Search for a standard model Higgs boson in the mass range 200-600 GeV in the $H \to ZZ \to \ell^+ \ell^- q \bar{q}$ decay channel with the ATLAS detector

arXiv:1206.2443v1 [hep-ex] 12 Jun 2012

EUROPEAN ORGANISATION FOR NUCLEAR RESEARCH (CERN)

CERN-PH-EP-2012-125

Submitted to: Physics Letters B

Search for a Standard Model Higgs boson in the mass range

200

_–

600 GeV

_{in the}

_{H → ZZ → ℓ}

+

_ℓ

−

q ¯

q

decay channel with

the ATLAS Detector

The ATLAS Collaboration

Abstract

A search for a heavy Standard Model Higgs boson decaying via

_{H → ZZ → ℓ}

+

ℓ

−

_{q ¯}

_q

_{, where}

_{ℓ = e}

or

µ

, is presented. The search uses a data set of

pp

collisions at

√

s = 7 TeV

, corresponding to

an integrated luminosity of

4.7

fb

−1

_{collected in 2011 by the ATLAS detector at the CERN LHC. No}

significant excess of events above the estimated background is found. Upper limits at 95% confidence

level on the production cross section of a Higgs boson with a mass in the range between 200 and

600 GeV

are derived. A Standard Model Higgs boson with a mass in the range

_{300 GeV ≤ m}

H

≤

322 GeV

or

_{353 GeV ≤ mH}

_{≤ 410 GeV}

is excluded at 95% CL. The corresponding expected exclusion

range is

_{351 GeV ≤ mH}

_{≤ 404 GeV}

at 95% CL.

Search for a Standard Model Higgs boson in the mass range 200–600 GeV

in the H

_{→ ZZ → ℓ}

+

ℓ

−

q

q

¯

decay channel with the ATLAS Detector

The ATLAS Collaboration

Abstract

A search for a heavy Standard Model Higgs boson decaying via H → ZZ → ℓ+_ℓ−_{q ¯q, where ℓ = e or µ,}

is presented. The search uses a data set of pp collisions at √s = 7 TeV, corresponding to an integrated

luminosity of 4.7 fb−1 _{collected in 2011 by the ATLAS detector at the CERN LHC. No significant excess}

of events above the estimated background is found. Upper limits at 95% confidence level on the production cross section of a Higgs boson with a mass in the range between 200 and 600 GeV are derived. A Standard

Model Higgs boson with a mass in the range 300 GeV ≤ mH ≤ 322 GeV or 353 GeV ≤ mH ≤ 410 GeV is

excluded at 95% CL. The corresponding expected exclusion range is 351 GeV ≤ mH≤ 404 GeV at 95% CL.

Keywords: Standard Model Higgs Boson, ATLAS

1. Introduction

In the Standard Model (SM), the as-yet-unobserved Higgs boson [1–3] gives mass to the weak vec-tor bosons and other particles. Direct searches performed at the CERN Large Electron-Positron Collider

(LEP) excluded at 95% confidence level (CL) the production of a SM Higgs boson with mass mH less than

114.4 GeV [4]. Searches at the Fermilab Tevatron p¯p collider have excluded at 95% CL the regions 100–

106 GeV and 147–179 GeV [5]. At the ATLAS experiment at the LHC, the search was extended as far as

600 GeV using up to 4.9 fb−1 _of √_{s = 7 TeV data recorded through 2011 (including an earlier version of}

this analysis with less data), ruling out the production of a SM Higgs boson at 95% CL in the regions 112.5–

115.5 GeV, 131–237 GeV, and 251–468 GeV [6]. Corresponding results from CMS [7], using 4.6–4.8 fb−1 _of

√

s = 7 TeV data, excluded at 95% CL the region 127–600 GeV.

If mH is larger than twice the Z boson mass, mZ, the Higgs boson is expected to decay to two on-shell

Z bosons with a large branching ratio. This Letter reports a search for a SM Higgs boson in the mass range 200–600 GeV decaying to a pair of Z bosons, where one Z boson decays into two leptons and the other to

two quarks: H → ZZ → ℓ+_ℓ−_{q ¯q with ℓ ≡ e, µ. The analysis uses the full data set of 4.7 fb}−1 _recorded

by the ATLAS experiment in 2011. Previous results from the ATLAS Collaboration in this channel [6, 8],

using up to 2.05 fb−1_{of data, excluded a SM Higgs boson production cross section between 1.2 and 12 times}

the SM cross section over this mass range. The corresponding exclusions from the CMS collaboration with

4.6 fb−1 _{of data are between 1.0 and 4 times the SM cross section over the same mass range [9].}

2. Data and Monte Carlo samples

The data used in this search were recorded by the ATLAS experiment during the 2011 LHC run with pp

collisions at√s = 7 TeV. They correspond to an integrated luminosity of approximately 4.7 fb−1_{after data}

quality selections to require that all systems used in this analysis were operational. The data were collected

using single-lepton triggers with a transverse momentum (pT) threshold of 20 to 22 GeV for electrons and

18 GeV for muons, supplemented with a dielectron trigger with a threshold of 12 GeV. The resulting trigger criteria are about 95% efficient in the muon channel and close to 100% efficient in the electron channel, relative to the selection criteria described below. Collision events are selected by requiring a reconstructed

primary vertex with at least three associated tracks with pT> 0.4 GeV. The average number of collisions

per bunch crossing in this data sample is about nine.

The H → ZZ → ℓ+_ℓ−_{q ¯q signal is modelled with the powheg Monte Carlo (MC) event generator [10,}

11], which calculates separately the gluon and vector-boson fusion Higgs boson production mechanisms up to next-to-leading order (NLO). Generated signal events are hadronised with pythia [12], interfaced to

photos[13] to model final-state radiation and tauola [14, 15] to simulate τ decays. The parton distribution

function (PDF) is MRSTMCal [16]. The Higgs boson pTspectrum is reweighted to match Ref. [17], which

provides QCD corrections up to NLO and QCD soft-gluon resummations up to next-to-next-to-leading logarithms. The small contribution from Z boson decay to τ leptons is also included.

The Higgs boson production cross sections and decay branching ratios as well as their uncertainties, are taken from Refs. [18, 19]. The predicted cross sections for the gluon fusion processes are based on calculations to next-to-next-to-leading order (NNLO) in QCD [20–25], and also include QCD soft-gluon resummations up to next-to-next-to-leading logarithms [26] and NLO electroweak (EW) corrections [27, 28]. These results are compiled in Refs. [29–31] and assume factorisation between QCD and EW corrections. The cross sections for the vector-boson fusion processes are calculated with full NLO QCD and EW corrections [32–34] and approximate NNLO QCD corrections [35]. The uncertainty in the production cross section due to the choice

of the QCD scale is+12₋₈ % for the gluon fusion process and ±1% for the vector-boson fusion process [18, 19].

The uncertainty in the production cross section due to uncertainties in the PDFs and αs is ±8% for the

gluon-initiated process and ±4% for quark-initiated processes [36–40]. The Higgs boson decay branching ratio [41] to the four-fermion final state is predicted by prophecy4f [42, 43]. The combined production

cross section and decay branching ratio for the H → ZZ → ℓ+_ℓ−_{q ¯q channel ranges from 140 ± 20 fb for}

mH= 200 GeV to 10 ± 2 fb for mH= 600 GeV.

The cross section calculations do not take into account the width of the Higgs boson, which increases

from 1.4 GeV at mH = 200 GeV to 120 GeV at mH = 600 GeV, and which is implemented through a

relativistic Breit-Wigner line shape applied at the event generator level. It has been suggested [19, 44–46] that effects related to off-shell Higgs boson production and interference with other SM processes may become

sizeable for the highest masses (mH > 400 GeV) considered in this search. Currently, in the absence of a

full calculation for the different production mechanisms, a conservative estimate of the possible size of such

effects is included as a signal normalisation systematic uncertainty parameterised as a function of mH as

1.5 × m3

H[TeV], for mH≥ 300 GeV [19].

