Han, CC (reprint author), Acad Sinica, Inst Theoret Phys, State Key Lab Theoret Phys, Beijing 100190, Peoples R China.
We consider the current experimental constraints on the parameter space of the MSSM and NMSSM. Then in the allowed parameter space we examine the Higgs pair production at the 14TeV LHC via b (b) over bar -> hh (h is the 125GeV SM-like Higg boson) with one-loop SUSY QCD correction and compare it with the production via gg -> hh. We obtain the following observations: (i) For the MSSM the production rate of b (b) over bar -> hh can reach 50 fb and thus can be competitive with gg -> hh, while for the NMSSM b (b) over bar -> hh has a much smaller rate than gg. hh due to the suppression of the hb (b) over bar coupling; (ii) The SUSY-QCD correction to b (b) over bar -> hh is sizable, which can reach 45% for the MSSM and 15% for the NMSSM within the 1s region of the Higgs data; (iii) In the heavy SUSY limit (all soft mass parameters become heavy), the SUSY effects decouple rather slowly from the Higgs pair production (especially the gg -> hh process), which, for M S U S Y = 5TeV and m A < 1TeV, can enhance the production rate by a factor of 1.5 and 1.3 for the MSSM and NMSSM, respectively. So, the Higgs pair production may be helpful for unraveling the effects of heavy SUSY.