142 research outputs found
Study of the lepton flavor violating decays of the Higgs boson at the ATLAS experiment
No full textTitle: Study of the Lepton Flavor Violating Decays of the Higgs Boson at the ATLAS Experiment Author: Petr Kouba Institute: Institute of Particle and Nuclear Physics Supervisor: Mgr. Daniel Scheirich, Ph.D., Institute of Particle and Nuclear Physics Abstract: The thesis contains an analysis of the potential lepton flavor violating Higgs boson decays performed on the data acquired by the ATLAS experiment during the Run II period of the LHC. The analysis comprised of an event selection aiming at the reduction of the backgrounds, while keeping the highest possible amount of the signal events. An estimate of the leptons misidentified by the reconstruction algorithms of the ATLAS experiment was included in the anal- ysis. For the selected events, invariant mass was reconstructed in the collinear approximation. The distribution of the invariant mass according to the MMC was provided for reference purposes. Keywords: Higgs boson, ATLAS, collinear approximation i
Studium rozpadů Higgsova bosonu narušujících leptonové číslo na experimentu ATLAS
No full textNázev práce: Studium rozpadů Higgsova bosonu narušujících leptonové číslo na experimentu ATLAS Autor: Petr Kouba Katedra: Ústav částicové a jaderné fyziky Vedoucí bakalářské práce: Mgr. Daniel Scheirich, Ph.D., Ústav částicové a jaderné fyziky Abstrakt: Práce obsahuje analýzu potenciálních rozpadů Higgsova bosonu naru- šujících leptonové číslo, vykonanou na datech z experimentu ATLAS pořízených během periody RUN2 na urychlovači LHC. Analýza sestávala z výběru eventů, cíleného na potlačení pozadí a současného zachování nejvyššího možného počtu signálních eventů. Do analýzy byl zahrnut i odhad leptonů, chybně identifiko- vaných rekonstrukčími algoritmy experimentu ATLAS. Pro vybrané eventy byla zrekonstruována invariantní hmota v kolineární aproximací. Pro porovnání je uvedeno i rozdělení invariantní hmoty dle metody MMC. Klíčová slova: Higgsův boson, ATLAS, kolineární aproximace 23Title: Study of the Lepton Flavor Violating Decays of the Higgs Boson at the ATLAS Experiment Author: Petr Kouba Institute: Institute of Particle and Nuclear Physics Supervisor: Mgr. Daniel Scheirich, Ph.D., Institute of Particle and Nuclear Physics Abstract: The thesis contains an analysis of the potential lepton flavor violating Higgs boson decays performed on the data acquired by the ATLAS experiment during the Run II period of the LHC. The analysis comprised of an event selection aiming at the reduction of the backgrounds, while keeping the highest possible amount of the signal events. An estimate of the leptons misidentified by the reconstruction algorithms of the ATLAS experiment was included in the anal- ysis. For the selected events, invariant mass was reconstructed in the collinear approximation. The distribution of the invariant mass according to the MMC was provided for reference purposes. Keywords: Higgs boson, ATLAS, collinear approximation iiInstitute of Particle and Nuclear PhysicsÚstav částicové a jaderné fyzikyFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult
Studium vzácných rozpadů B-mesonů v experimentu ATLAS
No full textNázov práce: Štúdium vzácných rozpadov B-mezónov v experimente ATLAS Author: Marek Biroš Ústav: Ústav částicové a jaderné fyziky Vedúci diplomovej práce: RNDr. Pavel Řezníček, Ph.D, Ústav částicové a jaderné fyziky Abstrakt: Štúdium vzácneho rozpadu B0 d → K∗0 (892) μμ má veľký potenciál pozorovať prejavy fyziky za Štandardným modelom, ktoré by sa mohli prejaviť v uhlovom rozdelení jeho produktov. Táto práca je zameraná na prípravu rôznych medzičlánkov, potrebných v počiatočnom štádiu zložitej analýzy rozpadu B0 d → K∗0(892) μμ a to konkrétne: validácia fitu uhlového rozdelenia a predvýber signálnych udalostí. Plánované fitovacie funkcie sú testované na generovaných toy Monte Carlo dátach. V rámci stanovených testovacích rozsahov, množine parametrov kde funkcia nadobúda iba kladné hodnoty pre všetky kombinácie uhlov, sú skúmané prejavy vnútorných skreslení, resp. vychýlení (tzv. biasov) fitu. Skúmaná bola najmä závislosť biasov na počte nameraných signálnych udalostí očakávaných v Rune 2 a v HL-LHC a na rôznom pomere