The Z +light-jets background is modelled with the alpgen generator [47] with the cteq6l1 PDF set [48], interfaced to herwig [49] for parton showers and hadronisation, while sherpa [50] with the cteq6l1 PDF

set is used for Z + heavy-flavour events. Top quark production, both t¯t and single-top, is modelled using

the mc@nlo generator [51] with the ct10 PDF set [38], interfaced to herwig for parton showers and hadronisation.

The SM ZZ process is an irreducible background for H → ZZ. The q¯q → ZZ process (also W Z) is modelled using herwig with the MRSTMCal PDF set, interfaced to photos and tauola. Alternative samples with pythia and mc@nlo are used for systematics studies: herwig and pythia use only leading-order matrix elements, but they can generate off-shell vector bosons, while mc@nlo generates only on-shell

bosons. The q ¯q → ZZ production cross section has been calculated up to NLO in QCD [52]. Due to the

large gluon flux at the LHC, NNLO gluon pair quark-box diagrams (gg → ZZ) are significant and the q¯q cross section is increased by 6% to account for this additional contribution [53].

Those simulations that use herwig for hadronisation use jimmy [54] for the modelling of the underlying event, while pythia and sherpa implement their own underlying event model.

3. Event selection

The ATLAS detector [55] has a forward-backward symmetric cylindrical geometry1_{. An inner tracking}

detector immersed in a 2 Tesla axial magnetic field covers |η| < 2.5 with silicon detectors and straw tubes. A

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

liquid-argon electromagnetic calorimeter is divided into barrel (|η| < 1.475), endcap (1.375 < |η| < 3.1), and forward (3.1 < |η| < 4.9) regions. Hadronic calorimeters (using liquid argon or scintillating tiles as active materials) surround the electromagnetic calorimeter and cover |η| < 4.9. A muon spectrometer measures the deflection of muon tracks in the field of three large toroidal magnets and covers |η| < 2.7. A three-level trigger system selects events to be recorded for offline analysis.

The offline selection starts with the reconstruction of either a Z → ee or a Z → µµ lepton pair.

Electron and muon candidates must satisfy pT > 20 GeV and |η| < 2.5, in addition to standard ATLAS

quality requirements [56–58], and must also be isolated from surrounding tracks. Electrons within ∆R ≡

p(∆η)2_{+ (∆φ)}2 _{= 0.2 of a muon are rejected. The two muons in a pair are required to have opposite charge,}

but this requirement is not imposed for electrons because larger energy losses from showering in material in the inner tracking detector lead to higher charge misidentification probabilities. The invariant mass of the

lepton pair mℓℓ must lie within the range 83–99 GeV, and events with any additional selected electrons or

muons are rejected to reduce background from W Z production where both bosons decay leptonically.

H → ZZ → ℓ+_ℓ−_{q ¯q decays contain a pair of jets from Z → q¯q decay. Events are thus required to contain}

at least two jets with pT> 25 GeV and |η| < 2.5. Jets are reconstructed with the anti-ktalgorithm [59] with

radius parameter R = 0.4. They are calibrated using energy- and η-dependent correction factors based on MC simulation and validated with data [60]; this calibration includes effects of energy from additional proton-proton interactions. Jets within ∆R = 0.4 of an electron or in which less than 75% of the momentum of the associated tracks originates from the primary vertex are rejected. The missing transverse momentum, with

magnitude Emiss

T , is the (negative) vectorial sum of the transverse momenta of all cells in the calorimeters

with |η| < 4.9, calibrated appropriately based on their identification as electrons, photons, τ leptons, jets, or unassociated calorimeter cells, and all selected muons in the event [61]. Calorimeter deposits associated

with muons are subtracted from Emiss

T to avoid double counting. Since no high-pTneutrinos are present in

the signal, events are required to satisfy Emiss

T < 50 GeV, which primarily reduces the background from t¯t

production.

Jets originating from b-quarks can be discriminated from other jets (“tagged”) based on the relatively long lifetime of hadrons containing b-quarks. This discrimination is important for this analysis because about 21% of signal events contain b-jets from Z → b¯b decay, while b-jets are produced less often (∼ 2%) in the dominant (Z → ℓℓ)+jets background. A jet is tagged by taking the set of tracks associated with the jet and looking for either a secondary vertex or for tracks that have a significant impact parameter with respect to the primary event vertex [62]. This information is combined into a single discriminating variable and a selection is applied that gives an efficiency of about 70% (20%) for identifying true b-jets (c-jets) with a light-quark jet rejection of about 130 [63, 64]. To optimise the expected sensitivity, the analysis is divided into “tagged” and “untagged” subchannels, containing events with exactly two and with fewer than two b-tags, respectively. Events with more than two b-tags (< 3% of the data sample with two b-tags) are rejected.

Events are required to have at least one candidate Z → q¯q decay with dijet invariant mass mjj within

70–105 GeV in order to be consistent with a Z boson decay. This selection is asymmetric around the Z boson mass to account for non-Gaussian tails extending to lower masses. The jets forming a candidate must also be separated by ∆R > 0.7, excluding phase space regions poorly modelled by MC simulation. For untagged

events, all pairs of jets formed from the three highest-pTjets are considered. All such pairs are retained with

unit weight, leading to the possibility of multiple candidates per event. The fraction of untagged events with

multiple pairs retained is 13–16% (2–5%) for the low-mH (high-mH) selection defined below. For tagged

events, the two tagged jets are used to form the dijet invariant mass; their energies are scaled up by 5% to take into account the average energy scale difference between heavy- and light-quark jets. The resulting dijet invariant mass distributions are well described by the MC simulation, as shown in Fig. 1.

The selection criteria above define the “low-mH” selection, which is applied when searching for a Higgs

bo-son with mH< 300 GeV. For higher Higgs boson masses, the Z bosons from the H → ZZ decay have large

momenta in the laboratory reference frame, decreasing the opening angles between their decay products.

ring, and the y-axis points upward. Cylindrical coordinates (r,φ) are used in the transverse plane, φ being the azimuthal angle around the beam pipe. The pseudorapidity is defined in terms of the polar angle θ as η = − ln tan(θ/2).

[GeV] jj m 0 50 100 150 200 250 Entries / 5 GeV 0 1000 2000 3000 4000 5000 6000 7000 8000 Data 2011 Total BG Z+jets 100 × Signal =200 GeV) H (m Other BG ATLAS = 7 TeV s , -1 L dt=4.7 fb

∫

untagged channel [GeV] bb m 0 50 100 150 200 250 Entries / 10 GeV 0 20 40 60 80 100 120 Data 2011 Total BG Z+jets 10 × Signal =200 GeV) H (m Other BG ATLAS = 7 TeV s , -1 L dt=4.7 fb

∫

tagged channel

Figure 1: Distributions of the invariant mass of selected dijet pairs, mjj, for the data and the MC simulation, in the untagged

(left) and tagged (right) samples, which contain fewer than two b-jets and exactly two b-jets respectively. Scale factors and corrections described in Section 4 have been applied. The signal has been scaled up by a factor of 100 (10) in the untagged

(tagged) case to be more visible. The vertical lines show the range of the mjjselection.

Accordingly, in addition to the low-mH selection, the following requirements are applied for mH ≥ 300 GeV:

the two jets must have pT> 45 GeV and the azimuthal difference between the two leptons (∆φℓℓ) and the

two jets (∆φjj) must both be less than π/2. These criteria define the “high-mH” selection.

Following this event selection, a H → ZZ → ℓ+_ℓ−_{q ¯q signal should appear as a peak in the invariant}

mass distribution of the ℓℓjj system, with mℓℓjj around mH. To improve the Higgs boson mass resolution,

the energies of the jets forming each dijet pair are scaled event-by-event by a single multiplicative factor to

set the dijet invariant mass mjj to the nominal mass of the Z boson. The resolution is improved by a factor

of 2.4 at mH= 200 GeV; the improvement decreases with increasing mH due to the increase in the natural

width of the Higgs boson. The total efficiency for the selection of signal events is about 8% over most of the mass range.

