Search for T Violation and CP Violation in the Weak Semileptonic Λ0b and Λ+C Decays with the Lhcb Detector Mohamad Kozeiha
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Search for T violation and CP violation in the Weak Semileptonic Λ0b and Λ+c Decays with the LHCb Detector Mohamad Kozeiha To cite this version: Mohamad Kozeiha. Search for T violation and CP violation in the Weak Semileptonic Λ0b and Λ+c Decays with the LHCb Detector. Nuclear Experiment [nucl-ex]. Université Clermont Auvergne, 2017. English. NNT : 2017CLFAC103. tel-01980282 HAL Id: tel-01980282 https://tel.archives-ouvertes.fr/tel-01980282 Submitted on 14 Jan 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Universit´eClermont Auvergne U.F.R Sciences et technologies Ecole´ Doctorale des Sciences Fondamentales Th`ese en vue de l'obtention du grade de Docteur en Physique Sp´ecialit´e:Constituants ´el´ementaires Pr´esent´eepar Mohamad KOZEIHA Search for T violation and CP violation in the 0 + Weak Semileptonic Λb and Λc Decays with the LHCb Detector Soutenue publiquement le 30 Novembre 2017 devant la commission d'examen constitu´eede : Pr´esident: M. Pascal PERRET Rapporteurs : M. Olivier LEROY M. Patrick OWEN Examinateurs : Mrs. Marina ARTUSO Directeur de th`ese: M. Ziad Jean AJALTOUNI 2 1 R´esum´e Trois sym´etriesdiscr`etes:C, P, T sont importantes en Physique Subatomique; leur produit combin´e´etant suppos´e^etreune sym´etrieexacte. La sym`etrieCPT est con- sid´er´eecomme la pierre angulaire de la Physique des Particules. Etant´ donn´eque C et P sont viol´ees,il est important de tester la violation de la sym´etrieT. L'objet de cette th`ese,y compris l'ensemble des th`emes´etudi´es,est de proposer d'une mani`ere directe une nouvelle strat´egiepour tester la sym´etriede renversement du temps (T). Le collisioneur LHC nous donne l'opportunit´ede le faire gr^ace`al'´enorme 0 + ∗ − production de baryons beaux. La d´esint´egrationΛb ! (Λc ! Λπ)(W ! µ νµ), qui est consid´er´eecomme une source d'observables impaires par la sym´etrieT est 0 utilis´ee. Une ´etudeexhaustive de la Polarisation du Λb et des r´esonancesissues du baryon beau est effectu´ee.En premier lieu, le cadre th´eorique, concernant les sym´etrieset leur r^ole,est pr´esent´e.Des progr`essignificatifs ont ´et´er´ealis´es dans le d´eveloppement d'un mod`elecin´ematique `apartir duquel sont calcul´eesles distri- butions angulaires des particules issues des diff´erentes d´esintegrations. Une ´etude d´etaill´eede la reconstruction et de la s´electiondes ´ev´enements est expos´eeainsi que la m´ethodologie suivie pour extraire les polarisations `apartir des diff´erentes distributions angulaires. Cette ´etudeest r´ealis´eeen utilisant les donn´ees2011-2012 enregistr´eespar le d´etecteurLHCb lors de la premi`erephase du LHC. Mots-Cl´es: Cin´ematiquede d´esint´egration.LHCb. Violation de T. Violation de CP. Polarisation, D´esint´egrationsen cascade. Abstract Three discrete symmetries: C,P,T are important in subatomic Physics, their com- bination (CPT) is considered as the corner stone of investigation in Particle Physics and many other fields. Since C and P are violated, it is important to investigate the direct violation of the T symmetry. This thesis, with all the discussed top- ics, aims to propose in a direct way a new strategy to test the symmetry of time reversal (T). The Collider LHC gives us the opportunity to do that throughout the enormous production of the beauty baryons. Here, the emphasis will be put 0 + ∗ − on the decay Λb ! (Λc ! Λπ)(W ! µ νµ), that is considered as a source of observables that are odd under T symmetry. A special attention is paid to the po- 0 larization of Λb and the resonating particles coming from it. First, the theoretical framework concerning the symmetries and their role in physics are presented. Sig- nificant progress has been achieved in the development of a kinematic framework from which the angular distributions of the particles involved in the decays are calculated. A detailed study of the reconstruction and selection of the events have been exposed as well as the methodology used to extract the different polarizations from the angular distribution fits. This study is performed using the 2011-2012 data recorded by the LHCb detector during the first run of the LHC. Key Words : Decay Kinematics. LHCb. T violation. CP violation. Polarization. Cascade Decays. 