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Observation of b → dγ decays and determination of |V<sub>td</sub>/V<sub>ts</sub>|Mohapatra, Debabrata 15 August 2006 (has links)
The flavor changing neutral current process b → dγ is a sensitive probe to the Standard Model of elementary particle physics. Using a sample of 386 × 10⁶ B meson pairs accumulated by the Belle detector at the KEKB e⁺e⁻ collider, we measure the branching fractions for the exclusive modes B⁻ → ρ⁻γ, B̅⁰ → ρ⁰γ and B̅⁰ → ωγ as follows:
B(B⁻ → ρ⁻γ) = 0.55 <sub>−0.36</sub><sup>+0.42</sup><sub>−0.08</sub><sup>+0.09</sup>
B(B̅⁰ → ρ⁰γ) = 1.25 <sub>−0.33</sub><sup>+0.37</sup><sub>−0.06</sub><sup>+0.07</sup>
B(B̅⁰ → ωγ) = 0.56 <sub>−0.27</sub><sup>+0.34</sup><sub>−0.10</sub><sup>+0.05</sup>
where the first error on each value is statistical and the second is systematic. Assuming that these three modes are related by isospin conservation rules, we find the combined branching fraction
B(B̅ → (ρ,ω)γ) = 1.32 <sub>−0.31</sub><sup>+0.34</sup><sub>−0.09</sub><sup>0.10</sup>.
This result is used to determine the ratio of CKM matrix elements,
|V<sub>td</sub>/V<sub>ts</sub>| = 0.199 <sub>−0.025</sub><sup>+0.026</sup><sub>−0.015</sub><sup>0.018</sup>. / Ph. D.
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Angular analysis of the decay B°→ΦK*(892)°Lambert, Dean January 2015 (has links)
The LHCb experiment is a single-arm forward spectrometer situated at the Large Hadron Collider, CERN. LHCb is optimised for the precision study of beauty and charm flavoured hadrons and in 2011 collected 1 fb-1 of proton- proton collision data at a centre-of-mass energy of 7TeV. The aim of LHCb is to search for rare decays and make precise measurements of Charge-Parity (CP) violation in the beauty and charm sectors. In the Standard Model the decay B°→ ΦK*(892)° is described by a loop mediated process, providing a sensitive test for new physics. In this decay, signs of CP violation could indicate the presence of physics beyond the Standard Model. This thesis presents a study of the flavour eigenstate B° → Φ(→ K+K-)K*(892)°(→ K+π-) and its charge conjugate -B°-decay. The decay products form an admixture of CP-even and CP-odd eigenstates, which can have longitudinal or transverse polarisation. An angular analysis is performed to disentangle these different contributions and the polarisation amplitudes and strong phases are measured. No difference is observed between B0 and -B0 amplitudes, supporting the hypothesis that CP is conserved in this decay. In addition, the Triple Product Asymmetries (TPAs) are determined from the products of the polarisation amplitudes and strong phases. True TPAs are zero in the event that CP symmetry is conserved, while fake TPAs can arise due to final-state interactions. Although the measured true TPAs are consistent with zero, several significant fake TPAs are observed.
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Experimental Study of Three-body Cabibbo-suppressed D<sup>0</sup> Decays and Extraction of <i>CP</i> Violation ParametersMishra, Kalanand Mishra 22 April 2008 (has links)
No description available.
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Leptonic Decays of the Charged B MesonCorwin, Luke Andrew 10 December 2008 (has links)
No description available.
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Real-time alignment of the LHCb vertex detector and observation of charmless baryonic decays B⁰(s) → pp̄h⁺ h'⁻Dujany, Giulio January 2017 (has links)
This thesis presents measurements of the branching fractions of the charmless baryonic decays B(s) → p anti-p h+ h'-, where h(') denotes a kaon or a pion. Three new modes (B → p anti-p pi+ pi-, Bs → p anti-p K+ K- and Bs → p anti-p K+(-) pi-(+)) are observed for the first time and evidence is found for a fourth (B → p anti-p K+ K-). The inclusive branching fraction of B → p anti-p K+(-) pi-(+) is measured for the first time and the upper limit is set on the branching fraction of the Bs → p anti-p pi+ pi- decay. This represents the first observation of four-body charmless baryonic decays of a Bs meson and one of the first observations of baryonic Bs decays. The implementation of the real-time alignment of LHCb's vertex detector is also described. The novel real-time alignment and calibration strategy adopted by LHCb is essential to allow more stable data taking conditions and an optimal 'offline-quality' reconstruction to be performed at the trigger level, ensuring more efficient trigger selections and the possibility to perform physics analyses directly on the trigger output.
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Measurement of the Partial Branching Fraction for Inclusive Semileptonic B Meson Decays to Light Hadrons B-&gt;Xu l nu and an Improved Determination of the Quark-Mixing Matrix Element |V_ub|Volk, Alexei 15 September 2009 (has links) (PDF)
This thesis presents an analysis of inclusive semileptonic $B \to X_u e \nu$ decays using approximately 454 million $\Upsilon(4S) \to B \bar{B}$ decays collected during the years 1999 to 2008 with the BABAR detector.
The electron energy, $E_e$, and the invariant mass squared of the electron-neutrino pair,$ q^2$, are reconstructed, where the neutrino kinematics is deduced from the decay products of both B mesons.
The final hadronic state,$ X_u$, consists of a sum of many hadronic channels, each of which contains at least one $u$ quark.
