Performance of missing transverse momentum reconstruction in proton-proton collisions at $\sqrt{s}=7$ TeV with ATLAS

Performance of missing transverse momentum reconstruction in proton-proton collisions at $\sqrt{s} = 7$ TeV with ATLAS

The measurement of missing transverse momentum in the ATLAS detector, described in this paper, makes use of the full event reconstruction and a calibration based on reconstructed physics objects. The performance of the missing transverse momentum reconstruction is evaluated using data collected in pp collisions at a centre-of-mass energy of 7 TeV in 2010. Minimum bias events and events with jets of hadrons are used from data samples corresponding to an integrated luminosity of about 0.3 inverse nb and 600 inverse nb, together with events containing a Z boson decaying to two leptons (electrons or muons) or a W boson decaying to a lepton (electron or muon) and a neutrino, from a data sample corresponding to an integrated luminosity of about 36 inverse pb. An estimate of the systematic uncertainty on the missing transverse momentum scale is presented.

29 August 2011

Contact: PERF conveners internal

Eur. Phys. J. C 72 (2012) 1844

e-print arXiv:1108.5602 - pdf from arXiv

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Figures

Figures

Figure 01a

Distribution of Exmiss as measured in a data sample of minimum bias events. The expectation from MC simulation, normalized to the number of events in data, is superimposed.

png (47kB) eps (23kB) pdf (15kB)

Figure 01b

Distribution of Eymiss as measured in a data sample of minimum bias events. The expectation from MC simulation, normalized to the number of events in data, is superimposed.

png (47kB) eps (24kB) pdf (15kB)

Figure 01c

Distribution of Etmiss as measured in a data sample of minimum bias events. The expectation from MC simulation, normalized to the number of events in data, is superimposed.

png (42kB) eps (21kB) pdf (8kB)

Figure 01d

Distribution of Phimiss as measured in a data sample of minimum bias events. The expectation from MC simulation, normalized to the number of events in data, is superimposed.

png (42kB) eps (18kB) pdf (7kB)

Figure 02a

Distribution of Exmiss as measured in the data sample of di-jet events. The expectation from MC simulation, normalized to the number of events in data, is superimposed. The events in the tails are discussed in the text.

png (47kB) eps (25kB) pdf (16kB)

Figure 02b

Distribution of Eymiss as measured in the data sample of di-jet events. The expectation from MC simulation, normalized to the number of events in data, is superimposed. The events in the tails are discussed in the text.

png (48kB) eps (26kB) pdf (17kB)

Figure 02c

Distribution of Etmiss as measured in the data sample of di-jet events. The expectation from MC simulation, normalized to the number of events in data, is superimposed. The events in the tails are discussed in the text.

png (43kB) eps (22kB) pdf (9kB)

Figure 02d

Distribution of Phimiss as measured in the data sample of di-jet events. The expectation from MC simulation, normalized to the number of events in data, is superimposed. The events in the tails are discussed in the text.

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Figure 03a

Distribution of Etmiss computed with cells from topoclusters in jets for data for di-jet events. The expectation from MC simulation, normalized to the number of events in data, is superimposed.

png (47kB) eps (26kB) pdf (19kB)

Figure 03b

Distribution of Etmiss computed with cells from topoclusters in soft jets for data for di-jet events. The expectation from MC simulation, normalized to the number of events in data, is superimposed.

png (42kB) eps (21kB) pdf (8kB)

Figure 03c

Distribution of Etmiss computed with cells from topoclusters outside reconstructed objects for data for di-jet events. The expectation from MC simulation, normalized to the number of events in data, is superimposed.

png (40kB) eps (21kB) pdf (7kB)

Figure 03d

Distribution of Etmiss computed from reconstructed muons for data for di-jet events. The expectation from MC simulation, normalized to the number of events in data, is superimposed. The events in the tail of the

E_{T}^{miss, μ}

distribution are discussed in the text.

png (40kB) eps (20kB) pdf (8kB)

