We employ the two independent Casimir operators of the Poincaré group, the squared fourmomentum, p 2 , and the squared Pauli-Lubanski vector, W 2 , in the construction of a covariant mass-m, and spin-3 2 projector in the four-vector-spinor, ψµ. This projector provides the basis for the construction of an interacting Lagrangian that describes a causally propagating spin-3 2 particle coupled to the electromagnetic field by a gyromagnetic ratio of g 3 2 = 2.

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We present the sensitivity of HAWC to Gamma Ray Bursts (GRBs). HAWC is a very high-energy gamma-ray observatory currently under construction in Mexico at an altitude of 4100 m. It will observe atmospheric air showers via the water Cherenkov method. HAWC will consist of 300 large water tanks instrumented with 4 photomultipliers each. HAWC has two data acquisition (DAQ) systems. The main DAQ system reads out coincident signals in the tanks and reconstructs the direction and energy of individual atmospheric showers. The scaler DAQ counts the hits in each photomultiplier tube (PMT) in the detector and searches for a statistical excess over the noise of all PMTs. We show that HAWC has a realistic opportunity to observe the high-energy power law components of GRBs that extend at least up to 30 GeV, as it has been observed by Fermi LAT. The two DAQ systems have an energy threshold that is low enough to observe events similar to GRB 090510 and GRB 090902b with the characteristics observed by Fermi LAT. HAWC will provide information about the high-energy spectra of GRBs which in turn could help to understanding about e-pair attenuation in GRB jets, extragalactic background light absorption, as well as establishing the highest energy to which GRBs accelerate particles

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We study the e e ÿ ! reaction for pions in an isoscalar s wave which is dominated by loop mechanisms. For kaon loops we start from the conventional R PT, but use the unitarized amplitude for K K ÿ scattering and the full kaon form factor instead of the lowest order terms. We study also effects of vector mesons using R PT supplemented with the conventional anomalous term for VVP interactions and taking into account the effects of heavy vector mesons in the K K transition form factor. We find a peak in m around the f 0 980 as in the experiment. Selecting the f 0 980 contribution as a function of the e e ÿ energy we also reproduce the experimental data except for a narrow peak, yielding support to the existence of a 1 ÿÿ resonance above the f 0 980 threshold, coupling strongly to this state.