Download or read book Measurements of H b b Decays and VH Production with the ATLAS Detector at the Large Hadron Collider in Proton proton Collisions at S written by Thomas Paul Charman and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Observation of H bb Decays and VH Production with the ATLAS Detector written by ATLAS Collaboration CERN and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: A search for the decay of the Standard Model Higgs boson into a pair when produced in association with a W or Z boson is performed with the ATLAS detector. The data, corresponding to an integrated luminosity of were collected in proton-proton collisions during Run 2 of the Large Hadron Collider at a centre-of-mass energy of . For a Higgs boson mass of , an excess of events over the expected background from other Standard Model processes is found with an observed (expected) significance of 4.9 (4.3) standard deviations. A combination with the results from other searches in Run 1 and in Run 2 for the Higgs boson in the decay mode is performed, which yields an observed (expected) significance of 5.4 (5.5) standard deviations, thus providing direct observation of the Higgs boson decay into b-quarks. The ratio of the measured event yield for a Higgs boson decaying into to the Standard Model expectation is . Additionally, a combination of Run 2 results searching for the Higgs boson produced in association with a vector boson yields an observed (expected) significance of 5.3 (4.8) standard deviations

Download or read book Observation of H bb Decays and VH Production with the ATLAS Detector Anglais written by Yanhui Ma and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for the Standard Model Higgs boson produced in association with a W or Z boson, and decaying to a bb pair has been performed with ATLAS detector. The data were collected in proton-proton collisions during Run 2 of the Large Hadron Collider at a centre-of-mass energy of 13 TeV, and correspond to an integrated luminosity of 79.8 fb−1. Three channels containing zero, one and two charged leptons (electrons or muons) have been considered to target each of the leptonic decays of the W or Z boson, Z->vv, W->lv et Z->ll, referred to as as the 0-lepton, 1-lepton and 2-lepton channels, respectively. For a Higgs boson mass of 125 GeV, an excess of events over the expected background from other Standard Model processes is found with an observed significance of 4.9 standard deviations, compared to an expectation of 4.3 standard deviations. The ratio of the measured signal events to the Standard Model expectation equal 1.16 +0.27/-0.25 = 1.16 +/-0.16(stat) +0.21/-0.19(syst). The result is also combined with the other results from the searches for the Higgs boson in the bb 18 decay mode in Run 1 and Run 2, the combination yields an observed (expected) significance of 5.4 (5.5) 20 standard deviations, and therefore provides a direct observation of the Higgs boson decay into a bb pair. In addition, a combination of Run 2 results searching for the Higgs boson produced in association with a W or Z boson yields an observed (expected) significance of 5.3 (4.8) standard deviations, and therefore provides a direct observation of Higgs boson being produced in association with a W or Z boson.

Download or read book Measurements of ZH and WH Production in the H Bb Decay Channel in Pp Collisions at 13 TeV with the ATLAS Detector written by ATLAS Collaboration CERN and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Measurements are presented of the Standard Model Higgs boson decaying into a bb ̄ pair and produced in association with a W or Z boson decaying into leptons, using proton-proton collision data collected between 2015 and 2018 by the ATLAS detector. The measurements use data delivered by the Large Hadron Collider at a centre-of-mass energy of s√=13 TeV, corresponding to an integrated luminosity of 139 fb−1. The production of a Higgs boson in association with a W or Z boson is established, with observed (expected) significances of 4.0 (4.1) and 5.3 (5.1) standard deviations, respectively. Cross-sections of associated production of a Higgs boson decaying into bottom quark pairs with an electroweak gauge boson, W or Z, decaying into leptons are measured as a function of the gauge boson transverse momentum in kinematic fiducial volumes. The cross-section measurements are all consistent with the Standard Model expectations, and the total uncertainties vary from 30% in the high gauge boson transverse momentum regions to 85% in the low regions

