A search for an excited muon decaying to a muon and two jets in $pp$ collisions at $\sqrt{s}$ = 8 TeV with the ATLAS detector

EUROPEAN ORGANISATION FOR NUCLEAR RESEARCH (CERN)

New J. Phys. 18 (2016) no. 7, 073021 DOI:10.1088/1367-2630/18/7/073021

CERN-PH-EP-2015-298 13th November 2019

A search for an excited muon decaying to a muon and two jets in

pp collisions at

√

s

= 8 TeV with the ATLAS detector

The ATLAS Collaboration

Abstract

A new search signature for excited leptons is explored. Excited muons are sought in the channel pp → µµ∗ →µµ jet jet, assuming both the production and decay occur via a contact interaction. The analysis is based on 20.3 fb−1of pp collision data at a centre-of-mass energy of √s= 8 TeV taken with the ATLAS detector at the Large Hadron Collider. No evidence of excited muons is found, and limits are set at the 95% confidence level on the cross section times branching ratio as a function of the excited-muon mass mµ∗. For m_µ∗between 1.3 TeV

and 3.0 TeV, the upper limit on σB(µ∗ → µq¯q) is between 0.6 and 1 fb. Limits on σB are converted to lower bounds on the compositeness scaleΛ. In the limiting case Λ = mµ∗,

excited muons with a mass below 2.9 TeV are excluded. With the same model assumptions, these limits at larger µ∗_{masses improve upon previous limits from traditional searches based}

on the gauge-mediated decay µ∗→µγ.

c

2019 CERN for the benefit of the ATLAS Collaboration.

Reproduction of this article or parts of it is allowed as specified in the CC-BY-3.0 license.

Contents

1 Introduction 2

2 ATLAS detector 3

3 Signal and background simulation 4

4 Data set and event selection 5

5 Background determination 6 6 Signal regions 7 7 Systematic uncertainties 8 8 Results 10 9 Conclusion 13

1 Introduction

The Standard Model (SM) of particle physics successfully describes a wide range of phenomena but does not explain the generational structure and mass hierarchy of quarks and leptons. Composite models of fermions [1–7] aim to reduce the number of matter constituents by postulating that SM fermions are bound states of more fundamental particles. A direct consequence of substructure would be the existence of excited fermion states.

This paper reports on a search for an excited muon µ∗using 20.3 fb−1of pp collision data at a centre-of-mass energy of √s= 8 TeV recorded in 2012 with the ATLAS detector at the Large Hadron Collider (LHC). The search is based on a benchmark model [7] that describes excited-fermion interactions with an effective Lagrangian containing four-fermion contact interactions and gauge-mediated interactions. A contact interaction decay signature not previously employed in excited leptons searches, µ∗ → µ j j ( j represents a jet), is used.

In this paper, as in Ref. [7], the model is assumed to be valid for µ∗masses up to the compositeness scale. The contact interaction terms are described by the Lagrangian

L_contact= g 2 ∗ 2Λ2j µ_j µ, with jµ = η fLγµfL+ η0f ∗ Lγµf ∗ L+ η 00 f∗_Lγµf_L+ h.c.,

whereΛ is the compositeness scale; jµ is the fermion current for ground states ( f ) and excited states ( f∗); g∗and the η’s are constants; “h.c.” stands for Hermitian conjugate; and only left-handed fermion

interactions are assumed. As is done in Ref. [7], g2∗ is set to 4π, and η, η0, and η00 are taken to be one

for all fermions. To calculate branching ratios, the compositeness scaleΛ is assumed to be the same for gauge-mediated interactions, and the parameters f and f0in Ref. [7] are taken to be one.

The search described here focuses on the predominant single-µ∗ production via the contact interaction (qq → µ∗µ) followed by the decay of the excited muon via the contact interaction to µqq, leading to a

µ

µ

µ

q

¯

q

q

¯

q

Figure 1: Feynman diagram for the process qq → µ∗µ → µµqq, where both the production and decay are via contact interactions.

final state with two muons and two jets (figure1). Top quarks from excited muons with masses accessible in the 8-TeV LHC data would not have sufficient energy to form narrow jets and are excluded from the analysis in this paper. Previous searches at LEP [8–11], the Tevatron [12–15], and the LHC [16–20] looked for the gauge-mediated decay µ∗→µγ. The analysis reported in Ref. [20] also includes the gauge-mediated decay µ∗ → µZ followed by Z → `` or q ¯q. In the model of Ref. [7], this decay is dominant at low µ∗ mass, but for mµ∗ & 0.25Λ, the µq ¯q decay mode is expected to have the largest branching

ratio, rising to 65% for mµ∗ = Λ. The search reported here complements the search in the µγ channel

and increases the sensitivity of the search for excited muons at higher masses. The ATLAS Collaboration recently published [21] another new search signature for excited muons decaying via a contact interaction to µ``, where ` is an electron or a muon.

2 ATLAS detector

The ATLAS experiment [22] uses a multi-purpose particle detector with a forward-backward symmetric cylindrical geometry and a near 4π coverage in solid angle.1 It consists of an inner tracking detector surrounded by a thin superconducting solenoid providing a 2 T axial magnetic field, electromagnetic and hadron calorimeters, and a muon spectrometer. The inner tracking detector covers the pseudorapidity range |η| < 2.5. It consists of silicon pixel, silicon microstrip, and transition radiation tracking detectors. Lead/liquid-argon (LAr) sampling calorimeters provide electromagnetic (EM) energy measurements with high granularity. A hadronic steel/scintillator-tile calorimeter covers the central pseudorapidity range (|η| < 1.7). The endcap and forward regions are instrumented with LAr calorimeters for EM and hadronic energy measurements up to |η| = 4.9. The muon spectrometer surrounding the calorimeters covers the pseudorapidty range |η| < 2.7 and is based on three large air-core toroid superconducting magnets with eight coils each. Their bending power is in the range from 2.0 to 7.5 T m. The muon spectrometer consists of three stations of precision tracking chambers and fast detectors for triggering. The majority of the precision tracking chambers are composed of drift tubes, while cathode-strip chambers provide coverage in the inner stations of the forward region for 2.0 < |η| < 2.7. A three-level trigger system is

1_{ATLAS uses a right-handed coordinate system with its origin at the nominal interaction point (IP) in the centre of the detector}

and the z-axis along the beam pipe. The x-axis points from the IP to the centre of the LHC ring, and the y-axis points upwards. Cylindrical coordinates (r, φ) are used in the transverse plane, φ being the azimuthal angle around the z-axis.

The pseudorapidity is defined in terms of the polar angle θ as η= − ln tan(θ/2). Angular distance is measured in terms of

used to select events. The first-level trigger is implemented in hardware and uses a subset of the detector information to reduce the accepted rate to at most 75 kHz. This is followed by two software-based trigger levels that together reduce the accepted event rate to 400 Hz on average, depending on the data-taking conditions during 2012.

3 Signal and background simulation

Simulation of the excited-muon signal is based on calculations from Ref. [7]. Signal samples are gener-ated at leading order (LO) with CompHEP 4.5.1 [23] using MSTW2008lo [24] parton distribution func-tions (PDFs). CompHEP is interfaced with Pythia 8.170 [25,26] with the AU2 parameters settings [27] for the simulation of parton showers and hadronization. Only the production of µµ∗followed by the de-cay µ∗ →µq¯q is simulated. Signal samples are produced for Λ = 5 TeV and for the µ∗masses given in table2. The distributions of kinematic variables should be independent ofΛ, which was checked with generator-level studies. For a compositeness scale ofΛ = 5 TeV, cross section times branching ratios are 10.4, 2.9, and 0.21 fb for µ∗masses of 500, 1500, and 2500 GeV, respectively. The intrinsic total width of the µ∗is expected to be less than 8% for mµ∗ < Λ, which is smaller than the mass resolution of about

20% over the range of µ∗masses considered here.

The dominant background is from the process Z/γ∗→µµ produced in association with jets (Z/γ∗+ jets). The second most important background is t¯t production. Other processes, such as diboson (WW, WZ, and ZZ), single-top, W+ jets, and multi-jet production, give small contributions to the background. The Z/γ∗+ jets samples are produced by the multi-leg LO generator Sherpa 1.4.1 [28] using CT10 [29] PDFs. The cross section for Z/γ∗→µµ (m_µµ> 70 GeV) plus any number of jets is 1.24 nb, calculated at next-to-leading order (NLO), corrected by a K-factor [30,31] to next-to-next-to-leading order (NNLO) in QCD couplings and NLO in electroweak couplings. The t¯t events are generated at the parton level at NLO with Powheg 1.0 [32] and the Perugia 2011c parameter settings [33], and the parton showering is done with Pythia 6.426 [34]. At least one of the t or t must have a semileptonic decay (e, µ, or τ), giving a cross section for this process of 137 pb, calculated at NNLO+ next-to-next-to-leading-log (NNLL) ac-curacy [35]. The diboson background samples are produced at LO by Herwig 6.52 [36] with the AUET2 parameter settings [37] using CTEQ6L1 PDFs, and it is required that at least one light lepton (e or µ) with transverse momentum (pT) above 10 GeV be produced. The W+ jets samples are produced by the

multi-leg LO generator Alpgen 2.14 [38] with Jimmy 4.31 [39] and Herwig 6.52 using the AUET2 para-meter settings with CTEQ6L1 PDFs, and the cross section is calculated at NNLO [30,31]. The multi-jet samples are generated at LO by Pythia 8.160 using the AU2 parameter settings with CT10 PDFs. The single-top t-channel samples are generated at LO corrected to NLO+ NNLL by AcerMC 3.8 [40] using the AUET2B parameters settings [41] with the CTEQ6L1 PDFs, and the parton showering is done with Pythia 6.426. The single-top s- and Wt-channel samples are generated at NLO with MC@NLO 4.01 [42–

44] using the AUET2 parameters settings with CT10 PDFs. The background predictions from the Z/γ∗+ jets and t¯t samples are normalized using control regions discussed in Section5. Cross sections for diboson processes are evaluated at NLO [45] with an uncertainty of 5%. The W+ jets and multi-jet backgrounds are determined from the Monte Carlo (MC) samples but are verified using data-driven methods. A sum-mary of the Standard Model samples used in this analysis is given in table1.

