Study of Thermodynamics in Generalized Holographic and Ricci Dark Energy   Models
  We have considered the flat FRW model of the universe which is filled with the combination of dark matter and dark energy. Here we have considered two types of dark energy models: (i) Generalized holographic and (ii) generalized Ricci dark energies. The general descriptions of first law and generalized second law (GSL) of thermodynamics have studied on the apparent horizon, particle horizon and event horizon of the universe. We have shown that the first law and GSL are always valid on apparent horizon and first law can not be satisfied on the particle and event horizons in Einstein's gravity. These results are always true for any types of dark energy models i.e., these results do not depend on the dark energy models in Einstein's gravity. But the GSL completely depends on the choices of dark energy models in Einstein's gravity. Here we have discussed the validity of GSL in Generalized holographic and generalized Ricci dark energy models. On the particle horizon GSL may be satisfied but on the event horizon the GSL can not be satisfied for both the dark energy models. Also we have considered the Generalized holographic dark energy and generalized Ricci dark energy as the original holographic dark energy, so in this situation we have calculated the expression of the radius of the horizon $L$. On this horizon, we have shown that the first law can not be satisfied. Finally, on the horizon of radius $L$, we have found that the GSL can not be satisfied for both the dark energy models. 
Samarpita Bhattacharya and Ujjal Debnath
physics.gen-ph gr-qc