Study Of B Hadron Decays Into Two Hadrons And A Photon At Lhcb And First Observation Of B Baryon Radiative Decays
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Study Of B Hadron Decays Into Two Hadrons And A Photon At Lhcb And First Observation Of B Baryon Radiative Decays
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Author : Vicente José Rives Molina
language : en
Publisher:
Release Date : 2016
Study Of B Hadron Decays Into Two Hadrons And A Photon At Lhcb And First Observation Of B Baryon Radiative Decays written by Vicente José Rives Molina and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
"This thesis is divided in different sections. After a short introduction about the thesis contents, the theory chapter presents the Standard Model of Particle Physics (SM), with an emphasis on those properties of flavour physics, such as oscillations. In this chapter a brief comment on radiative decays, the main topic through the thesis, is given, to present the specific theoretical description of these processes. The European Centre of Nuclear Research (CERN) is introduced in the second chapter, where the nature of such organization and the different experiments it holds are explained. Special emphasis is given for the LHCb experiment, which is the one that collected the data used in the analysis. The third chapter describes the monitorization and re-calibration of the SPD sub- detector, which is the one in charge of the discrimination between photons and other electromagnetic particles. During the Run 1 (2011-2012), this sub-detector suffered from ageing due to the presence of radiation inside the LHCb cavern. This ageing led to a drop in the SPD cell efficiencies, which could imply a loss in the data quality. The SPD is key in the context of radiative decays due to the presence of photons in the radiative final states and due to the fact that the main sources of background for radiative decays are related to the mis-identification of other particles as photons. With the work presented in this thesis, the performance of the SPD sub-detector reached the same status than it did for the beginning of Run 1, which corresponds to an almost flat cell efficiency around 95%. This recovery in efficiencies was performed by applying a correction factor calculated through the study of cosmic ray data and collision data from 2015. The fourth chapter describes a software tool developed within the radiative decays context. This tool is aimed for a better description of the photon/neutral pion separation variable, which is built making use of the electromagnetic clusters that these particles leave in the LHCb electromagnetic calorimeter (ECAL). This tool builds a variable that separates between the two particles but discrepancies between the data and the simulation distributions are observed. Because of this, two additional tools were developed to improve the agreement between them. These tools trust that the separation variable can be binned in terms of the particle transverse momentum and pseudorapidity. The first of the tools, "efficiency table tool", assigns the efficiency for a certain 2-dimensional bin as a weight to the simulation sample, so the distribution is corrected and matches the one for data. The "resampling tool", however, creates a new variable from calibration histograms built from background- subtracted distributions, trusting all radiative decays to have a similar behaviour in the 2-dimensional bins. The two tools can also be applied to neutral pions selection. The main chapter of the thesis is related to the measurement of the ratio of branching fractions for Bs decaying into phi (which decays into two kaons) and a photon and Lambda_b, decay into a Lambda bayron (which decays into a kaon and a proton) and a photon with respect to the best controlled radiative decay, Bd decaying into a K* (which decays into a kaon and a pion) and a photon, as well as the measurement of the direct CP asymmetry for the Lambda_b and Bd decays. This analysis also implies the first observation of a b-baryon radiative decay and constitutes the best measurement of the observables presented above. The analysis is performed over the whole Run 1 LHCb dataset (3 inverse fb). Special care is applied to the Lambda_b decay since it had never been done before; taking into account the different resonances that may intervene (that cannot be distinguished since they overlap and interfere). A 2- dimensional binning (on the resonance mass and on the proton angle) is defined for the study of the efficiencies, as recommended by the theory approaches to this decay and trusting (and confirmed afterwards) the different resonance decays to give a similar efficiency for the offline selection for a given bin. The thesis concludes with an overview of the whole work presented, given the calculated results for the physical observables and comparing them to the previously measured ones in the LHCb"--TDX.
Search For Radiative B Baryon Decays And Study Of Their Anomalous Photon Polarization At Lhcb
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Author : Luis Miguel García Martín
language : en
Publisher:
Release Date : 2020
Search For Radiative B Baryon Decays And Study Of Their Anomalous Photon Polarization At Lhcb written by Luis Miguel García Martín and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
Spectroscopy And Decay Of B Hadrons At The Tevatron
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Author :
language : en
Publisher:
Release Date : 2007
Spectroscopy And Decay Of B Hadrons At The Tevatron written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.
The authors review recent results on heavy quark physics focusing on Run II measurements of B hadron spectroscopy and decay at the Tevatron. A wealth of new B physics measurements from CDF and D0 has been available. These include the spectroscopy of excited B states (B**, B**{sub s}) and the observation of the [Sigma]{sub b} baryon. The discussion of the decays of B hadrons and measurements of branching fractions focuses on charmless two-body decays of B 2!hh−. They report several new B{sub s}° and [Lambda]{sub b}° decay channels.
Rare Decays Of B Mesons And Baryons At The Tevatron And The Lhc
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Author :
language : en
Publisher:
Release Date : 2008
Rare Decays Of B Mesons And Baryons At The Tevatron And The Lhc written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with categories.