The generated samples are processed using a detailed detector simulation [46] based on Geant4 [47] to propagate the particles through the detector material and account for the detector response. Simulated minimum-bias events are overlaid on both the signal and background samples to reproduce the effect

Process Generator Parton showering/ PDF hadronization

Z/γ∗(→ µµ)+ jets Sherpa 1.4.1 Sherpa 1.4.1 CT10

t¯t(≥ 1`) Powheg 1.0 Pythia 6.426 CT10

WW, WZ, ZZ (≥ 1`) Herwig 6.52 Herwig 6.52 CTEQ6L1

Single top, t-channel AcerMC 3.8 Pythia 6.426 CTEQ6L1

Single top, s-channel MC@NLO 4.01 Jimmy 4.31 + Herwig 6.52 CT10 Single top, Wt-channel MC@NLO 4.01 Jimmy 4.31 + Herwig 6.52 CT10

W(→ µν)+ jets Alpgen 2.14 Jimmy 4.31 + Herwig 6.52 CTEQ6L1

Multi-jet Pythia 8.160 Pythia 8.160 CT10

Signal (µµ∗→µµ j j) CompHEP 4.5.1 Pythia 8.170 MSTW2008lo

Table 1: Summary of the background and signal MC sample generation used in this search. The columns give the process generated, the generator program, the parton shower program, and the PDF utilized.

of additional pp collisions. The simulated events are weighted to give a distribution of the number of interactions per bunch crossing that agrees with the data. The simulated background and signal events are processed with the same reconstruction programs as used for the data.

4 Data set and event selection

The data were collected in 2012 during stable-beam periods of √s= 8 TeV pp collisions. After selecting events where the relevant parts of the detector were functioning properly, the data correspond to an integ-rated luminosity of 20.3 fb−1. The events are required to pass at least one of two single-muon triggers. The first has a nominal pTthreshold of 36 GeV, and the second has a lower nominal threshold of 24 GeV

but also has an isolation requirement that the sum of the pTof tracks with pTabove 1 GeV and within a

distance of∆R = 0.2 of the muon, excluding the muon from the sum, divided by the pTof the muon is

less than 0.12.

A primary vertex with at least three tracks with pT> 0.4 GeV within 200 mm of the centre of the detector

along the beam direction is required. If there is more than one primary vertex in an event, the one with the highest sum of p2_Tis selected, where the sum is over all tracks associated with the vertex.

Each muon candidate must be reconstructed independently in both the inner detector and the muon spec-trometer. Its momentum is determined by a combination of the two measurements using their covariance matrices. Only muon candidates with pµ_T above 30 GeV are considered. Muons must have a minimum number of hits in the inner detector and hits in each of the inner, middle, and outer layers of the muon spectrometer. These hit requirements, which restrict the muon acceptance to |η| < 2.5, guarantee a pre-cise momentum measurement. To suppress background from cosmic rays, the muon tracks are required to have transverse and longitudinal impact parameters |d0| < 0.2 mm and |z0| < 1 mm with respect to

the selected primary vertex. To reduce background from semileptonic decays of heavy-flavour hadrons, each muon is required to be isolated such thatP pT/pµ_T < 0.05, where the sum is over inner-detector

tracks with pT > 1 GeV within a distance ∆R = 0.3 of the candidate muon, excluding the muon from the

Z →µµ events [48,49], and pT- and η-dependent corrections are applied to simulated events. Events are

required to have exactly two muons of opposite charge that meet these selection requirements.

Although electrons are not part of the signal for this search, they are used to define one of the control regions (see Section5). Each electron candidate is formed from the energy in a cluster of cells in the electromagnetic calorimeter associated with a charged-particle track in the inner detector. Each electron must have pT above 30 GeV and have |η| < 2.47 but not be in the interval 1.37 < |η| < 1.52 to avoid the

transition region between the barrel and endcap calorimeters. The ATLAS tight electron identification criteria (based on the methodology described in [50] and updated for 2012 running conditions) for the transverse shower shape, longitudinal leakage into the hadronic calorimeter, the association with an inner-detector track, and hits in the transition radiation inner-detector are applied to the cluster. An electron track is required to have transverse and longitudinal impact parameters |d0| < 1 mm and |z0| < 5 mm with

respect to the selected primary vertex. Finally, the electrons must pass the isolation requirementP ET <

0.007E_Te + 5 GeV, where the sum is of transverse energies deposited in cells within a cone of ∆R = 0.2 around the electron, excluding those cells associated with the electron, and Ee_Tis the transverse energy of the electron.

Jets of hadrons are reconstructed using the anti-kt algorithm [51] with a radius parameter of R = 0.4

applied to clusters of calorimeter cells that are topologically connected. The jets are calibrated using energy- and η-dependent correction factors derived from simulation and with residual corrections from in-situ measurements [52]. Jets are required to have |η| < 2.8 and pT > 30 GeV. Jets that overlap

(∆R < 0.4) any electron or muon candidate satisfying the selection criteria described above are removed. The two jets with the highest pTare then selected.

The missing transverse momentum vector is the negative of the vector sum of the transverse momenta of muons, electrons, photons [53], jets, and clusters of calibrated calorimeter cells not associated with these objects. The missing transverse energy is the magnitude of the missing transverse momentum vector.

5 Background determination

Most of the SM background contributions are estimated from the MC samples. The expected yields from the Z/γ∗_{+ jets and t¯t production processes are normalized to the data using control regions. The}

Z/γ∗+ jets control region is defined by 70 < mµµ < 110 GeV in addition to the selection criteria given

in Section4. The t¯t control region is defined as events that meet the selection requirements given in Section4, except there is exactly one muon and one electron of opposite sign, so it should contain no signal events. The normalization scale factors are determined from simultaneous fits to data in the control and signal regions (see Section8). The scale factors are primarily determined from the control regions, giving the same values in all cases. From the fits, the scale factor is 1.010+0.087_−0.066for the Z/γ∗+ jets sample and is 1.050 ± 0.013 for the t¯t sample. The MC predictions agree well with the data in the control regions, as can be seen, for example, in figure2(a).

A jet can produce a prompt muon candidate either from the semileptonic decay of a heavy quark or from misidentification of a charged hadron in the jet as a muon. The expected background from jets, primarily from W+ jets and multi-jet processes, is determined from MC samples, giving zero expected events. This prediction is checked by the data-driven matrix method [54], which uses isolated and non-isolated muons and their data-determined efficiencies and misidentification rates to determine the number of prompt muons. The matrix method predicts −0.07 ± 0.55 events from these backgrounds.

(a) Z/γ∗_{+ jets Control Region} [TeV] jj µ µ m 0 0.5 1 1.5 2 2.5 3 3.5 4 Events / 0.2 TeV -1 10 1 10 µ µ → * γ Z/ t t Diboson = 0.5 TeV * µ m = 2 TeV * µ m = 3 TeV * µ m data ATLAS -1 L dt = 20.3 fb

∫

Figure 2: The µµ j j mass distribution for (a) the Z/γ∗+ jets control region with the MC predictions and (b) for SR 2 (mµµ > 550 GeV, ST > 900 GeV, and mµµ j j > 1000 GeV) with three representative signal distributions for µ∗

masses of 500, 2000, and 3000 GeV and forΛ = 5 TeV. The background expectations are determined after the fit, and the grey band on the ratio plot in (a) gives the systematic uncertainty. For (b) there are no expected events from the single top, W+ jets, and Z → ττ processes. SR 2 is not the most sensitive signal region for the latter two mµ∗

masses. They are shown for comparison.

6 Signal regions

Signal regions (SR) are defined by three kinematic variables - the dimuon invariant mass mµµ, the invariant mass mµµ j jof the two muons and two jets ( j), and ST, the scalar sum of transverse momenta of the four

signal objects, that is, ST= pµ1_T + pµ2_T + p_Tj1+ p_Tj2.2

For all three of these variables, the signal tends to have higher values than the backgrounds, so all criteria are lower bounds in the selection. The values of these bounds are chosen to maximize the search sensit-ivity for each signal mass considered by scanning the three-dimensional parameter space for the values that minimize the expected 95% confidence level (CL) upper limit on the cross section times branching ratio. The selection criteria for the signal regions are shown in table2. The mµµ j jand STcriteria increase

with increasing signal mass, but the mµµcriterion decreases. The latter is because the increase in the other parameters sufficiently reduces the expected background so that the signal efficiency may be increased by decreasing the mµµcriterion.

The dominant background in all signal regions is from the Z/γ∗+ jets process, which is 50% of the background in SR 1, rising to 90% or more in SR 5 through SR 10. The t¯t process contributes 40% of the background in SR 1, but this contribution falls quickly to 10% or less in SR 3 through SR 10. The contribution to the background from all other processes is between 10% and 20% in SR 1 through SR 5 and is less than 5% for SR 6 through SR 10.

2_{The µ j j invariant mass was considered as a discriminating variable instead of one of the three selection variables. Several}

methods for selecting the correct µ j j combination and the possibility of using both µ j j combinations were considered. No method that improved the sensitivity was found.

mµ∗ Signal m_µµ S_T m_{µµ j j} Acc × Exp Exp Exp Obs

[GeV] Region [GeV] [GeV] [GeV] Eff Signal BG BG Events

(prefit) (postfit) 100 1 500 450 0 0.041 3.0±0.3 73±17 71.7±8.6 71 300 2 550 900 1000 0.088 12.5±0.9 10.1±3.5 7.8±2.2 6 500 2 550 900 1000 0.15 29.4±1.6 10.1±3.5 7.8±2.2 6 750 3 450 900 1300 0.23 43.7±2.2 6.6±2.5 5.8±1.9 5 1000 4 450 1050 1300 0.31 44.1±1.8 4.6±1.8 4.6±1.9 5 1250 5 450 1200 1500 0.38 29.8±1.3 2.1 ±0.9 2.1±1.0 3 1500 6 400 1200 1700 0.38 19.8±0.8 1.5±0.7 1.3±0.6 1 1750 7 300 1350 1900 0.41 11.8±0.5 0.9±0.7 0.9±0.5 2 2000 8 300 1350 2000 0.40 6.6±0.2 0.7±0.4 0.7±0.4 2 2250 9 300 1500 2100 0.37 3.4±0.1 0.4±0.3 0.4±0.3 2 2500 10 110 1650 2300 0.39 1.65±0.07 0.2+1.3_−0.2 0.2+1.0_−0.2 2 2750 10 110 1650 2300 0.45 0.72±0.02 0.2+1.3_−0.2 0.2+1.0_−0.2 2 2900 10 110 1650 2300 0.45 0.52±0.02 0.2+1.3_−0.2 0.2+1.0_−0.2 2 3000 10 110 1650 2300 0.46 0.38±0.02 0.2+1.3_−0.2 0.2+1.0_−0.2 2 3100 10 110 1650 2300 0.45 0.30±0.02 0.2+1.3_−0.2 0.2+1.0_−0.2 2

Table 2: The signal masses considered and the corresponding signal regions are listed. The mµµ, ST, and mµµ j j

values giving the lower bound of each signal region are listed, along with the acceptance times efficiency, the expected number of signal events (Λ = 5 TeV), expected number of background events before and after the fit discussed in Section8, and the number of events observed in the data. The uncertainties in the expected numbers of signal and background events are the systematic uncertainties. The numbers of events observed are discussed in Section8.

