Ratios of dijet production cross sections as a function of the absolute difference in rapidity between jets in proton-proton collisions at sqrt(s) = 7 TeV

The CMS collaboration Chatrchyan, Serguei ; Khachatryan, Vardan ; Sirunyan, Albert M ; et al.
Eur.Phys.J.C 72 (2012) 2216, 2012.
Inspire Record 1102908 DOI 10.17182/hepdata.68066

A study of dijet production in proton-proton collisions was performed at sqrt(s) = 7 TeV for jets with pt > 35 GeV and abs(y) < 4.7 using data collected with the CMS detector at the LHC in 2010. Events with at least one pair of jets are denoted as 'inclusive'. Events with exactly one pair of jets are called 'exclusive'. The ratio of the cross section of all pairwise combinations of jets to the exclusive dijet cross section as a function of the rapidity difference between jets abs(Delta(y)) is measured for the first time up to abs(Delta(y)) = 9.2. The ratio of the cross section for the pair consisting of the most forward and the most backward jet from the inclusive sample to the exclusive dijet cross section is also presented. The predictions of the Monte Carlo event generators PYTHIA6 and PYTHIA8 agree with the measurements. In both ratios the HERWIG++ generator exhibits a more pronounced rise versus abs(Delta(y)) than observed in the data. The BFKL-motivated generators CASCADE and HEJ+ARIADNE predict for these ratios a significantly stronger rise than observed.

2 data tables

Inclusive to exclusive dijet production ratio.

Mueller-Navelet to exclusive dijet production ratio.


Shape, transverse size, and charged hadron multiplicity of jets in pp collisions at 7 TeV

The CMS collaboration Chatrchyan, Serguei ; Khachatryan, Vardan ; Sirunyan, Albert M ; et al.
JHEP 06 (2012) 160, 2012.
Inspire Record 1111014 DOI 10.17182/hepdata.70063

Measurements of jet characteristics from inclusive jet production in proton-proton collisions at a centre-of-mass energy of 7 TeV are presented. The data sample was collected with the CMS detector at the LHC during 2010 and corresponds to an integrated luminosity of 36 inverse picobarns. The mean charged hadron multiplicity, the differential and integral jet shape distributions, and two independent moments of the shape distributions are measured as functions of the jet transverse momentum for jets reconstructed with the anti-kT algorithm. The measured observables are corrected to the particle level and compared with predictions from various QCD Monte Carlo generators.

128 data tables

The measured differential jet shape $\rho(r)$ for jets with 20 GeV $< p_{\mathrm{T}} <$ 25 GeV and 0 <|y|< 0.5. The CF in the table refers to unfolding correction factor from {\sc pythia6} Tune Z2. The systematic uncertainties from different sources, jet energy scale (JES), unfolding, and single particle response (SPR), are also presented.

The measured differential jet shape $\rho(r)$ for jets with 25 GeV $< p_{\mathrm{T}} <$ 30 GeV and 0 <|y|< 0.5. The CF in the table refers to unfolding correction factor from {\sc pythia6} Tune Z2. The systematic uncertainties from different sources, jet energy scale (JES), unfolding, and single particle response (SPR), are also presented.

The measured differential jet shape $\rho(r)$ for jets with 30 GeV $< p_{\mathrm{T}} <$ 40 GeV and 0 <|y|< 0.5. The CF in the table refers to unfolding correction factor from {\sc pythia6} Tune Z2. The systematic uncertainties from different sources, jet energy scale (JES), unfolding, and single particle response (SPR), are also presented.

More…

Jet mass and substructure of inclusive jets in $\sqrt{s}=7$ TeV $pp$ collisions with the ATLAS experiment

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abdallah, Jalal ; et al.
JHEP 05 (2012) 128, 2012.
Inspire Record 1094564 DOI 10.17182/hepdata.58739

Recent studies have highlighted the potential of jet substructure techniques to identify the hadronic decays of boosted heavy particles. These studies all rely upon the assumption that the internal substructure of jets generated by QCD radiation is well understood. In this article, this assumption is tested on an inclusive sample of jets recorded with the ATLAS detector in 2010, which corresponds to 35 pb^-1 of pp collisions delivered by the LHC at sqrt(s) = 7 TeV. In a subsample of events with single pp collisions, measurementes corrected for detector efficiency and resolution are presented with full systematic uncertainties. Jet invariant mass, kt splitting scales and n-subjettiness variables are presented for anti-kt R = 1.0 jets and Cambridge-Aachen R = 1.2 jets. Jet invariant-mass spectra for Cambridge-Aachen R = 1.2 jets after a splitting and filtering procedure are also presented. Leading-order parton-shower Monte Carlo predictions for these variables are found to be broadly in agreement with data. The dependence of mean jet mass on additional pp interactions is also explored.

36 data tables

Normalised cross-section as a function of the mass of Cambridge-Aachen jets with R=1.2.

