Standard model effective field theory: Integrating out neutralinos and charginos in the MSSM

Huayong Han,Jing Shu,Minyuan Jiang,Ran Huo

doi:10.1103/physrevd.97.095003

Abstract

We apply the covariant derivative expansion method to integrate out the neutralinos and charginos in the minimal supersymmetric Standard Model. The results are presented as set of pure bosonic dimension-six operators in the Standard Model effective field theory. Nontrivial chirality dependence in fermionic covariant derivative expansion is discussed carefully. The results are checked by computing the $h\ensuremath{\gamma}\ensuremath{\gamma}$ effective coupling and the electroweak oblique parameters using the Standard Model effective field theory with our effective operators and direct loop calculation. In global fitting, the proposed lepton collider constraint projections, special phenomenological emphasis is paid to the gaugino mass unification scenario (${M}_{2}\ensuremath{\simeq}2{M}_{1}$) and anomaly mediation scenario (${M}_{1}\ensuremath{\simeq}3.3{M}_{2}$). These results show that the precision measurement experiments in future lepton colliders will provide a very useful complementary job in probing the electroweakino sector, in particular, filling the gap of the soft lepton plus the missing ${E}_{T}$ channel search left by the traditional collider, where the neutralino as the lightest supersymmetric particle is very degenerated with the next-to-lightest chargino/neutralino.

Highlights

As an effective tool of connecting the new physics to the experimental observations, the Standard Model effective field theory (SMEFT) is recently being intensively developed and applied
These results show that the precision measurement experiments in future lepton colliders will provide a very useful complementary job in probing the electroweakino sector, in particular, filling the gap of the soft lepton plus the missing ET channel search left by the traditional collider, where the neutralino as the lightest supersymmetric particle is very degenerated with the next-to-lightest chargino/neutralino
We have presented a convenient way of dealing two-component Weyl fermions in the covariant derivative expansion method

Summary

INTRODUCTION

As an effective tool of connecting the new physics to the experimental observations, the Standard Model effective field theory (SMEFT) is recently being intensively developed and applied (refer to [1,2] for a review). Comparing to the traditional way of Feynman diagram calculations, which is relatively tedious and not gauge invariant in the process, the CDE method can directly obtain the gauge-invariant operators in a much simpler way Using this method, the effective operators have been calculated for various new physics models and the corresponding phenomenological implications were discussed [15,16,17,18,19,20]. Applying the CDE method, people have already worked out the dimension-six effective operators by integrating out the sfermions in the minimal supersymmetric standard model (MSSM) to one-loop order. We apply our results in future lepton colliders, to see how the precise electroweak and Higgs observables constrain the MSSM electroweakino sector. Some discussions about the regularization options and the Wilson coefficients of the effective operators are presented in appendices

THE FORMULISM AND INPUT

ANALYTICAL RESULTS AND CHECK

PROJECTED FUTURE CONSTRAINTS

SUMMARY AND CONCLUSIONS