The hybrid N=1/N=2 supersymmetric model predicts scalar gluons (sgluons) as SUSY partners of the Dirac gluino. Their strikingly distinct phenomenology at the CERN Large Hadron Collider is discussed.
Elements of the phenomenology of color-octet scalars (sgluons), as predicted in the hybrid N=1/N=2 supersymmetric model, are discussed in the light of forthcoming experiments at the CERN Large Hadron Collider.
Using the event generator WHIZARD we study in a realistic ILC environment the prospects of measuring properties of sneutrinos that decay invisibly into the lightest neutralino and the neutrino.
For points in SUSY parameter space where the sneutrino is lighter than the lightest chargino and next-to-lightest neutralino, its direct mass determination from sneutrino pair production process at e+e- collider is impossible since it decays invisibly. In such a scenario the sneutrino can be discovered and its mass determined from measurements of two-body decays of charginos produced in pairs at the ILC. Using the event generator WHIZARD we study the prospects of measuring sneutrino properties in a realistic ILC environment. In our analysis we include beamstrahlung, initial state radiation, a complete account of reducible backgrounds from SM and SUSY processes, and a complete matrix-element calculation of the SUSY signal which encompasses all irreducible background and interference contributions. We also simulate photon induced background processes using exact matrix elements. Radiation effects and the cuts to reduce background strongly modify the edges of the lepton energy spectra from which the sneutrino and chargino mass are determined. We discuss possible approaches to measure the sneutrino mass with optimal precision.
We consider NLO chargino production and decays at the ILC. For this, we present an NLO extension of the Monte Carlo Event Generator Whizard including the NLO production. For photonic corrections, we use both a fixed order and a resummation approach. The latter method evades the problem of negative event weights and automatically includes leading higher order corrections. We present results for cross sections and event generation for both methods. As a first step towards a full NLO Monte Carlo, we consider a LO implementation of the chargino production and subsequent leptonic decay and investigate the precision of the sneutrino mass determination by means of lepton energy distributions in chargino decays. The SM and SUSY backgrounds are included in our study using full matrix elements as well as smearing effects from ISR and beamstrahlung. Without using energy distribution fits, the sneutrino mass can be determined with an error in the percent regime.
Combined analyses at the Large Hadron Collider and at the International Linear Collider are important to unravel a difficult region of supersymmetry that is characterized by scalar SUSY particles with masses around 2 TeV. Precision measurements of masses, cross sections and forward-backward asymmetries allow to determine the fundamental supersymmetric parameters even if only a small part of the spectrum is accessible. Mass constraints for the heavy particles can be derived.
Speculations on mechanisms which might be responsible for events with an isolated high p_T lepton, a hadron jet and missing energy, as observed in the H1 experiment at HERA, are discussed.
