M. Velasco

Higgs boson decays to quarkonia and the

In this paper we discuss decays of the Higgs boson to quarkonia in association with a photon. We identify a new mechanism for producing such final states in Higgs decays that leads to predictions for the decay rates that differ by an order of magnitude from previous estimates. Although the branching ratios for these processes are still small, the processes are experimentally clean, and the H \to J/\psi+gamma decay should be observable at a 14 TeV LHC. We point out that quantum interference between two different production mechanisms makes the decay rates sensitive to the HQQbar couplings. Consequently, measurements of the H \to J/\psi+gamma decay rate would allow one to probe the Higgs-charm coupling directly at the LHC. We discuss the experimental prospects for the observation of these decays and for the direct measurement of the Hccbar coupling.

H\bar{c}c

Abstract The subject of space charge due to positive ions slowly moving in parallel plate ionization chambers is considered. A model for the degradation of the detector response is developed, with particular emphasis on electromagnetic calorimeters.The topics discussed include: (a) the stationary; (b) the time dependent cases; (c) the limit of very large space charge; (d) the electric field dependence of the electron drift velocity; (e) the effect of longitudinal development of showers; (f) the behaviour of the average reductions of response; (g) the non-uniformity of response for different positions of the shower axis inside the cell defined by the electrodes. The NA48 calorimeter is used as application and for comparison of results.

coupling

The trigger used for the collection of the samples of K0→π0π0 decays in the NA48 experiment at CERN uses a novel pipeline design in order to satisfy the demanding specifications of a high rate kaon beam. The trigger algorithms, architecture and performance are described.

SPACE CHARGE IN IONIZATION DETECTORS AND THE NA48 ELECTROMAGNETIC CALORIMETER

Abstract. A new precision measurement of the

The trigger for K0→π0π0 decays of the NA48 experiment at CERN

\Xi^0

Precision measurement of the

mass has been performed at the NA48 experiment at the CERN SPS. The value obtained is [1314.82

\Xi^0

\pm

mass and the branching ratios of the decays

0.06 (stat.)

\Xi^0\rightarrow\Lambda\gamma

\pm

and

0.2 (syst.)]\,\mbox{MeV/c}