Normalised cross-section as a function of the mass of Cambridge-Aachen jets with R=1.2.

Normalised cross-section as a function of the mass of Cambridge-Aachen jets with R=1.2.

More…

Measurement of ttbar production with a veto on additional central jet activity in pp collisions at sqrt(s) = 7 TeV using the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abdallah, Jalal ; et al.
Eur.Phys.J.C 72 (2012) 2043, 2012.
Inspire Record 1094568 DOI 10.17182/hepdata.58936

A measurement of the jet activity in ttbar events produced in proton-proton collisions at a centre-of-mass energy of 7 TeV is presented, using 2.05 fb^-1 of integrated luminosity collected by the ATLAS detector at the Large Hadron Collider. The ttbar events are selected in the dilepton decay channel with two identified b-jets from the top quark decays. Events are vetoed if they contain an additional jet with transverse momentum above a threshold in a central rapidity interval. The fraction of events surviving the jet veto is presented as a function of this threshold for four different central rapidity interval definitions. An alternate measurement is also performed, in which events are vetoed if the scalar transverse momentum sum of the additional jets in each rapidity interval is above a threshold. In both measurements, the data are corrected for detector effects and compared to the theoretical models implemented in MC@NLO, POWHEG, ALPGEN and SHERPA. The experimental uncertainties are often smaller than the spread of theoretical predictions, allowing deviations between data and theory to be observed in some regions of phase space.

16 data tables

The measured fraction of events, the gap fraction, surviving the veto cut of having no additional jets in the |rapidity| interval < 0.8 having a transverse momentum greater than Q, as a function of Q.

The measured fraction of events, the gap fraction, surviving the veto cut of having no additional jets in the |rapidity| interval 0.8-1.5 having a transverse momentum greater than Q, as a function of Q.

The measured fraction of events, the gap fraction, surviving the veto cut of having no additional jets in the |rapidity| interval 1.5-2.1 having a transverse momentum greater than Q, as a function of Q.

More…

Search for events with large missing transverse momentum, jets, and at least two tau leptons in 7 TeV proton-proton collision data with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abdallah, Jalal ; et al.
Phys.Lett.B 714 (2012) 180-196, 2012.
Inspire Record 1095404 DOI 10.17182/hepdata.58711

A search for events with large missing transverse momentum, jets, and at least two tau leptons has been performed using 2 fb^-1 of proton-proton collision data at sqrt(s) = 7 TeV recorded with the ATLAS detector at the Large Hadron Collider. No excess above the Standard Model background expectation is observed and a 95% CL visible cross section upper limit for new phenomena is set. A 95% CL lower limit of 32 TeV is set on the GMSB breaking scale Lambda independent of tan(beta). These limits provide the most stringent tests to date in a large part of the considered parameter space.

16 data tables

The observed PT spectrum of the leading TAU candidates and the estimated SM background after pre-selection of candidate events, soft multi-jet rejection and the requirement of two or more TAUS and no light leptons.

The distribution of the effective mass of the two leading TAU candidates in data (with statistical uncertainties only) and the estimated SM background after pre-selection of candidate events, soft multi-jet rejection and the requirement of two or more TAUS and no light leptons.

The distribution of the sum of the transverse masses of the two leading TAU candidates in data (with statistical uncertainties only) and the estimated SM background after pre-selection of candidate events, soft multi-jet rejection and the requirement of two or more TAUS and no light leptons.

More…

Measurement of the cross section for production of b b-bar X, decaying to muons in pp collisions at sqrt(s)=7 TeV

The CMS collaboration Chatrchyan, Serguei ; Khachatryan, Vardan ; Sirunyan, Albert M ; et al.
JHEP 06 (2012) 110, 2012.
Inspire Record 1093951 DOI 10.17182/hepdata.58906

A measurement of the inclusive cross section for the process pp to b b-bar X to muon muon X' at sqrt(s) = 7 TeV is presented, based on a data sample corresponding to an integrated luminosity of 27.9 inverse picobarns collected by the CMS experiment at the LHC. By selecting pairs of muons each with pseudorapidity abs(eta)<2.1, the value of the cross section for pp to b b-bar X to muon muon X' is found to be 26.4 +/- 0.1 (stat.) +/- 2.4 (syst.) +/- 1.1 (lumi.) nb is obtained for muons with transverse momentum greater than 4 GeV, and 5.12 +/- 0.03 (stat.) +/- 0.48 (syst.) +/- 0.20 (lumi.) nb for transverse momenta greater than 6 GeV. These results are compared to QCD predictions at leading and next-to-leading orders.

1 data table

The measured integrated cross sections. The second systematic error is due to the luminosity uncertainty.


