000128121 001__ 128121
000128121 005__ 20181205220245.0
000128121 0247_ $$2doi$$a10.5075/epfl-thesis-4234
000128121 02470 $$2urn$$aurn:nbn:ch:bel-epfl-thesis4234-0
000128121 02471 $$2nebis$$a5666195
000128121 037__ $$aTHESIS
000128121 041__ $$aeng
000128121 088__ $$a4234
000128121 245__ $$aContribution to the inner tracker design and penguin sensitivity studies for the measurement of sin 2ß in LHCb
000128121 269__ $$a2008
000128121 260__ $$aLausanne$$bEPFL$$c2008
000128121 300__ $$a195
000128121 336__ $$aTheses
000128121 520__ $$aLHCb is one of the four large experiments hosted at the Large Hadron Collider (LHC) at CERN in Geneva. It will start taking data in September 2008, and will then operate for several years. It consists of a single-arm forward spectrometer dedicated to precise measurements of CP violation and rare decays in the B sector, with the aim of testing the Standard Model and possibly of discovering the first signatures of New Physics. Building such a large experiment as LHCb is a challenge, and many contributions are needed. The Lausanne lab is responsible for the design and the production of the Silicon Inner Tracker (IT) of LHCb. This detector is made of Silicon sensors which need to be cooled to avoid thermal runaway. We present here a contribution to the design of this sub-detector and a description of the production steps. In particular, a study of the cooling of the Inner Tracker is described. It is shown that the cooling abilities of the IT can avoid thermal runaway. CP violation in B meson decays was first observed in the measurement of the so-called "golden channel", in which a Bd0 meson decays into a J/ψ and a Κs0 . The time-dependent CP asymmetry in Bd0 → J/ψΚs0 allows to measure the angle β of the (d, b) unitary triangle. This parameter is now known with 4% accuracy at B factories. However, this determination of sin 2β is made under the assumption that there is only a single amplitude present in this decay : this means that penguin diagrams which might be present have been neglected. In 1999, Robert Fleischer [29] proposed a theoretical method to access those penguin diagrams in the Bd0 → J/ψΚs0 decay, using the Bs0→ J/ψΚs0 channel. This method relies on U-Spin symmetry and also allows to determine the γ angle of the (d, b) unitary triangle. We have developed a selection method for the Bd0 → J/ψΚs0 channel in order to strongly suppress the background and to allow the separation of the Bs0 and Bd0 peaks. We obtained mass resolution of 8 MeV/c2 and a B/S ratio for the channel Bd0 → J/ψΚs0 estimated to belong to [0, 0.039] at 90% confidence level in a ±2σ mass window around the Bd0 mass, after the first level of trigger (L0). For the channel Bs0 → J/ψΚs0 , the B/S ratio is calculated from the result for Bd0 → J/ψΚs0 assuming known branching fractions. It lies in the interval [0, 3.33] at 90% CL. The annual yield is expected to be around 300 events for an integrated luminosity of 2 fb-1. We have simulated with fast Monte Carlo the Bs0 → J/ψΚs0 signal using the parametrization proposed in [29] and taking as input the results of selection obtained for Bd0 → J/ψΚs0 . The simulation has been repeated several times for different integrated luminosities and B/S ratios. We conclude that after 5 years of normal running, LHCb will be able to determine the penguin contribution in the Bd0 → J/ψΚs0 decay with a sensitivity of (0.172 ± 0.004) using this method based on U-spin symmetry.
000128121 6531_ $$aHigh Energy Physics
000128121 6531_ $$aCERN
000128121 6531_ $$aLHC
000128121 6531_ $$aStandard Model
000128121 6531_ $$ab physics
000128121 6531_ $$aCP violation
000128121 6531_ $$aLHCb
000128121 6531_ $$asilicon tracker
000128121 6531_ $$acooling
000128121 6531_ $$aPhysique des hautes énergies
000128121 6531_ $$aCERN
000128121 6531_ $$aLHC
000128121 6531_ $$aModèle Standard
000128121 6531_ $$aPhysique du quark b
000128121 6531_ $$aViolation de CP
000128121 6531_ $$aLHCb
000128121 6531_ $$aDéctecteur trace au silicium
000128121 6531_ $$aRefroidissement
000128121 700__ $$aPerrin, Aurélie
000128121 720_2 $$0244632$$aTran, Minh Tâm$$edir.$$g123677
000128121 8564_ $$s11913195$$uhttps://infoscience.epfl.ch/record/128121/files/EPFL_TH4234.pdf$$yTexte intégral / Full text$$zTexte intégral / Full text
000128121 909C0 $$0252318$$pLPHE
000128121 909CO $$ooai:infoscience.tind.io:128121$$pthesis-bn2018$$pDOI$$pSB$$pthesis$$qDOI2
000128121 918__ $$aSB$$cIPEP$$dEDPY
000128121 919__ $$aLPHE1
000128121 920__ $$b2008
000128121 970__ $$a4234/THESES
000128121 973__ $$aEPFL$$sPUBLISHED
000128121 980__ $$aTHESIS