ARPES line shapes of two leg ladder compounds Sr$_{14-x}$Ca$_x$Cu$_{24}$O$_{41}$

Two leg ladder compounds, Sr$_{14-x}$Ca$_x$Cu$_{24}$O$_{41}$, are quasi-one-dimensional cuprate materials, and provide a reference for considering many interesting and controversial general issues such as non-Fermi liquid, Fermi surface reconstruction, and charge order on a more solid ground. Here we discuss how the line shapes observed for two leg ladder compounds in angle resolved photo- electron spectroscopy (ARPES) may shed light on continuing issues in physics of quasi-two-dimensional cuprates.