Contur Plots: Constaints On New Theories Using Rivet

Combined CL exclusion for these plots is 100.0 %

In each analysis pool, these plots contributed:

Analysis Pool:ATLAS_8_JETS

ATLAS_2015_I1394679/ATLAS_2015_I1394679_d42-x01-y01 :

Analysis Pool:ATLAS_8_Wjj

ATLAS_2015_I1397637/ATLAS_2015_I1397637_d01-x01-y01 :

Analysis Pool:ATLAS_8_ZZ

ATLAS_2015_I1394865/ATLAS_2015_I1394865_d02-x01-y01 :

Analysis Pool:CMS_8_WW

CMS_2017_I1467451/CMS_2017_I1467451_d01-x01-y01 :

Analysis Pool:ATLAS_8_WW

ATLAS_2016_I1426515/ATLAS_2016_I1426515_d15-x01-y01 :

Analysis Pool:CMS_8_Wjj

CMS_2016_I1454211/CMS_2016_I1454211_d10-x01-y01 :

Analysis Pool:ATLAS_8_GAMMA

ATLAS_2014_I1306615/ATLAS_2014_I1306615_d01-x01-y01 :

Analysis Pool:ATLAS_8_Z_GAMMA

ATLAS_2016_I1448301_EL/ATLAS_2016_I1448301_EL_d03-x01-y03 :

Analysis Pool:ATLAS_8_GAMMA_MET

ATLAS_2016_I1448301_NU/ATLAS_2016_I1448301_NU_d08-x01-y01 :

Analysis Pool:ATLAS_8_Zjj

ATLAS_2014_I1279489/ATLAS_2014_I1279489_d05-x04-y01:

List of all the analyses which were tried:

BB to Jpsi plus mu at 8 TeV (ATLAS_2017_I1598613)

Inspire | HepData | arXiv:1705.03374 [hep-ex] | submitted to JHEP

A measurement of $b$-hadron pair production is presented, based on a dataset corresponding to an integrated luminosity of 11.4 fb${}^{-1}$ of proton--proton collisions recorded at $\sqrt{s}=8$ TeV with the ATLAS detector at the LHC. Events are selected in which both a $b$-hadron $\to J/\psi(\to\mu\mu)+X$ and $b$-hadron $\to \mu + X$ were identified, and results are presented in a fiducial volume defined by kinematic requirements on three muons based on those used in the analysis. The fiducial cross section is measured to be $17.7\pm 0.1$(stat.)$\pm2.0$(syst.) nb. A number of normalised differential cross sections are i also measured, and compared to predictions from the Pythia8, Herwig++, MadGraph5\_aMC@NLO+Pythia8 and Sherpa event generators, providing constraints on heavy flavour production.

Inclusive diphoton cross-sections at 8 TeV (ATLAS_2017_I1591327)

Inspire | HepData | arXiv:1704.03839 [hep-ex] | submitted to PRD

A measurement of the production cross section for two isolated photons in proton--proton collisions at a center-of-mass energy of $\sqrt{s}=8$ TeV is presented. The results are based on an integrated luminosity of 20.2 fb$^{-1}$ recorded by the ATLAS detector at the Large Hadron Collider. The measurement considers photons with pseudorapidities satisfying $|\eta^\gamma| < 1.37$ or $1.56 < |\eta^\gamma| < 2.37$ and transverse energies of respectively $E^\gamma_\text{T,1}>40$ GeV and $E^\gamma_\text{T,2}> 30$ GeV for the two leading photons ordered in transverse energy produced in the interaction. The background due to hadronic jets and electrons is subtracted using data-driven techniques. The fiducial cross sections are corrected for detector effects and measured differentially as a function of six kinematic observables. The measured cross section integrated within the fiducial volume is $16.8\pm0.8$ pb. The data are compared to fixed-order QCD calculations at next-to-leading-order and next-to-next-to-leading-order accuracy as well as next-to-leading-order computations including resummation of initial-state gluon radiation at next-to-next-to-leading logarithm or matched to a parton shower, with relative uncertainties varying from 5% to 20%.

