The LHCb upgrade represents a major change of the experiment. The detectors have been almost completely renewed to allow running at an instantaneous luminosity five times larger than that of the previous running periods. Readout of all detectors into an all-software trigger is central to the new design, facilitating the reconstruction of events at the maximum LHC interaction rate, and their selection in real time. The experiment's tracking system has been completely upgraded with a new pixel vertex detector, a silicon tracker upstream of the dipole magnet and three scintillating fibre tracking stations downstream of the magnet. The whole photon detection system of the RICH detectors has been renewed and the readout electronics of the calorimeter and muon systems have been fully overhauled. The first stage of the all-software trigger is implemented on a GPU farm. The output of the trigger provides a combination of totally reconstructed physics objects, such as tracks and vertices, ready for final analysis, and of entire events which need further offline reprocessing. This scheme required a complete revision of the computing model and rewriting of the experiment's software.

Resonant contributions in $B^0\to \overline{D}{{}^{0}D}_s^{+}{\pi }^{-}$ and $B^{+}\to D^{-}{D}_s^{+}{\pi }^{+}$ decays are determined with an amplitude analysis, which is performed both separately and simultaneously, where in the latter case isospin symmetry between the decays is assumed. The analysis is based on data collected by the LHCb detector in proton-proton collisions at center-of-mass energies of 7, 8, and 13 TeV. The full data sample corresponds to an integrated luminosity of $9{\mathrm{fb}}^{-1}$. A doubly charged spin-0 open-charm tetraquark candidate together with a neutral partner, both with masses near 2.9 GeV, are observed in the $D_s\pi$ decay channel.

The time-integrated $CP$ asymmetry in the Cabibbo-suppressed decay $D^0\to K^{-}{K}^{+}$ is measured using proton-proton collision data, corresponding to an integrated luminosity of $5.7{\mathrm{fb}}^{-1}$ collected at a center-of-mass energy of 13 TeV with the LHCb detector. The $D^0$ mesons are required to originate from promptly produced $D^{*+}\to D^0{\pi }^{+}$ decays, and the charge of the companion pion is used to determine the flavor of the charm meson at production. The time-integrated $CP$ asymmetry is measured to be ${\mathcal{A}}_{CP}(K^{-}{K}^{+})=[6.8\pm 5.4\pm 1.6]\times {10}^{-4}$ where the first uncertainty is statistical and the second systematic. The direct $CP$ asymmetries in $D^0\to K^{-}{K}^{+}$ and $D^0\to {\pi }^{-}{\pi }^{+}$ decays, $a_{K^{-}{K}^{+}}^d$ and $a_{{\pi }^{-}{\pi }^{+}}^d$, are derived by combining ${\mathcal{A}}_{CP}(K^{-}{K}^{+})$ with the time-integrated $CP$ asymmetry difference, $\mathrm{\Delta }{A}_{CP}={\mathcal{A}}_{CP}(K^{-}{K}^{+})-{\mathcal{A}}_{CP}({\pi }^{-}{\pi }^{+})$, and other inputs, giving $a_{K^{-}{K}^{+}}^d=(7.7\pm 5.7)\times {10}^{-4},a_{{\pi }^{-}{\pi }^{+}}^d=(23.2\pm 6.1)\times {10}^{-4},$with a correlation coefficient corresponding to $\rho =0.88$. The compatibility of these results with $CP$ symmetry is 1.4 and 3.8 standard deviations for $D^0\to K^{-}{K}^{+}$ and $D^0\to {\pi }^{-}{\pi }^{+}$ decays, respectively. This is the first evidence for direct $CP$ violation in a specific $D^0$ decay.

Aim: To investigate the immune responses and antitumor efficacy of immunoactive polysaccharide functionalized gold nanocomposites (APS-AuNP). Materials & methods: Immunoregulation of APS-AuNP on de...

A study of Λ b 0 and Ξ b 0 decays to Λ h + h ′ − ( h ( ′ ) = π , K ) is performed using p p collision data collected by the LHCb experiment during LHC Runs 1–2, corresponding to an integrated luminosity of 9 fb − 1 . The branching fractions for these decays are measured using the Λ b 0 → Λ c + ( → Λ π + ) π − decay as a control channel. The decays Λ b 0 → Λ π + π − and Ξ b 0 → Λ K − π + are observed for the first time. For decay modes with sufficient signal yields, C P asymmetries are measured in the full and localized regions of the final-state phase space. Evidence is found for C P violation in the Λ b 0 → Λ K + K − decay, interpreted as originating primarily from an asymmetric Λ b 0 → N * + K − decay amplitude. The measured C P asymmetries for other decays are compatible with zero.

The branching fraction ratios of B ¯ 0 → D + τ − ν ¯ τ and B ¯ 0 → D * + τ − ν ¯ τ decays are measured with respect to their muonic counterparts, using a data sample corresponding to an integrated luminosity of 2.0 fb − 1 collected by the LHCb experiment in proton-proton collisions at s = 13 TeV . The reconstructed final states are formed by combining D + mesons with τ − → μ − ν ¯ μ ν τ candidates, where the D + is reconstructed via the D + → K − π + π + decay. The results are R ( D + ) = 0.249 ± 0.043 ± 0.047 , R ( D * + ) = 0.402 ± 0.081 ± 0.085 , where the first uncertainties are statistical and the second systematic. The two measurements have a correlation coefficient of − 0.39 and are compatible with the standard model.