Figure 04a

Distribution of SumET as measured in a data sample of minimum bias events. The expectation from MC simulation, normalized to the number of events in data, is superimposed. {\sc Pythia6} (ATLAS tune) is compared with the data.

png (47kB) eps (24kB) pdf (13kB)

Figure 04b

Distribution of SumET as measured in a data sample of minimum bias events. The expectation from MC simulation, normalized to the number of events in data, is superimposed. {\sc Pythia8} (ATLAS tune) is compared with the data.

png (46kB) eps (24kB) pdf (13kB)

Figure 04c

Distribution of SumET as measured in a data sample of di-jets events selecting two jets with \pT~

>

25 GeV. The expectation from MC simulation, normalized to the number of events in data, is superimposed. {\sc Pythia6} (ATLAS tune) is compared with the data.

png (43kB) eps (23kB) pdf (9kB)

Figure 04d

Distribution of SumET as measured in a data sample of di-jets events selecting two jets with \pT~

>

25 GeV. The expectation from MC simulation, normalized to the number of events in data, is superimposed. {\sc Pythia8} (ATLAS tune) is compared with the data.

png (45kB) eps (23kB) pdf (9kB)

Figure 05a

Distribution of Etmiss as measured in a data sample of \Zee. The expectation from Monte Carlo simulation is superimposed and normalized to data, after each MC sample is weighted with its corresponding cross-section.

png (38kB) eps (47kB) pdf (11kB)

Figure 05b

Distribution of Etmiss as measured in a data sample of \Zmumu. The expectation from Monte Carlo simulation is superimposed and normalized to data, after each MC sample is weighted with its corresponding cross-section.

png (40kB) eps (49kB) pdf (12kB)

Figure 05c

Distribution of Phimiss as measured in a data sample of \Zee. The expectation from Monte Carlo simulation is superimposed and normalized to data, after each MC sample is weighted with its corresponding cross-section. The sum of all backgrounds is shown.

png (39kB) eps (28kB) pdf (8kB)

Figure 05d

Distribution of Phimiss as measured in a data sample of \Zmumu. The expectation from Monte Carlo simulation is superimposed and normalized to data, after each MC sample is weighted with its corresponding cross-section. The sum of all backgrounds is shown.

png (42kB) eps (29kB) pdf (10kB)

Figure 06a

Distribution of Etmiss computed with calorimeter cells associated to muons (

E_{T}^{miss, calo, μ}

) for \Zmumu~ data. The expectation from Monte Carlo simulation is superimposed and normalized to data, after each MC sample is weighted with its corresponding cross-section.

png (35kB) eps (43kB) pdf (8kB)

Figure 06b

Distribution of Etmiss computed from reconstructed muons (

E_{T}^{miss, μ}

Figure 07a

Distribution of Etmiss computed with cells associated to electrons (

E_{T}^{miss, e}

) for \Zee~ data. The expectation from Monte Carlo simulation is superimposed and normalized to data, after each MC sample is weighted with its corresponding cross-section.

png (45kB) eps (49kB) pdf (18kB)

Figure 07b

Distribution of Etmiss computed with cells associated to jets with \pT~

> 20

GeV (

E_{T}^{miss, jets}

Figure 07c

Distribution of Etmiss computed with cells associated to jets with 7 GeV

<

\pT~

<

20 GeV (

E_{T}^{miss, softjets}

Figure 07d

Distribution of Etmiss computed from topoclusters outside reconstructed objects (

E_{T}^{miss, CellOut}

Figure 08a

Mean values of Etmiss along Z direction as a function of \pTZ in \Zee events.

