2026-09-24T00:35:36Zhttps://api.repository.cam.ac.uk/server/oai/requestoai:www.repository.cam.ac.uk:1810/2977412019-10-12T07:30:31Zcom_1810_198332com_1810_256064col_1810_214775
Doubly charmed B decays with the LHCb experiment
10.17863/CAM.44796
Tully, Alison Maria
0000000287129055
Gibson, Valerie
$CP$ violation is a necessary ingredient to create a matter-antimatter asymmetry. However, the amount of $CP$ violation incorporated in the Standard Model is orders of magnitude too small to explain the observed asymmetry. This thesis documents two studies of $CP$ violation with doubly charmed $B$ decays. Both were performed using Run I data collected by the LHCb experiment in $pp$ collisions at the LHC. This corresponds to 1.0 fb$^{-1}$ collected at a centre-of-mass energy of 7 TeV and 2.0 fb$^{-1}$ collected at a centre-of-mass energy of 8 TeV.
The first analysis is a search for $B_c^+$ decays to two charm mesons, $B_c^+\to D^{(*)+}_{(s)}D^{(*)}$, where the second charm meson is either $D^0$ or $\overline{D}{}^0$, which are sensitive to the CKM angle \gamma. No evidence for signal is found and limits are set on twelve decay modes. The second analysis is the measurement of the $CP$ asymmetry in $B^+\to D^+_{(s)} \overline{D}{}^0$ decays. The results are
\begin{align*}
\mathcal{A}^{CP}(B^+\to D^+_{s} \overline{D}{}^0) &= (-0.4\pm 0.5\pm 0.5)\%,\\
\mathcal{A}^{CP}(B^+\to D^+ \overline{D}{}^0) &= (+2.3\pm 2.7\pm 0.4)\%,
\end{align*}
where the first uncertainty is statistical and the second systematic. This is the first measurement of $\mathcal{A}^{CP}(B^+\to D^+_{s} \overline{D}{}^0)$ and the most precise measurement of $\mathcal{A}^{CP}(B^+\to D^+\overline{D}{}^0)$ to date. The results are consistent with $CP$ symmetry.
University of Cambridge
2019-10-26
Thesis
Doctoral
Doctor of Philosophy (PhD)
en
Funded by the Science and Technology Facilities Council (STFC).
https://www.repository.cam.ac.uk/handle/1810/297741
https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/c6a71b2d-1838-4806-80f0-d92b04e61ba2/download
e7e3b40a4c903a2d6d67e548edb30a39
https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/3a66fb58-d454-4cd9-a57b-e87bf3d52d86/download
87eda9de84448d1f82354d60eee3eb5f
https://creativecommons.org/licenses/by-nc-nd/4.0/
LHCb
LHC
CP violation
CKM angle gamma
B physics
CERN
CP asymmetry