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Searches for Higgs Boson Pair Production in the Hh{u2192}bb??, ??WW*, ??bb, Bbbb Channels with the ATLAS Detector

2015
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Release : 2015
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Book Synopsis Searches for Higgs Boson Pair Production in the Hh{u2192}bb??, ??WW*, ??bb, Bbbb Channels with the ATLAS Detector by :

Download or read book Searches for Higgs Boson Pair Production in the Hh{u2192}bb??, ??WW*, ??bb, Bbbb Channels with the ATLAS Detector written by . This book was released on 2015. Available in PDF, EPUB and Kindle. Book excerpt: Searches for both resonant and nonresonant Higgs boson pair production are performed in the hh → bb??, ??WW* final states using 20.3 fb-1 of pp collision data at a center-of-mass energy of 8 TeV recorded with the ATLAS detector at the Large Hadron Collider. No evidence of their production is observed and 95% confidence-level upper limits on the production cross sections are set. These results are then combined with the published results of the hh → ??bb, bbbb analyses. An upper limit of 0.69 (0.47) pb on the nonresonant hh production is observed (expected), corresponding to 70 (48) times the SM gg → hh cross section. For production via narrow resonances, cross-section limits of hh production from a heavy Higgs boson decay are set as a function of the heavy Higgs boson mass. The observed (expected) limits range from 2.1 (1.1) pb at 260 GeV to 0.011 (0.018) pb at 1000 GeV. In addition, these results are interpreted in the context of two simplified scenarios of the Minimal Supersymmetric Standard Model.

Observation of the Higgs Boson in the WW* Channel and Search for Higgs Boson Pair Production in the Bb̄bb̄ Channel with the ATLAS Detector

2016
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Release : 2016
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Book Synopsis Observation of the Higgs Boson in the WW* Channel and Search for Higgs Boson Pair Production in the Bb̄bb̄ Channel with the ATLAS Detector by : Tomo Lazovich

Download or read book Observation of the Higgs Boson in the WW* Channel and Search for Higgs Boson Pair Production in the Bb̄bb̄ Channel with the ATLAS Detector written by Tomo Lazovich. This book was released on 2016. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents the observation and measurement of the Higgs boson in the H→ WW*→ l[nu]l[nu] channel at √s = 7 TeV and √s = 8 TeV and a search for Higgs pair production in the HH→ bb̄bb̄ channel at √s = 13 TeV with the ATLAS detector in pp collisions at the Large Hadron Collider.

A Beauty-ful Boson

2023-01-01 Science
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Release : 2023-01-01
Genre : Science
Kind : eBook
Book Rating : 136/5 ( reviews)

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Book Synopsis A Beauty-ful Boson by : Giulia Di Gregorio

Download or read book A Beauty-ful Boson written by Giulia Di Gregorio. This book was released on 2023-01-01. Available in PDF, EPUB and Kindle. Book excerpt: The analysis described in this thesis is the search for the Higgs boson, decaying into bb pair, in the associated production with a vector boson, in the extreme Higgs boson transverse momentum region where the Higgs boson is reconstructed using the large-R jet technique. The use of the large-R jets allows to add a part of the phase space unexplored so far, which is particularly sensitive to possible new physics. The analysed data have been collected at LHC by the ATLAS detector between 2015 and 2018 at a centre-of-mass energy of √s = 13 TeV. The same dataset has been used to perform the differential pp → ZH and pp → WH cross-section measurements used to extract the information on the Higgs couplings and to put limits on Beyond the Standard Model effects. Furthermore the analysis has been re-used to perform a cross-section measurement of the diboson ZZ and WZ processes because the diboson and the Higgs processes have a similar topology. For the first time the ZZ(bb) and WZ(bb) cross-sections are measured at √s = 13 TeV and the observed cross-section measurements are consistent with the Standard Model predictions.

Search for the Higgs Boson in the Vector Boson Fusion Channel at the ATLAS Detector

2015-01-20 Science
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Release : 2015-01-20
Genre : Science
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Book Rating : 996/5 ( reviews)

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Book Synopsis Search for the Higgs Boson in the Vector Boson Fusion Channel at the ATLAS Detector by : Eric Ouellette

Download or read book Search for the Higgs Boson in the Vector Boson Fusion Channel at the ATLAS Detector written by Eric Ouellette. This book was released on 2015-01-20. Available in PDF, EPUB and Kindle. Book excerpt: This Thesis describes the first measurement of, and constraints on, Higgs boson production in the vector boson fusion mode, where the Higgs decays to b quarks (the most common decay channel), at the LHC. The vector boson fusion mode, in which the Higgs is produced simultaneously with a pair of quark jets, provides an unparalleled opportunity to study the detailed properties of the Higgs, including the possibility of parity and CP violation, as well as its couplings and mass. It thus opens up this new field of study for precision investigation as the LHC increases in energy and intensity, leading the way to this new and exciting arena of precision Higgs research.

Searches for Pair Production of Higgs Bosons in the Bbbb Final State Using the ATLAS Detector, Or

2021
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Release : 2021
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Book Synopsis Searches for Pair Production of Higgs Bosons in the Bbbb Final State Using the ATLAS Detector, Or by : Sean Gasiorowski

Download or read book Searches for Pair Production of Higgs Bosons in the Bbbb Final State Using the ATLAS Detector, Or written by Sean Gasiorowski. This book was released on 2021. Available in PDF, EPUB and Kindle. Book excerpt: This thesis discusses searches for pair production of Higgs bosons in the bbbb final state using data recorded by the ATLAS detector from $\sqrt{s} = 13$ TeV proton-proton ($pp$) collisions during the full period of LHC Run 2. It develops two separate analysis strategies: one targeting resonant pair production of Higgs bosons, in which Beyond the Standard Model resonances are produced which subsequently decay to two Higgs bosons, and one targeting non-resonant pair production of Higgs bosons, which is sensitive to Standard Model $HH$ production as well as to variations of the Higgs trilinear self-coupling. In the resonant searches, no significant excesses are seen, and upper limits on cross section are set on both spin-0 and spin-2 resonant hypotheses. Such limits are competitive with other leading ATLAS full Run 2 searches, and represent a significantly stronger statement than previous, beating the early Run 2 combined ATLAS results above 350 GeV and leading the ATLAS full Run 2 sensitivity above 700 GeV. In the non-resonant, no evidence of Standard Model $HH$ production is seen, but upper limits on cross section of $pp\rightarrow HH$ via gluon-gluon fusion are set to be 4.4 (5.9) observed (expected) times the value predicted by the Standard Model. Such limits represent a significant improvement in sensitivity over the early Run 2 bbbbresults, achieving a 30 (40)~\% additional gain in sensitivity beyond that predicted from a pure increase in dataset size. These limits are competitive with other leading ATLAS full Run 2 searches. Cross section limits are additionally set for a range of values of the Higgs self coupling, parametrized via its ratio to the value predicted by the Standard Model, $\kappa_{\lambda} = \lambda_{HHH}/\lambda_{HHH}^{SM}$. This is restricted to have values $-4.9 \leq \kappa_{\lambda} \leq 14.4$ observed ($-3.9 \leq \kappa_{\lambda} \leq 10.9$ expected). An excess of data over background is seen for values of $\kappa_{\lambda} \geq 5$, with maximum local significance of $3.8\sigma$ at $\kappa_{\lambda} = 6$. Such an excess is demonstrated to be due to low mass, where the bbbb channel has limited sensitivity, and is not seen in more sensitive channels in this region. Results on the development of two methods for the improvement of hadronic shower modeling in ATLAS fast calorimeter simulation are also presented.

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