7 Systematic uncertainties

Contributions to the systematic uncertainties in the background and signal yield predictions stem from both experimental and theoretical sources, as discussed below.

The luminosity is derived using the methodology in Ref. [55] and has an uncertainty of 2.8%. The luminosity uncertainty for the backgrounds is less than this because the largest backgrounds (Z/γ∗_{+ jets}

and t¯t) are normalized using control regions.

Uncertainties in the MC modelling of the detector, particularly for muons and jets in this analysis, must be taken into account and are derived from detailed studies of data. One-standard-deviation variation of a given parameter is determined, and then the parameter is varied up and down in the simulation by this amount to determine the effect on the signal and background yields.

The uncertainty in the jet energy scale is the largest contribution to the systematic uncertainty in the signal yield and a significant contribution to the uncertainty in the backgrounds. The uncertainty in the jet energy resolution also makes a contribution. These uncertainties are determined from pT balance

in γ+ jet and Z+ jet events and in events with high-pT jets recoiling against multiple, low-pT jets [52,

56]. The uncertainty in contributions from additional energy deposited in the calorimeters from other pp interactions in the event is also included. The various effects are investigated separately and combined to give the values summarized in tables3and4.

Muon performance is determined in Z → µµ events. The most important parameters for this analysis are the muon efficiency and the muon spectrometer pTresolution. The inner-detector resolution and the

muon pT scale are found to have negligible effect. The uncertainty in the trigger efficiency is less than

2% for the backgrounds and less than 1% for the signal yield.

The uncertainties in the signal and background yield predictions due to uncertainties in PDFs have two contributions. The first is from one-standard-deviation variation of the parameters of the relevant PDFs (Section3). The second is a comparison with the alternative NNPDF2.1 PDF set [57]. These variations produce changes in the predicted cross section and in kinematical distributions, which in turn affect the acceptance times efficiency. For the background, both effects are included in the systematic uncertainty. For the signal yield, the uncertainty in the acceptance times efficiency is included, but the uncertainty in the cross section is considered part of the uncertainty in the theoretical prediction and is not included in the statistical analysis.

The uncertainty in the background modelling in the signal regions is estimated by examining how well the MC prediction agrees with the data in two validation regions selected to be similar in kinematics to the signal regions but containing no signal. Both validation regions require the same selection as the signal regions except that mµµ j j < 500 GeV and mµµ> 200 GeV with no selection on ST. Requiring the

missing transverse energy be greater (less) than 50 GeV (40 GeV) selects a validation region dominated by t¯t (Z/γ∗) events. For some of the kinematic variables, an extrapolation of the predicted yield from the validation regions to the signal regions is necessary to evaluate possible mismodelling effects. Of the several kinematic variables studied, only the modelling of the ST variable is found to have a significant

effect. A linear fit to the ratio of the number of data events to the MC expectation is extrapolated to higher values of ST, and the deviation from unity symmetrized about zero gives the uncertainty, referred

to as “Z/γ∗_{+ jets modelling” and “t¯t modelling” in table4. For both validation regions, the linear fit is}

consistent within the statistical uncertainties with a flat line at a ratio of one.

To produce sufficient numbers of events for high dimuon masses, the Z/γ∗_{MC samples were produced}

in bins of dimuon mass above the Z mass. For the ST and mµµ j j criteria in this analysis, this yields

zero events in SR 7 through SR 10 for some ranges of the mµµ distribution (for example, 110 to 400

GeV for SR 10). For these signal regions, an additional systematic uncertainty (referred to as “Z/γ∗₊

jets extrapolation” in table4) is estimated by loosening the ST criteria and extrapolating into the signal

region. The uncertainty introduced by this procedure is small except in SR 10, where the effect on the statistical analysis is still small because the predicted number of background events is only 0.2.

Additional sources of uncertainty in the acceptance times efficiency are initial-state radiation, final-state radiation, renormalization and factorization scales, and the beam energy. The effects of initial- and final-state radiation are determined in generator-level studies by varying the relevant Pythia parameters and are less than 1%. The effect of the beam energy uncertainty (0.65%) [58] is determined by varying the momentum fraction of the initial partons in the PDFs by this amount, giving a change of less than 1%. The renormalization and factorization scales are independently varied in the simulation by factors of 2 and 1/2, changing the expected signal acceptance times efficiency by about 2% at low mass and by less than 1% for masses above 750 GeV.

The uncertainties in the signal yield depend on the µ∗mass, and the largest contributions are summarized in table3for three representative masses. For the signal yield, uncertainties in jet energy scale, PDFs, and luminosity are the dominant sources. The uncertainties in the background depend on the signal region, and the largest contributions are shown in table4for three representative regions. The most significant contributions to the background uncertainty are from the modelling of the Z/γ∗+ jets and t¯t processes.

mµ∗ [GeV] 500 1500 2500

Luminosity 2.8 2.8 2.8

Jet energy scale 2.7 1.5 1.1

Hadronization and factorization scales 2.0 0.5 0.1

PDFs 3.0 2.5 2.7

Muon efficiency 0.7 0.8 0.9

Jet energy resolution 0.9 0.2 0.5

Muon spectrometer resolution 0.3 <0.1 0.2

Total 5.1 4.1 4.2

Table 3: Largest contributions to the relative systematic uncertainty in the signal yield. The uncertainties for the hadronization and factorization scales and for the PDFs are only for the signal acceptance times efficiency. All uncertainties are given in percent and are determined after the fit discussed in Section8.

Signal region 2 6 10

Z/γ∗+ jets modelling 25 47 65

Jet energy scale 19 9.0 6.2

t¯tmodelling 12 <0.1 <0.1

Muon spectrometer resolution 6.2 0.6 63

PDFs 4.2 8.8 17

Jet energy resolution 3.2 1.7 0.6

Muon efficiency 0.7 0.8 0.9

Luminosity 0.4 0.1 <0.1

Z/γ∗+ jets extrapolation – – 500

Total 35 49 500

Table 4: Largest contributions to the relative systematic uncertainty in the expected background for three represent-ative signal regions. All uncertainties are given in percent and are determined after the fit discussed in Section8.

The jet energy scale and the parton distribution functions also make significant contributions. Any source of systematic uncertainty contributing less than 2% to the background for all signal regions and less than 1% to the signal yield for all µ∗masses would have negligible effect in the statistical analysis in Section8

and is not included.

8 Results

For each µ∗mass considered, the numbers of events in the corresponding signal region and in the two control regions are simultaneously fit [59] using a profile likelihood method [60, 61]. The likelihood function models the number of events as a Poisson distribution and the systematic effects are modelled using nuisance parameters with lognormal constraints. The parameters of interest in the fit are the signal yield in the corresponding signal region and the normalizations of the Z/γ∗ and t¯t backgrounds, with the latter two being primarily determined in the fit by the events in the control regions. The possible contribution of signal to the control regions is included in the fit and found to be negligible. Correlations of the systematic uncertainties are taken into account.

mµµ mµµ j j ST mµ1j j mµ2j j p µ1 T p µ2 T p j1 T p j2 T

Event SR [GeV] [GeV] [GeV] [GeV] [GeV] [GeV] [GeV] [GeV] [GeV]

A all 1800 2410 1820 1200 1090 650 630 350 190

B 7–9 310 2250 2010 2200 630 840 46 990 130

C 10 113 2440 1760 2230 1850 150 35 890 690

Table 5: Values of µµ mass, µµ j j mass, ST, µ j j mass for each µ j j combination, and pTof each muon and jet for

the three events in SR 9 or 10.

As an example of the result of the fit, the mµµ j j distribution for signal region 2 is shown in figure2(b) for the data, expected backgrounds, and three signal predictions forΛ = 5 TeV (the signal regions for the higher masses have fewer background events). The expected and observed numbers of events for each signal mass considered are shown in table2forΛ = 5 TeV. Due to correlations among the nuisance para-meters, the uncertainties on the expected backgrounds are reduced after the fits. The data are consistent with the Standard Model expectations, and no significant excess is observed. Thus, limits on the cross section times branching ratio as a function of the µ∗mass are calculated.

A modified frequentist CLs method [62, 63] is used to derive the 95% CL upper limits on the signal

yield. The expected limit is the median limit for a large number of background-only pseudo-experiments. The one- and two-standard-deviations bands cover 68% and 95%, respectively, of the pseudo-experiment limits. The observed limit is the 95% CL limit for the observed number of events. The p-value is a measure of how well the background-only hypothesis models the data. For a signal region, it is the fraction of background-only pseudo-experiments where the fitted signal value is greater than that for the observed data.

The smallest p-values are for SR 9 and 10 with values of 0.034 and 0.099, respectively, corresponding to 1.8 and 1.3 standard deviations on one side of a Gaussian distribution. Some kinematic properties of the events in these signal regions are given in table5. There is one event (event A) that is in all signal regions.

An upper limit on the cross section times branching ratio σ(pp → µµ∗) × B(µ∗ → µq¯q) (figure 3) is determined for each signal mass from the limit on the signal yield at the 95% CL. The theoretical uncertainties are not included in either the σB orΛ limit determinations. For mµ∗ above 1.3 TeV, the limit

is between 0.6 and 1 fb. The theoretical expectation forΛ = mµ∗ is also shown. The theoretical band

represents uncertainties from PDFs and from renormalization and factorization scales.

The expected cross section and branching ratio depend on the µ∗ mass and on Λ [7]. For each signal mass, the limit on σB is translated into a lower bound on the compositeness scale (figure4). The bound is the value ofΛ for which the theoretical prediction of σB(mµ∗, Λ) is equal to the upper limit on σB.

The region with mµ∗ > Λ is unphysical. For the limiting case where Λ = m_µ∗, excited-muon masses

below 2.9 TeV are excluded. Previous limits set by ATLAS [17,21] are also shown. for masses above 1200 GeV, the analysis presented here improves upon the limits from µ∗→µγ and is comparable to those from µ∗→µ``.

[TeV]

m

) [fb]

q

q

µ

→

*

µ

B(

σ

∫

Figure 3: Limit at 95% CL on cross section times branching ratio σ(pp → µµ∗)B(µ∗ → µq¯q) as a function of the µ∗_{mass, where q is any quark except the top quark. The solid line is the limit and the dotted line is the expected}

limit. The theoretical σB for the limiting caseΛ = mµ∗along with its uncertainties is also shown.