$k_T$ splittings in $Z$ events at 8 TeV (ATLAS_2017_I1589844)

Inspire | HepData | arXiv:1704.01530 [hep-ex] | submitted to JHEP

A measurement of the splitting scales occuring in the $k_\text{t}$ jet-clustering algorithm is presented for final states containing a $Z$ boson. The measurement is done using 20.2 fb$^{-1}$ of proton-proton collision data collected at a centre-of-mass energy of $\sqrt{s} = 8$ TeV by the ATLAS experiment at the LHC in 2012. The measurement is based on charged-particle track information, which is measured with excellent precision in the $p_\text{T}$ region relevant for the transition between the perturbative and the non-perturbative regimes. The data distributions are corrected for detector effects, and are found to deviate from state-of-the-art predictions in various regions of the observables.

High-mass Drell-Yan at 8 TeV, electron channel (ATLAS_2016_I1467454_EL)

Inspire | HepData | JHEP 1608 (2016) 009 | doi:10.1007/JHEP08(2016)009 | arXiv:1606.01736 [hep-ex]

This paper presents a measurement of the double-differential cross section for the Drell-Yan $Z/\gamma^\ast \rightarrow \ell^+\ell^-$ and photon-induced $\gamma\gamma \rightarrow \ell^+\ell^-$ processes where $\ell$ is an electron or muon. The measurement is performed for invariant masses of the lepton pairs, $m_{\ell\ell}$, between 116 GeV and 1500 GeV using a sample of 20.3 fb$^{-1}$ of pp collisions data at centre-of-mass energy of $\sqrt{s} = 8$ TeV collected by the ATLAS detector at the LHC in 2012. The data are presented double differentially in invariant mass and absolute dilepton rapidity as well as in invariant mass and absolute pseudorapidity separation of the lepton pair. The single-differential cross section as a function of $m_{\ell\ell}$ is also reported. The electron and muon channel measurements are combined and a total experimental precision of better than 1\% is achieved at low $m_{\ell\ell}$. A comparison to next-to-next-to-leading order perturbative QCD predictions using several recent parton distribution functions and including next-to-leading order electroweak effects indicates the potential of the data to constrain parton distribution functions. In particular, a large impact of the data on the photon PDF is demonstrated.

High-mass Drell-Yan at 8 TeV, muon channel (ATLAS_2016_I1467454_MU)

Inspire | HepData | JHEP 1608 (2016) 009 | doi:10.1007/JHEP08(2016)009 | arXiv:1606.01736 [hep-ex]

This paper presents a measurement of the double-differential cross section for the Drell-Yan $Z/\gamma^\ast \rightarrow \ell^+\ell^-$ and photon-induced $\gamma\gamma \rightarrow \ell^+\ell^-$ processes where $\ell$ is an electron or muon. The measurement is performed for invariant masses of the lepton pairs, $m_{\ell\ell}$, between 116 GeV and 1500 GeV using a sample of 20.3 fb$^{-1}$ of pp collisions data at centre-of-mass energy of $\sqrt{s} = 8$ TeV collected by the ATLAS detector at the LHC in 2012. The data are presented double differentially in invariant mass and absolute dilepton rapidity as well as in invariant mass and absolute pseudorapidity separation of the lepton pair. The single-differential cross section as a function of $m_{\ell\ell}$ is also reported. The electron and muon channel measurements are combined and a total experimental precision of better than 1\% is achieved at low $m_{\ell\ell}$. A comparison to next-to-next-to-leading order perturbative QCD predictions using several recent parton distribution functions and including next-to-leading order electroweak effects indicates the potential of the data to constrain parton distribution functions. In particular, a large impact of the data on the photon PDF is demonstrated.