Measurement of the azimuthal ordering of charged hadrons with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abdallah, Jalal ; et al.
Phys.Rev.D 86 (2012) 052005, 2012.
Inspire Record 1091481 DOI 10.17182/hepdata.58477

This paper presents a measurement of the ordering of charged hadrons in the azimuthal angle relative to the beam axis in high-energy proton-proton collisions at the Large Hadron Collider (LHC). A spectral analysis of correlations between longitudinal and transverse components of the momentum of the charged hadrons, driven by the search for phenomena related to the structure of the QCD field, is performed. Data were recorded with the ATLAS detector at centre-of-mass energies of sqrt(s) = 900 GeV and sqrt(s) = 7 TeV. The correlations measured in a phase space region dominated by low-pT particles are not well described by conventional models of hadron production. The measured spectra show features consistent with the fragmentation of a QCD string represented by a helix-like ordered gluon chain.

4 data tables

The corrected data for the power spectra S_E for the three different data samples at a centre-of-mass energy of 7 TeV.

The corrected data for the power spectra S_ETA for the three different data samples at a centre-of-mass energy of 7 TeV.

The corrected data for the power spectra S_E for the three different data samples at a centre-of-mass energy of 900 GeV.

More…

Search for supersymmetry in pp collisions at sqrt(s) = 7 TeV in final states with missing transverse momentum and b-jets with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abdallah, Jalal ; et al.
Phys.Rev.D 85 (2012) 112006, 2012.
Inspire Record 1095236 DOI 10.17182/hepdata.59853

The results of a search for supersymmetry in events with large missing transverse momentum and heavy flavour jets using an integrated luminosity corresponding to 2.05 fb^-1 of pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the Large Hadron Collider are reported. No significant excess is observed with respect to the prediction for Standard Model processes. Results are interpreted in a variety of R-parity conserving models in which scalar bottoms and tops are the only scalar quarks to appear in the gluino decay cascade, and in an SO(10) model framework. Gluino masses up to 600-900 GeV are excluded, depending on the model considered.

41 data tables

Acceptance in the GLUINO-NEUTRALINO plane in the Gbb model for the 1 btag signal region with Meff > 500 GeV.

Acceptance in the GLUINO-NEUTRALINO plane in the Gbb model for the 2 btags signal region with Meff > 500 GeV.

Acceptance in the GLUINO-NEUTRALINO plane in the Gbb model for the 1 btag signal region with Meff > 700 GeV.

More…

Measurement of inclusive two-particle angular correlations in pp collisions with the ATLAS detector at the LHC

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abdallah, Jalal ; et al.
JHEP 05 (2012) 157, 2012.
Inspire Record 1094061 DOI 10.17182/hepdata.59818

We present a measurement of two-particle angular correlations in proton-proton collisions at sqrt(s) = 900 GeV and 7 TeV. The collision events were collected during 2009 and 2010 with the ATLAS detector at the Large Hadron Collider using a single-arm minimum bias trigger. Correlations are measured for charged particles produced in the kinematic range of transverse momentum pT > 100 MeV and pseudorapidity |eta| < 2.5. A complex structure in pseudorapidity and azimuth is observed at both collision energies. Results are compared to Pythia 8 and Herwig++ as well as to the AMBT2B, DW and Perugia 2011 tunes of Pythia 6. The data are not satisfactorily described by any of these models.

5 data tables

Corrected two particle RCORR distribution as a function of Delta(ETARAP) obtained by integrating the foreground and background distributions over Delta(PHI) between 0 and PI.

Corrected two particle RCORR distribution as a function of Delta(ETARAP) obtained by integrating the foreground and background distributions over Delta(PHI) between 0 and PI/2.

Corrected two particle RCORR distribution as a function of Delta(ETARAP) obtained by integrating the foreground and background distributions over Delta(PHI) between PI/2 and PI.

More…

Forward-backward correlations and charged-particle azimuthal distributions in pp interactions using the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abdallah, Jalal ; et al.
JHEP 07 (2012) 019, 2012.
Inspire Record 1093734 DOI 10.17182/hepdata.68040

Using inelastic proton-proton interactions at sqrt(s) = 900 GeV and 7 TeV, recorded by the ATLAS detector at the LHC, measurements have been made of the correlations between forward and backward charged-particle multiplicities and, for the first time, between forward and backward charged-particle summed transverse momentum. In addition, jet-like structure in the events is studied by means of azimuthal distributions of charged particles relative to the charged particle with highest transverse momentum in a selected kinematic region of the event. The results are compared with predictions from tunes of the PYTHIA and HERWIG++ Monte Carlo generators, which in most cases are found to provide a reasonable description of the data.

27 data tables

$\sqrt{s} = 900$ GeV, $p_T > 500 $ MeV, $|\eta|<1$.

$\sqrt{s} = 7$ TeV, $p_T > 500 $ MeV, $|\eta|<1$.

$\sqrt{s} = 900$ GeV, $p_T > 500 $ MeV, $|\eta|<2$.

More…