4. Background estimates

The main background to this analysis is Z boson production in association with jets (Z + jets). The shapes of the relevant kinematic distributions for this background are taken from MC simulation, with a

small data-driven correction for the low-mH untagged selection, while the normalisations for all selections

are derived directly from data.

The flavour composition of the Z+jets sample is determined from three exclusive MC samples containing at least one true b-jet, at least one true c-jet, and all light jets, respectively. The relative normalisations of the three components are adjusted by fitting the distribution of the MC b-tagging discriminant to data.

To set the overall Z + jets normalisation, the mℓℓjj distribution is compared between data and MC

simulation for events in which the dijet invariant mass mjj is in sidebands of the Z boson mass: 40–70 GeV

or 105–150 GeV (see Figs. 2(a) and 2(b)). The numbers of events in the sidebands, after subtraction of the contribution from other background sources, are then used to derive scale factors to correct the normalisation of the Z +jets MC simulation to that observed in the data. The scale factors are determined for the untagged

channel separately for the low- and high-mH selections; the results agree within statistical uncertainties. In

the tagged channel, there are too few events in the sidebands to determine the scale factor for the high-mH

selection, hence the low-mH scale factor is used for both selections. Since the top quark background is not

negligible, the Z + jets MC normalisations are determined in a simultaneous fit to the Z + jets control region and the corresponding top quark control region (see below). The overall data to MC scale factors for Z + jets are approximately 0.9 for light-jets, 1.9 for c-jets, and 1.5 for b-jets.

In the mjj sidebands of the untagged low-mH selection, the Z + jets MC simulation is about 3% above

[GeV] lljj m 150 200 250 300 350 400 Entries / 20 GeV 0 2000 4000 6000 8000 10000 12000 Data 2011 Total BG Z+jets Other BG ATLAS = 7 TeV s , -1 L dt=4.7 fb

∫

Z+jets control region (untagged)

(a) mjjsidebands, untagged sample.

[GeV] llbb m 150 200 250 300 350 400 Entries / 20 GeV 0 20 40 60 80 100 120 Data 2011 Total BG Z+jets Other BG ATLAS = 7 TeV s , -1 L dt=4.7 fb

∫

Z+jets control region (tagged)

(b) mjjsidebands, tagged sample.

[GeV] jj m 0 50 100 150 200 250 Entries / 10 GeV 0 50 100 150 200 250 Data 2011 Total BG Top Other BG ATLAS = 7 TeV s , -1 L dt=4.7 fb

∫

top control region (untagged)

(c) mℓℓsidebands,untagged sample. [GeV] bb m 0 50 100 150 200 250 Entries / 10 GeV 0 10 20 30 40 50 60 70 Data 2011 Total BG Top Other BG ATLAS = 7 TeV s , -1 L dt=4.7 fb

∫

top control region (tagged)

(d) mℓℓsidebands,tagged sample.

Figure 2: Distributions from the background control samples, after application of scale factors, for the low-mHselection. Top

row: the ℓℓjj invariant mass for 40 GeV < mjj< 70 GeV or 105 GeV < mjj< 150 GeV for (a) the untagged and (b) the tagged

sample. Bottom row: the invariant mass of the jj system for events with 60 GeV < mℓℓ< 76 GeV or 106 GeV < mℓℓ< 150 GeV

and Emiss

results are seen for both the low and high mass sidebands, a linear fit to the ratio of data to MC simulation

in the mℓℓjj sideband distribution is used to correct the prediction in the signal region. For the high-mH

untagged selection and the tagged selections no difference between the data and MC distributions is seen within statistical uncertainties. Thus, no correction is applied to these samples, but similar fits to the one

described above are used to evaluate systematic uncertainties on the Z + jets mℓℓjj shape.

The second most significant background is top quark production, which is most important in the tagged channel. The shapes of the relevant kinematic distributions are taken from MC simulation and the

normal-isation from data, using the mℓℓ sidebands, 60–76 GeV or 106–150 GeV, with the E_Tmiss selection reversed.

Figures 2(c) and 2(d) show the mjj distributions for these control regions for the untagged and tagged

selections respectively; good agreement is found after scaling up the MC prediction by about 5% for the untagged selection and 20% for the tagged selection.

As in Ref. [8], the small irreducible background from diboson (ZZ and W Z) production is estimated directly from MC simulation. The background due to multijet events in which jets are misidentified as isolated electrons is estimated from data using a sample of events containing electron candidates that fail the selection requirements but pass loosened requirements. The multijet background to the muon channel was found to be negligible. The background from W + jets production was also found to be negligible. 5. Systematic uncertainties

The theoretical uncertainties on the Higgs boson production cross section from Refs. [18, 19] are 15–20% for the gluon fusion process and 3–9% for the vector-boson fusion process, depending on the Higgs boson

mass. As mentioned in Section 2, an additional uncertainty ∝ m3

H is applied for mH ≥ 300 GeV. The

selection efficiency uncertainty due to the production process modelling is estimated by varying parameters of the signal MC simulation, including the amount of initial- and final-state radiation, the factorisation and normalisation scales, and the underlying event model; a further comparison uses pythia instead of powheg.

This procedure gives a 3% (12%) uncertainty for the low- (high-) mH selection.

The uncertainty in the normalisation of the Z +jets background from the procedure described in Section 4 is evaluated by comparing the scale factors obtained from the upper or lower sideband separately. The uncertainty is taken as the difference between the scale factors or the statistical uncertainty, whichever

is larger. This procedure gives 1.7% for the low-mH untagged selection, 2.2% for the high-mH untagged

selection, and 5.5% for both tagged selections. The uncertainty in the flavour composition of the Z + jets background is estimated by varying the relative fraction of Z + c-jets by ±30% as determined by altering the selection criteria applied in the fitting procedure described in Section 4. An uncertainty due to the

modelling of the mℓℓjj shape as described in Section 4 is also applied. Additional uncertainties on the shape

of the Z + jets background are estimated by finding variations of the MC mjj and Z boson pTdistributions

that sufficiently cover any differences between MC simulation and data in the mjj sidebands.

The uncertainty in the normalisation of the t¯t background is derived from the statistical uncertainties

on the normalisation scale factors. It is found to be 2.7% for the untagged selection and 4.0% for the tagged selection. The diboson cross sections have a combined 5% QCD scale and PDF uncertainty [19]; adding an additional 10% uncertainty, corresponding to the maximum difference seen between mc@nlo and K-factor scaled pythia results, yields an overall uncertainty of 11% on the diboson background normalisation. A 50% systematic uncertainty is assigned to the normalisation of the multijet background in the electron channel

by comparing the result of fitting the mℓℓ distribution before and after the requirement of at least two jets.

An overall 3.9% uncertainty from the integrated luminosity [65, 66] is added to the uncertainties on all MC processes that are not normalised from data (i.e. excluding Z + jets and top quark production), correlated across all samples.

Contributions to systematic uncertainties also arise from detector effects, including the lepton and jet trigger and identification efficiencies, the energy or momentum calibration and resolution of the leptons and jets, and the b-tagging efficiency and mistag rates. The dominant uncertainty on the tagged sample comes from the b-tagging efficiency and corresponds to an average uncertainty of 9% on the signal [63, 64]. For the untagged sample, the uncertainties on the jet energy scale and resolution contribute 3% and 4% respectively to the uncertainty on the signal [60].

The normalisations of the Z + jets and top quark backgrounds are redetermined for each systematic variation following the procedures described in Section 4.

6. Results

Table 1 shows the numbers of candidates observed in data for each of the four selections compared with

the background expectations. Figure 3 shows the mℓℓjj distributions for both the tagged and untagged

channels for the low- and high-mH selections.