Inclusive prompt photons at 8 TeV (ATLAS_2016_I1457605)

Inspire | HepData | arXiv:1605.03495 [hep-ex]

A measurement of the cross section for the inclusive production of isolated prompt photons in proton-proton collisions at a centre-of-mass energy of $\sqrt{s} = 8$ TeV is presented. The measurement covers the pseudorapidity ranges $|\eta^\gamma| < 1.37$ $1.56 < |\eta^\gamma| < 2.37$ in the transverse energy range $25 < E^\gamma_\text{T} < 1500$ GeV. The results are based on an integrated luminosity of 20.2 fb${}^{-1}$, recorded by the ATLAS detector at the LHC. Photon candidates are identified by combining information from the calorimeters and the inner tracker. The background is subtracted using a data-driven technique, based on the observed calorimeter shower-shape variables and the deposition of hadronic energy in a narrow cone around the photon candidate.

Zg(g) cross sections at 8 TeV (ATLAS_2016_I1448301_NU)

Inspire | HepData | Phys.Rev. D93 (2016) no.11, 112002 | doi:10.1103/PhysRevD.93.112002 | arXiv:1604.05232 [hep-ex]

The production of $Z$ bosons with one or two isolated high-energy photons is studied using pp collisions at $\sqrt{s}=8$ TeV. The analyses use a data sample with an integrated luminosity of 20.3 fb${}^{-1}$ collected by the ATLAS detector during the 2012 LHC data taking. The $Z\gamma$ and $Z\gamma\gamma$ production cross sections are measured with leptonic ($e^+e^-$, $\mu^+\mu^-$, $\nu\bar{\nu}$) decays of the Z boson, in extended fiducial regions defined in terms of the lepton and photon acceptance. They are then compared to cross-section predictions from the Standard Model, where the sources of the photons are radiation off initial-state quarks and radiative Z-boson decay to charged leptons, and from fragmentation of final-state quarks and gluons into photons. The yields of events with photon transverse energy $E_\text{T}>250$ GeV from $\ell^+\ell^-\gamma$ events and with $E_\text{T}>400$ GeV from $\nu\bar{\nu}\gamma$ events are used to search for anomalous triple gauge-boson couplings $ZZ\gamma$ and $Z\gamma\gamma$. The yields of events with diphoton invariant mass $m_{\gamma\gamma}>200$ GeV from $\ell^+\ell^-\gamma\gamma$ events and with $m_{\gamma\gamma}>300$ GeV from $\nu\bar{\nu}\gamma\gamma$ events are used to search for anomalous quartic gauge-boson couplings $ZZ\gamma\gamma$ and $Z\gamma\gamma\gamma$. No deviations from Standard Model predictions are observed and limits are placed on parameters used to describe anomalous triple and quartic gauge-boson couplings. The lepton channel can be specified by using the relevant plugins (_EL, _MU, _NU). The default plugin uses the electron channel.

Zg(g) cross sections at 8 TeV (ATLAS_2016_I1448301_EL)

Inspire | HepData | Phys.Rev. D93 (2016) no.11, 112002 | doi:10.1103/PhysRevD.93.112002 | arXiv:1604.05232 [hep-ex]

The production of $Z$ bosons with one or two isolated high-energy photons is studied using pp collisions at $\sqrt{s}=8$ TeV. The analyses use a data sample with an integrated luminosity of 20.3 fb${}^{-1}$ collected by the ATLAS detector during the 2012 LHC data taking. The $Z\gamma$ and $Z\gamma\gamma$ production cross sections are measured with leptonic ($e^+e^-$, $\mu^+\mu^-$, $\nu\bar{\nu}$) decays of the Z boson, in extended fiducial regions defined in terms of the lepton and photon acceptance. They are then compared to cross-section predictions from the Standard Model, where the sources of the photons are radiation off initial-state quarks and radiative Z-boson decay to charged leptons, and from fragmentation of final-state quarks and gluons into photons. The yields of events with photon transverse energy $E_\text{T}>250$ GeV from $\ell^+\ell^-\gamma$ events and with $E_\text{T}>400$ GeV from $\nu\bar{\nu}\gamma$ events are used to search for anomalous triple gauge-boson couplings $ZZ\gamma$ and $Z\gamma\gamma$. The yields of events with diphoton invariant mass $m_{\gamma\gamma}>200$ GeV from $\ell^+\ell^-\gamma\gamma$ events and with $m_{\gamma\gamma}>300$ GeV from $\nu\bar{\nu}\gamma\gamma$ events are used to search for anomalous quartic gauge-boson couplings $ZZ\gamma\gamma$ and $Z\gamma\gamma\gamma$. No deviations from Standard Model predictions are observed and limits are placed on parameters used to describe anomalous triple and quartic gauge-boson couplings. The lepton channel can be specified by using the relevant plugins (_EL, _MU, _NU). The default plugin uses the electron channel.

