PACS 73.20.At -Surface states, band structure, electron density of states PACS 73.25.+i -Surface conductivity and carrier phenomena PACS 74.45.+c -Proximity effects; Andreev effect; SN and SNS junctions Abstract -We study the low-energy edge states of a superconductor -3D topological-insulator hybrid structure (NS junction) in the presence of a perpendicular magnetic field. The hybridization of electron-like and hole-like Landau levels due to Andreev reflection gives rise to chiral edge states within each Landau level. We show that by changing the chemical potential of the superconductor, this junction can be placed in a regime where the sign of the effective charge of the edge state within the zeroth Landau level changes more than once resulting in neutral edge modes with a finite value of the guiding-center coordinate. The appearance of these neutral edge modes is related to the level repulsion between the zeroth and the first Landau levels in the spectra. We also find that these neutral edge modes come in pairs, one in the zeroth Landau level and its corresponding pair in the first. Unlike ordinary neutral bogolon excitations in superconductors, the neutral modes found by us have a finite speed and, thus, the potential to carry a heat current.Introduction. -The integer quantum Hall (QH) state [1] represented the first example of a many-body state whose nontrivial properties do not stem from a spontaneously-broken symmetry, but rather its topological character [2]. The precise quantisation of the Hall conductance in integer multiples of e 2 /h was initially studied using a two-dimensional electron gas at a low temperature and in a strong perpendicular magnetic field, receiving a renewed attention with the discovery of graphene and its peculiar Dirac-like energy spectrum [3,4]. At the heart of transport in integer-QH systems -which based on their energy spectra could be expected to be insulating if the chemical potential lies in the gap between the neighbouring Landau levels (LLs) -is the existence of edge states. These LLs acquire dispersion as the guiding centers approach the physical edges of the sample (Hall bar), which gives rise to a current along the edges. The net current, resulting from a voltage (or chemical potential) drop in the direction perpendicular to the Hall-bar edges, is determined by the number of edge channels, i.e., of LLs occupied in the bulk.