Table 1: The expected numbers of signal and background candidates in the H → ZZ → ℓ+_ℓ−_{q ¯q channel, along with the}

numbers of candidates observed in data, for an integrated luminosity of 4.7 fb−1_{. The low-mH analysis is applied when}

searching for a Higgs boson with mH < 300 GeV and the high-mH analysis for mH≥ 300 GeV. The first error indicates the

statistical uncertainty, the second error the systematic uncertainty.

Untagged Tagged

Low-mH High-mH Low-mH High-mH

Z+jets 36190 ± 80 ± 640 1450 ±14 ±35 239 ±6 ±15 11 ±1 ±2 Top 85 ± 3 ± 10 7.1 ± 0.7 ± 0.8 23 ±₁ ± _{3 1.9 ± 0.4 ± 0.5} Multijet 15 ± 0 ± 8 0.2 ± 0.0 ± 0.1 <0.1 <0.1 ZZ 348 ± 3 ± 47 25 ± ₁ ± _{3 22} ±₁ ± _{4 2.3 ± 0.3 ± 0.4} W Z 434 ± 4 ± 70 45 ± ₁ ± _{7 0.7 ± 0.2 ± 0.3} <0.2 Total background 37070 ± 80 ± 670 1530 ±₁₄ ±_{37 285} ±₆ ±_{18 15} ±₁ ±₂ Data 36898 1444 286 18 Signal m_H= 200 GeV 118 ± 2 ± 19 6.4 ± 0.4 ± 1.3 mH= 300 GeV 24.3 ± 0.7 ± 4.1 2.1 ± 0.2 ± 0.4 m_H= 400 GeV 40.5 ± 0.5 ± 6.4 4.4 ± 0.2 ± 1.0 mH= 500 GeV 18.5 ± 0.2 ± 3.1 2.0 ± 0.1 ± 0.5 mH= 600 GeV 6.3 ± 0.1 ± 1.1 0.7 ± 0.0 ± 0.2

No significant excess of events above the expected background is seen; the smallest p0 value is 0.15 at

mH= 540, where p0represents the probability that a background-only experiment would yield a result that

is more signal-like than the observed result. Upper limits are set on the SM Higgs boson cross section at

95% CL as a function of mass, using the CLsmodified frequentist formalism with the profile likelihood test

statistic [67, 68]. This method is based on a likelihood that compares, bin-by-bin using Poisson statistics,

the observed mℓℓjj distribution to either the expected background or the sum of the expected background

and a mass-dependent hypothesised signal. The tagged and untagged channels, which contribute

approxi-mately equally across the mH range, are combined by forming the product of their likelihoods; systematic

uncertainties, with their correlations, are incorporated as nuisance parameters. Figure 4 shows the resulting

upper limit on the cross section for Higgs boson production and decay in the channel H → ZZ → ℓ+_ℓ−_{q ¯q}

relative to the Standard Model cross section as a function of the hypothetical Higgs boson mass. 7. Summary

A search for the SM Higgs boson in the decay mode H → ZZ → ℓ+_ℓ−_{q ¯q has been performed in the}

Higgs mass range 200 to 600 GeV using 4.7 fb−1 _of√_{s = 7 TeV pp data recorded by the ATLAS experiment}

at the LHC. No significant excess over the expected background is found. A Standard Model Higgs boson

is excluded at a 95% CL within the range 300 GeV ≤ mH ≤ 322 GeV and 353 GeV ≤ mH≤ 410 GeV. The

[GeV] lljj m 160 180 200 220 240 260 280 300 320 Entries / 5 GeV 0 500 1000 1500 2000 2500 3000 3500 Data 2011 5 × Signal =200 GeV) H (m Total BG Top Z+jets Diboson ATLAS = 7 TeV s , -1 L dt=4.7 fb

∫

untagged channel Data 2011 5 × Signal =200 GeV) H (m Total BG Top Z+jets Diboson

(a) Low-mH, untagged selection.

[GeV] llbb m 160 180 200 220 240 260 280 300 320 Entries / 10 GeV 0 10 20 30 40 50 60 Data 2011 Signal =200 GeV) H (m Total BG Top Z+jets Diboson ATLAS = 7 TeV s , -1 L dt=4.7 fb

∫

tagged channel Data 2011 Signal =200 GeV) H (m Total BG Top Z+jets Diboson

(b) Low-mH, tagged selection.

[GeV] lljj m 200 300 400 500 600 700 800 Entries / 20 GeV 0 50 100 150 200 250 Data 2011_{Signal × 5} =400 GeV) H (m Total BG Top Z+jets Diboson ATLAS = 7 TeV s , -1 L dt=4.7 fb

∫

untagged channel Data 2011 5 × Signal =400 GeV) H (m Total BG Top Z+jets Diboson

(c) High-mH, untagged selection.

[GeV] llbb m 200 300 400 500 600 700 800 Entries / 50 GeV 0 1 2 3 4 5 6 7 8 9 Data 2011 Signal =400 GeV) H (m Total BG Top Z+jets Diboson ATLAS = 7 TeV s , -1 L dt=4.7 fb

∫

tagged channel Data 2011 Signal =400 GeV) H (m Total BG Top Z+jets Diboson

(d) High-mH, tagged selection.

Figure 3: The invariant mass of the ℓℓjj system for both the untagged (a, c) and tagged (b, d) channels, for the low-mH

(top row) and high-mH (bottom row) selections. The hatched band represents the systematic error on the total background

prediction. Examples of the expected Higgs boson signal for mH= 200 and 400 GeV are also shown; in the untagged plots (a,

[GeV]

H

m

200

300

400

500

600

SM

σ

/

σ

9

5

%

C

L

l

im

it

o

n

0

2

4

6

8

10

Observed

Expected

σ

1

±

σ

2

±

ATLAS

llqq

→

ZZ

→

H

=7 TeV

s

,

-1

Ldt = 4.7 fb

∫

Figure 4: The expected (dashed line) and observed (solid line) upper limits on the total cross section divided by the expected

SM Higgs boson cross section, calculated using CLs at 95%. The inner and outer bands, obtained from pseudo-experiments,

indicate the ±1σ and ±2σ ranges in which the limit is expected to lie in the absence of a signal. The horizontal dotted line

shows the SM value of unity. The discontinuity in the limit at mH= 300 GeV is due to the transition between the use of the

low- and high-mH selections.

8. 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; BMWF, Aus-tria; 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, DNSRC and Lundbeck Foundation, Denmark; EPLANET and ERC, European Union; IN2P3-CNRS, CEA-DSM/IRFU, France; GNAS, Georgia; BMBF, DFG, HGF, MPG and AvH Foundation, Germany; GSRT, Greece; ISF, MINERVA, GIF, DIP and Benoziyo Center, Israel; INFN, Italy; MEXT and JSPS, Japan; CNRST, Morocco; FOM and NWO, Netherlands; RCN, Norway; MNiSW, Poland; GRICES and FCT, Portugal; MERYS (MECTS), Romania; MES of Russia and ROSATOM, Russian Federation; JINR; MSTD, Serbia; MSSR, Slovakia; ARRS and MVZT, Slove-nia; DST/NRF, South Africa; MICINN, Spain; SRC and Wallenberg Foundation, Sweden; SER, SNSF and Cantons of Bern and Geneva, Switzerland; NSC, Taiwan; TAEK, Turkey; STFC, the Royal Society and Leverhulme Trust, United Kingdom; DOE and NSF, United States of America.

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] F. Englert, R. Brout, Broken Symmetry and the Mass of Gauge Vector Mesons, Phys. Rev. Lett. 13 (1964) 321–323. doi:10.1103/PhysRevLett.13.321.

[2] P. W. Higgs, Broken Symmetries and the Masses of Gauge Bosons, Phys. Rev. Lett. 13 (1964) 508–509. doi:10.1103/PhysRevLett.13.508.

[3] G. S. Guralnik, C. R. Hagen, T. W. B. Kibble, Global Conservation Laws and Massless Particles, Phys. Rev. Lett. 13 (1964) 585–587. doi:10.1103/PhysRevLett.13.585.

