Hadron shower decomposition in a highly granular calorimeter
The spatial development of showers induced by positive hadrons with momenta 10-80 GeV in the highly granular CALICE scintillator-steel analogue hadronic calorimeter is analysed. The parametrisation of both longitudinal and radial shower profiles with the two- component functions are fit to the test beam data and simulations using the physics lists QGSP_BERT and FTFP_BERT from GEANT4 version 9.6 patch 01. The shower parameters, describing the longitudinal tail and radial halo, are in good agreement between data and simulations and are similar for pions and protons. For the longitudinal development, the most significant difference between data and simulations is in the relative containment of the separated components. For the radial development, the core slope parameter is underestimated by simulations. The physics list FTFP_BERT gives a very good description of proton showers in the studied energy range and gives better predictions of the pion shower development than QGSP_BERT.
Particle flow calorimetry and the PandoraPFA algorithm
Abstract The Particle Flow (PFlow) approach to calorimetry promises to deliver unprecedented jet energy resolution for experiments at future high energy colliders such as the proposed International Linear Collider (ILC). This paper describes the PandoraPFA particle flow algorithm which is then used to perform the first systematic study of the potential of high granularity PFlow calorimetry. For simulated events in the ILD detector concept, a jet energy resolution of σ E / E ≲ 3.8 % is achieved for 40–400 GeV jets. This result, which demonstrates that high granularity PFlow calorimetry can meet the challenging ILC jet energy resolution goals, does not depend strongly on the details of the Monte Carlo modelling of hadronic showers. The PandoraPFA algorithm is also used to investigate the general features of a collider detector optimised for high granularity PFlow calorimetry. Finally, a first study of the potential of high granularity PFlow calorimetry at a multi-TeV lepton collider, such as CLIC, is presented.
The unfolded universe of elementary particles. A geometric explanation of the standard model structure
We propose a geometric explanation of the standard model of Glashow, Weinberg and Salam for the known elementary particles. Our model is a generic Quantum Field Theory in dimension four, obtained by developing along a Lorentz sub-manifold the lagrangian of Einstein and Dirac in dimension twelve. The main mechanism which gives birth to the standard model is a certain gauge fixing of triality, which permits to identify the multiplicity of fermions, as seen from the four dimensional world, with the eight unseen dimensions of the generating universe. In this way we get the known tables of particles, explaining the series of fermions and the gauge bosons. We suggest that the Higgs field dynamics could appear through a bosonization of the right handed neutrino and correspond to a displacement in the unseen dimensions. We also propose hypotheses for dark matter, and perhaps dark energy. Then we suggest predictions to go beyond the standard model.