Download or read book Measurements of WH and ZH Production in the H bb Decay Channel in Pp Collisions at 13TeV with the ATLAS Detector written by ATLAS Collaboration CERN and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Measurements of the Standard Model Higgs boson decaying into a bb ̄ pair and produced in association with a W or Z boson decaying into leptons, using proton-proton collision data collected between 2015 and 2018 by the ATLAS detector, are presented. The measurements use collisions produced by the Large Hadron Collider at a centre-of-mass energy of s√=13TeV, corresponding to an integrated luminosity of 139fb−1. The production of a Higgs boson in association with a W or Z boson is established with observed (expected) significances of 4.0 (4.1) and 5.3 (5.1) standard deviations, respectively. Cross-sections of associated production of a Higgs boson decaying into bottom quark pairs with an electroweak gauge boson, W or Z, decaying into leptons are measured as a function of the gauge boson transverse momentum in kinematic fiducial volumes. The cross-section measurements are all consistent with the Standard Model expectations, and the total uncertainties vary from 30% in the high gauge boson transverse momentum regions to 85% in the low regions. Limits are subsequently set on the parameters of an effective Lagrangian sensitive to modifications of the WH and ZH processes as well as the Higgs boson decay into bb ̄

Download or read book Measurement of VH H Bb Production as a Function of the Vector boson Transverse Momentum in 13 TeV Pp Collisions with the ATLAS Detector written by Anne Kathrin Becker and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Cross-sections of associated production of a Higgs boson decaying into bottomquark pairs and an electroweak gauge boson, W or Z, decaying into leptons are measured as a function of the gauge boson transverse momentum. The measurements are performed in kinematic fiducial volumes defined in the 'simplified template cross-section' framework. The results are obtained using 79.8 fb−1 of proton-proton collisions recorded by the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 13 TeV. All measurements are found to be in agreement with the Standard Model predictions, and limits are set on the parameters of an effective Lagrangian sensitive to modifications of the Higgs boson couplings to the electroweak gauge bosons

Download or read book Measurement of the TtH Production Cross section with a Collimated H Bb Decay in Pp Collisions at Sqrt s written by Eftychia Tzovara and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The predictions of the Standard Model (SM) of particle physics have been probed with remarkable accuracy, so far. The Large Hadron Collider (LHC) at CERN has significantly contributed to this quest. A remarkable achievement of the ATLAS and CMS experiments at the LHC was the discovery of the Higgs boson in 2012, the last missing piece of the SM. With the increasing amount of proton-proton collisions delivered by the LHC, more precise measurements of the Higgs boson are now possible, while rare processes are accessible as well. A property of the Higgs boson that is of particular importance is its coupling to the top quark, which is expected to be the strongest in the SM due to the high mass of the top quark. Therefore, its precise measurement is a stringent test of the SM. A direct measurement of the top-quark Yukawa coupling can be assessed through the Higgs-boson production in association with a pair of top quarks (ttH). This thesis presents the measurement of the ttH process with a subsequent Higgs-boson decay to a pair of b-quarks (H -> bb), the decay mode with the largest branching ratio. The measurement is performed with data collected by the ATLAS detector, corresponding to an integrated luminosity of 139 fb^-1 at a center-of-mass energy of 13 TeV. Events with one or two charged leptons from the tt decay in the final state are considered to the measurement. The main challenge of the ttH(H -> bb) channel emerges from the large SM backgrounds from the production of top-quark pairs with additional jets (tt+jets). Also the many jets coming from b-hadrons (b-jets) in the final state cause combinatorial ambiguities. Thus, the identification of such jets is decisive in order to determine the signal and reject many background processes. The ttH events are split into exclusive analysis regions, based on the number of leptons, jets, and jets tagged as b-jets, providing regions enhanced in signal, or in the main background components. Specifically in the single-lepton channel, a boosted category is defined by selecting events in which the Higgs boson and possibly also the hadronically decaying top quark are produced with high transverse momentum (pT), with their decay products being collimated in large-radius jets. The single-lepton boosted channel targets events with Higgs-boson candidate pT >= 300 GeV and is the main scope of this thesis. To identify the reconstructed objects with the underlying particles and to maximise the discrimination of the ttH signal from the overwhelming tt+jets background events in the signal-enriched regions, machine-learning algorithms are employed. The background is dominated by a tt process with an additional gluon in the final state which further splits into a pair of b-quarks (tt+bb). Besides, a large number of heavy-flavour jets in the final state is not well modelled, thus many systematic uncertainties have to be considered, decreasing the sensitivity of the measurement. All the defined analysis regions are analysed together in a combined profile likelihood fit to test for the presence of signal. The fit simultaneously determines the event yields for the signal and the most important background component, while constraining the overall background model within the assigned systematic uncertainties. Eventually, the ratio of the measured ttH cross section to the SM expectation in the inclusive cross-section measurement is found to be 0.35 +0.36,-0.34}, corresponding to an observed (expected) significance of 1.0 (2.7) standard deviations. A ttH signal strength larger than the SM prediction is excluded at 95% confidence level. The measurement uncertainty is dominated by systematic uncertainties, mainly regarding the theoretical knowledge of the tt +>= 1b background process. Finally, to further test the SM, the cross-section is measured differentially as a function of the generator-level Higgs-boson pT, taking advantage of the reconstruction of the Higgs-boson kinematics.

