The SNO+ detector operated initially as a water Cherenkov detector. The implementation of a sealed covergas system midway through water data taking resulted in a significant reduction in the activity of $^{222}$Rn daughters in the detector and allowed the lowest background to the solar electron scattering signal above 5 MeV achieved to date. This paper reports an updated SNO+ water phase $^8$B solar neutrino analysis with a total livetime of 282.4 days and an analysis threshold of 3.5 MeV. The $^8$B solar neutrino flux is found to be $\left(2.32^{+0.18}_{-0.17}\text{(stat.)}^{+0.07}_{-0.05}\text{(syst.)}\right)\times10^{6}$ cm$^{-2}$s$^{-1}$ assuming no neutrino oscillations, or $\left(5.36^{+0.41}_{-0.39}\text{(stat.)}^{+0.17}_{-0.16}\text{(syst.)} \right)\times10^{6}$ cm$^{-2}$s$^{-1}$ assuming standard neutrino oscillation parameters, in good agreement with both previous measurements and Standard Solar Model Calculations. The electron recoil spectrum is presented above 3.5 MeV.

A measurement of the time-dependent ratio of the $D^0\rightarrow K^+\pi^-$ to $\overline{D}^0\rightarrow K^+\pi^-$ decay rates is reported. The analysis uses a sample of proton-proton collisions corresponding to an integrated luminosity of 6 fb$^-1$ recorded by the LHCb experiment from 2015 through 2018 at a center-of-mass energy of 13 TeV. The $D^0$ meson is required to originate from a $D^{*+}\rightarrow D^0\pi^+$ decay, such that its flavor at production is inferred from the charge of the accompanying pion. The measurement is performed simultaneously for the $K^+\pi^-$ and $K^-\pi^+$ final states, allowing both mixing and $CP$-violation parameters to be determined. The value of the ratio of the decay rates at production is determined to be $R_{K\pi} = (343.1 \pm 2.0) \times 10^{-5}$. The mixing parameters are measured to be $c_{K\pi} = (51.4 \pm 3.5) \times 10^{-4}$ and $c_{K\pi}^{\prime} = (13 \pm 4) \times 10^{-6}$, where $\sqrt{R_{K\pi}}c_{K\pi}$ is the linear coefficient of the expansion of the ratio as a function of decay time in units of the $D^0$ lifetime, and $c_{K\pi}^{\prime}$ is the quadratic coefficient, both averaged between the $K^+\pi^-$ and $K^-\pi^+$ final states. The precision is improved relative to the previous best measurement by approximately 60%. No evidence for $CP$ violation is found.

Charged particle reconstruction is one the most computationally heavy components of the full event reconstruction of Large Hadron Collider (LHC) experiments. Looking to the future, projections for the High Luminosity LHC (HL-LHC) indicate a superlinear growth for required computing resources for single-threaded CPU algorithms that surpass the computing resources that are expected to be available. The combination of these facts creates the need for efficient and computationally performant pattern recognition algorithms that will be able to run in parallel and possibly on other hardware, such as GPUs, given that these become more and more available in LHC experiments and high-performance computing centres. Line Segment Tracking (LST) is a novel such algorithm which has been developed to be fully parallelizable and hardware agnostic. The latter is achieved through the usage of the Alpaka library. The LST algorithm has been tested with the CMS central software as an external package and has been used in the context of the CMS HL-LHC High Level Trigger (HLT). When employing LST for pattern recognition in the HLT tracking, the physics and timing performances are shown to improve with respect to the ones utilizing the current pattern recognition algorithms. The latest results on the usage of the LST algorithm within the CMS HL-LHC HLT are presented, along with prospects for further improvements of the algorithm and its CMS central software integration.

This study investigates the characteristics of Silicon Photomultipliers (SiPMs) with different pixel densities, focusing on their response across a wide dynamic range. Using an experimental setup that combines laser source and photomultiplier tubes (PMTs) for accurate light intensity calibration, we evaluated SiPMs with pixel counts up to 244,719 and pixel sizes down to 6 micrometers. To complement the experimental findings, a "Toy Monte Carlo" was developed to replicate the SiPMs' reponses under different lighting conditions, incorporating essential parameters such as pixel density and photon detection efficiency. The simulations aligned well with the experimental results for laser light, demonstrating similar nonlinearity trends. For BGO scintillation light, the simulations, which included multi-firing effect of pixels, showed significantly higher photon counts compared to the laser simulations. Furthermore, the simulated response derived in this research offer a method to correct for SiPM saturation effect, enabling accurate measurements in high-energy events even with SiPMs having a limited number of pixels.

This paper presents the design and optimization of a LYSO crystal-based electromagnetic calorimeter (ECAL) for the DarkSHINE experiment, which aims to search for dark photon as potential dark force mediator. The ECAL design has been meticulously evaluated through comprehensive simulations, focusing on optimizing dimensions, material choices, and placement within the detector array to enhance sensitivity in search for dark photon signatures while balancing cost and performance. The concluded ECAL design, comprising 2.5$\times$2.5$\times$4 cm$^3$ LYSO crystals arranged in a 52.5$\times$52.5$\times$44 cm$^3$ structure, ensures high energy resolution and effective energy containment. The study also explored the energy distribution across different ECAL regions and established a dynamic range for energy measurements, with a 4 GeV limit per crystal deemed sufficient. Additionally, the radiation tolerance of ECAL components was assessed, confirming the sustainability of LYSO crystals and radiation-resistant silicon sensors.

Using inelastic scattering of charmed strange mesons by open-charm mesons in Pb-Pb collisions at the Large Hadron Collider, we study the production of $\psi (4040)$, $\psi (4160)$, and $\psi (4415)$ mesons. Master rate equations with the inelastic scattering are established. The scattering is caused by quark interchange in association with color interactions between all constituent pairs in different mesons. We consider fifty-one reactions between charmed strange mesons and open-charm mesons. Unpolarized cross sections for the reactions are obtained from a temperature-dependent interquark potential. Temperature dependence of the cross sections leads to that contributions of the reactions to the production of $\psi (4040)$, $\psi (4160)$, and $\psi (4415)$ change with decreasing temperature during evolution of hadronic matter. For central Pb-Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV it turned out from the master rate equations that the $\psi(4040)$ number density is larger than the $\psi(4160)$ number density which is larger than the $\psi(4415)$ number density.

In certain kinematic and particle mass configurations, triangle singularities may lead to line-shapes which mimic the effects of resonances. This well-known effect is scrutinized here in the presence of final-state rescattering. The goal is achieved first by utilizing general arguments provided by Landau equations, and second by applying a modern scattering formalism with explicit two- and three-body unitarity.

Exclusive diffractive meson production represents a golden channel for investigating gluonic saturation inside nucleons and nuclei. In this letter, we settle a systematic framework to deal with beyond leading power corrections at small-$x$, including the saturation regime, and obtain the $\gamma^{*} \rightarrow M (\rho, \phi, \omega)$ impact factor with both incoming photon and outgoing meson carrying arbitrary polarizations. This is of particular interest since the saturation scale at modern colliders, although entering a perturbative regime, is not large enough to prevents higher-twist effects to be sizable.