Zg(g) cross sections at 8 TeV (ATLAS_2016_I1448301_MU)

Inspire | HepData | Phys.Rev. D93 (2016) no.11, 112002 | doi:10.1103/PhysRevD.93.112002 | arXiv:1604.05232 [hep-ex]

The production of $Z$ bosons with one or two isolated high-energy photons is studied using pp collisions at $\sqrt{s}=8$ TeV. The analyses use a data sample with an integrated luminosity of 20.3 fb${}^{-1}$ collected by the ATLAS detector during the 2012 LHC data taking. The $Z\gamma$ and $Z\gamma\gamma$ production cross sections are measured with leptonic ($e^+e^-$, $\mu^+\mu^-$, $\nu\bar{\nu}$) decays of the Z boson, in extended fiducial regions defined in terms of the lepton and photon acceptance. They are then compared to cross-section predictions from the Standard Model, where the sources of the photons are radiation off initial-state quarks and radiative Z-boson decay to charged leptons, and from fragmentation of final-state quarks and gluons into photons. The yields of events with photon transverse energy $E_\text{T}>250$ GeV from $\ell^+\ell^-\gamma$ events and with $E_\text{T}>400$ GeV from $\nu\bar{\nu}\gamma$ events are used to search for anomalous triple gauge-boson couplings $ZZ\gamma$ and $Z\gamma\gamma$. The yields of events with diphoton invariant mass $m_{\gamma\gamma}>200$ GeV from $\ell^+\ell^-\gamma\gamma$ events and with $m_{\gamma\gamma}>300$ GeV from $\nu\bar{\nu}\gamma\gamma$ events are used to search for anomalous quartic gauge-boson couplings $ZZ\gamma\gamma$ and $Z\gamma\gamma\gamma$. No deviations from Standard Model predictions are observed and limits are placed on parameters used to describe anomalous triple and quartic gauge-boson couplings. The lepton channel can be specified by using the relevant plugins (_EL, _MU, _NU). The default plugin uses the electron channel.

WW production at 8 TeV (ATLAS_2016_I1426515)

Inspire | HepData | JHEP 1609 (2016) 029 | doi:10.1007/JHEP09(2016)029 | arXiv:1603.01702 [hep-ex]

The production of $W$ boson pairs in proton-proton collisions at $\sqrt{s} = 8$ TeV is studied using data corresponding to 20.3 fb${}^{-1}$ of integrated luminosity collected by the ATLAS detector during 2012 at the CERN Large Hadron Collider. The $W$ bosons are reconstructed using their leptonic decays into electrons or muons and neutrinos. Events with reconstructed jets are not included in the candidate event sample. A total of 6636 $WW$ candidate events are observed. Measurements are performed in fiducial regions closely approximating the detector acceptance. The integrated measurement is corrected for all acceptance effects and for the $W$ branching fractions to leptons in order to obtain the total $WW$ production cross section, which is found to be $71.1 \pm 1.1$ (stat) ${}^{+5.7}_{-5.0}$ (syst) $\pm 1.4$ (lumi) pb. This agrees with the next-to-next-to-leading-order Standard Model prediction of $63.2 {}^{+1.6}_{-1.4}$ (scale) $\pm 1.2$ (PDF) pb. Fiducial differential cross sections are measured as a function of each of six kinematic variables. The distribution of the transverse momentum of the leading lepton is used to set limits on anomalous triple-gauge-boson couplings.

