Fractional charge and emergent mass hierarchy in diagonal two-leg t-J   cylinders
  We define a new class of "diagonal" t-J ladders rotated by $\pi$/4 relative to the canonical lattice directions of the square lattice, and study it using density matrix renormalization group (DMRG). Here, we focus on the two-leg cylinder with a doped hole concentration near x = 1/4. At exactly x = 1/4, the system forms a period 4 charge density wave (CDW) and exhibits spin-charge separation. Slightly away from 1/4 doping we observe several topologically distinct types of solitons with well defined fractionalized quantum numbers. Remarkably, given the absence of any obvious small parameter, the effective masses of the emergent solitons differ by several orders of magnitude. 
Yi-Fan Jiang, Hong-Chen Jiang, Hong Yao and Steven A. Kivelson
cond-mat.str-el