Download or read book Searches for Dijet Resonances written by Lydia Audrey Beresford and published by Springer. This book was released on 2018-09-04 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses one of the most intriguing mysteries of our universe: the nature of dark matter. The results presented here mark a significant and substantial contribution to the search for new physics, in particular for new particles that couple to dark matter. The first analysis presented is a search for heavy new particles that decay into pairs of hadronic jets (dijets). This pioneering analysis explores unprecedented dijet invariant masses, reaching nearly 7 TeV, and sets constraints on several important new physics models. The two subsequent analyses focus on the difficult low dijet mass region, down to 200 GeV, and employ a novel technique to efficiently gather low-mass dijet events. The results of these analyses transcend the long-standing constraints on dark matter mediator particles set by several existing experiments.

Download or read book Measurement of Hadronic Event Shapes and Jet Substructure in Proton Proton Collisions at 7 0 TeV Center of Mass Energy with the ATLAS Detector at the Large Hadron Collider written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents the first measurement of 6 hadronic event shapes in proton-proton collisions at a center-of-mass energy of √s = 7 TeV using the ATLAS detector at the Large Hadron Collider. Results are presented at the particle-level, permitting comparisons to multiple Monte Carlo event generator tools. Numerous tools and techniques that enable detailed analysis of the hadronic final state at high luminosity are described. The approaches presented utilize the dual strengths of the ATLAS calorimeter and tracking systems to provide high resolution and robust measurements of the hadronic jets that constitute both a background and a signal throughout ATLAS physics analyses. The study of the hadronic final state is then extended to jet substructure, where the energy flow and topology within individual jets is studied at the detector level and techniques for estimating systematic uncertainties for such measurements are commissioned in the first data. These first substructure measurements in ATLAS include the jet mass and sub-jet multiplicity as well as those concerned with multi-body hadronic decays and color flow within jets. Finally, the first boosted hadronic object observed at the LHC - the decay of the top quark to a single jet - is presented.

Download or read book Measurement of Hadronic Event Shapes and Jet Substructure in Proton proton Collisions at 7 0 TeV Center of mass Energy with the ATLAS Detector at the Large Hadron Collider written by David Wilkins Miller and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents the first measurement of 6 hadronic event shapes in proton-proton collisions at a center-of-mass energy of 7.0 TeV using the ATLAS detector at the Large Hadron Collider. Results are presented at the particle-level, permitting comparisons to multiple Monte Carlo event generator tools. Numerous tools and techniques that enable detailed analysis of the hadronic final state at high luminosity are described. The approaches presented utilize the dual strengths of the ATLAS calorimeter and tracking systems to provide high resolution and robust measurements of the hadronic jets that constitute both a background and a signal throughout ATLAS physics analyses. The study of the hadronic final state is then extended to jet substructure, where the energy flow and topology within individual jets is studied at the detector level and techniques for estimating systematic uncertainties for such measurements are commissioned in the first data. These first substructure measurements in ATLAS include the jet mass and sub-jet multiplicity as well as those concerned with multi-body hadronic decays and color flow within jets. Finally, the first boosted hadronic object observed at the LHC -- the decay of the top quark to a single jet -- is presented.

Download or read book Measurements of Higgs Boson Production Cross sections in the H tau plus tau minus Decay Channel in Pp Collisions at square Root s written by ATLAS Collaboration CERN and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurement of the Cross section for W Boson Production in Association with B jets in Proton proton Collisions at Sqrt s written by Giovanni Zevi Della Porta and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents a measurement of the W+b-jets (pp --> W+bb+X) production cross-section in proton--proton collisions at a center-of-mass energy of 7 TeV at the LHC. The results are based on data corresponding to an integrated luminosity of 4.6 fb-1, collected with the ATLAS detector.