[TeV]

m

[TeV]

Λ

∫

Figure 4: Limit at 95% CL on the compositeness scaleΛ as a function of the µ∗_{mass. The solid line is the observed}

limit and the short dashed line is the expected limit. Also indicated are previous results from ATLAS based on µ∗_{→µγ (long dashed line) and µ}∗_{→µ`` (dot-dashed line), where ` is an electron or muon.}

9 Conclusion

The results of a search for excited muons decaying to µ j j via a contact interaction are reported based on data from √s= 8 TeV pp collisions collected with the ATLAS detector at the LHC corresponding to an integrated luminosity of 20.3 fb−1. The observed data are consistent with SM expectations. An upper limit is set at 95% CL on the cross section times branching ratio σB(µ∗ → µq¯q) as a function of the excited-muon mass. For mµ∗ between 1.3 and 3.0 TeV, the limit on σB is between 0.6 and 1 fb.

The σB upper limits are converted to lower bounds on the compositeness scaleΛ. In the limiting case whereΛ = mµ∗, excited-muon masses below 2.9 TeV are excluded. At higher µ∗masses, the signature

explored in this paper, µ∗ → µ j j, has better sensitivity than the traditional signature µ∗ →µ γ. For µ∗ masses above 1.2 TeV, the sensitivity is comparable to a previous search using the signature µ∗→µ``. In models other than the benchmark model used here, the branching ratios to these modes could be different, affecting their relative importance for limits on the compositeness scale.

Acknowledgements

We thank CERN for the very successful operation of the LHC, as well as the support staff from our institutions without whom ATLAS could not be operated efficiently.

We acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; BMWFW and FWF, Austria; ANAS, Azerbaijan; SSTC, Belarus; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; CONICYT, Chile; CAS, MOST and NSFC, China; COLCIENCIAS, Colombia; MSMT CR, MPO CR and VSC CR, Czech Republic; DNRF and DNSRC, Denmark; IN2P3-CNRS, CEA-DSM/IRFU, France; GNSF, Georgia; BMBF, HGF, and MPG, Germany; GSRT, Greece; RGC, Hong Kong SAR, China; ISF, I-CORE and Benoziyo Center, Israel; INFN, Italy; MEXT and JSPS, Japan; CNRST, Morocco; FOM and NWO, Netherlands; RCN, Norway; MNiSW and NCN, Poland; FCT, Por-tugal; MNE/IFA, Romania; MES of Russia and NRC KI, Russian Federation; JINR; MESTD, Serbia; MSSR, Slovakia; ARRS and MIZŠ, Slovenia; DST/NRF, South Africa; MINECO, Spain; SRC and Wallenberg Foundation, Sweden; SERI, SNSF and Cantons of Bern and Geneva, Switzerland; MOST, Taiwan; TAEK, Turkey; STFC, United Kingdom; DOE and NSF, United States of America. In addition, individual groups and members have received support from BCKDF, the Canada Council, CANARIE, CRC, Compute Canada, FQRNT, and the Ontario Innovation Trust, Canada; EPLANET, ERC, FP7, Ho-rizon 2020 and Marie Skłodowska-Curie Actions, European Union; Investissements d’Avenir Labex and Idex, ANR, Région Auvergne and Fondation Partager le Savoir, France; DFG and AvH Foundation, Ger-many; Herakleitos, Thales and Aristeia programmes co-financed by EU-ESF and the Greek NSRF; BSF, GIF and Minerva, Israel; BRF, Norway; Generalitat de Catalunya, Generalitat Valenciana, Spain; the Royal Society and Leverhulme Trust, United Kingdom.

The crucial computing support from all WLCG partners is acknowledged gratefully, in particular from CERN and the ATLAS Tier-1 facilities at TRIUMF (Canada), NDGF (Denmark, Norway, Sweden), CC-IN2P3 (France), KIT/GridKA (Germany), INFN-CNAF (Italy), NL-T1 (Netherlands), PIC (Spain), ASGC (Taiwan), RAL (UK) and BNL (USA) and in the Tier-2 facilities worldwide.

References

[1] J. C. Pati, A. Salam, Phys. Rev. D 10 (1974) 275. [2] J. C. Pati, A. Salam, Phys. Rev. D 11 (1975) 703. [3] H. Terazawa, et al., Phys. Lett. B 112 (1982) 137.

[4] E. J. Eichten, K. D. Lane, M. E. Peskin, Phys. Rev. Lett. 50 (1983) 811. [5] N. Cabibbo, L. Maiani, Y. Srivastava, Phys. Lett. B 139 (1984) 459. [6] K. Hagiwara, S. Komamiya, D. Zeppenfeld, Z. Phys. C29 (1985) 115. [7] U. Baur, M. Spira, M. Zerwas, Phys. Rev. D 42 (1990) 815–824. [8] ALEPH Collaboration, D. Buskulic et al., Phys. Lett. B 385 (1996) 445. [9] OPAL Collaboration, G. Abbiendi et al., Eur. Phys. J. C14 (2000) 73,

arXiv:hep-ex/0001056 [hep-ex].

[10] L3 Collaboration, P. Achard et al., Phys. Lett. B 568 (2003) 23, arXiv:hep-ex/0306016 [hep-ex].

[11] DELPHI Collaboration, J. Abdallah et al., Eur. Phys. J. C46 (2006) 277, arXiv:hep-ex/0603045 [hep-ex].

[12] CDF Collaboration, D. Acosta et al., Phys. Rev. Lett. 94 (2005) 101802, arXiv:hep-ex/0410013 [hep-ex].

[13] CDF Collaboration, A. Abulencia et al., Phys. Rev. Lett. 97 (2006) 191802, arXiv:hep-ex/0606043 [hep-ex].

[14] D0 Collaboration, V. M. Abazov et al., Phys. Rev. D 73 (2006) 111102, arXiv:hep-ex/0604040 [hep-ex].

[15] D0 Collaboration, V. M. Abazov et al., Phys. Rev. D 77 (2008) 091102, arXiv:0801.0877 [hep-ex].

[16] ATLAS Collaboration, Phys. Rev. D 85 (2012) 072003, arXiv:1201.3293 [hep-ex]. [17] ATLAS Collaboration, New J. Phys. 15 (2013) 093011, arXiv:1308.1364 [hep-ex]. [18] CMS Collaboration, Phys. Lett. B 704 (2011) 143, arXiv:1107.1773 [hep-ex]. [19] CMS Collaboration, Phys. Lett. B 720 (2013) 309, arXiv:1210.2422 [hep-ex].

[20] CMS Collaboration, J. High Energy Phys. 1603 (2015) 125, arXiv:1511.01407 [hep-ph]. [21] ATLAS Collaboration, J. High Energy Phys. 1508 (2015) 138, arXiv:1411.2921v2 [hep-ex]. [22] ATLAS Collaboration, JINST 3 (2008) S08003.

[23] E. Boos et al., Nucl. Instrum. Meth. A534 (2004) 250, arXiv:hep-ph/0403113 [hep-ph]. [24] A. Martin, W. Stirling, R.S. Thorne, and G. Watt, Eur. Phys. J. C63 (2009) 189,

arXiv:0901.0002 [hep-ph].

[25] A. S. Belyaev et al., AIP Conf. Proc. 583 (2001) 211, arXiv:hep-ph/0101232 [hep-ph]. [26] T. Sjöstrand, S. Mrenna, and P. Skands, Comp. Phys. Comm. 178 (2008) 852,

[27] ATLAS Collaboration, ATL-PHYS-PUB-2012-003, 2012, url:http://cds.cern.ch/record/1474107.

[28] T. Gleisberg et al., J. High Energy Phys. 0902 (2009) 007, arXiv:0811.4622 [hep-ph]. [29] H.-L. Lai et al., Phys. Rev. D 82 (2010) 074024, arXiv:1007.2241 [hep-ph].

[30] K. Melnikov and F. Petriello, Phys. Rev. D 74 (2006) 114017, arXiv:hep-ph/0609070 [hep-ph].

[31] Y. Li and F. Petriello, Phys. Rev. D 86 (2012) 094034, arXiv:1208.5967 [hep-ph]. [32] T. Melia et al., J. High Energy Phys. 1111 (2011) 078, arXiv:1107.5051 [hep-ph]. [33] P.Z. Skands, Phys. Rev. D 82 (2010) 074018, arXiv:1005.3457 [hep-ph].

[34] T. Sjöstrand, S. Mrenna, and P. Skands, J. High Energy Phys. 0605 (2006) 026, arXiv:hep-ph/0603175 [hep-ph].

[35] M. Czakon and A. Mitov, Comp. Phys. Comm. 185 (2014) 2930, arXiv:1112.5675 [hep-ph]. [36] G. Corcella et al., J. High Energy Phys. 0101 (2001) 010, arXiv:hep-ph/0011363 [hep-ph]. [37] ATLAS Collaboration, ATL-PHYS-PUB-2011-008, 2011,

url:http://cds.cern.ch/record/1345343.

[38] M. L. Mangano et al., J. High Energy Phys. 0307 (2003) 001, arXiv:hep-ph/0206293 [hep-ph].

[39] J. M. Butterworth, J. R. Forshaw, and M. H. Seymour, Z. Phys.C 72 (1996) 637, arXiv:hep-ph/9601322 [hep-ph].

[40] B. P. Kersevan and E. Richter-Was, Comp. Phys. Comm. 184 (2013) 919, arXiv:hep-ph/0405297 [hep-ph].

[41] ATLAS Collaboration, ATL-PHYS-PUB-2011-014, 2011, url:http://cds.cern.ch/record/1400677.

[42] S. Frixione and B. R. Webber, J. High Energy Phys. 0206 (2002) 029, arXiv:hep-ph/0204244 [hep-ph].

[43] S. Frixione, E. Laenen, P. Motylinski, and B. R. Webber, J. High Energy Phys. 0603 (2006) 092, arXiv:hep-ph/0512250 [hep-ph].

[44] S. Frixione et al., J. High Energy Phys. 0807 (2008) 029, arXiv:0805.3067 [hep-ph]. [45] J. M. Campbell, R. K. Ellis, and C. Williams, J. High Energy Phys. 1107 (2011) 018,

arXiv:1105.0020 [hep-ph].

[46] ATLAS Collaboration, Eur. Phys. J. C 70 (2010) 823, arXiv:1005.4568 [hep-ex]. [47] S. Agostinelli et al. (Geant 4 Collaboration), Nucl. Instrum. Meth. A506 (2003) 250. [48] ATLAS Collaboration, Eur. Phys. J. C 75 (2015) 120, arXiv:1408.3179 [hep-ex]. [49] ATLAS Collaboration, Eur. Phys. J. C 74 (2014) 3130, arXiv:1407.3935 [hep-ex]. [50] ATLAS Collaboration, Eur. Phys. J. C 74 (2014) 2941, arXiv:1404.2240 [hep-ex]. [51] M. Cacciari, G. P. Salam, and G. Soyez, J. High Energy Phys. 0804 (2008) 063,

arXiv:0802.1189 [hep-ph].