[4] LEP Working Group for Higgs boson searches, ALEPH, DELPHI, L3 and OPAL Collaborations, Search for the standard model Higgs boson at LEP, Phys. Lett. B 565 (2003) 61–75. arXiv:hep-ex/0306033.

[5] The Tevatron New Physics and Higgs Working Group, Combined CDF and D0 Search for Standard Model Higgs Boson

Production with up to 10.0 fb−1_{of Data (2012). arXiv:1203.3774.}

[6] ATLAS Collaboration, Combined search for the Standard Model Higgs boson using up to 4.9 fb−1_{pp collisions at}√_{s =}

7 TeV with the ATLAS detector at the LHC, Phys. Lett. B710 (2012) 49–66. arXiv:1202.1408.

[7] CMS Collaboration, Combined results of searches for the standard model Higgs boson in pp collisions at√s = 7 TeV,

Phys. Lett. B710 (2012) 26–48. arXiv:1202.1488.

[8] ATLAS Collaboration, Search for a heavy Standard Model Higgs boson in the channel H → ZZ → ℓ+_ℓ−_{q ¯q using the}

ATLAS detector, Phys. Lett. B 707 (2012) 27–45. arXiv:1108.5064.

[9] CMS Collaboration, Search for a Higgs boson in the decay channel H → ZZ(∗)_{→ q ¯ql}−_l+_{in pp collisions at}√_{s = 7 TeV,}

J. High Energy Phys. 04 (2012) 036. arXiv:1202.1416.

[10] S. Alioli, P. Nason, C. Oleari, E. Re, NLO Higgs boson production via gluon fusion matched with shower in POWHEG, JHEP 04 (2009) 002. arXiv:0812.0578.

[11] P. Nason, C. Oleari, NLO Higgs boson production via vector-boson fusion matched with shower in POWHEG, JHEP 02 (2010) 037. arXiv:0911.5299.

[12] T. Sjostrand, S. Mrenna, P. Z. Skands, PYTHIA 6.4 Physics and Manual, JHEP 05 (2006) 026. arXiv:hep-ph/0603175. [13] P. Golonka, Z. Was, PHOTOS Monte Carlo: A Precision tool for QED corrections in Z and W decays, Eur. Phys. J. C 45

(2006) 97–107. arXiv:hep-ph/0506026.

[14] S. Jadach, Z. Was, R. Decker, J. H. Kuhn, The tau decay library TAUOLA: Version 2.4, Comput. Phys. Commun. 76 (1993) 361–380. doi:10.1016/0010-4655(93)90061-G.

[15] P. Golonka, et al., The tauola-photos-F environment for the TAUOLA and PHOTOS packages, release II, Comput. Phys. Commun. 174 (2006) 818–835. arXiv:hep-ph/0312240.

[16] A. Sherstnev, R. Thorne, Different PDF approximations useful for LO Monte Carlo generators, Proc. of XVI

Int. Workshop on Deep-Inelastic Scattering and Related Topics, London, England, April 2008. arXiv:0807.2132,

doi:10.3360/dis.2008.149.

[17] D. de Florian, G. Ferrera, M. Grazzini, D. Tommasini, Transverse-momentum resummation: Higgs boson production at the Tevatron and the LHC, JHEP 11 (2011) 064. arXiv:1109.2109.

[18] LHC Higgs Cross Section Working Group, S. Dittmaier, C. Mariotti, G. Passarino, R. Tanaka (Eds.), Handbook of LHC Higgs cross sections: 1. Inclusive observables, CERN-2011-002 (2011). arXiv:1101.0593.

[19] LHC Higgs Cross Section Working Group, S. Dittmaier, C. Mariotti, G. Passarino, R. Tanaka (Eds.), Handbook of LHC Higgs Cross Sections: 2. Differential distributions (2012). arXiv:1201.3084.

[20] A. Djouadi, M. Spira, P. M. Zerwas, Production of Higgs bosons in proton colliders: QCD corrections, Phys. Lett. B 264 (1991) 440–446. doi:10.1016/0370-2693(91)90375-Z.

[21] S. Dawson, Radiative corrections to Higgs boson production, Nucl. Phys. B 359 (1991) 283–300.

doi:10.1016/0550-3213(91)90061-2.

[22] M. Spira, A. Djouadi, D. Graudenz, P. M. Zerwas, Higgs boson production at the LHC, Nucl. Phys. B 453 (1995) 17–82. arXiv:hep-ph/9504378.

[23] R. V. Harlander, W. B. Kilgore, Next-to-next-to-leading order Higgs production at hadron colliders, Phys. Rev. Lett. 88 (2002) 201801. arXiv:hep-ph/020106.

[24] C. Anastasiou, K. Melnikov, Higgs boson production at hadron colliders in NNLO QCD, Nucl. Phys. B 646 (2002) 220–256. arXiv:hep-ph/0207004.

[25] V. Ravindran, J. Smith, W. L. van Neerven, NNLO corrections to the total cross section for Higgs boson production in hadron hadron collisions, Nucl. Phys. B 665 (2003) 325–366. arXiv:hep-ph/0302135.

[26] S. Catani, D. de Florian, M. Grazzini, P. Nason, Soft-gluon resummation for Higgs boson production at hadron colliders, JHEP 07 (2003) 028. arXiv:hep-ph/0306211.

[27] U. Aglietti, R. Bonciani, G. Degrassi, A. Vicini, Two-loop light fermion contribution to Higgs production and decays, Phys. Lett. B 595 (2004) 432–441. arXiv:hep-ph/0404071.

[28] S. Actis, G. Passarino, C. Sturm, S. Uccirati, NLO Electroweak Corrections to Higgs Boson Production at Hadron Colliders, Phys. Lett. B 670 (2008) 12–17. arXiv:0809.1301.

[29] C. Anastasiou, R. Boughezal, F. Petriello, Mixed QCD-electroweak corrections to Higgs boson production in gluon fusion, JHEP 04 (2009) 003. arXiv:0811.3458.

[30] D. de Florian, M. Grazzini, Higgs production through gluon fusion: updated cross sections at the Tevatron and the LHC, Phys. Lett. B 674 (2009) 291–294. arXiv:0901.2427.

[31] J. Baglio, A. Djouadi, Higgs production at the lHC, JHEP 03 (2011) 055. arXiv:1012.0530.

[32] M. Ciccolini, A. Denner, S. Dittmaier, Strong and electroweak corrections to the production of Higgs+2jets via weak interactions at the LHC, Phys. Rev. Lett. 99 (2007) 161803. arXiv:0707.0381.

[33] M. Ciccolini, A. Denner, S. Dittmaier, Electroweak and QCD corrections to Higgs production via vector-boson fusion at the LHC, Phys. Rev. D 77 (2008) 013002. arXiv:0710.4749.

[34] K. Arnold, et al., VBFNLO: A parton level Monte Carlo for processes with electroweak bosons, Comput. Phys. Commun. 180 (2009) 1661–1670. arXiv:0811.4559.

[35] P. Bolzoni, F. Maltoni, S.-O. Moch, M. Zaro, Higgs production via vector-boson fusion at NNLO in QCD, Phys. Rev. Lett. 105 (2010) 011801. arXiv:1003.4451.

[36] M. Botje, et al., The PDF4LHC working group interim recommendations (2011). arXiv:1101.0538. [37] S. Alekhin, et al., The PDF4LHC working group interim report (2011). arXiv:1101.0536.

[38] H.-L. Lai, et al., New parton distributions for collider physics, Phys. Rev. D 82 (2010) 074024. arXiv:1007.2241. [39] A. D. Martin, W. J. Stirling, R. S. Thorne, G. Watt, Parton distributions for the LHC, Eur. Phys. J. C 63 (2009) 189–285.

arXiv:0901.0002.

[40] R. D. Ball, et al., Impact of heavy quark masses on parton distributions and LHC phenomenology, Nucl. Phys. B 849 (2011) 296–363. arXiv:1101.1300.