The variables $q^2$ and $E_e$ are then combined to compute the maximum kinematically allowed invariant mass squared of the hadronic system, $s_h^{max}$.
Using these kinematic quantities, the partial branching fraction, $\Delta BR(B \to X_u e \nu)$, unfolded for detector effects, is measured to be
$\Delta BR(E_e&gt;2.0 GeV, s_h^{max}&lt;3.52 GeV^2) = (3.33 \pm 0.18 \pm 0.21) \times 10^{-4}
in the $\Upsilon(4S)$ and
\Delta \tilde{\BR}(\tilde E_e&gt;1.9 GeV, \tilde {s}^{max}_{h} &lt; 3.5 GeV^2) = (4.57 \pm 0.24 \pm 0.32) \times 10^{-4}
in the $B$ meson rest frames. The quoted errors are statistical and systematic, respectively.
The CKM matrix element $|V_{ub}|$ is determined from the measured $\Delta \tilde{\BR}$ using theoretical calculation based on Heavy Quark Expansion. The result is
$|V_{ub}| = (4.19 \pm 0.18{}^{+0.26}_{-0.20} {}^{+0.26}_{-0.25}) \times 10^{-3}, where the errors represent experimental uncertainties, uncertainties from HQE parameters and theoretical uncertainties, respectively.
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Power Corrections in e<sup>+</sup>e<sup>-</sup> →M<sub>1</sub>M<sub>2</sub> and in Charmless Two Body B meson DecaysDuraisamy, Murugeswaran January 2009 (has links)
No description available.
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Search for B → π τ ν with hadronic tagging at BelleHamer, Philipp 09 November 2015 (has links)
Eine Suche nach dem Zerfall B → π τ ν wird vorgestellt. Die Suche wird auf dem vollständigen Belle Datensatz durchgeführt, der 772E6 B anti-B Paare beinhaltet, die auf der Y(4s) Resonanz mit Belle Detektor am asymmetrischen e+e- KEKB Beschleuniger gesammelt wurden. Das τ Lepton wird in den Zerfallskanälen τ → e ν ν, τ → μ ν ν, τ → π ν und τ → ρ ν rekonstruiert. Eines der beiden B Mesonen, das Btag, wird mittels eines auf NeuroBayes beruhenden Algorithmus vollständig in einem hadronischen Zerfallskanal rekonstruiert. Der Rest des Kollisionsereignisses beinhaltet genau zwei geladene Spuren im Falle eines Signalzerfalls. Die weitere Trennung zwischen Signal und Untergrund wird mithilfe von Boosted Decision Trees durchgeführt. Ein Fit wird in der Verteilung der Extra Energie im elektromagnetischen Kalorimeter ECL, welche definiert ist als alle Energie die weder vom Btag noch von der rekonstruierten Signalseite stammt, durchgeführt. Kein signifikantes Signal wird beobachtet und ein oberes Limit von Br( B → π τ ν ) < 2.5E-4 basierend auf einem Vertrauensintervall von 90% wird bestimmt. Das Ergebnis ist in guter Übereinstimmung mit der Vorhersage des Standard Modells.
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Measurement of B-> pi pi l nu with Full Hadronic Reconstruction at BelleBeleno de la Barrera, Cesar Augusto 01 October 2018 (has links)
No description available.
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Measurement of the Partial Branching Fraction for Inclusive Semileptonic B Meson Decays to Light Hadrons B-&gt;Xu l nu and an Improved Determination of the Quark-Mixing Matrix Element |V_ub|Volk, Alexei 22 June 2009 (has links)
This thesis presents an analysis of inclusive semileptonic $B \to X_u e \nu$ decays using approximately 454 million $\Upsilon(4S) \to B \bar{B}$ decays collected during the years 1999 to 2008 with the BABAR detector.
The electron energy, $E_e$, and the invariant mass squared of the electron-neutrino pair,$ q^2$, are reconstructed, where the neutrino kinematics is deduced from the decay products of both B mesons.
The final hadronic state,$ X_u$, consists of a sum of many hadronic channels, each of which contains at least one $u$ quark.
The variables $q^2$ and $E_e$ are then combined to compute the maximum kinematically allowed invariant mass squared of the hadronic system, $s_h^{max}$.
Using these kinematic quantities, the partial branching fraction, $\Delta BR(B \to X_u e \nu)$, unfolded for detector effects, is measured to be
$\Delta BR(E_e&gt;2.0 GeV, s_h^{max}&lt;3.52 GeV^2) = (3.33 \pm 0.18 \pm 0.21) \times 10^{-4}
in the $\Upsilon(4S)$ and
\Delta \tilde{\BR}(\tilde E_e&gt;1.9 GeV, \tilde {s}^{max}_{h} &lt; 3.5 GeV^2) = (4.57 \pm 0.24 \pm 0.32) \times 10^{-4}
in the $B$ meson rest frames. The quoted errors are statistical and systematic, respectively.
The CKM matrix element $|V_{ub}|$ is determined from the measured $\Delta \tilde{\BR}$ using theoretical calculation based on Heavy Quark Expansion. The result is
$|V_{ub}| = (4.19 \pm 0.18{}^{+0.26}_{-0.20} {}^{+0.26}_{-0.25}) \times 10^{-3}, where the errors represent experimental uncertainties, uncertainties from HQE parameters and theoretical uncertainties, respectively.
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