[53] ATLAS Collaboration, Phys. Rev. D 83 (2011) 052005, arXiv:1012.4389 [hep-ex]. [54] ATLAS Collaboration, Eur. Phys. J. C 71 (2011) 1577, arXiv:1012.1792 [hep-ex]. [55] ATLAS Collaboration, Eur. Phys. J. C 73 (2013) 2518, arXiv:1302.4393 [hep-ex]. [56] ATLAS Collaboration, Eur. Phys. J. C 75 (2015) 17, arXiv:1406.0076 [hep-ex]. [57] R. D. Ball et al., Nucl. Phys. B 849 (2011) 296, arXiv:1101.1300 [hep-ph].

[58] J. Wenninger, CERN-ATS-2013-040, 2013, url:http://cdsweb.cern.ch/record/1546734. [59] M. Baak et al., Eur. Phys. J. C75 (2015) 153, arXiv:1410.1280 [hep-ex].

[60] G. Cowan K. Cranmer, E. Gross, and O. Vitells, Eur. Phys. J. C71 (2011) 1554, arXiv:1007.1727 [phys.data-an].

[61] G. Cowan K. Cranmer, E. Gross, and O. Vitells, Eur. Phys. J. C73 (2013) 2501, arXiv:1007.1727 [phys.data-an].

[62] T. Junk, Nucl. Instrum. Meth. A434 (1999) 435, arXiv:hep-ex/9902006 [hep-ex]. [63] A. L. Read, J. Phys. G 28 (2002) 2693.

The ATLAS Collaboration

G. Aad100, B. Abbott127, J. Abdallah76, O. Abdinov13,*, B. Abeloos131, R. Aben118, M. Abolins105, O.S. AbouZeid165, H. Abramowicz160, H. Abreu159, R. Abreu130, Y. Abulaiti45a,45b,

B.S. Acharya66a,66b,n, C. Adam Bourdarios131, L. Adamczyk82a, D.L. Adams29, J. Adelman119, S. Adomeit112, T. Adye143, A.A. Affolder89, T. Agatonovic-Jovin16, J. Agricola53,

J.A. Aguilar-Saavedra139f,139a, S.P. Ahlen25, F. Ahmadov78,ab, G. Aielli73a,73b, H. Akerstedt45a,45b, T.P.A. Åkesson95, A.V. Akimov109, G.L. Alberghi23b,23a, J. Albert174, S. Albrand58,

M.J. Alconada Verzini87, M. Aleksa36, I.N. Aleksandrov78, C. Alexa27b, G. Alexander160, T. Alexopoulos10, M. Alhroob127, G. Alimonti68a, L. Alio100, J. Alison37, S.P. Alkire40,

B.M.M. Allbrooke155_{, B.W. Allen}130_{, P.P. Allport}21_{, A. Aloisio}69a,69b_{, A. Alonso}41_{, F. Alonso}87_,

C. Alpigiani147, B. Alvarez Gonzalez36, D. Álvarez Piqueras172, M.G. Alviggi69a,69b, B.T. Amadio18, K. Amako80, Y. Amaral Coutinho79b, C. Amelung26, D. Amidei104, S.P. Amor Dos Santos139a,139c, A. Amorim139a_{, S. Amoroso}36_{, N. Amram}160_{, G. Amundsen}26_{, C. Anastopoulos}148_{, L.S. Ancu}54_,

N. Andari119, T. Andeen11, C.F. Anders62b, G. Anders36, J.K. Anders89, K.J. Anderson37, A. Andreazza68a,68b, V. Andrei62a, S. Angelidakis9, I. Angelozzi118, P. Anger48, A. Angerami40, F. Anghinolfi36, A.V. Anisenkov120b,120a, N. Anjos14, A. Annovi71a, M. Antonelli51, A. Antonov110,*, J. Antos28b, F. Anulli72a, M. Aoki80, L. Aperio Bella21, G. Arabidze105, Y. Arai80, J.P. Araque139a, A.T.H. Arce49, F.A. Arduh87, J-F. Arguin108, S. Argyropoulos76, M. Arik12c, A.J. Armbruster36, O. Arnaez36, H. Arnold52, M. Arratia32, O. Arslan24, A. Artamonov121,*, G. Artoni134, S. Artz98, S. Asai162, N. Asbah46, A. Ashkenazi160, B. Åsman45a,45b, L. Asquith155, K. Assamagan29,

R. Astalos28a, M. Atkinson171, N.B. Atlay150, K. Augsten141, G. Avolio36, B. Axen18, M.K. Ayoub131, G. Azuelos108,ap, M.A. Baak36, A.E. Baas62a, M.J. Baca21, H. Bachacou144, K. Bachas161, M. Backes36, M. Backhaus36, P. Bagiacchi72a,72b, P. Bagnaia72a,72b, Y. Bai15a, J.T. Baines143, O.K. Baker181,

E.M. Baldin120b,120a, P. Balek142, T. Balestri154, F. Balli99, W.K. Balunas136, E. Banas83,

Sw. Banerjee179,j, A.A.E. Bannoura180, L. Barak36, E.L. Barberio103, D. Barberis55b,55a, M. Barbero100, T. Barillari113, T. Barklow152, N. Barlow32, S.L. Barnes99, B.M. Barnett143, R.M. Barnett18,

Z. Barnovska-Blenessy5, A. Baroncelli74a, G. Barone26, A.J. Barr134, L. Barranco Navarro172, F. Barreiro97, J. Barreiro Guimarães da Costa15a, R. Bartoldus152, A.E. Barton88, P. Bartos28a, A. Basalaev137, A. Bassalat131,ak, A. Basye171, R.L. Bates57, S.J. Batista165, J.R. Batley32, M. Battaglia145, M. Bauce72a,72b, F. Bauer144, H.S. Bawa31,l, J.B. Beacham125, M.D. Beattie88, T. Beau135, P.H. Beauchemin168, R. Beccherle55b,55a, P. Bechtle24, H.P. Beck20,p, K. Becker134, M. Becker98, M. Beckingham176, C. Becot131, A. Beddall12e, A.J. Beddall12e, V.A. Bednyakov78, M. Bedognetti118, C.P. Bee154, L.J. Beemster118, T.A. Beermann36, M. Begel29, J.K. Behr134, C. Belanger-Champagne102, G. Bella160, L. Bellagamba23b, A. Bellerive34, M. Bellomo101,

K. Belotskiy110, O. Beltramello36, O. Benary160,*, D. Benchekroun35a, M. Bender112, K. Bendtz45a,45b, N. Benekos10, Y. Benhammou160, E. Benhar Noccioli181, J.A. Benitez Garcia166b, D.P. Benjamin49, J.R. Bensinger26, S. Bentvelsen118, L. Beresford134, M. Beretta51, D. Berge118,

E. Bergeaas Kuutmann170, N. Berger5, F. Berghaus36, J. Beringer18, C. Bernard25, N.R. Bernard101, C. Bernius123, F.U. Bernlochner24, T. Berry92, P. Berta142, C. Bertella98, G. Bertoli45a,45b,

F. Bertolucci71a,71b, C. Bertsche127, D. Bertsche127, G.J. Besjes41, O. Bessidskaia Bylund45a,45b,

M. Bessner46, N. Besson144, C. Betancourt52, S. Bethke113, A.J. Bevan91, W. Bhimji50, R.M. Bianchi138, L. Bianchini26, M. Bianco36, O. Biebel112, D. Biedermann19, N.V. Biesuz71a,71b, M. Biglietti74a,

J. Bilbao De Mendizabal54, H. Bilokon51, M. Bindi53, S. Binet131, A. Bingul12e, C. Bini72a,72b, S. Biondi23b,23a, D.M. Bjergaard49, C.W. Black156, J.E. Black152, K.M. Black25, D. Blackburn147, R.E. Blair6, J.-B. Blanchard144, J.E. Blanco92, T. Blazek28a, I. Bloch46, C. Blocker26, W. Blum98,*,

U. Blumenschein53_{, S. Blunier}146a_{, G.J. Bobbink}118_{, V.S. Bobrovnikov}120b,120a_{, S.S. Bocchetta}95_,

A. Bocci49, C. Bock112, M. Boehler52, D. Boerner180, J.A. Bogaerts36, D. Bogavac16,

A.G. Bogdanchikov120b,120a, C. Bohm45a, V. Boisvert92, T. Bold82a, V. Boldea27b, A.S. Boldyrev66a,66c, M. Bomben135, M. Bona91, M. Boonekamp144, A. Borisov122, G. Borissov88, J. Bortfeldt112,

V. Bortolotto64a,64b,64c, D. Boscherini23b, M. Bosman14, J.D. Bossio Sola30, J. Boudreau138, J. Bouffard2, E.V. Bouhova-Thacker88, D. Boumediene38, N. Bousson128, S.K. Boutle57, A. Boveia36, J. Boyd36, I.R. Boyko78, J. Bracinik21, A. Brandt8, G. Brandt53, O. Brandt62a, U. Bratzler163, B. Brau101, J.E. Brau130, H.M. Braun180,*, W.D. Breaden Madden57, K. Brendlinger136, A.J. Brennan103,

L. Brenner118, R. Brenner170, S. Bressler178, T.M. Bristow50, D. Britton57, D. Britzger46, F.M. Brochu32, I. Brock24, R. Brock105, G. Brooijmans40, T. Brooks92, W.K. Brooks146c, J. Brosamer18, E. Brost130, P.A. Bruckman de Renstrom83, D. Bruncko28b, R. Bruneliere52, A. Bruni23b, G. Bruni23b, B.H. Brunt32, M. Bruschi23b, N. Bruscino24, P. Bryant37, L. Bryngemark95, T. Buanes17, Q. Buat151, P. Buchholz150, A.G. Buckley57, I.A. Budagov78, L. Bugge133, M.K. Bugge133, F. Bührer52, O. Bulekov110, D. Bullock8, H. Burckhart36, S. Burdin89, C.D. Burgard52, B. Burghgrave119, S. Burke143, I. Burmeister47,

E. Busato38, D. Büscher52, V. Büscher98, P.J. Bussey57, J.M. Butler25, A.I. Butt3, C.M. Buttar57, J.M. Butterworth93, P. Butti118, W. Buttinger29, A. Buzatu57, A.R. Buzykaev120b,120a,