$Z$ $p_T$ and $Z$ $\phi^*$ in electron channel (ATLAS_2015_I1408516_EL)

Inspire | HepData | arXiv:1512.02192 [hep-ex] | submitted to EPJC

Distributions of transverse momentum $p_\text{T}^{\ell\ell}$ and the angular variable $\phi^\ast_\eta$ of Drell-Yan lepton pairs are measured in $20.3\,\text{fb}^{-1}$ of proton-proton collisions at $\sqrt{s}=8$\,TeV with the ATLAS detector at the LHC. Measurements in electron-pair and muon-pair final states are corrected for detector effects. Compared to previous measurements in proto--proton collisions at i$\sqrt{s}=7$\,TeV, these new measurements benefit from a larger data sample and improved control of systematic uncertainties. Measurements are performed in bins of lepton-pair mass above, around and below the $Z$-boson mass peak. Specify the lepton channel (default is Z->ee) by using the dedicated plugins ATLAS_2015_I1408516_EL and ATLAS_2015_I1408516_MU.

$Z$ $p_T$ and $Z$ $\phi^*$ in muon channel (ATLAS_2015_I1408516_MU)

Inspire | HepData | arXiv:1512.02192 [hep-ex] | submitted to EPJC

Distributions of transverse momentum $p_\text{T}^{\ell\ell}$ and the angular variable $\phi^\ast_\eta$ of Drell-Yan lepton pairs are measured in $20.3\,\text{fb}^{-1}$ of proton-proton collisions at $\sqrt{s}=8$\,TeV with the ATLAS detector at the LHC. Measurements in electron-pair and muon-pair final states are corrected for detector effects. Compared to previous measurements in proto--proton collisions at i$\sqrt{s}=7$\,TeV, these new measurements benefit from a larger data sample and improved control of systematic uncertainties. Measurements are performed in bins of lepton-pair mass above, around and below the $Z$-boson mass peak. Specify the lepton channel (default is Z->ee) by using the dedicated plugins ATLAS_2015_I1408516_EL and ATLAS_2015_I1408516_MU.

Boosted ttbar differential cross-section (ATLAS_2015_I1397637)

Inspire | HepData | Phys.Rev. D93 (2016) no.3, 032009 | doi:10.1103/PhysRevD.93.032009 | arXiv:1510.03818 [hep-ex]

The differential cross-section for pair production of top quarks with high transverse momentum is measured in 20.3fb${}^{-1}$ of proton-proton collisions at a center-of-mass energy of 8 TeV. The measurement is performed for $t\bar{t}$ events in the lepton+jets channel. The cross-section is reported as a function of the hadronically decaying top quark transverse momentum for values above 300 GeV. The hadronically decaying top quark is reconstructed as an anti-$k_\text{t}$ jet with radius parameter $R=1.0$ and identified with jet substructure techniques. The observed yield is corrected for detector effects to obtain a cross-section at particle level in a fiducial region close to the event selection.

Inclusive 4-lepton lineshape (ATLAS_2015_I1394865)

Inspire | HepData | Phys.Lett. B753 (2016) 552-572 | doi:10.1016/j.physletb.2015.12.048 | arXiv:1509.07844 [hep-ex]

The four-lepton (4$\ell$, $\ell = e,\mu$) production cross section is measured in the mass range from 80 to 1000 GeV using 20.3 fb$^{-1}$ of data in $pp$ collisions at $\sqrt{s}=8$ TeV collected with the ATLAS detector at the LHC. The $4\ell$ events are produced in the decays of resonant $Z$ and Higgs bosons and the non-resonant $ZZ$ continuum originating from $q\bar{q}$, $gg$, $qg$ initial states. A total of 476 signal candidate events are observed with a background expectation of 26.2$\pm$3.6 events, enabling the measurement of the integrated cross section and the differential cross section as a function of the invariant mass and transverse momentum of the four-lepton system.

Multijets at 8 TeV (ATLAS_2015_I1394679)

Inspire | HepData | arXiv:1509.07335 [hep-ex]

Differential cross sections for the production of at least four jets have been measured in proton-proton collisions at $\sqrt{s}=8$\,TeV at the Large Hadron Collider using the ATLAS detector. The dataset corresponds to an integrated luminosity of 20.3\,fb^{−1}. The cross sections are corrected for detector effects and presented as a function of the jet momenta, invariant masses, minimum and maximum opening angles and other kinematic variables.

