1. Lei Wu arXiv:1310.4274 JHEP 1402 (2014) 049 In collaboration with: C. Han, A. Kobakhidze, N. Liu, A. Saavedra and J.M. Yang Light Higgsinos and Naturalness in Natural MSSM

2. Outline 125 GeV Higgs boson & Naturalness ； Light Higgsinos in Natural MSSM and Monojet; Conclusions.

3. 125 GeV Higgs boson & Naturalness The ATLAS and CMS experiments have unequivocally discovered a new neutral boson of mass ~ 125 GeV; Measuring its properties is a fundamental step to determine its nature:  Signal strengths;  Couplings (to fermions and bosons);  Quantum numbers (spin and parity);  Exotic Higgs decays.

4. 4 Signal strengths: Couplings: Spin & CP: But CP mixing state not excluded Exotic Higgs decays:

5. arXiv:1112.3028 125 GeV Higgs boson & Naturalness

6. A heavy stop will jeopardize the naturalness. But it does NOT always ruin the Naturalness! Focus Point SuperSymmetry Phys. Rev. D 86, 055015 (2012) Besides, non-universal gaugino SUSY, Refs: arXiv:1212.2593; arXiv:1312.0582, etc

7. In MSSM, the starting point for most discussions of fine-tuning is the predicted value of Mz obtained from the minimization of the Higgs boson potential ： A model is natural if its predictions can be obtained without the need for dedicated cancellations between various independent contributions that are combined to obtain the predicted value of any quantity Light Higgsinos in Natural MSSM & Monojet

8. In large tanβ approximation (favored by Higgs mass), Tree level 1 loop level 2 loop level To get the low fine-tuning, each term should be around Mz. Then, we can get a constraint on the sparticle mass. JHEP 1204 (2012) 131 Phys. Rev. D 46, 3981 (1992)

9. A natural spectrum of sparticles should be: 10 % Fine tuning The contributions of stop and gluino to the naturalness are model/scenario-dependent. So, the most robust way to test Naturalness is : Search for Light Higgsinos!

10. Current LHC searches for electroweakinos But, the situation is a little bit special in the Natural MSSM!

11. 1. Feature of light higgsinos in natural MSSM at collider But still large enough to avoid displaced vertex!

12. Small-splitting region is generally less sensitive because visible particles are soft and LSPs are back-to-back causing small MET. Small-splitting region is generally less sensitive because visible particles are soft and LSPs are back-to-back causing small MET.

13. To improve, ISR jet will be very helpful. ISR jet can boost the mother electrowinos, making MET become larger as LSPs align. 2. Monojet for light Hhiggsinos

14. ATLAS 8TeV result: ATLAS-CONF-2012-147

15. The Signals are: Signal is enhanced by the sum of all the higgsinos final states !

16. The backgrounds are:

17. The Low Fine Tuning region can be excluded by the LHC!

18. Conclusions The most robust way to test Naturalness of the MSSM is to search for Light Higgsinos. Monojet signature may be the only way to make it at HL-LHC, but the significance is very sensitive to the systematic error. Otherwise, exclusion of 100-150 GeV light Higgsino can be achieved at 14 TeV HL-LHC.

19. So, Keep Your Faith: “Naturalness & Supersymmetry” Let’s see LHC-2 ! Thanks for your attention!

20. Back-up Higgsino-gauge bosons couplings arXiv:1312.7350

21. Nucl. Phys. B 306 (1988) 63; Phys. Rev. D 88, 095013 (2013).