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First observation of the decay $\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^{(\ast)0} K^-$ in preparation of a pentaquark search in the $\Lambda_c^+ \bar{D}^{(\ast)0}$ system at the LHCb experiment
This thesis reports the first observation of the decays $\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^0 K^-$ and $\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^\ast(2007)^0 K^-$ using data corresponding to an integrated luminosity of 3 fb${}^-1$ collected at 7 and 8 TeV center-of-mass energies in proto...
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Lenguaje: | eng |
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2018
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Acceso en línea: | http://cds.cern.ch/record/2640677 |
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author | Stahl, Marian |
author_facet | Stahl, Marian |
author_sort | Stahl, Marian |
collection | CERN |
description | This thesis reports the first observation of the decays $\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^0 K^-$ and $\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^\ast(2007)^0 K^-$ using data corresponding to an integrated luminosity of 3 fb${}^-1$ collected at 7 and 8 TeV center-of-mass energies in proton-proton collisions with the LHCb detector. A future amplitude analysis of these $\Lambda_b^0$ decays allows to search the $\Lambda_c^+ \bar{D}^{(\ast)0}$ system for resonant contributions from $P_c^+$ pentaquarks. Two of which have been discovered in 2015 by the LHCb experiment in the J/$\psi p$ system. Observing $P_c^+$ pentaquarks in the $\Lambda_c^+ \bar{D}^{(\ast)0}$ system would allow for further insight to the nature of these resonances. In addition, the measurement of the $\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^0 K^-$ and $\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^\ast(2007)^0 K^-$ branching fractions relative to the decay $\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^0 K^-$ is made, resulting in \begin{alignat}{1} \frac{\mathscr{B}(\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^0 K^-)}{\mathscr{B}(\Lambda_b^0 \rightarrow \Lambda_c^+ D_s^-)} &= \left(14.04 \pm 0.58 \pm 0.33 \pm 0.45 \right)\,\% \nonumber \\ \frac{\mathscr{B}(\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^\ast(2007)^0 K^-)}{\mathscr{B}(\Lambda_b^0 \rightarrow \Lambda_c^+ D_s^-)} &= \left(43.5 \pm 1.4 {}^{+1.2}_{-0.8} \pm 1.4 \right)\,\% \nonumber \end{alignat} The first uncertainty is statistical, the second systematic and the third is due to the knowledge of the branching fractions of $D_s^- \rightarrow K^- K^+ \pi^-$ and $\bar{D}^0 \rightarrow K^+ \pi^-$. It is shown that the obtained result agrees with previously measured $B\rightarrow D\bar{D}^{(\ast)0} K^-$ branching fractions, as expected from the lowest order approximation of QCD factorisation. The developed methods are integral components of the future amplitude analysis of $\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^0 K^-$. These and further algorithms presented here were developed in a modularised way to be applied to a variety of analyses at LHCb, in particular pentaquark searches. |
id | cern-2640677 |
institution | Organización Europea para la Investigación Nuclear |
language | eng |
publishDate | 2018 |
record_format | invenio |
spelling | cern-26406772019-09-30T06:29:59Zhttp://cds.cern.ch/record/2640677engStahl, MarianFirst observation of the decay $\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^{(\ast)0} K^-$ in preparation of a pentaquark search in the $\Lambda_c^+ \bar{D}^{(\ast)0}$ system at the LHCb experimentParticle Physics - ExperimentThis thesis reports the first observation of the decays $\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^0 K^-$ and $\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^\ast(2007)^0 K^-$ using data corresponding to an integrated luminosity of 3 fb${}^-1$ collected at 7 and 8 TeV center-of-mass energies in proton-proton collisions with the LHCb detector. A future amplitude analysis of these $\Lambda_b^0$ decays allows to search the $\Lambda_c^+ \bar{D}^{(\ast)0}$ system for resonant contributions from $P_c^+$ pentaquarks. Two of which have been discovered in 2015 by the LHCb experiment in the J/$\psi p$ system. Observing $P_c^+$ pentaquarks in the $\Lambda_c^+ \bar{D}^{(\ast)0}$ system would allow for further insight to the nature of these resonances. In addition, the measurement of the $\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^0 K^-$ and $\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^\ast(2007)^0 K^-$ branching fractions relative to the decay $\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^0 K^-$ is made, resulting in \begin{alignat}{1} \frac{\mathscr{B}(\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^0 K^-)}{\mathscr{B}(\Lambda_b^0 \rightarrow \Lambda_c^+ D_s^-)} &= \left(14.04 \pm 0.58 \pm 0.33 \pm 0.45 \right)\,\% \nonumber \\ \frac{\mathscr{B}(\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^\ast(2007)^0 K^-)}{\mathscr{B}(\Lambda_b^0 \rightarrow \Lambda_c^+ D_s^-)} &= \left(43.5 \pm 1.4 {}^{+1.2}_{-0.8} \pm 1.4 \right)\,\% \nonumber \end{alignat} The first uncertainty is statistical, the second systematic and the third is due to the knowledge of the branching fractions of $D_s^- \rightarrow K^- K^+ \pi^-$ and $\bar{D}^0 \rightarrow K^+ \pi^-$. It is shown that the obtained result agrees with previously measured $B\rightarrow D\bar{D}^{(\ast)0} K^-$ branching fractions, as expected from the lowest order approximation of QCD factorisation. The developed methods are integral components of the future amplitude analysis of $\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^0 K^-$. These and further algorithms presented here were developed in a modularised way to be applied to a variety of analyses at LHCb, in particular pentaquark searches.CERN-THESIS-2018-176oai:cds.cern.ch:26406772018-09-28T08:00:41Z |
spellingShingle | Particle Physics - Experiment Stahl, Marian First observation of the decay $\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^{(\ast)0} K^-$ in preparation of a pentaquark search in the $\Lambda_c^+ \bar{D}^{(\ast)0}$ system at the LHCb experiment |
title | First observation of the decay $\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^{(\ast)0} K^-$ in preparation of a pentaquark search in the $\Lambda_c^+ \bar{D}^{(\ast)0}$ system at the LHCb experiment |
title_full | First observation of the decay $\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^{(\ast)0} K^-$ in preparation of a pentaquark search in the $\Lambda_c^+ \bar{D}^{(\ast)0}$ system at the LHCb experiment |
title_fullStr | First observation of the decay $\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^{(\ast)0} K^-$ in preparation of a pentaquark search in the $\Lambda_c^+ \bar{D}^{(\ast)0}$ system at the LHCb experiment |
title_full_unstemmed | First observation of the decay $\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^{(\ast)0} K^-$ in preparation of a pentaquark search in the $\Lambda_c^+ \bar{D}^{(\ast)0}$ system at the LHCb experiment |
title_short | First observation of the decay $\Lambda_b^0 \rightarrow \Lambda_c^+ \bar{D}^{(\ast)0} K^-$ in preparation of a pentaquark search in the $\Lambda_c^+ \bar{D}^{(\ast)0}$ system at the LHCb experiment |
title_sort | first observation of the decay $\lambda_b^0 \rightarrow \lambda_c^+ \bar{d}^{(\ast)0} k^-$ in preparation of a pentaquark search in the $\lambda_c^+ \bar{d}^{(\ast)0}$ system at the lhcb experiment |
topic | Particle Physics - Experiment |
url | http://cds.cern.ch/record/2640677 |
work_keys_str_mv | AT stahlmarian firstobservationofthedecaylambdab0rightarrowlambdacbardast0kinpreparationofapentaquarksearchinthelambdacbardast0systematthelhcbexperiment |