S. Cabrera Urbán172, D. Caforio141, V.M.M. Cairo42b,42a, O. Cakir4a, N. Calace54, P. Calafiura18, A. Calandri100, G. Calderini135, P. Calfayan112, L.P. Caloba79b, D. Calvet38, S. Calvet38, T.P. Calvet100, R. Camacho Toro37, S. Camarda46, P. Camarri73a,73b, D. Cameron133, R. Caminal Armadans171, C. Camincher58, S. Campana36, M. Campanelli93, A. Campoverde154, V. Canale69a,69b, A. Canepa166a, M. Cano Bret61c, J. Cantero97, R. Cantrill139a, T. Cao43, M.D.M. Capeans Garrido36, I. Caprini27b, M. Caprini27b, M. Capua42b,42a, R. Caputo98, R.M. Carbone40, R. Cardarelli73a, F. Cardillo52, I. Carli142, T. Carli36, G. Carlino69a, L. Carminati68a,68b, S. Caron117, E. Carquin146a, G.D. Carrillo-Montoya36, J.R. Carter32, J. Carvalho139a, D. Casadei93, M.P. Casado14,h, M. Casolino14, D.W. Casper169, E. Castaneda-Miranda33a, A. Castelli118, V. Castillo Gimenez172, N.F. Castro139a, A. Catinaccio36, J.R. Catmore133, A. Cattai36, J. Caudron98, V. Cavaliere171, D. Cavalli68a, M. Cavalli-Sforza14,

V. Cavasinni71a,71b, F. Ceradini74a,74b, L. Cerda Alberich172, B.C. Cerio49, A.S. Cerqueira79a, A. Cerri155, L. Cerrito91, F. Cerutti18, M. Cerv36, A. Cervelli20, S.A. Cetin12d, A. Chafaq35a, D. Chakraborty119, Y.L. Chan64a, P. Chang171, J.D. Chapman32, D.G. Charlton21, C.C. Chau165, C.A. Chavez Barajas155, S. Che125, S. Cheatham88, A. Chegwidden105, S. Chekanov6, S.V. Chekulaev166a, G.A. Chelkov78,ao, M.A. Chelstowska104, C.H. Chen77, H. Chen29, K. Chen154, S. Chen162, S.J. Chen15c, X. Chen15b,an, Y. Chen81, H.C. Cheng104, Y. Cheng37, A. Cheplakov78, E. Cheremushkina122,

R. Cherkaoui El Moursli35e, V. Chernyatin29,*, E. Cheu7, L. Chevalier144, V. Chiarella51, G. Chiarelli71a, G. Chiodini67a, A.S. Chisholm21, R.T. Chislett93, A. Chitan27b, M.V. Chizhov78, K. Choi65,

S. Chouridou9_{, B.K.B. Chow}112_{, V. Christodoulou}93_{, D. Chromek-Burckhart}36_{, J. Chudoba}140_,

A.J. Chuinard102, J.J. Chwastowski83, L. Chytka129, G. Ciapetti72a,72b,*, A.K. Ciftci4a, D. Cinca57, V. Cindro90, I.A. Cioar˘a24, A. Ciocio18, F. Cirotto69a,69b, Z.H. Citron178, M. Ciubancan27b, A. Clark54, B.L. Clark60, P.J. Clark50, R.N. Clarke18, C. Clement45a,45b, Y. Coadou100, M. Cobal66a,66c,

A. Coccaro54, J. Cochran77, L. Coffey26, L. Colasurdo117, B. Cole40, S. Cole119, A.P. Colijn118, J. Collot58, T. Colombo62c, G. Compostella113, P. Conde Muiño139a, E. Coniavitis52, S.H. Connell33b, I.A. Connelly92, V. Consorti52, S. Constantinescu27b, C. Conta70a,70b, G. Conti36, F. Conventi69a,aq, M. Cooke18, B.D. Cooper93, A.M. Cooper-Sarkar134, T. Cornelissen180, M. Corradi72a,72b,

F. Corriveau102,z, A. Corso-Radu169, A. Cortes-Gonzalez14, G. Cortiana113, G. Costa68a, M.J. Costa172, D. Costanzo148, G. Cottin32, G. Cowan92, B.E. Cox99, K. Cranmer123, S.J. Crawley57, G. Cree34, S. Crépé-Renaudin58, F. Crescioli135, W.A. Cribbs45a,45b, M. Crispin Ortuzar134, M. Cristinziani24, V. Croft117, G. Crosetti42b,42a, T. Cuhadar Donszelmann148, J. Cummings181, M. Curatolo51, J. Cúth98, C. Cuthbert156, H. Czirr150, P. Czodrowski3, M.J. Da Cunha Sargedas De Sousa139a,139b, C. Da Via99,

W. Dabrowski82a_{, A. Dafinca}134_{, T. Dai}104_{, O. Dale}17_{, F. Dallaire}108_{, C. Dallapiccola}101_{, M. Dam}41_,

J.R. Dandoy37, N.P. Dang52, A.C. Daniells21, M. Danninger173, M. Dano Hoffmann144, V. Dao52, G. Darbo55b, S. Darmora8, J. Dassoulas3, A. Dattagupta65, S. D’Auria57, W. Davey24, C. David174, T. Davidek142, E. Davies134, M. Davies160, P. Davison93, Y. Davygora62a, E. Dawe103, I. Dawson148, R.K. Daya-Ishmukhametova101, K. De8, R. De Asmundis69a, A. De Benedetti127, S. De Castro23b,23a, S. De Cecco135, N. De Groot117, P. de Jong118, H. De la Torre97, F. De Lorenzi77, D. De Pedis72a, A. De Salvo72a, U. De Sanctis155, A. De Santo155, J.B. De Vivie De Regie131, W.J. Dearnaley88, R. Debbe29, C. Debenedetti145, D.V. Dedovich78, A.M. Deiana104, I. Deigaard118, J. Del Peso97, T. Del Prete71a,71b, D. Delgove131, F. Deliot144, C.M. Delitzsch54, M. Deliyergiyev90,

M. Della Pietra69a,69b, D. Della Volpe54, A. Dell’Acqua36, L. Dell’Asta25, M. Dell’Orso71a,71b, M. Delmastro5, P.A. Delsart58, C. Deluca118, D.A. DeMarco165, S. Demers181, M. Demichev78, A. Demilly135, S.P. Denisov122, D. Denysiuk144, D. Derendarz83, J.E. Derkaoui35d, F. Derue135, P. Dervan89, K. Desch24, C. Deterre46, K. Dette47, P.O. Deviveiros36, A. Dewhurst143, S. Dhaliwal26, A. Di Ciaccio73a,73b, L. Di Ciaccio5, C. Di Donato72a,72b, A. Di Girolamo36, B. Di Girolamo36, B. Di Micco74a,74b, R. Di Nardo51, A. Di Simone52, R. Di Sipio165, D. Di Valentino34, C. Diaconu100, M. Diamond165, F.A. Dias50, M.A. Diaz146a, E.B. Diehl104, J. Dietrich19, S. Diglio100, A. Dimitrievska16, J. Dingfelder24, P. Dita27b, S. Dita27b, F. Dittus36, F. Djama100, T. Djobava158b, J.I. Djuvsland62a,

M.A.B. Do Vale79c, D. Dobos36, M. Dobre27b, C. Doglioni95, T. Dohmae162, J. Dolejsi142, Z. Dolezal142, B.A. Dolgoshein110,*, M. Donadelli79d, S. Donati71a,71b, P. Dondero70a,70b, J. Donini38, M. D’Onofrio89, J. Dopke143, A. Doria69a, M.T. Dova87, A.T. Doyle57, E. Drechsler53, M. Dris10, Y. Du61b,

J. Duarte-Campderros160, E. Dubreuil38, E. Duchovni178, G. Duckeck112, O.A. Ducu27b, D. Duda118, A. Dudarev36, L. Duflot131, L. Duguid92, M. Dührssen36, M. Dunford62a, H. Duran Yildiz4a,

M. Düren56, A. Durglishvili158b, D. Duschinger48, B. Dutta46, M. Dyndal82a, C. Eckardt46,

K.M. Ecker113, R.C. Edgar104, W. Edson2, N.C. Edwards50, T. Eifert36, G. Eigen17, K. Einsweiler18, T. Ekelof170, M. El Kacimi35c, V. Ellajosyula100, M. Ellert170, S. Elles5, F. Ellinghaus180, A.A. Elliot174, N. Ellis36, J. Elmsheuser112, M. Elsing36, D. Emeliyanov143, Y. Enari162, O.C. Endner98, M. Endo132, J.S. Ennis176, J. Erdmann47, A. Ereditato20, G. Ernis180, J. Ernst2, M. Ernst29, S. Errede171, E. Ertel98, M. Escalier131, H. Esch47, C. Escobar138, B. Esposito51, A.I. Etienvre144, E. Etzion160, H. Evans65, A. Ezhilov137, L. Fabbri23b,23a, G. Facini37, R.M. Fakhrutdinov122, S. Falciano72a, R.J. Falla93, J. Faltova142, Y. Fang15a, M. Fanti68a,68b, A. Farbin8, A. Farilla74a, C. Farina138, T. Farooque14, S. Farrell18, S.M. Farrington176, P. Farthouat36, F. Fassi35e, P. Fassnacht36, D. Fassouliotis9,

M. Faucci Giannelli92, A. Favareto55b,55a, L. Fayard131, O.L. Fedin137,o, W. Fedorko173, S. Feigl133, L. Feligioni100, C. Feng61b, E.J. Feng36, H. Feng104, A.B. Fenyuk122, L. Feremenga8,

P. Fernandez Martinez172, S. Fernandez Perez14, J. Ferrando57, A. Ferrari170, P. Ferrari118, R. Ferrari70a, D.E. Ferreira de Lima57_{, A. Ferrer}172_{, D. Ferrere}54_{, C. Ferretti}104_{, A. Ferretto Parodi}55b,55a_{, F. Fiedler}98_,

M. Filipuzzi46, A. Filipˇciˇc90, F. Filthaut117, M. Fincke-Keeler174, K.D. Finelli156,

M.C.N. Fiolhais139a,139c,c, L. Fiorini172, A. Firan43, A. Fischer2, C. Fischer14, J. Fischer180, W.C. Fisher105, N. Flaschel46, I. Fleck150, P. Fleischmann104, G. Fletcher91, G.T. Fletcher148, R.R.M. Fletcher136, T. Flick180, A. Floderus95, L.R. Flores Castillo64a, M.J. Flowerdew113,

G.T. Forcolin99, A. Formica144, A.C. Forti99, D. Fournier131, H. Fox88, S. Fracchia14, P. Francavilla135, M. Franchini23b,23a, D. Francis36, L. Franconi133, M. Franklin60, M. Frate169, M. Fraternali70a,70b, D. Freeborn93, S.M. Fressard-Batraneanu36, F. Friedrich48, D. Froidevaux36, J.A. Frost134, C. Fukunaga163, T. Fusayasu114, J. Fuster172, C. Gabaldon58, O. Gabizon180, A. Gabrielli23b,23a, A. Gabrielli18, G.P. Gach82a, S. Gadatsch36, S. Gadomski54, G. Gagliardi55b,55a, P. Gagnon65,

C. Galea117, B. Galhardo139a,139c, E.J. Gallas134, B.J. Gallop143, P. Gallus141, G. Galster41, K.K. Gan125, J. Gao61a,100, Y. Gao50, Y.S. Gao31,l, C. García172, J.E. García Navarro172, M. Garcia-Sciveres18, R.W. Gardner37, N. Garelli152, V. Garonne133, A. Gascon Bravo46, C. Gatti51, A. Gaudiello55b,55a,

G. Gaudio70a_{, B. Gaur}150_{, L. Gauthier}108_{, I.L. Gavrilenko}109_{, C. Gay}173_{, G. Gaycken}24_{, E.N. Gazis}10_,

Z. Gecse173, C.N.P. Gee143, Ch. Geich-Gimbel24, M.P. Geisler62a, C. Gemme55b, M.H. Genest58, C. Geng61a,q, S. Gentile72a,72b, S. George92, D. Gerbaudo169, A. Gershon160, S. Ghasemi150, H. Ghazlane39, B. Giacobbe23b, S. Giagu72a,72b, P. Giannetti71a, B. Gibbard29, S.M. Gibson92, M. Gignac173, M. Gilchriese18, T.P.S. Gillam32, D. Gillberg34, G. Gilles38, D.M. Gingrich3,ap, N. Giokaris9,*, M.P. Giordani66a,66c, F.M. Giorgi19, F.M. Giorgi23b, P.F. Giraud144, P. Giromini60, D. Giugni68a, C. Giuliani113, M. Giulini62b, B.K. Gjelsten133, S. Gkaitatzis161, I. Gkialas9,i,

E.L. Gkougkousis131, L.K. Gladilin111, C. Glasman97, J. Glatzer36, P.C.F. Glaysher50, A. Glazov46, M. Goblirsch-Kolb113, J. Godlewski83, S. Goldfarb104, T. Golling54, D. Golubkov122, A. Gomes139a,139b, J. Goncalves Pinto Firmino Da Costa144, R. Gonçalo139a, L. Gonella24, S. González de la Hoz172, G. Gonzalez Parra14, S. Gonzalez-Sevilla54, L. Goossens36, P.A. Gorbounov121, H.A. Gordon29, I. Gorelov116, B. Gorini36, E. Gorini67a,67b, A. Gorišek90, E. Gornicki83, A.T. Goshaw49, C. Gössling47, M.I. Gostkin78, C.R. Goudet131, D. Goujdami35c, A.G. Goussiou147, N. Govender33b,d, E. Gozani159, L. Graber53, I. Grabowska-Bold82a, P.O.J. Gradin58, P. Grafström23a, J. Gramling54, E. Gramstad133, S. Grancagnolo19, V. Gratchev137, H.M. Gray36, E. Graziani74a, Z.D. Greenwood94, C. Grefe24, K. Gregersen93, I.M. Gregor46, P. Grenier152, K. Grevtsov5, J. Griffiths8, A.A. Grillo145, K. Grimm88, S. Grinstein14,u, Ph. Gris38, J.-F. Grivaz131, S. Groh98, J.P. Grohs48, E. Gross178, J. Grosse-Knetter53, G.C. Grossi94, Z.J. Grout155, L. Guan104, J. Guenther141, F. Guescini54, D. Guest169, O. Gueta160, E. Guido55b,55a, T. Guillemin5, S. Guindon2, U. Gul57, C. Gumpert36, J. Guo61c, Y. Guo61a,q,

S. Gupta134, G. Gustavino72a,72b, P. Gutierrez127, N.G. Gutierrez Ortiz93, C. Gutschow48, C. Guyot144, C. Gwenlan134, C.B. Gwilliam89, A. Haas123, C. Haber18, H.K. Hadavand8, A. Hadef100, P. Haefner24, S. Hageböck24, Z. Hajduk83, H. Hakobyan182,*, M. Haleem46, J. Haley128, D. Hall134, G. Halladjian105, G.D. Hallewell100, K. Hamacher180, P. Hamal129, K. Hamano174, A. Hamilton33a, G.N. Hamity148, P.G. Hamnett46, L. Han61a, K. Hanagaki80,t, K. Hanawa162, M. Hance145, B. Haney136, P. Hanke62a, R. Hanna144, J.B. Hansen41, J.D. Hansen41, M.C. Hansen24, P.H. Hansen41, K. Hara167, A.S. Hard179, T. Harenberg180, F. Hariri131, S. Harkusha106, R.D. Harrington50, P.F. Harrison176, M. Hasegawa81, Y. Hasegawa149, A. Hasib127, S. Hassani144, S. Haug20, R. Hauser105, L. Hauswald48, M. Havranek140, C.M. Hawkes21, R.J. Hawkings36, A.D. Hawkins95, T. Hayashi167, D. Hayden105, C.P. Hays134, J.M. Hays91, H.S. Hayward89, S.J. Haywood143, S.J. Head21, T. Heck98, V. Hedberg95, L. Heelan8, K.K. Heidegger52, S. Heim136, T. Heim18, B. Heinemann18, L. Heinrich123, J. Hejbal140, L. Helary25, S. Hellman45a,45b, C. Helsens36, J. Henderson134, R.C.W. Henderson88, Y. Heng179, S. Henkelmann173, A.M. Henriques Correia36, S. Henrot-Versille131, G.H. Herbert19, Y. Hernández Jiménez172, G. Herten52, R. Hertenberger112, L. Hervas36, G.G. Hesketh93, N.P. Hessey118, J.W. Hetherly43, R. Hickling91, E. Higón-Rodriguez172, E. Hill174, J.C. Hill32, K.H. Hiller46, S.J. Hillier21, I. Hinchliffe18, E. Hines136, R.R. Hinman18_{, M. Hirose}164_{, D. Hirschbuehl}180_{, J. Hobbs}154_{, N. Hod}118_{, M.C. Hodgkinson}148_,

P. Hodgson148, A. Hoecker36, M.R. Hoeferkamp116, F. Hoenig112, M. Hohlfeld98, D. Hohn24, T.R. Holmes18, M. Homann47, T.M. Hong138, B.H. Hooberman171, W.H. Hopkins130, Y. Horii115, A.J. Horton151, J-Y. Hostachy58, S. Hou157, A. Hoummada35a, J. Howard134, J. Howarth46,

M. Hrabovsky129, I. Hristova19, J. Hrivnac131, A. Hrynevich107, T. Hryn’ova5, C. Hsu33c, P.J. Hsu157, S.-C. Hsu147, D. Hu40, Q. Hu61a, Y. Huang46, Z. Hubacek141, F. Hubaut100, F. Huegging24,

T.B. Huffman134, E.W. Hughes40, G. Hughes88, M. Huhtinen36, T.A. Hülsing98, N. Huseynov78,ab, J. Huston105, J. Huth60, G. Iacobucci54, G. Iakovidis29, I. Ibragimov150, L. Iconomidou-Fayard131, E. Ideal181, P. Iengo36, O. Igonkina118,w,*, T. Iizawa177, Y. Ikegami80, M. Ikeno80, Y. Ilchenko11,r, D. Iliadis161, N. Ilic152, T. Ince113, G. Introzzi70a,70b, P. Ioannou9,*, M. Iodice74a, K. Iordanidou40, V. Ippolito60, A. Irles Quiles172, C. Isaksson170, M. Ishino84, M. Ishitsuka164, R. Ishmukhametov125, C. Issever134, S. Istin12c, J.M. Iturbe Ponce99, R. Iuppa73a,73b, J. Ivarsson95, W. Iwanski83, H. Iwasaki80, J.M. Izen44, V. Izzo69a, S. Jabbar3, B. Jackson136, M. Jackson89, P. Jackson1, V. Jain2, K.B. Jakobi98,

K. Jakobs52_{, S. Jakobsen}36_{, T. Jakoubek}140_{, D.O. Jamin}128_{, D.K. Jana}94_{, E. Jansen}93_{, R. Jansky}75_,

J. Janssen24, M. Janus53, G. Jarlskog95, N. Javadov78,ab, T. Jav˚urek52, M. Javurkova52, F. Jeanneau144, L. Jeanty18, J. Jejelava158a,ac, G.-Y. Jeng156, D. Jennens103, P. Jenni52,e, J. Jentzsch47, C. Jeske176, S. Jézéquel5, H. Ji179, J. Jia154, H. Jiang77, Y. Jiang61a, S. Jiggins93, J. Jimenez Pena172, S. Jin15a, A. Jinaru27b, O. Jinnouchi164, P. Johansson148, K.A. Johns7, W.J. Johnson147, K. Jon-And45a,45b, G. Jones176, R.W.L. Jones88, S. Jones7, T.J. Jones89, J. Jongmanns62a, P.M. Jorge139a,139b,

J. Jovicevic166a, X. Ju179, A. Juste Rozas14,u, M. Kaci172, A. Kaczmarska83, M. Kado131, H. Kagan125, M. Kagan152, S.J. Kahn100, E. Kajomovitz49, C.W. Kalderon134, A. Kaluza98, S. Kama43,

A. Kamenshchikov122, N. Kanaya162, S. Kaneti32, V.A. Kantserov110, J. Kanzaki80, B. Kaplan123, L.S. Kaplan179, A. Kapliy37, D. Kar33c, K. Karakostas10, A. Karamaoun3, N. Karastathis10,118, M.J. Kareem53, E. Karentzos10, M. Karnevskiy98, S.N. Karpov78, Z.M. Karpova78, K. Karthik123, V. Kartvelishvili88, A.N. Karyukhin122, K. Kasahara167, L. Kashif179, R.D. Kass125, A. Kastanas17, Y. Kataoka162, C. Kato162, A. Katre54, J. Katzy46, K. Kawade115, K. Kawagoe86, T. Kawamoto162, G. Kawamura53, S. Kazama162, V.F. Kazanin120b,120a, R. Keeler174, R. Kehoe43, J.S. Keller46, J.J. Kempster92, H. Keoshkerian99, O. Kepka140, S. Kersten180, B.P. Kerševan90, R.A. Keyes102, F. Khalil-Zada13, H. Khandanyan45a,45b, A. Khanov128, A.G. Kharlamov120b,120a, T.J. Khoo32, V. Khovanskiy121,*, E. Khramov78, J. Khubua158b, S. Kido81, H.Y. Kim8, S.H. Kim167, Y.K. Kim37, N. Kimura161, O.M. Kind19, B.T. King89,*, M. King172, S.B. King173, J. Kirk143, A.E. Kiryunin113, T. Kishimoto81, D. Kisielewska82a, F. Kiss52, K. Kiuchi167, O. Kivernyk144, E. Kladiva28b,*, M.H. Klein40, M. Klein89, U. Klein89, K. Kleinknecht98, P. Klimek45a,45b, A. Klimentov29, R. Klingenberg47,*, J.A. Klinger148, T. Klioutchnikova36, E.-E. Kluge62a, P. Kluit118, S. Kluth113, J. Knapik83, E. Kneringer75, E.B.F.G. Knoops100, A. Knue57, A. Kobayashi162, D. Kobayashi164, T. Kobayashi162, M. Kobel48, M. Kocian152, P. Kodys142, T. Koffas34, E. Koffeman118, L.A. Kogan134, M.K. Köhler178, S. Kohlmann180, T. Koi152, H. Kolanoski19, M. Kolb62b, I. Koletsou5, A.A. Komar109,*, Y. Komori162, T. Kondo80, N. Kondrashova46, K. Köneke52, A.C. König117, T. Kono124,aj,