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Figure 08b

Mean values of Etmiss along Z direction as a function of \pTZ in \Zmumu events.

png (28kB) eps (12kB) pdf (6kB)

Figure 09a

Mean value of Etmiss along the Z direction as a function of \pTZ~ requiring either zero jets with \pT~

>

20 GeV or at least 1 jet with \pT~

>

20 GeV in the event for \Zee~ events.

png (40kB) eps (14kB) pdf (6kB)

Figure 09b

Mean value of Etmiss along the Z direction as a function of \pTZ~ requiring either zero jets with \pT~

>

20 GeV or at least 1 jet with \pT~

>

20 GeV in the event for \Zmumu~ events.

png (41kB) eps (15kB) pdf (6kB)

Figure 10a

Mean value of Etmiss along the Z direction as a function of \pTZ~ in \Zee~ for events with no jets with \pT~

>

7 GeV. The default Etmiss is compared with Etmiss calculated in the same way with the exception that the track-cluster matching algorithm is not used for the calculation of

E_{T}^{miss, CellOut}

.

png (36kB) eps (13kB) pdf (6kB)

Figure 10b

Mean value ofEtmiss along the Z direction as a function of \pTZ~ in \Zmumu~ for events with no jets with \pT~

>

7 GeV. The default Etmiss is compared with Etmiss calculated in the same way with the exception that the track-cluster matching algorithm is not used for the calculation of

E_{T}^{miss, CellOut}

.

png (36kB) eps (14kB) pdf (6kB)

Figure 11a

Distribution of Etmiss as measured in a data sample of \Wen~ events. The expectation from Monte Carlo simulation is superimposed and normalized to data, after each MC sample is weighted with its corresponding cross-section.

png (52kB) eps (77kB) pdf (20kB)

Figure 11b

Distribution of Etmiss as measured in a data sample of \Wmun~ events. The expectation from Monte Carlo simulation is superimposed and normalized to data, after each MC sample is weighted with its corresponding cross-section.

png (53kB) eps (82kB) pdf (21kB)

Figure 11c

Distribution of Phimiss as measured in a data sample of \Wen~ events. The expectation from Monte Carlo simulation is superimposed and normalized to data, after each MC sample is weighted with its corresponding cross-section. The sum of all backgrounds is shown.

png (36kB) eps (25kB) pdf (10kB)

Figure 11d

Distribution of Phimiss as measured in a data sample of \Wmun~ events. The expectation from Monte Carlo simulation is superimposed and normalized to data, after each MC sample is weighted with its corresponding cross-section. The sum of all backgrounds is shown.

png (40kB) eps (27kB) pdf (10kB)

Figure 12a

Distribution of Etmiss computed with cells from muons (

E_{T}^{miss, calo, μ}

) for \Wmun~ data. The expectation from Monte Carlo simulation is superimposed and normalized to data, after each MC sample is weighted with its corresponding cross-section.

png (39kB) eps (69kB) pdf (9kB)

Figure 12b

Distribution of Etmiss computed from reconstructed muons (

E_{T}^{miss, muon}

Figure 13a

Distribution of Etmiss computed with cells associated to electrons (

E_{T}^{miss, e}

) for data. The expectation from Monte Carlo simulation is superimposed and normalized to data, after each MC sample is weighted with its corresponding cross-section.

png (54kB) eps (80kB) pdf (21kB)

Figure 13b

Distribution of Etmiss computed with cells associated to jets with \pT~

> 20

GeV (

E_{T}^{miss, jets}

) for data. The expectation from Monte Carlo simulation is superimposed and normalized to data, after each MC sample is weighted with its corresponding cross-section.

png (58kB) eps (89kB) pdf (25kB)

Figure 13c

Distribution of Etmiss computed with cells associated to jets with \pT~

< 20

GeV (

E_{T}^{miss, softjets}

) for data. The expectation from Monte Carlo simulation is superimposed and normalized to data, after each MC sample is weighted with its corresponding cross-section.

png (47kB) eps (68kB) pdf (14kB)

Figure 13d

Distribution of Etmiss computed from topoclusters outside reconstructed objectsc (

E_{T}^{miss, CellOut}

) for data. The expectation from Monte Carlo simulation is superimposed and normalized to data, after each MC sample is weighted with its corresponding cross-section.

