Malcolm John

Abstract:

A bstract This paper reports the observation of the decays $$ {B}_{(s)}^0 $$ B s 0 → D s 1 (2536) ∓ K ± using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb − 1 . The branching fractions of these decays are measured relative to the normalisation channel B 0 → $$ \overline{D} $$ D ¯ 0 K + K − . The D s 1 (2536) − meson is reconstructed in the $$ \overline{D} $$ D ¯ * (2007) 0 K − decay channel and the products of branching fractions are measured to be $$ {\displaystyle \begin{array}{c}\mathcal{B}\left({B}_s^0\to {D}_{s1}{(2536)}^{\mp }{K}^{\pm}\right)\times \mathcal{B}\left({D}_{s1}{(2536)}^{-}\to {\overline{D}}^{\ast }{(2007)}^0{K}^{-}\right)\\ {}=\left(2.49\pm 0.11\pm 0.12\pm 0.25\pm 0.06\right)\times {10}^{-5},\\ {}\mathcal{B}\left({B}^0\to {D}_{s1}{(2536)}^{\mp }{K}^{\pm}\right)\times \mathcal{B}\left({D}_{s1}{(2536)}^{-}\to {\overline{D}}^{\ast }{(2007)}^0{K}^{-}\right)\\ {}=\left(0.510\pm 0.021\pm 0.036\pm 0.050\right)\times {10}^{-5}.\end{array}} $$ B B s 0 → D s 1 2536 ∓ K ± × B D s 1 2536 − → D ¯ ∗ 2007 0 K − = 2.49 ± 0.11 ± 0.12 ± 0.25 ± 0.06 × 10 − 5 , B B 0 → D s 1 2536 ∓ K ± × B D s 1 2536 − → D ¯ ∗ 2007 0 K − .

Abstract:

Abstract The thermal properties of the LHCb Vertex Locator (VELO) are studied using the real-time detector alignment procedure. The variation of the position and orientation of the detector elements as a function of the operating temperature of the VELO is presented. This study uses a dataset collected by the LHCb experiment during a VELO temperature scan performed at the end of LHC Run 2 (October 2018). Significant shrinkage of the VELO modules is observed at the operating temperature of -30°C compared to the laboratory measurements on a single module taken at a range of temperatures from +45°C to -25°C. The thermal shrinkage expected from the extrapolation of laboratory measurements to lower temperatures, and the results of this alignment study are in good agreement.