signal-vs- pozadie. Ďalšou časťou bolo spolupodieľanie sa na rekonštrukcii predspracovaných dát z detektora do n-tuplov za účelom tvorby viac kompaktného datasetu, neskôr použitého v samotnej analýze. Pre efektívnejšiu redukciu veľkosti datasetu, boli aplikované základné výberové kritéria na...Title: Study of the rare B-meson decays with the ATLAS experiment Author: Marek Biroš Institute: Institute of Particle and Nuclear Physics Supervisor: RNDr. Pavel Řezníček, Ph.D., Institute of Particle and Nuclear Physics Abstract: The rare B0 d → K∗0 (892) μμ decay is one of the B-physics channels sensitive to Beyond Standard Model effects. The potential deviation from Standard Model predictions could be observed in the angular distribution of this decay. The work compiles several sub-tasks at the initial stage of this complex analysis: decay angles fit validation and signal event preselection. The fit functions used in the analysis are verified on generated toy Monte Carlo data. Ranges of parameters, for which are these functions positive, are established and within this parametric space, the testing of possible intrinsic fit biases is evaluated. A dependence of the fit bias with respect to the collected number of events (expected in Run 2 as well as at HL-LHC) and to the different signal-to- background ratio is studied. The second part of the thesis deals with processing of raw reconstructed data from the detector into n-tuples resulting in a more compact dataset that would be used in the final analysis. Within the process, baseline cuts are applied in order to minimize size of final datasets by reducing...Ústav částicové a jaderné fyzikyInstitute of Particle and Nuclear PhysicsFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult
Physical model of asteroid (130) Elektra based on adaptive optics images obtained by the VLT/SPHERE instrument
No full textUsing the ADAM software package, the shape model of the asteroid (130) Elektra was reconstructed. The model is based on 60 lightcurves from the DAMIT database, 46 AO images obtained by the NIRC2 and SPHERE in- struments and two occultations. The best-fit model assigns Elektra the vol- ume of (4.3 ± 0.1) × 106 km3 . After that, using the Xitau program, the orbital model of the two moons S/2014 1 and S/2003 was constructed. It is based on astrometry of the moons reduced from the 2014 and 2019 SPHERE images of Elektra. The model is a dipole non-Keplerian one, which resulted in an adjustment to the periods of the two moons to P1 = (1.2185 ± 0.0004) d & P2 = (5.3015 ± 0.0001) d. The main result is the more precise mass of Elektra at (6.59 ± 0.08) × 1018 kg, which revises the bulk density to ̄ρ = (1.533 ± 0.066) g cm−3
Jet substructure at Future Circular Collider (FCC)
No full textTitle: Jet substructure at Future Circular Collider (FCC) Author: Tadeáš Petrů Department: Institute of Particle and Nuclear Physics Supervisor: Mgr. Jana Faltová, Ph.D., Institute of Particle and Nuclear Physics Abstract: Future Circular Collider (FCC-hh) is a proposed next-generation hadron collider with a center-of-mass energy of 100 TeV that could be built in CERN. This collider would serve both as a powerful discovery machine and also as a precision measurements machine. One of the challenges for detectors installed at FCC-hh would be an identification of highly boosted objects that subsequently decay hadronically. Within this thesis, we will study the ability of the calorime- ter system of the FCC-hh reference detector in distinguishing two-pronged jets from highly boosted W boson decays and one-pronged jets from light quarks. We will introduce several jet substructure variables and use them as inputs for multivariate analysis (boosted decision trees). Keywords: FCC, substructure, boosted objects ii
Associated production of and in ATLAS
No full textWe present the discovery of associated vector boson+prompt production and subsequent measurement of the production rate, which is a key observable to furthering understanding of quarkonium production mechanisms. We estimate the relative contributions to the signal from single and double parton scattering and discuss possible implications of this novel final state for study of multiple parton interactions. The single parton scattering cross-sections are compared to cutting-edge theoretical calculations in the colour singlet and colour octet formalisms