Higgs diphoton events at 8 TeV in ATLAS (ATLAS_2014_I1306615)

Inspire | HepData | arXiv:1407.4222 | JHEP 09 (2014) 112

Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of 8TeV. The analysis is performed in the Higgs diphoton decay channel using 20.3/fb of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal yields are corrected for the effects of detector inefficiency and resolution. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations.

Measurements of electroweak production of dijets + $Z$ boson, and distributions sensitive to vector boson fusion (ATLAS_2014_I1279489)

Inspire | HepData | JHEP 1404 (2014) 031 | arXiv:1401.7610 [hep-ex]

Measurements differential distributions for inclusive $Z$-boson-plus-dijet production are performed in five fiducial regions, each with different sensitivity to the electroweak contribution. Measured distributions include the differential cross section as a function of the dijet invariant mass, the differential cross section and a function of the dijet rapidity separation, the differential cross section as a function of the number of jets in the rapidity interval bounded by the two leading jets. Other measurements include the jet veto effiency as a function of the dijet invariant mass and rapdity separation, the normalized transverse momentum balance cut efficiency, and the average number of jets falling into the rapidity interval boundd by the two leading jets, as a function of dijet invariant mass and dijet rapidity separation.

Differential $t\bar{t}$ production cross-section as a function of the leading jet mass for boosted top quarks at 8 TeV (CMS_2017_I1518399)

Inspire | HepData | TOP-15-015 | arXiv:1703.06330 | Submitted to Eur. Phys. J. C.

Measurement of the differential and normalised differential $t\bar{t}$ production cross section as a function of the leading jet mass. The measurement was performed in the lepton+jets channel and the fiducial measurement phase space is enriched with events where the leading jet includes all decay products of a hadronically decaying top quark. This analysis is to be run on ${t\bar{t}}$ simulation. The objects are defined as follows - Lepton: electron or muon originating from the decay of a W boson - Jets: jets are clustered from final state particles using the Cambridge-Aachen algorithm with a distance parameter of 1.2. If a lepton overlaps with a jet (distance in the eta-phi plane smaller 1.2) its four momentum is subtracted from the four momentum of the jet. Definition of the particle level phase space: - only ${\rm t\bar{t}}$ decays with one top quark decaying hadronically and one top quark decaying leptonically including an electron or muon from the W decay. - lepton $\pt > 45\;\text{GeV}$ and $|\eta| < 2.1$ - at least one jet with $\pt > 400\;\text{GeV}$ and $|\eta| < 2.5$ - a second jet with $\pt > 150\;\text{GeV}$ and $|\eta| < 2.5$ - veto on additional jets with $\pt > 150\;\text{GeV}$ and $|\eta| < 2.5$ - distance between the second jet and the lepton in the eta-phi plane $\Delta R(jet2, lepton)$ smaller 1.2 - invariant mass of the leading jet larger than the invariant mass of the combination of the second jet and lepton The differential and normalised differential cross section was measured as a function of the leading jet mass.

Measurement of the transverse momentum spectrum of the Higgs boson produced in $pp$collisions at $\sqrt{s} = 8$ TeV using H to WW decays (CMS_2017_I1467451)

Inspire | HepData | JHEP 1703 (2017) 032, 2017 | DOI:10.1007/JHEP03(2017)032 | arXiv:1606.01522 | CMS-HIG-15-010