png (43kB) eps (72kB) pdf (11kB)

Figure 14

Etmiss linearity in \Wen~ MC events as a function of

E_{T}^{m i s s, T r u e}

png (40kB) eps (14kB) pdf (7kB)

Figure 15a

Exmiss and Eymiss resolution as a function of the total transverse energy in the event calculated by summing the \pT~ of muons and the total transverse energy in the calorimeter in data at

\sqrt{s}

= 7 TeV. The resolution of the two Etmiss~ components is fitted with a function

σ = k \cdot \sqrt{Σ E_{T}}

and the fitted values of the parameter

k

, expressed in GeV

^{1 / 2}

, are reported in the figure.

png (54kB) eps (15kB) pdf (8kB)

Figure 15b

Exmiss and Eymiss resolution as a function of the total transverse energy in the event calculated by summing the \pT~ of muons and the total transverse energy in the calorimeter in MC simulation. The resolution of the two Etmiss~ components is fitted with a function

σ = k \cdot \sqrt{Σ E_{T}}

and the fitted values of the parameter

k

, expressed in GeV

^{1 / 2}

, are reported in the figure.

png (69kB) eps (19kB) pdf (10kB)

Figure 16a

Fractional systematic uncertainty (calculated as in Equations 9 and 10) on different Etmiss terms as a function of respective \sumet

^{term}

~ in MC \Wen~ events.

png (44kB) eps (12kB) pdf (10kB)

Figure 16b

Contributions of different term uncertainties on Etmiss uncertainty as a function of sumET in MC \Wen~ events. The overall systematic uncertainty on the Etmiss scale, obtained combining the various contributions is shown (filled circles). The uncertainties on \etmissmag

^{, softjets}

and \etmissmag

^{, CellOut}

are considered to be fully correlated.

png (48kB) eps (15kB) pdf (10kB)

Figure 16c

Fractional systematic uncertainty (calculated as in Equations 9 and 10) on different Etmiss terms as a function of respective \sumet

^{term}

~ in MC \Wmun~ events.

png (42kB) eps (13kB) pdf (10kB)

Figure 16d

Contributions of different term uncertainties on Etmiss uncertainty as a function of sumET in MC \Wmun~ events. The overall systematic uncertainty on the Etmiss scale, obtained combining the various contributions is shown (filled circles). The uncertainties on \etmissmag

^{, softjets}

and \etmissmag

^{, CellOut}

are considered to be fully correlated.

png (47kB) eps (15kB) pdf (9kB)

Figure 17a

Distributions of the transverse mass, \mT, of the muon-Etmiss system for data. The \mT~distributions from Monte Carlo simulation are superimposed, after each background sample is weighted as explained in the text. The main backgrounds are shown. The \Wln~ MC signal histogram is obtained using the true Etmiss smeared as in Equation 12 with the scale and resolution parameters obtained from the fit.

png (57kB) eps (43kB) pdf (14kB)

Figure 17b

Distributions of the transverse mass, \mT, of the electron-Etmiss system for data. The \mT~distributions from Monte Carlo simulation are superimposed, after each background sample is weighted as explained in the text. The sum of all backgrounds is shown. The \Wln~ MC signal histogram is obtained using the true Etmiss smeared as in Equation 12 with the scale and resolution parameters obtained from the fit.

png (52kB) eps (23kB) pdf (10kB)

Figure 18a

Transverse momentum distribution of electron candidates in data, in signal MC with nominal event selection and with reversed cuts for background (QCD) from data.

png (46kB) eps (20kB) pdf (9kB)

Figure 18b

Relative bias in the reconstructed Etmiss. Only statistical uncertainties are shown.

png (36kB) eps (14kB) pdf (7kB)

Performance of missing transverse momentum reconstruction in proton-proton collisions at s=7 TeV with ATLAS

Contact: PERF conveners internal

Performance of missing transverse momentum reconstruction in proton-proton collisions at $\sqrt{s} = 7$ TeV with ATLAS