  The hybrid multi-bend achromat (HMBA) lattice concept is adopted in some
diffraction-limited storage ring designs, which can permit relatively large
on-momentum dynamic aperture and relatively weak sextupoles. In a typical HMBA
lattice, the main arc section is constrained by the transverse phase advances
making -I transformation for sextupole cancellation. In this paper, a new HMBA
lattice concept with sextupole cancellation across straight section is
proposed, where -I is made between adjacent dispersion bumps of two lattice
cells. This makes the main arc section free of the phase advance constraint,
and as a result, the number of bending magnets (bends) in the lattice cell and
the cell tunes can be easily changed, thus providing more choices for lattice
design. To achieve the large phase advances required for -I in this new
concept, split bend is used as the matching bend, which is a bend split into
two pieces with a quadrupole in between. The split bend also serves to reduce
the emittance, and the large phase advances also give low beta functions in the
straight section enhancing the insertion device brightness. Besides, for a
given emittance goal, this new HMBA lattice can have less bends than the
typical HMBA lattice due to stronger focusing in bend unit cells, which is
beneficial for saving space and suppressing intra-beam scattering effect. Two
lattices are given as examples to demonstrate this new concept and show its
linear and nonlinear properties, and further extension is also discussed.