The experimental study of rare decays of hadrons containing the b quark has been a fertile ground for some time, and keeps being one of the most interesting subjects in high energy physics. It has improved our understanding of hadronic processes, and allows investigating various aspects of the Standard Model and searching for hints of physics beyond the Standard Model. Examples are the comparison of branching fractions of charmless modes with predictions of models, the constraints on CKM angles (B0 → [pi]+[pi]-, B → DK, with D in suppressed modes), the observation of purely leptonic modes (B± → [tau]±v), the recently established difference in ACP between B0 → K+[pi]- and B± → K±[pi]0, suspected to be a hint new physics. All of them came from a long and successful experimental activity with e+e- collisions at the Y(4S) resonance. With hadronic colliders now coming into play, the study of rare decays is reaching new heights. Given the high cross section for production of all kinds of B hadrons, the record luminosities now provided by the Tevatron collider, and the LHC program in view for the next years, there is the potential for a rich program of interesting new measurements, including even rarer modes as the Bs0 → [mu]+[mu]-, strongly suppressed in the standard model but very sensitive to many NP scenarios. The complexity of the hadronic collision environment, however, requires detectors with high precision and high quality tracking, and a trigger system capable of complex event selections at high rates. The CDF experiment, thanks to a fast trigger on impact parameter, has been able to reconstruct many rare B decays, including previously unobserved modes Bs0 → K+K- and Bs0 → K-[pi]+, the latter being particularly interesting for its relationship with the puzzling difference in CP asymmetry between neutral and charged modes. In this thesis we go beyond B mesons, and present the first measurements of Branching fractions and CP asymmetries in charmless b-baryon modes. We study two-body [Lambda]b0 decays into final states with a proton and a charged pion or kaon. Their branching fractions can be significantly affected by New Physics contributions; under supersymmetric models with R-parity violation, they can be increased by two orders of magnitude. Their CP-violating asymmetries are also interesting to measure in search for possible further anomalies: then may reach significant size O(30%) in the Standard Model, and are also sensitive to possible new physics sources.
Radiative Decays Of B Mesons At Lhcb
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Author :
language : en
Publisher:
Release Date : 2011
Radiative Decays Of B Mesons At Lhcb written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
B Baryon Production And Decays And B Hadron Lifetimes
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Author :
language : en
Publisher:
Release Date : 2010
B Baryon Production And Decays And B Hadron Lifetimes written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
In this paper we review the most recent results concerning B Baryons at CDF and D0, including the observation and the study of the properties of the?{sub b}−,?{sub b}− and?{sub b}{sup ±(*)}, the observation of new?{sub b}° decay modes, and a new measurement of the lifetime of the b hadrons in decays with a J/?. The?{sub b}− baryon is observed through the decay chain?{sub b}− → J/??−, where J/? →??−,?− →?K−, and? → pK−, using 4.2 fb−1 of data. The?{sub b}− mass is measured to be 6054.4 ± 6.8(stat.) ± 0.9(syst.) MeV/c2, and the lifetime 1.13{sub -0.40}{sup +0.53}(stat.) ± 0.02(syst.) ps. For the?{sub b}− the mass is measured 5790.9 ± 2.6(stat.) ± 0.8(syst.) MeV/c2 and the lifetime 1.56{sub -0.25}{sup +0.27}(stat.) ± 0.02(syst.) ps. A new accurate measurement of the properties of the resonances?{sub b}+,?{sub b}−,?*{sub b}+, and?*{sub b}− has been performed in 6 fb−1 of data, and the masses have been determined, m(?{sub b}+) = 5811.2{sub -0.8}{sup +0.9}(stat.) ± 1.7(syst.), m(?{sub b}−) = 5815.5{sub -0.5}{sup +0.6}(stat.) ± 1.7(syst.), m(?*{sub b}+) = 5832.0 ± 0.7(stat.) ± 1.8(syst.), and m(?*{sub b}−) = 5835.0 ± 0.6(stat.) ± 1.8(syst.). The?{sub b}° →?{sub c}(2595)+?− →?{sub c}+?−?+?−,?{sub b}° →?{sub c}(2625)+?− →?{sub c}+?−?+?−,?{sub b}° →?{sub c}(2455){sup ++}?−?− →?{sub c}+?−?+?−, and?{sub b}° →?{sub c}(2455)°?+?− →?{sub c}+?−?+?−. CDF has performed new measurements of the b hadron lifetimes in decays with a J/?. The measured lifetimes are the currently most precise determination of the B+, B° and?{sub b}° lifetimes. The measured values are c?(B+) = 491.4 ± 2.6(stat.) ± 2.6(syst.)?m, c?(B) = 451.7 ± 3.0(stat.) ± 2.5(syst.)?m, and c?(?{sub b}°) = 460.8 ± 13.4(stat.) {+-} 4.1(syst.)?m.
First Observation Of Charmed Resonances In The B C 3p Decays
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Author : Patrizia Barria
language : en
Publisher: LAP Lambert Academic Publishing
Release Date : 2013-01
First Observation Of Charmed Resonances In The B C 3p Decays written by Patrizia Barria and has been published by LAP Lambert Academic Publishing this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-01 with categories.
The Tevatron and Large Hadron Collider (LHC) experiments, unlike the B-Factories, have the unique opportunity to study the production and the decays of b-hadrons with c and s quarks, and among them especially the b-baryons which are the less known to date. The Collider Detector at Fermilab (CDF) experiment pioneered this eld of research. Moreover, it currently has the world's largest data sample of bottom baryons and this is mainly due to the combination of the large accumulated integrated luminosity delivered and the use of the displaced track trigger, a sophisticated piece of hardware, which is capable to select online events with secondary vertices, a typical feature of heavy hadrons decays, thus rejecting most part of the background from light quarks.
First Measurements Of Radiative B Decays In Lhcb
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Author : Albert Puig Navarro
language : en
Publisher:
Release Date : 2012
First Measurements Of Radiative B Decays In Lhcb written by Albert Puig Navarro and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
Observation And Study Of B Meson Decays With Lambda C Baryons With The Babar Detector
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Author :
language : en
Publisher:
Release Date : 2013
Observation And Study Of B Meson Decays With Lambda C Baryons With The Babar Detector written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
Discovery And Measurement Of Excited B Hadrons At The Collider Detector At Fermilab
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Author :
language : en
Publisher:
Release Date : 2007
Discovery And Measurement Of Excited B Hadrons At The Collider Detector At Fermilab written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.