The cross section for Higgs boson production in pp collisions is studied using the $H\rightarrow W^+ W^-$ decay mode, followed by leptonic decays of the W bosons to an oppositely charged electron-muon pair in the final state. The measurements are performed using data collected by the CMS experiment at the LHC at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of $19.4\,\text{fb}^{-1}$. The Higgs boson transverse momentum ($p_\text{T}$) is reconstructed using the lepton pair $p_\text{T}$ and missing $p_\text{T}$. The differential cross section times branching fraction is measured as a function of the Higgs boson $p_\text{T}$ in a fiducial phase space defined to match the experimental acceptance in terms of the lepton kinematics and event topology. The production cross section times branching fraction in the fiducial phase space is measured to be $39 \pm 8\,\text{(stat)} \pm 9\,\text{(syst)}\,\text{fb}$. The measurements are found to agree, within experimental uncertainties, with theoretical calculations based on the standard model. The fiducial region is defined at particle level (using Born level leptons) as: - emununu, leptons are required not to originate from leptonic tau decays - leading lepton $p_T > 20$ GeV - subleading lepton $p_T > 10$ GeV - psudorapidity of electrons and muons $|\eta| < 2.5$ - Invariant mass of the two charged leptons $m_{ll} > 12$ GeV - Charged lepton pair $p_T > 30$ GeV - Invariant mass of the leptonic system in the transverse plane $m_T^{e\mu\nu\nu} > 50$ GeV

Boosted $t\bar{t}$ in $pp$ collisions at $\sqrt{s} = 8 \text{TeV}$ (CMS_2016_I1454211)

Inspire | HepData | CMS-PAS-TOP-14-012 (PAS) | CERN-EP-2016-078 (paper)

The cross section for pair production of top quarks with high transverse momenta ($p_{\rm T} > 400$ GeV) is measured in 19.7 fb$^{-1}$ of $\mathrm{pp}$ collisions, collected with the CMS detector at $\sqrt{s} = 8$ TeV. The measurement is performed for lepton+jets events, where one top quark decays according to $t \rightarrow Wb \rightarrow \ell \nu b$, with $\ell$ denoting an electron or muon, and the second top quark decays to an hadronic final state and is reconstructed as a single, large-radius jet and identified as a top quark candidate using jet substructure techniques. Integrated cross sections, as well as differential cross sections as a function of the top quark $p_{\rm T}$ and rapidity, are measured both at particle level within a fiducial region resembling the detector-level selections and at parton level. RIVET: This analysis is to be run on ${\rm t\bar{t}}$ Monte Carlo. It utilizes the PartonicTops projection, which assumes top quarks in the event record. The analysis has been validated with Powheg+Pythia6. The parton-level phase space is defined by requiring two PartonicTops. Exactly one PartonicTop must decay directly to a muon or electron (no intermediate tau), and exactly one PartonicTop decays hadronically. For for $t\bar{t}$ Monte Carlo, this is equivalent to requiring the event to be semileptonic at parton level. The parton-level top quark is defined as the hadronically decaying top. The parton-level top quark is required to have $p_{T} > 400$ GeV. The particle-level phase space is defined using the following object definitions: - Lepton: A dressed electron or muon, meaning the lepton has been clustered with all photons within a cone of $R=0.1$. The DressedLepton projection is used to construct the dressed lepton. The lepton is required to have $p_{T} > 45$ GeV and $|\eta| < 2.1$. - B Jet Candidate: Gen AK5 jets are formed by clustering the final state particles in the event using the anti-$k_{T}$ algorithm with distance parameter $R=0.5$. Neutrinos are excluded from the clustering, as are any particles included in the dressed lepton. The gen AK5 jet is required to have $p_{T} > 30$ GeV and $|\eta| < 2.4$. Gen AK5 jets in the same hemisphere as the lepton ($\Delta {\rm R(e/\mu, jet)} < \pi/2$) are defined as b-jet candidates. - Top Jet Candidate: Gen CA8 jets are formed by clustering the final state particles in the event using the Cambridge-Aachen algorithm with distance parameter $R=0.8$. Neutrinos are excluded from the clustering, as are any particles included in the dressed lepton. The gen CA8 jet is required to have $p_{T} > 30$ GeV and $|\eta| < 2.4$. Gen CA8 jets which have $p_{T} > 400$ GeV, 140 GeV $<$ mass $<$ 250 GeV, and are in the opposite hemisphere from the lepton ($\Delta{\rm R(e/\mu, jet)} > \pi/2$) are defined as top jet candidates. The particle-level phase space is defined by requiring $\geq 1$ b jet candidate, $\geq 1$ top jet candidate, and exactly one lepton. This is in addition to the parton-level semileptonic requirement. The highest-$p_{T}$ top jet candidate is defined as the particle-level t jet.


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