An analysis of the B 0 → K * 0 ( → K + π − ) μ + μ − decay is presented using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 8.4 fb − 1 . The full set of C P -averaged and C P -asymmetric angular observables is determined in bins of the invariant mass squared of the dimuon system, as well as the branching fraction relative to the B 0 → J / ψ ( → μ + μ − ) K + π − decay. For the first time, the full set of observables pertaining to the K + π − S-wave contribution to the final state are presented and consideration is given to effects arising from the mass of the muons. The extracted C P -asymmetry observables show no significant deviations from zero. The measurements of the C P -averaged observables and the branching fractions continue to exhibit the pattern of tensions with the standard model predictions that have been seen in previous analyses that use part of the dataset considered in this Letter.

The first observation of the doubly charmed baryon Ξ c c + is reported through its decay to the Λ c + K − π + final state, with a statistical significance exceeding seven standard deviations. The observation is made using proton-proton collision data collected in 2024 with the LHCb Run 3 detector at a center-of-mass energy of 13.6 TeV, corresponding to a total integrated luminosity of 6.9 fb − 1 . The Ξ c c + mass is measured to be 3619.97 ± 0.83 ± 0.26 − 1.30 + 1.90 MeV / c 2 , where the first uncertainty is statistical, the second is systematic, and the third is due to the unknown Ξ c c + lifetime, which is assumed to lie in the range 15–160 fs with a baseline value of 45 fs. The difference between the masses of the Ξ c c + and Ξ c c + + baryons is determined to be − 1.77 ± 0.84 ± 0.15 − 1.30 + 1.90 MeV / c 2 . This is the first observation of a new particle made with the LHCb Run 3 detector.

A bstract: A measurement of the branching fraction for the decay $$ \Lambda \to p{\mu}^{-}{\overline{\nu}}_{\mu } $$ Λ → p μ − ν ¯ μ is presented using pp collision data collected by the LHCb experiment at a centre-of-mass energy of 13 TeV. The analysis is based on data recorded between 2016 and 2018, corresponding to an integrated luminosity of 5.4 fb ^{− 1} . The result is obtained using Λ → pμ ⁻ decays as a normalisation channel. The measured branching fraction is $$ \mathcal{B}\left(\Lambda \to p{\mu}^{-}{\overline{\nu}}_{\mu}\right)=\left(1.462\pm 0.016\pm 0.100\pm 0.011\right)\times {10}^{-4} $$ B Λ → p μ − ν ¯ μ = 1.462 ± 0.016 ± 0.100 ± 0.011 × 10 − 4 , where the uncertainties are statistical, systematic, and due to the limited knowledge of the normalisation mode branching fraction, respectively. This result improves the precision of the branching fraction measurement by a factor of two compared to the previous best measurement and sets a more stringent bound on lepton flavour universality in s → u quark transitions. It is consistent with previous measurements, and the extracted lepton flavour universality test observable, $$ {R}^{\mu e}=\frac{\Gamma \left(\Lambda \to p{\mu}^{-}{\overline{\nu}}_{\mu}\right)}{\Gamma \left(\Lambda \to p{e}^{-}{\overline{\nu}}_e\right)}=0.175\pm 0.012 $$ R μe = Γ Λ → p μ − ν ¯ μ Γ Λ → p e − ν ¯ e = 0.175 ± 0.012 , agrees with the Standard Model prediction.

Future experiments at hadron colliders require an evolution of the tracking sensors to ensure sufficient radiation hardness as well as space and time resolution to handle unprecedented particle fluxes. 3D diamond sensors with laser-graphitized electrodes are promising candidates due to their strong binding energy, small atomic number, and high carrier mobility. However, the high resistance of the engraved electrodes delays the propagation of the induced signals towards the readout electronics, thereby degrading the precision of the timing measurements. So far, this effect has been the dominant factor limiting the time resolution of these devices, with other contributions, such as those due to electric field inhomogeneities or electronic noise, typically neglected. Recent advancements in graphitization technology, however, motivate a renewed effort in modeling signal generation in 3D diamond detectors, to achieve more reliable predictions. To this purpose, we apply an extended version of the Ramo-Shockley theorem, describing the effect of signal propagation as a time-dependent weighting potential, obtained by numerically solving the Maxwell's equations in a quasi-static approximation. We developed a custom spectral method solver and validated it against COMSOL MultiPhysics® . The response of the modeled sensor to a beam of particles is then simulated using Garfield++ and is compared to the data acquired in a beam test carried on in 2021 by the TimeSPOT Collaboration at the SPS, at CERN. Based on the results obtained with this simulation workflow, we conclude that reducing the resistivity of the graphitic columns remains the priority for significantly improving the time resolution of 3D diamond detectors. Once achieved, optimization of the detector geometry and readout electronics design will become equally important steps to further enhance the timing performance of these devices.

Hydrogenated amorphous silicon (a-Si:H) devices on flexible substrates are currently being studied for application in dosimetry and beam flux measurements. The necessity of in vivo dosimetry requires thin devices with maximal transparency and flexibility. For this reason, a thin (<10 µm) a-Si:H device deposited on a thin polyimide sheet is a very valid option for this application. Furthermore, a-Si:H is a material that has an intrinsically high radiation hardness. In order to develop these devices, the HASPIDE (Hydrogenated Amorphous Silicon Pixel Detectors) collaboration has implemented two different device configurations: n-i-p type diodes and charge-selective contact devices.Charge-selective contact-based devices have been studied for solar cell applications and, recently, the above-mentioned collaboration has tested these devices for X-ray dose measurements. In this paper, the HASPIDE collaboration has studied the X-ray and proton response of charge-selective contact devices deposited on Polyimide. The linearity of the photocurrent response to X-ray versus dose-rate has been assessed at various bias voltages. The sensitivity to protons has also been studied at various bias voltages and the wide range linearity has been tested for fluxes in the range from 8.3 × 10⁷ to 2.49 × 10¹⁰ p/(cm² s).

An amplitude analysis of the B + → ( π + π − ) ( K S 0 π + ) decay is performed in the mass regions 0.30 < m π + π − < 1.10 GeV / c 2 and 0.75 < m K S 0 π + < 1.20 GeV / c 2 , using p p collision data recorded with the LHCb detector corresponding to an integrated luminosity of 9 fb − 1 . The polarization fractions and C P asymmetries for B + → ρ ( 770 ) 0 K * ( 892 ) + decays are measured. Violation of the C P symmetry in the decay B + → ρ ( 770 ) 0 K * ( 892 ) + is observed for the first time, with a significance exceeding 9 standard deviations. The C P asymmetry is measured to be A C P = 0.507 ± 0.062 ( stat ) ± 0.024 ( syst ) and the C P -averaged longitudinal polarization fraction of f L = 0.720 ± 0.028 ( stat ) ± 0.009 ( syst ) . The measurements help to shed light on the polarization puzzle of B mesons decaying to two vector mesons.