KM3NeT/ARCA sensitivity to a diffuse cosmic neutrino flux

KM3NeT is a neutrino telescope being built in the Mediterranean Sea. In December 2015, a big step in the first construction phase has been achieved with the successful deployment of the first detection unit. In a second phase, the full KM3NeT/ARCA detector, comprising 2 detector blocks with an instrumented volume of 1 cubic kilometre, will be built to investigate high-energy cosmic neutrinos. The high-energy cosmic neutrino flux must be distinguished against a background of atmospheric neutrinos and down-going tracks originating from atmospheric muons. Using Monte Carlo simulations, dedicated track and shower reconstruction algorithms have been developed allowing for a high precision in the determination of the kinematic event variables. For showers, the obtained energy resolution amounts to roughly 10% and the median angular resolution is less than 2 degrees, while in the track channel the angular and energy resolution is below 0.2 degrees on average and about 0.27 in the logarithm of the energy, respectively. The reconstruction algorithms also provide reconstruction parameters that help to efficiently discriminate signal from background. In this talk, an analysis dedicated to the sensitivity of KM3NeT/ARCA to a diffuse cosmic neutrino flux will be presented, incorporating a spectral fitting method, thus also being sensitive to the spectral shape of such a flux.