2 3 Remerciements No matter what one writes or how he writes, the words will be always unable to describe the feelings or even deliver the thanks to people who deserve. My acknowledgments go to everyone who has contributed in some way to the development of this work. I start by thanking the former director of the LPC, Alain Falvard, for granting me the chance to prepare my thesis in good conditions. I also would thank the director Dominique Pallin for facilitating my stay in the LPC also. I am so happy to make my PhD with LHCb team in the LPC. I would like to bring thanks to all the members of the team especially Ziad Ajaltouni who have worked hard with me so as to elaborate this work and make it in a good condition. In the past three years I have experienced the most beautiful moments, memories that I will never forget. Also I am so happy to know and work with the Semileptonic group, so I would like to thank all the members of those groups especially Patrick Owen, Basem Khanji for their continuous support and help. My friends in the LPC, Moustafa, Ibrahim, Marouen, Jan, Christus, Maxime, Boris, Giulio, Gabriella, Sara.. I want to thank you for your help and the time you have spent with me. My friends in Le Mans, Fatima, Zainab, Alaa, Natalia, Rim, Haidar, and Amal, thank you for you support and help (for cooking also). Every now and then, a series of beautiful moments that I lived with you flash in my mind, reminding me how I was so lucky to have you in my life. Giulio and Boris, I will never forget all the times we spent in the office eating and joking, those moments were the best moments of a so called working day. Rima, even I lack the words, I would like to thank you for your continuous, very well appreciated support. I wish you all the best in your life. My friends in Clermont, Noura, Wassim, Moujtaba, and Ali, thank you for you support. Every now and then, a series of beautiful moments that I lived with you flash in my mind, reminding me how I was so lucky to have you during the journey of my PhD and in my life. Also, I am very grateful to Pascal Perret, Patrick Owen, Marina Artuso and Olivier Leroy for having accepted to be a part of my thesis jury. I am to mention my brothers: Ahmad, Mahmoud, Hussein, and my sisters: Fatima, Zainab and Iman, since their presence has made me realize more and more their importance in my life. I can not just pass by such situation without 4 realizing how much my parents cared about me and how much they have sacrificed. Thanking them is not enough to express the enormous amount of gratitude that I have towards them. I feel how much they are happy to see that I has achieved something in this life. So with all my greeting and kind regards.... Thank you all... Contents 5 Contents 1 Theoretical Overview 11 1.1 Symmetries in Classical Mechanics . 12 1.2 Symmetries in Quantum Mechanics . 12 1.3 Discrete Symmetries . 13 1.3.1 Charge Conjugation . 13 1.3.2 Parity . 14 1.3.3 Time Symmetry . 15 1.3.4 CPT Theorem . 16 1.4 Violation of the Discrete Symmetries . 17 1.4.1 Parity Violation . 17 1.4.2 C-Violation . 18 1.5 CP-Symmetry . 18 1.6 CP Violation in Neutral Kaons . 19 1.7 Searching For Discrete Time Reversal Violation . 20 1.7.1 Electric Dipole Moment of the Neutron . 20 1.7.2 Experimental situation of the nEDM . 21 1.7.3 Neutron's β Decays . 22 1.7.4 Kabir Parameter [15] . 22 + − + − 1.7.5 KL ! π π e e decay at KTeV . 23 1.8 BaBar and Time Reversal Violation . 23 0 1.9 Search for Time Reversal Violation in the Weak Semileptonic Λb ! + − Λc µ νµ Decays . 23 2 The Collider and The Detector 27 2.1 Large Hadron Collider . 28 2.1.1 Production of B-mesons . 29 2.2 LHCb : Beauty Detector . 30 2.2.1 Data taking periods and operating conditions . 30 2.2.2 LHCb luminosity . 31 2.2.3 Vertex LOcator: The VELO . 32 2.2.4 RICH detectors . 33 2.2.5 Mirrors and radiators . 34 2.2.6 Seeing the light . 35 2.2.7 The Dipole Magnet . 36 2.2.8 Tracking system . 36 2.2.9 Calorimeter system . 39 2.2.10 Muon system . 41 2.3 Particle Identification . 42 2.4 The LHCb trigger system . 43 2.4.1 The Level-0 trigger . 44 2.4.2 The High Level Trigger . 44 2.5 LHCb Software . 45 2.6 Data flow in LHCb . 46 2.7 Stripping: .