In the Standard Model, the Higgs boson is a CP-even state with CP-conserving couplings; any deviations from this would be a sign of new physics. These CP properties can be probed by measuring Higgs ...decays to τ lepton pairs, in which the transverse correlation between the τ spins depends on CP. This paper develops such an analysis, using full simulation of signal and background events in the International Large Detector concept for the International Linear Collider. We consider Higgs-strahlung events (e+e−→HZ) in which the Z boson decays to electrons, muons, or hadrons, and the Higgs boson decays to τ leptons, which then decay either to τ±→π±ν or τ±→π±π0ν. Assuming 2 ab−1 of integrated luminosity at a center-of-mass energy of 250 GeV, the mixing angle between even and odd CP components of the τ pair from Higgs boson decays can be measured to a precision of 75 mrad (4.3°).
This paper presents a full simulation study of the measurement of the production cross section (σZH) of the Higgsstrahlung process e+e−→ZH and the Higgs boson mass (MH) at the International Linear ...Collider (ILC), using events in which a Higgs boson recoils against a Z boson decaying into a pair of muons or electrons. The analysis is carried out for three center-of-mass energies s=250, 350, and 500 GeV, and two beam polarizations eL−eR+ and eR−eL+, for which the polarizations of e− and e+ are (Pe−,Pe+)=(−80%,+30%) and (+80%, −30%), respectively. Assuming an integrated luminosity of 250 fb−1 for each beam polarization at s=250 GeV, where the best lepton momentum resolution is obtainable, σZH and MH can be determined with a precision of 2.5% and 37 MeV for eL−eR+ and 2.9% and 41 MeV for eR−eL+, respectively. Regarding a 20 year ILC physics program, the expected precisions for the HZZ coupling and MH are estimated to be 0.4% and 14 MeV, respectively. The event selection is designed to optimize the precisions of σZH and MH while minimizing the bias on the measured σZH due to discrepancy in signal efficiencies among Higgs decay modes. For the first time, model independence has been demonstrated to a sub-percent level for the σZH measurement at each of the three center-of-mass energies. The results presented show the impact of center-of-mass energy and beam polarization on the evaluated precisions and serve as a benchmark for the planning of the ILC run scenario.
The technological prototype of the CALICE highly granular silicon–tungsten electromagnetic calorimeter (SiW-ECAL) was tested in a beam at DESY in 2017. The setup comprised seven layers of silicon ...sensors. Each layer comprised four sensors, with each sensor containing an array of 256 5.5×5.5 mm2 silicon PIN diodes. The four sensors covered a total area of 18 × 18 cm and comprised a total of 1024 channels. The readout was split into a trigger line and a charge signal line. Key performance results for signal over noise for the two output lines are presented, together with a study of the uniformity of the detector response. Measurements of the response to electrons for the tungsten loaded version of the detector are also presented.
The first results of a multisensor airborne survey conducted off the western Iberian Coast are presented (including visible, lidar, and infrared imagery) and reveal the presence of internal solitary ...waves (ISWs) propagating into the nearshore region. For the first time, two‐dimensional lidar imagery is shown to detect the presence of ISWs, and the results are interpreted in a more comprehensive framework provided by the remaining instrumentation. Sea surface roughness patterns, resulting from the ISWs, are found to be imaged in the lidar data, where specular reflection causes slicks to appear as areas of significantly reduced backscatter. Moreover, the lidar data reveal an unprecedented view into the ISW surface and subsurface structures. Possible interpretations are discussed based on the accumulation of surfactants and air bubble entrainment at the leading edge of the ISWs (where maximum convergence occurs).
Key Points
Lidar imaging scanner is capable to detect near surface internal waves
2D lidar images reveal surfactants and air bubbles associated to internal waves
Lidar may be used to study small‐scale processes involving air‐sea interactions
Beam test performance of the SKIROC2 ASIC Amjad, M.S.; Anduze, M.; Augustin, J.-E. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2015, Letnik:
778
Journal Article
Recenzirano
Beam tests of the first layers of CALICE silicon tungsten ECAL technological prototype were performed in April and July 2012 using 1–6GeV electron beam at DESY. This paper presents an analysis of the ...SKIROC2 readout ASIC performance under test beam conditions.
The precise measurement of hadronic jet energy is crucial to maximise the physics reach of a future Linear Collider. An important ingredient required to achieve this is the efficient identification ...of photons within hadronic showers. One configuration of the ILD detector concept employs a highly granular silicon-tungsten sampling calorimeter to identify and measure photons, and the GARLIC algorithm described in this paper has been developed to identify photons in such a calorimeter. We describe the algorithm and characterise its performance using events fully simulated in a model of the ILD detector.
Why are the internal waves observed on the Portuguese shelf at 41°N (which have thermocline displacements of up to
45
m
) many times larger than expected from 2D shelf edge internal tide generation ...theory? Barotropic tidal forcing is too small to create them, either at the local shelf edge or from the nearby Oporto seamount. Using wave refraction techniques it is demonstrated that they must be created by the interaction between tidal currents and a major westward projection of the shelf edge about
50
km
to the south. The off-shelf propagating internal tidal energy thus generated is subsequently refracted back onto the shelf in the form of non-linear internal wave packets. Refraction explains not only how the energy reaches the shelf, but also the orientation of the waves relative to the shelf edge and details of their appearance in a synthetic aperture radar image. The result demonstrates that shelf edge internal tide generation can be more complex than is suggested by the 2D approach, and that global shelf edge internal tide energy must be larger than previously thought.
The concept of "particle flow" has been developed to optimise the jet energy resolution by distinguishing the different jet components. A highly granular calorimeter designed for the particle flow ...algorithm provides an unprecedented level of detail for the reconstruction of calorimeter showers and enables new approaches to shower analysis. In this paper the measurement and use of the fractal dimension of showers is described. The fractal dimension is a characteristic number that measures the global compactness of the shower. It is highly dependent on the primary particle type and energy. Its application in identifying particles and estimating their energy is described in the context of a calorimeter designed for the International Linear Collider.
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