| 1. |
- Pelikan, Daniel, 1985-
(författare)
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Searches for a Charged Higgs Boson in ATLAS and Development of Novel Technology for Future Particle Detector Systems
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The discovery of a charged Higgs boson (H±) would be a clear indication for physics beyond the Standard Model. This thesis describes searches for charged Higgs bosons with the ATLAS experiment at CERN’s Large Hadron Collider (LHC). The first data collected during the LHC Run 1 is analysed, searching for a light charged Higgs boson (mH±<mtop), which decays predominantly into a tau-lepton and a neutrino. Different final states with one or two leptons (electrons or muons), as well as leptonically or hadronically decaying taus, are studied, and exclusion limits are set.The background arising from misidentified non-prompt electrons and muons was estimated from data. This so-called "Matrix Method'' exploits the difference in the lepton identification between real, prompt, and misidentified or non-prompt electrons and muons. The Matrix Method is used in all charged Higgs boson searches in this thesis.In 2024 the LHC will be upgraded into a High Luminosity LHC (HL-LHC). The ATLAS detector is expected to collect around 300 fb-1 of collision data until 2022, whereas the HL-LHC will deliver about 250-300 fb-1 of data per year. This will increase the mean number of interactions per bunch crossing, resulting in larger particle fluxes. This puts challenging requirements on the electronics. In order to keep trigger and data rates at manageable levels, new trigger concepts require more intelligence at early stage which possibly results in more cables and connectors, inside the detector which lead to degraded performance of the detector system.This thesis presents new concepts using wireless technology at 60 GHz, in order add more data links inside the detector system without adding much material. Patch antennas have been developed, operating at 60 GHz. Manufacture methods have been investigated, and the fabrication tolerances and bandwidth of these antennas have been studied. Also, concepts of using passive repeaters have been investigated, to make the 60 GHz signal pass boundaries. These repeaters can be used to connect intelligence inside the detector, but also for reading out data from the whole detector radially.
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| 2. |
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| 3. |
- Schael, S, et al.
(författare)
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Precision electroweak measurements on the Z resonance
- 2006
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Forskningsöversikt (refereegranskat)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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| 4. |
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| 5. |
- Niemi, MEK, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 6. |
- Kanai, M, et al.
(författare)
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- 2023
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swepub:Mat__t
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| 7. |
- Bokan, Petar
(författare)
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Pair production of Higgs bosons in the final state with bottom quarks and τ leptons in the ATLAS experiment : Search results using LHC Run 2 data and prospect studies at the HL-LHC
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- After the discovery of the Higgs boson, the ultimate test of the electroweak symmetry breaking and the Standard Model (SM) of particle physics is to establish evidence of Higgs boson self-coupling, which can be achieved by searching for pair production of Higgs bosons. In addition, many theories beyond the SM predict heavy resonances that could decay into pairs of Higgs bosons. A search for non-resonant and resonant pair production of Higgs bosons in the final state with two bottom quarks and two τ leptons (bb̄τ+ τ−) is presented for 36.1 fb-1 of proton-proton collision data at a centre-of-mass energy of 13 TeV recorded by the ATLAS experiment at the Large Hadron Collider (LHC). The observed (expected) 95% confidence level (CL) upper limit on the non-resonant Higgs boson pair production cross-section times the bb̄τ+τ- branching ratio corresponds to 12.7 (14.8) times the SM prediction. The ratio of the Higgs boson self-coupling to its SM expectation, κλ, is observed (expected) to be constrained to κλ ∈ [-7.4, 15.7] ([-8.9, 16.8]) at 95% CL. The sensitivity is extrapolated to a 14 TeV centre-of-mass energy and 3000 fb-1, which is the target integrated luminosity of the High-Luminosity LHC (HL-LHC). Various extrapolation assumptions are taken into account. The estimated expected signal significance for the SM Higgs boson pair production in the bb̄τ+τ- final state at the HL-LHC reaches 2.1 standard deviations, while the expected allowed κλ interval is κλ ∈ [-0.8, 8.8] at 95% CL, assuming the SM Higgs boson couplings. Furthermore, potential improvements of the analysis techniques are discussed in the context of searches for pair production of Higgs bosons with the full Run 2 ATLAS data.
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| 8. |
- Carninci, P, et al.
(författare)
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The transcriptional landscape of the mammalian genome
- 2005
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Ingår i: Science (New York, N.Y.). - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 309:5740, s. 1559-1563
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Tidskriftsartikel (refereegranskat)abstract
- This study describes comprehensive polling of transcription start and termination sites and analysis of previously unidentified full-length complementary DNAs derived from the mouse genome. We identify the 5′ and 3′ boundaries of 181,047 transcripts with extensive variation in transcripts arising from alternative promoter usage, splicing, and polyadenylation. There are 16,247 new mouse protein-coding transcripts, including 5154 encoding previously unidentified proteins. Genomic mapping of the transcriptome reveals transcriptional forests, with overlapping transcription on both strands, separated by deserts in which few transcripts are observed. The data provide a comprehensive platform for the comparative analysis of mammalian transcriptional regulation in differentiation and development.
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| 10. |
- Coignard, J, et al.
(författare)
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A case-only study to identify genetic modifiers of breast cancer risk for BRCA1/BRCA2 mutation carriers
- 2021
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Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 12:1, s. 1078-
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Tidskriftsartikel (refereegranskat)abstract
- Breast cancer (BC) risk for BRCA1 and BRCA2 mutation carriers varies by genetic and familial factors. About 50 common variants have been shown to modify BC risk for mutation carriers. All but three, were identified in general population studies. Other mutation carrier-specific susceptibility variants may exist but studies of mutation carriers have so far been underpowered. We conduct a novel case-only genome-wide association study comparing genotype frequencies between 60,212 general population BC cases and 13,007 cases with BRCA1 or BRCA2 mutations. We identify robust novel associations for 2 variants with BC for BRCA1 and 3 for BRCA2 mutation carriers, P < 10−8, at 5 loci, which are not associated with risk in the general population. They include rs60882887 at 11p11.2 where MADD, SP11 and EIF1, genes previously implicated in BC biology, are predicted as potential targets. These findings will contribute towards customising BC polygenic risk scores for BRCA1 and BRCA2 mutation carriers.
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