Unconventional high-energy-state contribution to the Cooper pairing in   under-doped copper-oxide superconductor HgBa$_2$Ca$_2$Cu$_3$O$_{8+\delta}$
  We study the temperature-dependent electronic B1g Raman response of a slightly under-doped single crystal HgBa$_2$Ca$_2$Cu$_3$O$_{8+\delta}$ with a superconducting critical temperature Tc=122 K. Our main finding is that the superconducting pair-breaking peak is associated with a dip on its higher-energy side, disappearing together at Tc. This result hints at an unconventional pairing mechanism, whereas spectral weight lost in the dip is transferred to the pair-breaking peak at lower energies. This conclusion is supported by cellular dynamical mean-field theory on the Hubbard model, which is able to reproduce all the main features of the B1g Raman response and explain the peak-dip behavior in terms of a nontrivial relationship between the superconducting and the pseudo gaps. 
B. Loret, S. Sakai, Y. Gallais, M. Cazayous, M.-A. M\'easson, A.   Forget, D. Colson, M. Civelli and A. Sacuto
cond-mat.supr-con