Detecting new hadrons or excited ones
No full textWe review Tevatron Run II results of heavy quark hadron searches, including measurements of , B^{**}B_s^{**}Sigma_bSigma_b^*Xi_b^-Omega_b^-K_s opi^+pi^-Lambda o ppi^-arLambda o ar ppi^+$ decays reconstruction, which will be final state particles in some of the heavy hadron decays. In addition some of the promising new heavy baryon decays are reviewed
Mixing and CP violation in the Bs system with ATLAS
No full textA measurement of the Bs0 → J/ψφ decay parameters, updated to include flavour tagging is reported using 4.9 fb−1 of integrated luminosity collected by the ATLAS detector from √s = 7 TeV pp collisions recorded in 2011 at the LHC. The values measured for the physical parameters are: φs = 0.12 ± 0.25 (stat.) ± 0.05 (syst.) rad ∆Γs = 0.053 ± 0.021 (stat.) ± 0.010 (syst.) ps−1 where the parameter ∆Γs is constrained to be positive. The S-wave contribution was measured and found to be compatible with zero. Results for φs and ∆Γs are in agreement with the Standard Model expectations
Fyzikální model planetky (130) Elektra ze snímků pořízených přístrojem VLT/SPHERE
No full textUsing the ADAM software package, the shape model of the asteroid (130) Elektra was reconstructed. The model is based on 60 lightcurves from the DAMIT database, 46 AO images obtained by the NIRC2 and SPHERE in- struments and two occultations. The best-fit model assigns Elektra the vol- ume of (4.3 ± 0.1) × 106 km3 . After that, using the Xitau program, the orbital model of the two moons S/2014 1 and S/2003 was constructed. It is based on astrometry of the moons reduced from the 2014 and 2019 SPHERE images of Elektra. The model is a dipole non-Keplerian one, which resulted in an adjustment to the periods of the two moons to P1 = (1.2185 ± 0.0004) d & P2 = (5.3015 ± 0.0001) d. The main result is the more precise mass of Elektra at (6.59 ± 0.08) × 1018 kg, which revises the bulk density to ̄ρ = (1.533 ± 0.066) g cm−3 .Pomocí softwarového balíku ADAM byl zrekonstruován model tvaru aste- roidu (130) Elektra. Model je zaloen na 60 svtelných kivkách z databáze DA- MIT, 46 AO snímcích získaných pístroji NIRC2 a SPHERE a dvou zákrytech. Nejvhodnjí model pidluje Elekte objem (4, 3 ± 0, 1) × 106 km3 . Dále byl, pomocí programu Xitau, zkonstruován orbitální model dvou m- síc S/2014 1 a S/2003. Ten je zaloen na astrometrii tchto msíc vypracované ze SPHERE snímk Elektry z let 2014 a 2019. Model je dipólový a nekeple- rovský, co vedlo k úprav period tch dvou msíc na P1 = (1,2185 ± 0,0004) d & P2 = (5,3015 ± 0,0001) d. Hlavním výsledkem je pesnjí hmotnost Elektry pi (6,59 ± 0,08) × 1018 kg, která reviduje objemovou hustotu na ̄ρ = (1,533 ± 0,066) g cm−3 .Astronomical Institute of Charles UniversityAstronomický ústav UKMatematicko-fyzikální fakultaFaculty of Mathematics and Physic
Studium CP narušení na experimentu Belle
No full textWe present a first measurement of time-dependent CP-violation in B0 → D∗∓ ρ± , where D∗∓ → D0 π. The analysis was performed using the final Belle dataset containing 772 × 106 B ¯B pairs collected at the KEKB e+ e− collider. Three D0 decay modes are analyzed, K∓ π± , K∓ π± π0 , and K∓ π± π∓ π± . Since the studied decay is a scalar → vector vector decay, three helicity configurations are present. Exploiting the helicity configura- tions via angular analysis, the time-dependent CP-violation parameters encoding 2ϕ1 +ϕ3 are obtained from the fit. 1Předkládáme první měření časově závislého CP narušení v rozpadu B0 → D∗∓ ρ± , kde D∗∓ → D0 π. Analýza byla provedena s použitím finálního Belle datasetu obsahujícího 772×106 B ¯B párů. Tento vzorek byl získán na e+ e− urychlovači KEKB. Studovali jsme tři rozpadové módy D0 : K∓ π± , K∓ π± π0 a K∓ π± π∓ π± . Jelikož jde o rozpad typu skalár → vektor vektor, obsahuje tři helicitní konfigurace. Úhlová analýza nám poskytla přístup k těmto konfiguracím, což nám umožnilo provést časově závislý fit parametrů CP narušení, které obsahují informaci o 2ϕ1 + ϕ3. 1Ústav částicové a jaderné fyzikyInstitute of Particle and Nuclear PhysicsFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult
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