Imaging Atmospheric Cherenkov Telescopes pointing determination using the trajectories of the stars in the field of view

We present a new approach to the pointing determination of Imaging Atmospheric Cherenkov Telescopes (IACTs). This method is universal and can be applied to any IACT with minor modifications. It uses the trajectories of the stars in the field of view of the IACT's main camera and requires neither dedicated auxiliary hardware nor a specific data taking mode. The method consists of two parts: firstly, we reconstruct individual star positions as a function of time, taking into account the point spread function of the telescope; secondly, we perform a simultaneous fit of all reconstructed star trajectories using the orthogonal distance regression method. The method does not assume any particular star trajectories, does not require a long integration time, and can be applied to any IACT observation mode. The performance of the method is assessed with commissioning data of the Large-Sized Telescope prototype (LST-1), showing the method's stability and remarkable pointing performance of the LST-1 telescope.Comment: Presented at the 38th International Cosmic Ray Conference (ICRC 2023), 2023 (arXiv:2309.08219

Exploring the Jet Multiplicity in the 750 GeV Diphoton Excess

The recent diphoton excess at the LHC has been explained tentatively by a Standard Model (SM) singlet scalar of 750 GeV in mass, in the association of heavy particles with SM gauge charges. These new particles with various SM gauge charges induce loop-level couplings of the new scalar to $WW$, $ZZ$, $Z\gamma$, $\gamma\gamma$, and $gg$. We show that the strength of the couplings to the gauge bosons also determines the production mechanism of the scalar particle via $WW,\, ZZ,\, Z\gamma,\, \gamma\gamma,\, gg$ fusion which leads to individually distinguishable jet distributions in the final state where the statistics will be improved in the ongoing run. The number of jets and the leading jet's transverse momentum distribution in the excess region of the diphoton signal can be used to determine the coupling of the scalar to the gauge bosons arising from the protons which subsequently determine the charges of the heavy particles that arise from various well-motivated models.Comment: 4 pages, 4 figures, 1 tabl

Reconstruction of extensive air shower images of the first Large Size Telescope prototype of CTA using a novel likelihood technique

Ground-based gamma-ray astronomy aims at reconstructing the energy and direction of gamma rays from the extensive air showers they initiate in the atmosphere. Imaging Atmospheric Cherenkov Telescopes (IACT) collect the Cherenkov light induced by secondary charged particles in extensive air showers (EAS), creating an image of the shower in a camera positioned in the focal plane of optical systems. This image is used to evaluate the type, energy and arrival direction of the primary particle that initiated the shower. This contribution shows the results of a novel reconstruction method based on likelihood maximization. The novelty with respect to previous likelihood reconstruction methods lies in the definition of a likelihood per single camera pixel, accounting not only for the total measured charge, but also for its development over time. This leads to more precise reconstruction of shower images. The method is applied to observations of the Crab Nebula acquired with the Large Size Telescope prototype (LST-1) deployed at the northern site of the Cherenkov Telescope Array.Comment: Proceedings of the 37th International Cosmic Ray Conference (ICRC 2021), Berlin, Germany. https://pos.sissa.it/395/71

Bottom-quark fusion processes at the LHC for probing \u3ci\u3eZ\u27\u3c/i\u3e models and \u3ci\u3eB\u3c/i\u3e-meson decay anomalies

We investigate models of a heavy neutral gauge boson Z\u27 coupling mostly to third generation quarks and second generation leptons. In this scenario, bottom quarks arising from gluon splitting can fuse into Z\u27 allowing the LHC to probe it. In the generic framework presented, anomalies in B-meson decays reported by the LHCb experiment imply a flavor-violating bs coupling of the featured Z\u27 constraining the lowest possible production cross section. A novel approach searching for a Z\u27(→ μμ) in association with at least one bottom-tagged jet can probe regions of model parameter space existing analyses are not sensitive to

Imaging Atmospheric Cherenkov Telescopes pointing determination using the trajectories of the stars in the field of view

38th International Cosmic Ray Conference (ICRC2023), 26 July - 3 August, 2023, Nagoya, Japan.Mykhailo Dalchenko and Matthieu Heller on behalf of the CTA-LST Project. Luis del Peral Gochicoa, Jose Julio Lozano Bahilo and Maria Dolores Rodriguez Frias belong to the CTA-LST Project.We present a new approach to the pointing determination of Imaging Atmospheric Cherenkov Telescopes (IACTs). This method is universal and can be applied to any IACT with minor modifications. It uses the trajectories of the stars in the field of view of the IACT’s main camera and requires neither dedicated auxiliary hardware nor a specific data taking mode. The method consists of two parts: firstly, we reconstruct individual star positions as a function of time, taking into account the point spread function of the telescope; secondly, we perform a simultaneous fit of all reconstructed star trajectories using the orthogonal distance regression method. The method does not assume any particular star trajectories, does not require a long integration time, and can be applied to any IACT observation mode. The performance of the method is assessed with commissioning data of the Large-Sized Telescope prototype (LST-1), showing the method’s stability and remarkable pointing performance of the LST-1 telescope

Bottom-quark fusion processes at the LHC for probing \u3ci\u3eZ\u27\u3c/i\u3e models and \u3ci\u3eB\u3c/i\u3e-meson decay anomalies

We investigate models of a heavy neutral gauge boson Z\u27 coupling mostly to third generation quarks and second generation leptons. In this scenario, bottom quarks arising from gluon splitting can fuse into Z\u27 allowing the LHC to probe it. In the generic framework presented, anomalies in B-meson decays reported by the LHCb experiment imply a flavor-violating bs coupling of the featured Z\u27 constraining the lowest possible production cross section. A novel approach searching for a Z\u27(→ μμ) in association with at least one bottom-tagged jet can probe regions of model parameter space existing analyses are not sensitive to

Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio