Higgs self-coupling in the MSSM and NMSSM after the LHC Run 1

Measuring the Higgs self-coupling is one of the crucial physics goals at the LHC Run-2 and other future colliders. In this work, we attempt to figure out the size of SUSY effects on the trilinear self-coupling of the 125 GeV Higgs boson in the MSSM and NMSSM after the LHC Run-1. Taking account of current experimental constraints, such as the Higgs data, flavor constraints, electroweak precision observables and dark matter detections, we obtain the observations: (1) In the MSSM, the ratio λ3hMSSM/λ3hSM has been tightly constrained by the LHC data, which can be only slightly smaller than 1 and minimally reach 97%; (2) In the NMSSM with λ<0.7λ<0.7, a sizable reduction of λ3h2NMSSM/λ3h2SM can occur and minimally reach 10% when the lightest CP-even Higgs boson mass mh1mh1 is close to the SM-like Higgs boson mh2mh2 due to the large mixing angle between the singlet and doublet Higgs bosons; (3) In the NMSSM with λ>0.7λ>0.7, a large enhancement or reduction −1.1<λ3h1NMSSM/λ3h1SM<2 can occur, which is accompanied by a sizable change of h1τ+τ−h1τ+τ− coupling. The future colliders, such as the HL-LHC and ILC, will have the capacity to test these large deviations in the NMSSM.