Search for a Light Higgs Boson with the BABAR Detector PDF Download

Author: Rocky Yat Cheung So
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Languages : en
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Author:
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Languages : en
Pages : 4

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The BABAR Collaboration has performed three searches for a light Higgs boson, A°, in radiative Upsilon decays:?(3S) →?A°, A° →??−;?(nS) →?A°, A° →?+?− (n = 2,3); and?(3S) →?A°, A° → invisible. Such a Higgs boson (A°) appears in the Next-to-Minimal Supersymmetric extensions of the Standard Model, where a light CP-odd Higgs boson couples strongly to b-quarks. The searches are based on data samples that consist of 122 x 106?(3S) and 99 x 106?(2S) decays, collected by the BABAR detector at the SLAC National Accelerator Laboratory. The searches reveal no evidence for an A°, and product of branching fractions upper limits, at 90% C.L., of (1.5-16) x 10−5, (0.44-44) x 10−6, and (0.7-31) x 10−6 were obtained for these searches, respectively. Also, we set the upper limits?(?{sub b} →?+?−)

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Languages : en
Pages : 8

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We search for evidence of a light Higgs boson (A°) in the radiative decays of the narrow?(3S) resonance:?(3S) →?A°, where A° → invisible or A° →??−. Such an object appears in extensions of the Standard Model, where a light CP-odd Higgs boson naturally couples strongly to b-quarks. We find no evidence for such processes in a sample of 122 x 106?(3S) decays collected by the BABAR collaboration at the PEP-II B-factory, and set 90% C.L. upper limits on the product of the branching fractions?(?(3S) →?A°) x?(A° → invisible) at (0.7-31) x 10−6 in the mass range mA° ≤ 7.8 GeV, and on the product?(?(3S) →?A°) x?(A° →?+?−) at (0.25-5.2) x 10−6 in the mass range 0.212 ≤ mA° ≤ 9.3GeV. We also set a limit on the dimuon branching fraction of the recently discovered?{sub b} meson?(?{sub b} →?+?−)

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Languages : en
Pages : 7

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We search for a light Higgs boson A° in the radiative decay Y(3S) →?A°, A° → TT−, T+ → e+?{sub e}?{sub T}, or T+ →?+?{sub {mu}T}. The data sample contains 122 x 106 Y(3S) events recorded with the BABAR detector. We find no evidence for a narrow structure in the studied T+T− invariant mass region of 4.03 m{sub T+T−}

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Languages : en
Pages : 7

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Several new-physics (NP) models predict the existence of low-mass Higgs states and light dark matter candidates. Previous BABAR searches have given null results for these new states and have excluded large regions of the NP models parameter space. We report on new searches on light Higgs and light dark matter at BABAR using the 516 fb-1 of data collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at the SLAC National Accelerator Laboratory.

Author: Luis Roberto Flores Castillo
Publisher: Morgan & Claypool Publishers
ISBN: 1681740788
Category : Science
Languages : en
Pages : 76

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This book provides a general description of the search for and discovery of the Higgs boson (particle) at CERN’s Large Hadron Collider. The goal is to provide a relatively brief overview of the issues, instruments and techniques relevant for this search; written by a physicist who was directly involved. The Higgs boson mat be the one particle that was studied the most before its discovery and the story from postulation in 1964 to detection in 2012 is a fascinating one. The story is told here while detailing the fundamentals of particle physics.

Author:
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Languages : en
Pages : 101

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Although the standard model of particle physics has been very successfull in describing nature it needs to be extended by the Higgs mechanism to explain the particle masses observed in experiments. This mechanism introduces a new elementary particle called the Higgs boson. Current research at particle accelerators focuses on the search for the Higgs boson as a major goal. This analysis uses the data recorded with the D0-detector of the Tevatron at the Fermi National Accelerator Laboratory (FNAL). The Tevatron collides protons and antiprotons at a center of mass energy of √s=1.96 TeV. The primary goal of the analysis was the search for a light Higgs boson in the WH channel. For this the process pp→ WH → ev bb was used. Furthermore a measurement of the Wbb production cross section has been performed. For the measurements a total intagrated luminosity of L=255pb-1 was available. For the selection of the desired processes events with electrons, missing transverse momentum and at least two jets have been used. At least two of the jets were required to be identified as b-jets. To obtain an efficient event selection many event properties had to be calculated and methods to cut on them needed to be optimized. Based on the selected events the Wbb production cross section has been calculated. After includinng the branching ratio BR(W→ev)=0.108 the result is ?(Wbb)=21.8 pb (+15.5; -20.0 pb(sys+stat)) for events where the b-quarks satisfy p_T>8 GeV und.

Author: Eric Ouellette
Publisher: Springer
ISBN: 3319135996
Category : Science
Languages : en
Pages : 114

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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.

Author: Giulia Di Gregorio
Publisher: Springer Nature
ISBN: 3031200136
Category : Science
Languages : en
Pages : 229

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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.

Author: Maria Mironova
Publisher: Springer Nature
ISBN: 3031362209
Category : Science
Languages : en
Pages : 206

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This book explores the Higgs boson and its interactions with fermions, as well as the detector technologies used to measure it. The Standard Model of Particle Physics has been a groundbreaking theory in our understanding of the fundamental properties of the universe, but it is incomplete, and there are significant hints which require new physics. The discovery of the Higgs boson in 2012 was a substantial confirmation of the Standard Model, but many of its decay modes remain elusive. This book presents the latest search for Higgs boson decays into c-quarks using a proton-proton collision dataset collected by the ATLAS experiment at the Large Hadron Collider (LHC). This decay mode has yet to be observed and requires advanced machine learning algorithms to identify c-quarks in the experiment. The results provide an upper limit on the rate of Higgs boson decays to c-quarks and a direct measurement of the Higgs boson coupling strength to c-quarks. The book also discusses the future of particle physics and the need for significant improvements to the detector to cope with increased radiation damage and higher data rates at the High-Luminosity LHC. It presents the characterization of the ATLAS pixel detector readout chip for the inner detector upgrade (ITk). The chip was subjected to irradiations using X-rays and protons to simulate the radiation environment at the HL-LHC. The tests showed that all readout chip components, including the digital logic and analogue front-end, are sufficiently radiation-tolerant to withstand the expected radiation dose. Finally, this book describes monolithic pixel detectors as a possible technology for future pixel detectors. This book is ideal for individuals interested in exploring particle physics, the Higgs boson, and the development of silicon pixel detectors.