Download or read book Search for Massive Supersymmetric Particles Decaying to Many Jets Using the ATLAS Detector in Pp Collisions at Root S written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Results of a search for decays of massive particles to fully hadronic final states are presented. This search uses 20.3 fb-1 of data collected by the ATLAS detector in [arrow]" TeV proton-proton collisions at the LHC. Signatures based on high jet multiplicities without requirements on the missing transverse momentum are used to search for R-parity-violating supersymmetric gluino pair production with subsequent decays to quarks. Our analysis was performed using a requirement on the number of jets, in combination with separate requirements on the number of b-tagged jets, as well as a topological observable formed from the scalar sum of the mass values of large-radius jets in the event. Results were interpreted in the context of all possible branching ratios of direct gluino decays to various quark flavors. No significant deviation is observed from the expected Standard Model backgrounds estimated using jet counting as well as data-driven templates of the total-jet-mass spectra. Gluino pair decays to ten or more quarks via intermediate neutralinos are excluded for a gluino with mass mg~

Download or read book PEM 16 Entwicklung hersteller bergreifender Module f r den nutzerorientierten Einsatz der offenen Steuerungsarchitektur written by Gebrüder Heller and published by . This book was released on 1995 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Precision Measurement of the Higgs Boson Mass and Search for Dilepton Mass Resonances in H to 4l Decays Using the CMS Detector at the LHC written by Jake Rosenzweig and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Expectations of the total uncertainty are placed on the Higgs boson mass (mH) in the H to ZZstar to 4l (l = e, mu) decay channel. The value of mH, including statistical and systematic uncertainties, is estimated to be mH = 125.38 +- 0.11 [0.11 (stat.) +- 0.02 (syst.)] GeV. Once the data are unblinded, this measurement is predicted to be the world's most precise measurement of mH to date. The data used in the analysis were produced by proton-proton collisions at the Large Hadron Collider (LHC) with a center-of-mass energy of 13 TeV during Run 2 (2016-2018), corresponding to an integrated luminosity of 137.1 fb-1, and were collected by the Compact Muon Solenoid experiment. Using data sets from the same LHC run period, a search for low-mass dilepton resonances in Higgs boson decays to the 4l final state is also conducted. The Hidden Abelian Higgs Model is used in the search for a beyond the Standard Model dark photon (ZD) particle. Constraints are placed at 95% confidence level on the Higgs-mixing parameter k

Download or read book A Search for New Resonant Phenomena in Dijet Final States With the ATLAS Detector at the Large Hadron Collider written by Brian Clark and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation describes a model-agnostic search for new resonant phenomena decaying to two jets (dijets) in 3.6 fb-1 of proton-proton collisions at center-of-mass energy sqrt(s)=13 TeV. The collisions were produced by the Large Hadron Collider and recorded by the ATLAS detector in 2015. A dijet invariant mass spectrum is examined for local excesses above a data-driven background estimation accounting for Standard Model production. No statistically significant excess is observed. New physics models are excluded at 95% credibility-level for quantum black holes with production mass thresholds below 5.3 TeV, 8.1 TeV, and 8.3 TeV for three different production scenarios and for excited quarks of masses less than 5.2 TeV. Furthermore, limits are provided on generic Gaussian signal shapes for additional generalization of the 2015 dijet resonant analysis search results.

Download or read book Observation and Measurement of Higgs Boson Decays to WW with the ATLAS Detector written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We report the observation of Higgs boson decays to WW* based on an excess over background of 6.1 standard deviations in the dilepton final state, where the Standard Model expectation is 5.8 standard deviations. Evidence for the vector-boson fusion (VBF) production process is obtained with a significance of 3.2 standard deviations. The results are obtained from a data sample corresponding to an integrated luminosity of 25 fb-1 from [arrow]"=7 and 8 TeV pp collisions recorded by the ATLAS detector at the LHC. For a Higgs boson mass of 125.36 GeV, the ratio of the measured value to the expected value of the total production cross section times branching fraction is 1.09+0.16-0.15(stat)+0.17-0.14(syst). The corresponding ratios for the gluon fusion and vector-boson fusion production mechanisms are 1.02 " 0.19(stat)+0.22-0.18(syst) and 1.27+0.44-0.40(stat)+0.30-0.21(syst), respectively. At [arrow]"=8 TeV, the total production cross sections are measured to be [sigma](gg 2!>H 2!WW*)=4.6"0.9(stat)+0.8-0.7(syst) pb and [sigma](VBF H 2!W*)=0.51+0.17-0.15(stat)+0.13-0.08(syst) pb. The fiducial cross section is determined for the gluon-fusion process in exclusive final states with 0 or one associated jet.