R. Konoplich123,af, N. Konstantinidis93, R. Kopeliansky65, S. Koperny82a, L. Köpke98, A.K. Kopp52, K. Korcyl83, K. Kordas161, A. Korn93, A.A. Korol120b,120a,ai, I. Korolkov14, E.V. Korolkova148, O. Kortner113, S. Kortner113, T. Kosek142, V.V. Kostyukhin24, V.M. Kotov78, A. Kotwal49, A. Kourkoumeli-Charalampidi9, C. Kourkoumelis9, V. Kouskoura29, A. Koutsman166a, R. Kowalewski174, T.Z. Kowalski82a, W. Kozanecki144, A.S. Kozhin122, V.A. Kramarenko111, G. Kramberger90, D. Krasnopevtsev110, M.W. Krasny135, A. Krasznahorkay36, J.K. Kraus24, A. Kravchenko29, M. Kretz62c, J. Kretzschmar89, K. Kreutzfeldt56, P. Krieger165, K. Krizka37, K. Kroeninger47, H. Kroha113, J. Kroll136, J. Kroseberg24, J. Krstic16, U. Kruchonak78, H. Krüger24, N. Krumnack77, A. Kruse179, M.C. Kruse49, M. Kruskal25, T. Kubota103, H. Kucuk93, S. Kuday4b, J.T. Kuechler180_{, S. Kuehn}52_{, A. Kugel}62c_{, F. Kuger}175_{, A. Kuhl}145_{, T. Kuhl}46_{, V. Kukhtin}78_,

R. Kukla144, Y. Kulchitsky106, S. Kuleshov146c, M. Kuna72a,72b, T. Kunigo84, A. Kupco140,

H. Kurashige81, Y.A. Kurochkin106, V. Kus140, E.S. Kuwertz174, M. Kuze164, J. Kvita129, T. Kwan174, D. Kyriazopoulos148, A. La Rosa113, J.L. La Rosa Navarro79d, L. La Rotonda42b,42a, C. Lacasta172, F. Lacava72a,72b, J. Lacey34, H. Lacker19, D. Lacour135, V.R. Lacuesta172, E. Ladygin78, R. Lafaye5, B. Laforge135, S. Lai53, L. Lambourne93, S. Lammers65, C.L. Lampen7, W. Lampl7, E. Lançon144, U. Landgraf52, M.P.J. Landon91, V.S. Lang62a, J.C. Lange14, A.J. Lankford169, F. Lanni29,

K. Lantzsch24, A. Lanza70a, S. Laplace135, C. Lapoire36, J.F. Laporte144, T. Lari68a,

F. Lasagni Manghi23b,23a, M. Lassnig36, P. Laurelli51, W. Lavrijsen18, A.T. Law145, P. Laycock89, T. Lazovich60, O. Le Dortz135, E. Le Guirriec100, E. Le Menedeu14, M. LeBlanc174, T. LeCompte6, F. Ledroit-Guillon58, C.A. Lee29, L. Lee1, S.C. Lee157, G. Lefebvre135, M. Lefebvre174, F. Legger112, C. Leggett18, A. Lehan89, G. Lehmann Miotto36, X. Lei7, W.A. Leight34, A.G. Leister181,

R. Leone7_{, S. Leone}71a_{, C. Leonidopoulos}50_{, S. Leontsinis}10_{, C. Leroy}108_{, C.G. Lester}32_,

M. Levchenko137, J. Levêque5, D. Levin104, L.J. Levinson178, M. Levy21, A.M. Leyko24, B. Li61a,q, H. Li154, H.L. Li37, L. Li49, L. Li61c, S. Li49, X. Li99, Y. Li150, Z. Liang145, H. Liao38, B. Liberti73a, A. Liblong165, P. Lichard36, K. Lie171, J. Liebal24, W. Liebig17, C. Limbach24, A. Limosani156, S.C. Lin157,b, T.H. Lin98, B.E. Lindquist154, E. Lipeles136, A. Lipniacka17, M. Lisovyi62b,

T.M. Liss171,am, D. Lissauer29, A. Lister173, A.M. Litke145, B. Liu157,y, D. Liu157, H.B. Liu29, H. Liu104, J.B. Liu61a, J. Liu100, K. Liu100, L. Liu171, M. Liu61a, M. Liu49, Y.L. Liu61a, Y.W. Liu61a, M. Livan70a,70b, A. Lleres58, J. Llorente Merino97, S.L. Lloyd91, F. Lo Sterzo157, E.M. Lobodzinska46, P. Loch7,

W.S. Lockman145, F.K. Loebinger99, A.E. Loevschall-Jensen41, K.M. Loew26, A. Loginov181,*,

T. Lohse19, K. Lohwasser46, M. Lokajicek140, B.A. Long25, J.D. Long171, R.E. Long88, K.A. Looper125, L. Lopes139a, D. Lopez Mateos60, B. Lopez Paredes148, I. Lopez Paz14, A. Lopez Solis135, J. Lorenz112, N. Lorenzo Martinez65, M. Losada22, P.J. Lösel112, X. Lou15a, A. Lounis131, J. Love6, P.A. Love88, H. Lu64a, N. Lu104, H.J. Lubatti147, C. Luci72a,72b, A. Lucotte58, C. Luedtke52, F. Luehring65, W. Lukas75, L. Luminari72a, O. Lundberg45a,45b, B. Lund-Jensen153, D. Lynn29, R. Lysak140, E. Lytken95, H. Ma29, L.L. Ma61b, G. Maccarrone51, A. Macchiolo113, C.M. Macdonald148, J. Machado Miguens136,139b, D. Madaffari100, R. Madar38, H.J. Maddocks170, W.F. Mader48,

A. Madsen46, J. Maeda81, S. Maeland17, T. Maeno29, A.S. Maevskiy111, E. Magradze53, J. Mahlstedt118, C. Maiani131, C. Maidantchik79b, A.A. Maier113, T. Maier112, A. Maio139a,139b,139d, S. Majewski130, Y. Makida80, N. Makovec131, B. Malaescu135, Pa. Malecki83, V.P. Maleev137, F. Malek58, U. Mallik76, D. Malon6, C. Malone152, S. Maltezos10, S. Malyukov36, J. Mamuzic46, G. Mancini51, B. Mandelli36, L. Mandelli68a, I. Mandi´c90, J. Maneira139a,139b, L. Manhaes de Andrade Filho79a,

J. Manjarres Ramos166b, A. Mann112, B. Mansoulie144, R. Mantifel102, M. Mantoani53,

S. Manzoni68a,68b, L. Mapelli36, L. March54, G. Marchiori135, M. Marcisovsky140, M. Marjanovic16, D.E. Marley104, F. Marroquim79b, S.P. Marsden99, Z. Marshall18, L.F. Marti20, S. Marti-Garcia172, B. Martin105, T.A. Martin176, V.J. Martin50, B. Martin dit Latour17, M. Martinez14,u,

S. Martin-Haugh143, V.S. Martoiu27b, A.C. Martyniuk93, M. Marx147, F. Marzano72a, A. Marzin36, L. Masetti98, T. Mashimo162, R. Mashinistov109, J. Masik99, A.L. Maslennikov120b,120a, I. Massa23b,23a, L. Massa23b,23a, P. Mastrandrea5, A. Mastroberardino42b,42a, T. Masubuchi162, P. Mättig180,

J. Mattmann98, J. Maurer27b, B. Maˇcek90, S.J. Maxfield89, D.A. Maximov120b,120a, R. Mazini157, S.M. Mazza68a,68b, N.C. Mc Fadden116, G. Mc Goldrick165, S.P. Mc Kee104, R.L. McCarthy154, T.G. McCarthy34, K.W. McFarlane59,*, J.A. Mcfayden93, S.J. McMahon143, R.A. McPherson174,z, M. Medinnis46, S. Meehan147, S. Mehlhase112, A. Mehta89, K. Meier62a,*, C. Meineck112, B. Meirose44, B.R. Mellado Garcia33c, F. Meloni20, A. Mengarelli23b,23a, S. Menke113, E. Meoni168, K.M. Mercurio60, S. Mergelmeyer19, P. Mermod54, L. Merola69a,69b, C. Meroni68a, F.S. Merritt37, A. Messina72a,72b, J. Metcalfe6_{, A.S. Mete}169_{, C. Meyer}98_{, C. Meyer}136_{, J. Meyer}118_{, J-P. Meyer}144_,

H. Meyer Zu Theenhausen62a, R.P. Middleton143, S. Miglioranzi66a,66c, L. Mijovi´c24, G. Mikenberg178, M. Mikestikova140, M. Mikuž90, M. Milesi103, A. Milic36, D.W. Miller37, C. Mills50, A. Milov178, D.A. Milstead45a,45b, A.A. Minaenko122, Y. Minami162, I.A. Minashvili158b, A.I. Mincer123, B. Mindur82a, M. Mineev78, Y. Ming179, L.M. Mir14, K.P. Mistry136, T. Mitani177, J. Mitrevski112, V.A. Mitsou172, A. Miucci54, P.S. Miyagawa148, J.U. Mjörnmark95, T. Moa45a,45b, K. Mochizuki100, S. Mohapatra40, W. Mohr52, S. Molander45a,45b, R. Moles-Valls24, R. Monden84, M.C. Mondragon105, K. Mönig46, J. Monk41, E. Monnier100, A. Montalbano154, J. Montejo Berlingen36, F. Monticelli87, S. Monzani68a, R.W. Moore3, N. Morange131, D. Moreno22, M. Moreno Llácer53, P. Morettini55b, D. Mori151, T. Mori162, M. Morii60, M. Morinaga162, V. Morisbak133, S. Moritz98, A.K. Morley156, G. Mornacchi36, J.D. Morris91, L. Morvaj154, M. Mosidze158b, J. Moss31,m, K. Motohashi164, R. Mount152, E. Mountricha29, S.V. Mouraviev109,*, E.J.W. Moyse101, S. Muanza100, R.D. Mudd21, F. Mueller113, J. Mueller138, R.S.P. Mueller112, T. Mueller32, D. Muenstermann88, P. Mullen57,