1,668 research outputs found
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 , ,
, , and . We show that the strength of the couplings
to the gauge bosons also determines the production mechanism of the scalar
particle via 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
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