[41] A. Djouadi, J. Kalinowski, M. Spira, HDECAY: A program for Higgs boson decays in the standard model and its super-symmetric extension, Comput. Phys. Commun. 108 (1998) 56–74. arXiv:hep-ph/9704448.

[42] A. Bredenstein, A. Denner, S. Dittmaier, M. M. Weber, Precise predictions for the Higgs-boson decay H → W W/ZZ → 4 leptons, Phys. Rev. D 74 (2006) 013004. arXiv:hep-ph/0604011.

[43] A. Bredenstein, A. Denner, S. Dittmaier, M. M. Weber, Radiative corrections to the semileptonic and hadronic Higgs-boson decays H → W W/ZZ → 4 fermions, JHEP 02 (2007) 080. arXiv:hep-ph/0611234.

[44] M. H. Seymour, The Higgs boson line shape and perturbative unitarity, Phys. Lett. B 354 (1995) 409–414. arXiv:hep-ph/9505211.

[45] G. Passarino, C. Sturm, S. Uccirati, Higgs pseudo-observables, second Riemann sheet and all that, Nucl. Phys. B 834 (2010) 77–115. arXiv:1001.3360.

[46] C. Anastasiou, S. Buehler, F. Herzog, A. Lazopoulos, Total cross-section for Higgs boson hadroproduction with anomalous Standard Model interactions, JHEP 12 (2011) 058. arXiv:1107.0683.

[47] M. L. Mangano, et al., ALPGEN, a generator for hard multiparton processes in hadronic collisions, JHEP 07 (2003) 001. arXiv:hep-ph/0206293.

[48] J. Pumplin, D. Stump, J. Huston, H. Lai, P. M. Nadolsky, et al., New generation of parton distributions with uncertainties from global QCD analysis, JHEP 0207 (2002) 012. arXiv:hep-ph/0201195.

[49] G. Corcella, et al., HERWIG 6.5: an event generator for Hadron Emission Reactions With Interfering Gluons (including supersymmetric processes), JHEP 01 (2001) 010. arXiv:hep-ph/0011363.

[50] T. Gleisberg, et al., Event generation with SHERPA 1.1, JHEP 02 (2009) 007. arXiv:0811.4622.

[51] S. Frixione, P. Nason, B. R. Webber, Matching NLO QCD and parton showers in heavy flavour production, JHEP 08 (2003) 007. arXiv:hep-ph/0305252.

[52] J. M. Campbell, R. K. Ellis, An update on vector boson pair production at hadron colliders, Phys. Rev. D 60 (1999) 113006. arXiv:hep-ph/9905386.

[53] T. Binoth, N. Kauer, P. Mertsch, Gluon-induced QCD corrections to pp → ZZ → ℓ¯ℓℓ′_ℓ¯′ _{(2008). arXiv:0807.0024,}

doi:10.3360/dis.2008.142.

[54] J. M. Butterworth, J. R. Forshaw, M. H. Seymour, Multiparton interactions in photoproduction at HERA, Z. Phys. C 72 (1996) 637–646. arXiv:hep-ph/9601371.

[55] ATLAS Collaboration, The ATLAS Experiment at the CERN Large Hadron Collider, JINST 3 (2008) S08003. doi:10.1088/1748-0221/3/08/S08003.

[56] ATLAS Collaboration, Electron performance measurements with the ATLAS detector using the 2010 LHC proton-proton collision data, Eur. Phys. J. C72 (2012) 1909. arXiv:1110.3174.

[57] Measurement of the W → ℓν and Z/γ∗_{→ ℓℓ production cross sections in proton-proton collisions at}√_{s = 7 TeV with}

the ATLAS detector, JHEP 12 (2010) 060. arXiv:1010.2130.

[58] ATLAS Collaboration, Muon reconstruction efficiency in reprocessed 2010 LHC proton-proton collision data recorded with the ATLAS detector, ATLAS-CONF-2011-063.

URL http://cdsweb.cern.ch/record/1345743

[59] M. Cacciari, G. P. Salam, G. Soyez, The anti-ktjet clustering algorithm, JHEP 04 (2008) 063. arXiv:0802.1189.

[60] Jet energy measurement with the ATLAS detector in proton-proton collisions at sqrt(s) = 7 TeV, Submitted to Eur. Phys. J. C (2011). arXiv:1112.6426.

[61] ATLAS Collaboration, Performance of Missing Transverse Momentum Reconstruction in Proton-Proton Collisions at 7 TeV with ATLAS, Eur. Phys. J. C72 (2012) 1844. arXiv:1108.5602.

[62] ATLAS Collaboration, Commissioning of the ATLAS high-performance b-tagging algorithms in the 7 TeV collision data, ATLAS-CONF-2011-102 (Jul 2011).

URL https://cdsweb.cern.ch/record/1369219

[63] ATLAS Collaboration, Measurement of the b-tag Efficiency in a Sample of Jets Containing Muons with 5 fb−1 _{of Data}

from the ATLAS Detector, ATLAS-CONF-2012-043 (Mar 2012). URL https://cdsweb.cern.ch/record/1435197

[64] ATLAS Collaboration, Measurement of the Mistag Rate with 5 fb−1_{of Data Collected by the ATLAS Detector,}

ATLAS-CONF-2012-040 (Mar 2012).

URL https://cdsweb.cern.ch/record/1435194

[65] ATLAS Collaboration, Luminosity Determination in pp Collisions at√s = 7 TeV Using the ATLAS Detector at the LHC,

Eur. Phys. J. C 71 (2011) 1630. arXiv:1101.2185.

[66] ATLAS Collaboration, Luminosity determination in pp collisions at√s = 7 TeV using the ATLAS detector in 2011,

ATLAS-CONF-2011-116 (Aug 2011).

URL http://cdsweb.cern.ch/record/1376384

[67] G. Cowan, K. Cranmer, E. Gross, O. Vitells, Asymptotic formulae for likelihood-based tests of new physics, Eur. Phys. J. C 71 (2011) 1554. arXiv:1007.1727.

The ATLAS Collaboration

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S. Aefsky22_{, J.A. Aguilar-Saavedra}124b,a_{, M. Agustoni}16_{, M. Aharrouche}81_{, S.P. Ahlen}21_{, F. Ahles}48_,

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D. Capriotti99_{, M. Capua}36a,36b_{, R. Caputo}81_{, R. Cardarelli}133a_{, T. Carli}29_{, G. Carlino}102a_,

L. Carminati89a,89b_{, B. Caron}85_{, S. Caron}104_{, E. Carquin}31b_{, G.D. Carrillo Montoya}173_{, A.A. Carter}75_,

J.R. Carter27_{, J. Carvalho}124a,h_{, D. Casadei}108_{, M.P. Casado}11_{, M. Cascella}122a,122b_{, C. Caso}50a,50b,∗_,

A.M. Castaneda Hernandez173,i_{, E. Castaneda-Miranda}173_{, V. Castillo Gimenez}167_{, N.F. Castro}124a_,

G. Cataldi72a_{, P. Catastini}57_{, A. Catinaccio}29_{, J.R. Catmore}29_{, A. Cattai}29_{, G. Cattani}133a,133b_,

S. Caughron88_{, P. Cavalleri}78_{, D. Cavalli}89a_{, M. Cavalli-Sforza}11_{, V. Cavasinni}122a,122b_{, F. Ceradini}134a,134b_,

A.S. Cerqueira23b_{, A. Cerri}29_{, L. Cerrito}75_{, F. Cerutti}47_{, S.A. Cetin}18b_{, A. Chafaq}135a_{, D. Chakraborty}106_,

I. Chalupkova126_{, K. Chan}2_{, B. Chapleau}85_{, J.D. Chapman}27_{, J.W. Chapman}87_{, E. Chareyre}78_,

D.G. Charlton17_{, V. Chavda}82_{, C.A. Chavez Barajas}29_{, S. Cheatham}85_{, S. Chekanov}5_{, S.V. Chekulaev}159a_,

G.A. Chelkov64_{, M.A. Chelstowska}104_{, C. Chen}63_{, H. Chen}24_{, S. Chen}32c_{, X. Chen}173_{, Y. Chen}34_,

A. Cheplakov64_{, R. Cherkaoui El Moursli}135e_{, V. Chernyatin}24_{, E. Cheu}6_{, S.L. Cheung}158_{, L. Chevalier}136_,

G. Chiefari102a,102b_{, L. Chikovani}51a_{, J.T. Childers}29_{, A. Chilingarov}71_{, G. Chiodini}72a_{, A.S. Chisholm}17_,

R.T. Chislett77_{, A. Chitan}25a_{, M.V. Chizhov}64_{, G. Choudalakis}30_{, S. Chouridou}137_{, I.A. Christidi}77_,

A. Christov48_{, D. Chromek-Burckhart}29_{, M.L. Chu}151_{, J. Chudoba}125_{, G. Ciapetti}132a,132b_{, A.K. Ciftci}3a_,

R. Ciftci3a_{, D. Cinca}33_{, V. Cindro}74_{, C. Ciocca}19a,19b_{, A. Ciocio}14_{, M. Cirilli}87_{, P. Cirkovic}12b_,

M. Citterio89a_{, M. Ciubancan}25a_{, A. Clark}49_{, P.J. Clark}45_{, R.N. Clarke}14_{, W. Cleland}123_{, J.C. Clemens}83_,

B. Clement55_{, C. Clement}146a,146b_{, Y. Coadou}83_{, M. Cobal}164a,164c_{, A. Coccaro}138_{, J. Cochran}63_,

J.G. Cogan143_{, J. Coggeshall}165_{, E. Cogneras}178_{, J. Colas}4_{, A.P. Colijn}105_{, N.J. Collins}17_,

C. Collins-Tooth53_{, J. Collot}55_{, T. Colombo}119a,119b_{, G. Colon}84_{, P. Conde Mui˜no}124a_{, E. Coniavitis}118_,

M.C. Conidi11_{, S.M. Consonni}89a,89b_{, V. Consorti}48_{, S. Constantinescu}25a_{, C. Conta}119a,119b_{, G. Conti}57_,

F. Conventi102a,j_{, M. Cooke}14_{, B.D. Cooper}77_{, A.M. Cooper-Sarkar}118_{, K. Copic}14_{, T. Cornelissen}175_,

M. Corradi19a_{, F. Corriveau}85,k_{, A. Cortes-Gonzalez}165_{, G. Cortiana}99_{, G. Costa}89a_{, M.J. Costa}167_,

D. Costanzo139_{, T. Costin}30_{, D. Cˆot´e}29_{, L. Courneyea}169_{, G. Cowan}76_{, C. Cowden}27_{, B.E. Cox}82_,

K. Cranmer108_{, F. Crescioli}122a,122b_{, M. Cristinziani}20_{, G. Crosetti}36a,36b_{, R. Crupi}72a,72b_,

S. Cr´ep´e-Renaudin55_{, C.-M. Cuciuc}25a_{, C. Cuenca Almenar}176_{, T. Cuhadar Donszelmann}139_,

M. Curatolo47_{, C.J. Curtis}17_{, C. Cuthbert}150_{, P. Cwetanski}60_{, H. Czirr}141_{, P. Czodrowski}43_,

Z. Czyczula176_{, S. D’Auria}53_{, M. D’Onofrio}73_{, A. D’Orazio}132a,132b_{, M.J. Da Cunha Sargedas De Sousa}124a_,

C. Da Via82_{, W. Dabrowski}37_{, A. Dafinca}118_{, T. Dai}87_{, C. Dallapiccola}84_{, M. Dam}35_{, M. Dameri}50a,50b_,

D.S. Damiani137_{, H.O. Danielsson}29_{, V. Dao}49_{, G. Darbo}50a_{, G.L. Darlea}25b_{, W. Davey}20_{, T. Davidek}126_,

N. Davidson86_{, R. Davidson}71_{, E. Davies}118,c_{, M. Davies}93_{, A.R. Davison}77_{, Y. Davygora}58a_{, E. Dawe}142_,

I. Dawson139_{, R.K. Daya-Ishmukhametova}22_{, K. De}7_{, R. de Asmundis}102a_{, S. De Castro}19a,19b_,

S. De Cecco78_{, J. de Graat}98_{, N. De Groot}104_{, P. de Jong}105_{, C. De La Taille}115_{, H. De la Torre}80_,

F. De Lorenzi63_{, L. de Mora}71_{, L. De Nooij}105_{, D. De Pedis}132a_{, A. De Salvo}132a_{, U. De Sanctis}164a,164c_,

A. De Santo149, J.B. De Vivie De Regie115, G. De Zorzi132a,132b, W.J. Dearnaley71, R. Debbe24,

C. Debenedetti45, B. Dechenaux55, D.V. Dedovich64, J. Degenhardt120, C. Del Papa164a,164c,

J. Del Peso80, T. Del Prete122a,122b, T. Delemontex55, M. Deliyergiyev74, A. Dell’Acqua29, L. Dell’Asta21, M. Della Pietra102a,j_{, D. della Volpe}102a,102b_{, M. Delmastro}4_{, P.A. Delsart}55_{, C. Deluca}105_{, S. Demers}176_,

M. Demichev64_{, B. Demirkoz}11,l_{, J. Deng}163_{, S.P. Denisov}128_{, D. Derendarz}38_{, J.E. Derkaoui}135d_,

F. Derue78_{, P. Dervan}73_{, K. Desch}20_{, E. Devetak}148_{, P.O. Deviveiros}105_{, A. Dewhurst}129_{, B. DeWilde}148_,

S. Dhaliwal158_{, R. Dhullipudi}24,m_{, A. Di Ciaccio}133a,133b_{, L. Di Ciaccio}4_{, A. Di Girolamo}29_,

A. Di Simone133a,133b_{, R. Di Sipio}19a,19b_{, M.A. Diaz}31a_{, E.B. Diehl}87_{, J. Dietrich}41_{, T.A. Dietzsch}58a_,

S. Diglio86, K. Dindar Yagci39, J. Dingfelder20, F. Dinut25a, C. Dionisi132a,132b, P. Dita25a, S. Dita25a,

F. Dittus29_{, F. Djama}83_{, T. Djobava}51b_{, M.A.B. do Vale}23c_{, A. Do Valle Wemans}124a,n_{, T.K.O. Doan}4_,

M. Dobbs85_{, R. Dobinson}29,∗_{, D. Dobos}29_{, E. Dobson}29,o_{, J. Dodd}34_{, C. Doglioni}49_{, T. Doherty}53_,

Y. Doi65,∗_{, J. Dolejsi}126_{, I. Dolenc}74_{, Z. Dolezal}126_{, B.A. Dolgoshein}96,∗_{, T. Dohmae}155_{, M. Donadelli}23d_,

J. Donini33_{, J. Dopke}29_{, A. Doria}102a_{, A. Dos Anjos}173_{, A. Dotti}122a,122b_{, M.T. Dova}70_{, A.D. Doxiadis}105_,

A.T. Doyle53_{, M. Dris}9_{, J. Dubbert}99_{, S. Dube}14_{, E. Duchovni}172_{, G. Duckeck}98_{, A. Dudarev}29_,

F. Dudziak63_{, M. D¨uhrssen}29_{, I.P. Duerdoth}82_{, L. Duflot}115_{, M-A. Dufour}85_{, M. Dunford}29_,

H. Duran Yildiz3a_{, R. Duxfield}139_{, M. Dwuznik}37_{, F. Dydak}29_{, M. D¨uren}52_{, J. Ebke}98_{, S. Eckweiler}81_,

K. Edmonds81_{, W. Edson}1_{, C.A. Edwards}76_{, N.C. Edwards}53_{, W. Ehrenfeld}41_{, T. Eifert}143_{, G. Eigen}13_,

K. Einsweiler14_{, E. Eisenhandler}75_{, T. Ekelof}166_{, M. El Kacimi}135c_{, M. Ellert}166_{, S. Elles}4_{, F. Ellinghaus}81_,

