Simulation of $e^+e^-\rightarrow\mbox{Hadrons}$ and Comparison to ALEPH Data at Full Detector Simulation with an Emphasis on Four-Jet States

Kile, J.; Wimmersperg-Toeller, Julian von

doi:10.48550/arxiv.1706.02269

Cited by 5 publications

(24 citation statements)

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“…Our data and MC samples are the same as those described in detail in our previous works [17,18]. A detailed description of the ALEPH detector and its performance can be found in Refs.…”

Section: Data and Monte Carlo Samplesmentioning

confidence: 99%

“…The data and MC luminosities are given in Ref. [18] and reproduced here in Table I. We briefly describe the data and MC samples here.…”

Section: Data and Monte Carlo Samplesmentioning

confidence: 99%

“…As in Ref. [18], we use the entire LEP2 dataset from the ALEPH detector, which is approximately composed of 735pb −1 at 18 center-of-mass energies in the range √ s = 130 − 208 GeV; luminosities for these energies are displayed in Table I. As described in Ref.…”

Section: A Data Samplesmentioning

confidence: 99%

“…We adopted the LO SHERPA MC sample, reweighted using LEP1 data, as described in Ref. [18], as this appeared to provide the most reliable simulation. We decided to use the LUCLUS [19] jet-clustering algorithm following the conclusions of Ref.…”

Section: Introductionmentioning

confidence: 99%

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Localized 4σ and 5σ dijet mass excesses in ALEPH LEP2 four-jet events

Kile

Wimmersperg-Toeller

2018

J. High Energ. Phys.

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We investigate an excess observed in hadronic events in the archived LEP2 ALEPH data. This excess was observed at preselection level during data-MC comparisons of four-jet events when no search was being performed. The events are clustered into four jets and paired such that the mass difference between the two dijet systems is minimized. The excess occurs in the region M 1 + M 2 ∼ 110 GeV; about half of the excess is concentrated in the region M 1 ∼ 80 GeV, M 2 ∼ 25 GeV, with a local significance between 4.7σ and 5.5σ, depending on assumptions about hadronization uncertainties. The other half of the events are in a broad excess near M 1 ∼ M 2 ∼ 55 GeV; these display a local significance of 4.1 − 4.5σ. We investigate the effects of changing the SM QCD Monte Carlo sample, the jet-clustering algorithm, and the jet rescaling method. We find that the excess is remarkably robust under these changes, and we find no source of systematic uncertainty that can explain the excess. No analogue of the excess is seen at LEP1. than either of the masses measured separately; such a plot also displays a nice separation of QCD and W + W − events, useful for data-MC comparisons.Unlike what was typical during the LEP era, we plotted M 1 + M 2 using the entire ALEPH LEP2 data sample (∼ 735pb −1 ) simultaneously; with our very loose cuts, this amounts to O(17, 000) events. In doing so, we noticed an excess of about 200 events (∼ 3σ) in the dijet mass sum in the region M 1 + M 2 ∼ 110 GeV. Interestingly, this is the same region in which ALEPH observed an excess in the search for hA final states [2] with a much smaller dataset (5.7pb −1 ) and after analysis cuts; the excess was later dismissed as a statistical fluctuation [3] 3 . This excess brought with it a set of unusual challenges. The first of these is that we had no model on which to base selection cuts for an analysis. Second, as this excess was found during data-MC comparisons at preselection level when no search was being conducted, we had to develop the machinery of the analysis after knowing of the excess; the analysis is unavoidably unblind.Were the experiment still running, a simple solution to these challenges would be to explore the features of the excess region, design a set of cuts which efficiently selects the excess, and then see if such cuts also yield an excess in future data. Unfortunately, this is not possible in our case. However, there are three additional LEP data sets which could potentially be used to confirm or refute our findings. With this in mind, we follow the philosophy of Ref.[2] and set about cataloging the features in the excess region to develop analyses which can be used by the three other LEP experiments. In this paper, we will concentrate on establishing the location of the excess, its significance, and its dependence upon MC samples, jet-clustering algorithm, etc. We will reserve further details, including distributions of many observables in the excess region, for future work.At the time that we initially noticed the excess near M 1 + M 2 ∼ 110 G...

