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In condensed matter systems, chiral topological nodes are robust bandcrossing points in momentum space that carry nonzero Chern numbers. Thechirality is manifested by the presence of surface Fermi arcs connecting theprojections of nodes with opposite Chern numbers. In addition to the well-knownWeyl nodes, theorists have proposed several other types of chiral topologicalnodes in condensed matter systems, but the direct experimental evidence oftheir existence is still lacking. Here, using angle-resolved photoemissionspectroscopy, we reveal two types of new chiral nodes, namely the spin-1 nodesand charge-2 Dirac nodes, at the band crossing points near the Fermi level inCoSi, the projections of which on the (001) surface are connected bytopologically protected surface Fermi arcs. As these chiral nodes in CoSi areenforced at the Brillouin zone (BZ) center and corner by the crystallinesymmetries, the surface Fermi arcs connecting their projections form anon-contractible path traversing the entire (001) surface BZ, in sharp contrastto pairs of Weyl nodes with small separation. Our work marks the firstexperimental observation of chiral topological nodes beyond the Weyl nodes bothin the bulk and on the surface in condensed matter systems.

New classes of chiral topological nodes with non-contractible surface Fermi arcs in CoSi