Combining Triggers in HEP data analysis

Dijet events produced in LHC proton-proton collisions at a center-of-mass energy ffiffi ffi s p ¼ 8 TeV are studied with the ATLAS detector using the full 2012 data set, with an integrated luminosity of 20.3 fb −1 . Dijet masses up to about 4.5 TeV are probed. No resonancelike features are observed in the dijet mass spectrum. Limits on the cross section times acceptance are set at the 95% credibility level for various hypotheses of new phenomena in terms of mass or energy scale, as appropriate. This analysis excludes excited quarks with a mass below 4.06 TeV, color-octet scalars with a mass below 2.70 TeV, heavy W 0 bosons with a mass below 2.45 TeV, chiral W Ã bosons with a mass below 1.75 TeV, and quantum black holes with six extra space-time dimensions with threshold mass below 5.66 TeV.

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“…Each event is weighted according to the average effective integrated luminosity recorded by the given trigger combination [51].…”

Section: Jet and Event Selectionmentioning

confidence: 99%

Search for new phenomena in the dijet mass distribution usingppcollision data ats=8 TeVwith the ATLAS detector

et al. 2015

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“…To correctly normalise the data, events are assigned weights depending on the luminosity and the trigger decisions, according to the exclusion method described in Ref. [80]. …”

Section: Relative Forward-jet Calibration Using Dijet Eventsmentioning

confidence: 99%

Jet energy measurement and its systematic uncertainty in proton–proton collisions at $$\sqrt{s}=7$$ s = 7 TeV with the ATLAS detector

Aad¹,

Abajyan²,

Abbott³

et al. 2015

Eur. Phys. J. C

263

212

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The jet energy scale (JES) and its systematic uncertainty are determined for jets measured with the ATLAS detector using proton–proton collision data with a centre-of-mass energy of TeV corresponding to an integrated luminosity of . Jets are reconstructed from energy deposits forming topological clusters of calorimeter cells using the anti- algorithm with distance parameters or , and are calibrated using MC simulations. A residual JES correction is applied to account for differences between data and MC simulations. This correction and its systematic uncertainty are estimated using a combination of in situ techniques exploiting the transverse momentum balance between a jet and a reference object such as a photon or a boson, for and pseudorapidities . The effect of multiple proton–proton interactions is corrected for, and an uncertainty is evaluated using in situ techniques. The smallest JES uncertainty of less than 1 % is found in the central calorimeter region () for jets with . For central jets at lower , the uncertainty is about 3 %. A consistent JES estimate is found using measurements of the calorimeter response of single hadrons in proton–proton collisions and test-beam data, which also provide the estimate for TeV. The calibration of forward jets is derived from dijet balance measurements. The resulting uncertainty reaches its largest value of 6 % for low- jets at . Additional JES uncertainties due to specific event topologies, such as close-by jets or selections of event samples with an enhanced content of jets originating from light quarks or gluons, are also discussed. The magnitude of these uncertainties depends on the event sample used in a given physics analysis, but typically amounts to 0.5–3 %.

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“…Several standard methods to combine data samples selected with independent trigger requirements are presented in detail by a paper inspired by work from the H1 collaboration at the HERA accelerator [2]: the inclusion, division, and exclusion methods. In this section we briefly review the key points of each method.…”

Section: Review Of Existing Trigger Combination Methodsmentioning

confidence: 99%

A novel in situ trigger combination method

Buzatu¹,

Warburton²,

Krumnack³

et al. 2013

Nuclear Instruments and Methods in Physics Research Section A:

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Searches for rare physics processes using particle detectors in high-luminosity colliding hadronic beam environments require the use of multi-level trigger systems to reject colossal background rates in real time. In analyses like the search for the Higgs boson, there is a need to maximize the signal acceptance by combining multiple different trigger chains when forming the offline data sample. In such statistically limited searches, datasets are often amassed over periods of several years, during which the trigger characteristics evolve and system performance can vary significantly. Reliable production cross-section measurements and upper limits must take into account a detailed understanding of the effective trigger inefficiency for every selected candidate event. We present as an example the complex situation of three trigger chains, based on missing energy and jet energy, that were combined in the context of the search for the Higgs (H) boson produced in association with a W boson at the Collider Detector at Fermilab (CDF). We briefly review the existing techniques for combining triggers, namely the inclusion, division, and exclusion methods. We introduce and describe a novel fourth in situ method whereby, for each candidate event, only the trigger chain with the highest a priori probability of selecting the event is considered. We compare the inclusion and novel in situ methods for signal event yields in the CDF W H search. This new combination method, by virtue of its scalability to large numbers of differing trigger chains and insensitivity to correlations between triggers, will benefit future long-running collider experiments, including those currently operating on the Large Hadron Collider.

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Combining Triggers in HEP data analysis

Cited by 19 publications

References 5 publications

Search for new phenomena in the dijet mass distribution usingppcollision data ats=8 TeVwith the ATLAS detector

Search for new phenomena in the dijet mass distribution usingppcollision data ats=8 TeVwith the ATLAS detector

Jet energy measurement and its systematic uncertainty in proton–proton collisions at $$\sqrt{s}=7$$ s = 7 TeV with the ATLAS detector

A novel in situ trigger combination method

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