Measurements

To be useful in our approach, measurements must be made in as model-independent a fashion as possible. Cross sections should be measured in a kinematic region closely matching the detector acceptance — commonly called ’fiducial cross sections’ — to avoid extrapolation into unmeasured regions, since such extrapolations must always make theoretical assumptions; usually that the SM is valid. The measurements should generally be made in terms of observable final state particles (e.g. leptons, photons) or objects constructed from such particles (e.g. hadronic jets, missing energy) rather than assumed intermediate states (\(W, Z, H\), top). Finally, differential measurements are most useful, as features in the shapes of distributions are a more sensitive test than simple event rates — especially when there are highly-correlated systematic experimental uncertainties, such as those on the integrated luminosity, or the jet energy scale.

The measurements we consider fall into five loose and independent classes.

  1. Jets: event topologies with any number of jets but no missing energy, leptons, or photons. In this category there are important measurements from both ATLAS and CMS, many of which have existing analyses. We make use of the highest integrated-luminosity inclusive [35][137], dijet [27][32] and three-jet [36] measurements made in 7 TeV collisions, as well as the jet mass measurement from CMS [136]. Unfortunately results from 8 TeV collisions are rarer, and the only one we can use currently is the four-jet measurement from ATLAS [34].

  2. Electroweak: events with leptons, with or without missing energy or photons. The high-statistics \(W+\)jet and \(Z+\)jet measurements from ATLAS [37][22] and CMS [205],:cite:Khachatryan:2014zya, are used. We also use the ATLAS \(ZZ\) and \(W/Z+\gamma\) analyses [20][23], the former of which includes \(E_T^{\rm miss}\), via the \(Z \rightarrow \nu\bar{\nu}\) measurement.

  3. Missing energy, possibly with jets but no leptons or photons. This channel could in principle provide powerful constraints, and has been used in searches (see for example [25]). Unfortunately however, there are currently no fully-corrected particle-level distributions available in this category.

  4. Isolated photons, with or without missing energy, but no leptons. Here we make use of the inclusive [29], diphoton [21] and photon-plus-jet [16] measurements, where available. We also made a new routine for the CMS photon-plus jet measurement [138].

  5. Signatures specifically based on top quark or Higgs candidates. Many early measurements of top and/or Higgs have been made at the ’parton’ level (that is, corrected using SM MC back to the top or Higgs before decay), and many of them are extrapolated to \(4\pi\) phase space. Both steps increase the model dependence and make them unsuitable for the approach. Recently, however, fiducial, differential, particle-level measurements have begun appearing (see for example [40] and [210]). These are very powerful in excluding some models, though care has to be taken with the overlap with the previous categories, depending on the decay mode. We make use of them where they are available.

The choice of which measurements are actually included at this stage is driven mainly by the availability of particle-level differential fiducial cross sections implemented in Rivet.

Datasets

These are not up-to-date at present. Should be extracted automatically from the DB.

Original Dataset (2016a)

Contur Category

Inspire ID

Description

ATLAS 7 Jets

ATLAS_2014_I1325553 [35]

Measurement of the inclusive jet cross-section

ATLAS_2014_I1268975 [27]

High-mass dijet cross section

ATLAS_2014_I1326641 [36]

3-jet cross section

ATLAS_2014_I1307243 [32]

Measurements of jet vetoes and azimuthal decorrelations in dijet events

CMS 7 Jets

CMS_2014_I1298810 [137]

Ratios of jet pT spectra, which relate to the ratios of inclusive,differential jet cross sections

ATLAS 8 Jets

ATLAS_2015_I1394679 [34]

Multijets at 8 TeV

ATLAS 7 \(Z\) Jets

ATLAS_2013_I1230812 [37]

\(Z\) + jets

CMS 7 \(Z\) Jets

CMS_2015_I1310737 [206]

Jet multiplicity and differential cross- sections of \(Z\)+jets events

CMS 7 \(W\) Jets

CMS_2014_I1303894 [205]

Differential cross-section of \(W\) bosons + jets

ATLAS 7 \(W\) jets

ATLAS_2014_I1319490 [22]

\(W\) + jets

ATLAS 7 Photon Jet

ATLAS_2013_I1263495 [29]

Inclusive isolated prompt photon analysis with 2011 LHC data

ATLAS_2012_I1093738 [16]

Isolated prompt photon + jet cross-section

CMS 7 Photon Jet

CMS_2014_I1266056 [138]

Photon + jets triple differential cross-section

ATLAS 7 Diphoton

ATLAS_2012_I1199269 [21]

Inclusive diphoton \(+ X\) events

ATLAS 7 \(ZZ\)

ATLAS_2012_I1203852 [20]

Measurement of the \(ZZ(*)\) production cross-section

ATLAS \(W\)/ \(Z\) gamma

ATLAS_2013_I1217863 [23]

\(W\)/\(Z\) gamma production

Dataset 2016b

Contur Category

Inspire ID

Description

ATLAS 8 \(Z\) Jets

http://rivet.hepforge.org/analyses#ATLAS_2014_I1279489

\(Z\) + dijets (Vector boson fusion motivated)

ATLAS 8 Photons

http://rivet.hepforge.org/analyses#ATLAS_2016_I1457605

Inclusive photons

ATLAS 8 \(Z\) Jets

http://rivet.hepforge.org/analyses#ATLAS_2015_I1408516

Drell Yan dileptons

many more than this used now…