A detailed study exploiting novel trigger and reconstruction techniques developed to search for Beyond Standard Model (BSM) Long-Lived Particles (LLPs) with very displaced vertices is presented. Building on feasibility studies that have successfully reconstructed Standard Model decays occurring up to 8m forward of the interaction point in LHCb’s magnet region, the search for LLP particles into charged final states exploits LHCb’s unique forward geometry and segmented tracking system—comprising the Vertex Locator, Upstream Tracker, and SciFi stations—to extend sensitivity into previously inaccessible regions. The proceeding will cover innovative trigger strategies implemented in LHCb’s software trigger for inclusively selecting very displaced dimuon pairs, alongside advanced offline selection methods using multivariate analysis methods to robustly suppress background while maintaining high signal efficiency. Preliminary sensitivity estimates for Dark Higgs 𝐻′ → 𝜇+𝜇− search indicate that these approaches can achieve competitive performance compared to dedicated LLP experiments. Future prospects will also be discussed. This work aims to provide a comprehensive framework for enhancing LLP discovery potential at LHCb and offers insights that could be beneficial for the broader BSM LLP search community.

containing an anticharm quark in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=13.6 \ \text{TeV}$ using data recorded by the LHCb experiment. The asymmetries of $D^0$, $D^+$ and $D^+_s$ mesons are measured for two-dimensional intervals in transverse momentum and pseudorapidity, within the range $2.5 < p_T < 25.0 \ \text{GeV}/c$ and $2.0 < \eta < 4.5$. No significant production asymmetries are observed. Comparisons to the Pythia 8 and Herwig 7 event generators are also presented, and their agreement with the data is evaluated. These measurements constitute the first measurements of production asymmetries at this centre-of-mass energy of colliding beams, and the first measurements with the LHCb Run 3 detector.

Prospects to search for dilepton resonances below 100 MeV/$c^2$ with the upgraded LHCb detector are presented. These resonances could be mediators between the Standard Model and a hypothesised dark sector, and are investigated for the first time at a hadron collider in the energy region below the dimuon threshold. The search is based on radiative charmed-meson decays, by combining a displaced charmed meson to an electron-positron pair. Increased instantaneous luminosity and triggering efficiency on charmed hadrons since Run 3 are crucial to obtain results competitive with B factories. Ongoing efforts, based on 2024 data, aim to use this unique dataset to test dark-photons, and in particular protophobic models that could explain the X17 anomaly observed by the ATOMKI collaboration in collisions between protons and nuclei.

A measurement of CP asymmetry in D0→ K0 SK0 S decays is reported, based on a data sample of proton-proton collisions collected with the LHCb Upgrade I detector in 2024 at a centre-of-mass energy of 13.6 TeV, corresponding to an integrated luminosity of 6.2 fb−1 . The D0→ K0 S π +π − decay is used as calibration channel to cancel residual detection and production asymmetries. The time-integrated CP asymmetry for the D0→ K0 SK0 S mode is measured to be A CP (D0→ K0 SK0 S ) = (1.86 ± 1.04 ± 0.41)%, where the first uncertainty is statistical, and the second is systematic. This is the most precise determination of this quantity to date.

Heavy Neutral Leptons (HNLs) are hypothetical long-lived particles that extend the Standard Model (SM) and provide a natural explanation for the non-zero neutrino masses. In addition, they could play a key role in addressing some of the most profound open questions in particle physics and cosmology, including the origin of the matter–antimatter asymmetry via baryogenesis. In this poster, we present the status and state-of-the-art of HNL searches at the LHCb experiment. We report the latest and most stringent LHCb limits on muon-coupled HNLs in the 1.6–5 GeV mass range, obtained from a Run 2 (2016–2018) analysis targeting displaced vertices corresponding to HNL flight distances of 0.02–0.5 m. Looking ahead, for Run 3 we introduce a novel reconstruction technique that exploits track segments downstream of the LHCb magnet, thereby extending the accessible displacement window to 0.5–8.0 m. This approach enhances sensitivity dramatically, providing a 40-fold increase in the number of accessible HNL events and extending the lifetime reach by a factor of 16 compared to the Run 2 analysis. A dedicated sensitivity study shows how these improvements translate into a significantly extended reach in the HNL mass–coupling parameter space, positioning LHCb to set world-leading constraints on HNLs.

I hope I understood your question correctly, but tell me if you would like me to submit the abstract somewhere else. In any case, here is my abstract: During the Long Shutdown 2 (LS2) period, the LHCb experiment underwent an upgrade to its tracking system. Part of this is a new pixel detector close to the interaction point called the VErtex LOcator’s (VELO). An accurate simulation of its behaviour is crucial to exploit the detector in physics analysis. In this poster, a method for measuring cluster efficiencies in data and how it is used to optimize the LHCb VELO simulation, will be shown. The presented method has shown to be sensitive to minor variations due to local ASIC inefficiencies or evolution of the sensor behaviour with radiation and high voltage, and is applied in blocks of similar operation condition. These improved simulation conditions are applied centrally and will be used by all analyses.

The innovative fixed-target programme initiated by the LHCb exper- iment during the LHC Run 2 has been enhanced for Run 3 with the introduction of a dedicated gas injection system, SMOG2. This upgrade features a gas cell to boost fixed-target luminosity and that allows the injection of non-noble gases. SMOG2 enables the collection of large datasets from pA and PbA fixed-target collisions, including high-statistics samples of charm hadrons. Recent results on charm hadronization in fixed-target collisions with SMOG are reported and the latest open charm samples recorded with SMOG2 during Run 3 are also presented.

A search for K0 S(L) → π +π −µ +µ − decays is performed using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb−1 . No K0 S(L) → π +π −µ +µ − signals are found and upper limits are set for the first time on the branching fractions B(K0 S → π +π −µ +µ −) < 1.4 × 10−9 and B(K0 L→ π +π −µ +µ −) < 6.6 × 10−7 , at the 90% confidence level

The second software trigger (HLT2) of the LHCb experiment employs a combination of cut-based and multivariate selections, with the latter achieving superior performance but requiring background samples for training. This work investigates an alternative, unsupervised approach based on an autoencoder trained exclusively on signal Monte Carlo (MC) samples of the decay $\Lambda_b^0 \rightarrow p \pi^- \mu^+ \mu^-$. The autoencoder is trained using approximately 200k truth-matched events and evaluated using HLT1-filtered data to estimate trigger rates as a function of the reconstruction-error threshold. For the studied decay, the method provides both higher signal efficiency and lower rate compared to the current cut-based HLT2 line. The trained model is deployed in HLT2 through the ONNX framework, enabling real-time operation. The new selection has been active since the September MD, and its performance during data taking and its implications for offline analyses are currently under evaluation.

The LHCb experiment in Run 3 features a full software trigger: the GPU-based HLT1 with O(100) and the CPU-based HLT2 with O(3000) trigger lines. Human control of every aspect of data quality in a complex system of this scale is extremely difficult and requires a high degree of automation to be efficient. To address this, we present IntelliRTA, a monitoring dashboard that provides a holistic view of the trigger lines and the data quality. It correlates HLT1 rates with detector and beam conditions to identify the impact of potential issues. It features automated trend analysis for all HLT2 lines and flags unexpected rate and bandwidth changes. Furthermore, it consolidates several other tools such as a bandwidth monitor onto a single webpage, providing a unified user interface.