Brave new world of unconventional density waves

Recently many people discuss unconventional density wave (i.e. UCDW and USDW). Unlike in conventional density waves, the quasiparticle excitations in these systems are gapless. The appearence of these systems suggests paradigm shift from quasi ID system to quasi 2D and 3D systems. Here we limit ourselves to the angular dependent magnetoresistance (ADMR) observed in the low temperature phase (LTP) of $\alpha$-(BEDT-TTF)$_2$KHg(SCN)$_4$. Here we show that UCDW describes successfully many features of ADMR as manifestation of the Landau quantization of the quasiparticle spectrum in magnetic field. Indeed ADMR will provide a unique window to access UDW like the AF phase in URu$_2$Si$_2$, the pseudogap phase in high $T_c$ cuprates and the glassy phase in organic superconductor $\kappa$-(ET)$_2$ salts