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“…Our data and MC samples are the same as those described in detail in our previous works [17,18]. A detailed description of the ALEPH detector and its performance can be found in Refs.…”

Section: Data and Monte Carlo Samplesmentioning

confidence: 99%

“…The data and MC luminosities are given in Ref. [18] and reproduced here in Table I. We briefly describe the data and MC samples here.…”

Section: Data and Monte Carlo Samplesmentioning

confidence: 99%

Section: A Data Samplesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Localized 4σ and 5σ dijet mass excesses in ALEPH LEP2 four-jet events

Kile

Wimmersperg-Toeller

2018

J. High Energ. Phys.

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“…[52] to search for new physics and by Refs. [53][54][55] to perform QCD studies. While analyses using public collider data cannot match the sophistication or scope of official measurements by the experimental collaborations, they can enable proof-of-concept collider investigations and help stress-test archival data strategies.…”

Section: Introductionmentioning

confidence: 99%

Exploring the space of jets with CMS open data

et al. 2020

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We explore the metric space of jets using public collider data from the CMS experiment. Starting from 2.3 fb −1 of proton-proton collisions at √ s = 7 TeV collected at the Large Hadron Collider in 2011, we isolate a sample of 1,690,984 central jets with transverse momentum above 375 GeV. To validate the performance of the CMS detector in reconstructing the energy flow of jets, we compare the CMS Open Data to corresponding simulated data samples for a variety of jet kinematic and substructure observables. Even without detector unfolding, we find very good agreement for trackbased observables after using charged hadron subtraction to mitigate the impact of pileup. We perform a range of novel analyses, using the "energy mover's distance" (EMD) to measure the pairwise difference between jet energy flows. The EMD allows us to quantify the impact of detector effects, visualize the metric space of jets, extract correlation dimensions, and identify the most and least typical jet configurations. To facilitate future jet studies with CMS Open Data, we make our datasets and analysis code available, amounting to around two gigabytes of distilled data and one hundred gigabytes of simulation files. CONTENTS

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Searching in CMS open data for dimuon resonances with substantial transverse momentum

et al. 2019

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We study dimuon events in 2.11 fb −1 of 7 TeV pp collisions, using CMS Open Data, and search for a narrow dimuon resonance with moderate mass (14-66 GeV) and substantial transverse momentum (pT ). Applying dimuon pT cuts of 25 GeV and 60 GeV, we explore two overlapping samples: one with isolated muons, and one with prompt muons without an isolation requirement. Using the latter sample requires information about detector effects and QCD backgrounds, which we obtain directly from the CMS Open Data. We present model-independent limits on the product of cross section, branching fraction, acceptance, and efficiencies. These limits are stronger, relative to a corresponding inclusive search without a pT cut, by factors of as much as nine. Our "pT -enhanced" dimuon search strategy provides improved sensitivity to models in which a new particle is produced mainly in the decay of something heavier, as could occur, for example, in decays of the Higgs boson or of a TeV-scale top partner. An implementation of this method with the current 13 TeV data should improve the sensitivity to such signals further by roughly an order of magnitude. CONTENTS

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Simulation of $e^+e^-\rightarrow\mbox{Hadrons}$ and Comparison to ALEPH Data at Full Detector Simulation with an Emphasis on Four-Jet States

Cited by 5 publications

References 0 publications

Localized 4σ and 5σ dijet mass excesses in ALEPH LEP2 four-jet events

Localized 4σ and 5σ dijet mass excesses in ALEPH LEP2 four-jet events

Exploring the space of jets with CMS open data

Searching in CMS open data for dimuon resonances with substantial transverse momentum

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