K. Ellis75_{, N. Ellis}29_{, J. Elmsheuser}98_{, M. Elsing}29_{, D. Emeliyanov}129_{, R. Engelmann}148_{, A. Engl}98_,

B. Epp61_{, J. Erdmann}54_{, A. Ereditato}16_{, D. Eriksson}146a_{, J. Ernst}1_{, M. Ernst}24_{, J. Ernwein}136_,

D. Errede165_{, S. Errede}165_{, E. Ertel}81_{, M. Escalier}115_{, H. Esch}42_{, C. Escobar}123_{, X. Espinal Curull}11_,

B. Esposito47_{, F. Etienne}83_{, A.I. Etienvre}136_{, E. Etzion}153_{, D. Evangelakou}54_{, H. Evans}60_{, L. Fabbri}19a,19b_,

C. Fabre29_{, R.M. Fakhrutdinov}128_{, S. Falciano}132a_{, Y. Fang}173_{, M. Fanti}89a,89b_{, A. Farbin}7_{, A. Farilla}134a_,

J. Farley148_{, T. Farooque}158_{, S. Farrell}163_{, S.M. Farrington}170_{, P. Farthouat}29_{, P. Fassnacht}29_,

D. Fassouliotis8_{, B. Fatholahzadeh}158_{, A. Favareto}89a,89b_{, L. Fayard}115_{, S. Fazio}36a,36b_{, R. Febbraro}33_,

P. Federic144a_{, O.L. Fedin}121_{, W. Fedorko}88_{, M. Fehling-Kaschek}48_{, L. Feligioni}83_{, D. Fellmann}5_,

C. Feng32d_{, E.J. Feng}5_{, A.B. Fenyuk}128_{, J. Ferencei}144b_{, W. Fernando}5_{, S. Ferrag}53_{, J. Ferrando}53_,

V. Ferrara41_{, A. Ferrari}166_{, P. Ferrari}105_{, R. Ferrari}119a_{, D.E. Ferreira de Lima}53_{, A. Ferrer}167_,

D. Ferrere49_{, C. Ferretti}87_{, A. Ferretto Parodi}50a,50b_{, M. Fiascaris}30_{, F. Fiedler}81_{, A. Filipˇciˇc}74_,

F. Filthaut104_{, M. Fincke-Keeler}169_{, M.C.N. Fiolhais}124a,h_{, L. Fiorini}167_{, A. Firan}39_{, G. Fischer}41_,

M.J. Fisher109_{, M. Flechl}48_{, I. Fleck}141_{, J. Fleckner}81_{, P. Fleischmann}174_{, S. Fleischmann}175_{, T. Flick}175_,

A. Floderus79_{, L.R. Flores Castillo}173_{, M.J. Flowerdew}99_{, T. Fonseca Martin}16_{, A. Formica}136_{, A. Forti}82_,

D. Fortin159a_{, D. Fournier}115_{, H. Fox}71_{, P. Francavilla}11_{, M. Franchini}19a,19b_{, S. Franchino}119a,119b_,

D. Francis29_{, T. Frank}172_{, S. Franz}29_{, M. Fraternali}119a,119b_{, S. Fratina}120_{, S.T. French}27_{, C. Friedrich}41_,

F. Friedrich43_{, R. Froeschl}29_{, D. Froidevaux}29_{, J.A. Frost}27_{, C. Fukunaga}156_{, E. Fullana Torregrosa}29_,

B.G. Fulsom143_{, J. Fuster}167_{, C. Gabaldon}29_{, O. Gabizon}172_{, T. Gadfort}24_{, S. Gadomski}49_,

G. Gagliardi50a,50b_{, P. Gagnon}60_{, C. Galea}98_{, E.J. Gallas}118_{, V. Gallo}16_{, B.J. Gallop}129_{, P. Gallus}125_,

K.K. Gan109_{, Y.S. Gao}143,e_{, A. Gaponenko}14_{, F. Garberson}176_{, M. Garcia-Sciveres}14_{, C. Garc´ıa}167_,

J.E. Garc´ıa Navarro167_{, R.W. Gardner}30_{, N. Garelli}29_{, H. Garitaonandia}105_{, V. Garonne}29_{, J. Garvey}17_,

C. Gatti47_{, G. Gaudio}119a_{, B. Gaur}141_{, L. Gauthier}136_{, P. Gauzzi}132a,132b_{, I.L. Gavrilenko}94_{, C. Gay}168_,

G. Gaycken20_{, E.N. Gazis}9_{, P. Ge}32d_{, Z. Gecse}168_{, C.N.P. Gee}129_{, D.A.A. Geerts}105_{, Ch. Geich-Gimbel}20_,

K. Gellerstedt146a,146b_{, C. Gemme}50a_{, A. Gemmell}53_{, M.H. Genest}55_{, S. Gentile}132a,132b_{, M. George}54_,

S. George76_{, P. Gerlach}175_{, A. Gershon}153_{, C. Geweniger}58a_{, H. Ghazlane}135b_{, N. Ghodbane}33_,

B. Giacobbe19a_{, S. Giagu}132a,132b_{, V. Giakoumopoulou}8_{, V. Giangiobbe}11_{, F. Gianotti}29_{, B. Gibbard}24_,

A. Gibson158_{, S.M. Gibson}29_{, D. Gillberg}28_{, A.R. Gillman}129_{, D.M. Gingrich}2,d_{, J. Ginzburg}153_,

N. Giokaris8_{, M.P. Giordani}164c_{, R. Giordano}102a,102b_{, F.M. Giorgi}15_{, P. Giovannini}99_{, P.F. Giraud}136_,

D. Giugni89a_{, M. Giunta}93_{, P. Giusti}19a_{, B.K. Gjelsten}117_{, L.K. Gladilin}97_{, C. Glasman}80_{, J. Glatzer}48_,

A. Glazov41_{, K.W. Glitza}175_{, G.L. Glonti}64_{, J.R. Goddard}75_{, J. Godfrey}142_{, J. Godlewski}29_{, M. Goebel}41_,

T. G¨opfert43_{, C. Goeringer}81_{, C. G¨ossling}42_{, S. Goldfarb}87_{, T. Golling}176_{, A. Gomes}124a,b_,

L.S. Gomez Fajardo41_{, R. Gon¸calo}76_{, J. Goncalves Pinto Firmino Da Costa}41_{, L. Gonella}20_,

S. Gonzalez173_{, S. Gonz´alez de la Hoz}167_{, G. Gonzalez Parra}11_{, M.L. Gonzalez Silva}26_,

S. Gonzalez-Sevilla49, J.J. Goodson148, L. Goossens29, P.A. Gorbounov95, H.A. Gordon24, I. Gorelov103, G. Gorfine175, B. Gorini29, E. Gorini72a,72b, A. Goriˇsek74, E. Gornicki38, B. Gosdzik41, A.T. Goshaw5, M. Gosselink105, M.I. Gostkin64, I. Gough Eschrich163, M. Gouighri135a, D. Goujdami135c,

M.P. Goulette49_{, A.G. Goussiou}138_{, C. Goy}4_{, S. Gozpinar}22_{, I. Grabowska-Bold}37_{, P. Grafstr¨om}19a,19b_,

K-J. Grahn41_{, F. Grancagnolo}72a_{, S. Grancagnolo}15_{, V. Grassi}148_{, V. Gratchev}121_{, N. Grau}34_,

H.M. Gray29_{, J.A. Gray}148_{, E. Graziani}134a_{, O.G. Grebenyuk}121_{, T. Greenshaw}73_{, Z.D. Greenwood}24,m_,

K. Gregersen35_{, I.M. Gregor}41_{, P. Grenier}143_{, J. Griffiths}138_{, N. Grigalashvili}64_{, A.A. Grillo}137_,