata, Potenza, Italy

t Scuola Normale Superiore, Pisa, Italy

u Universit a di Modena e Reggio Emilia, Modena, Italy

v Iligan Institute of Technology (IIT), Iligan, Philippines

w Novosibirsk State University, Novosibirsk, Russia

x Moscow Institute of Physics and Technology, Moscow, Russia Deceased

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JHEP03(2017)001