Measuring neutrino dynamics in NMSSM with a right-handed sneutrino LSP at the ILC

Stefano Moretti,Harri Waltari,Yi Liu

doi:10.1007/jhep01(2022)034

Stefano Moretti, Harri Waltari

Open Access

https://doi.org/10.1007/jhep01(2022)034

Copy DOI

Abstract

We study the possibility of measuring neutrino Yukawa couplings in the Next-to-Minimal Supersymmetric Standard Model with right-handed neutrinos (NMSSMr) when the lightest right-handed sneutrino is the Dark Matter (DM) candidate, by exploiting a ‘dijet + dilepton + Missing Transverse Energy’ (MET or ) signature. We show that, contrary to the miminal realisation of Supersymmetry (SUSY), the MSSM, wherein the DM candidate is typically a much heavier (fermionic) neutralino state, this extended model of SUSY offers one with a much lighter (bosonic) state as DM that can then be produced at the next generation of e+e− colliders with energies up to 500 GeV or so. The ensuing signal, energing from chargino pair production and subsequent decay, is extremely pure so it also affords one with the possibility of extracting the Yukawa parameters of the (s)neutrino sector. Altogether, our results serve the purpose of motivating searches for light DM signals at such machines, where the DM candidate can have a mass around the Electro-Weak (EW) scale.

Highlights

JHEP01(2022)034 extended with Type-I seesaw right-handed sneutrinos lead to overabundance of the relic density of the CMB, unless there is significant mixing between the left- and right-handed sneutrinos [34]
We study the possibility of measuring neutrino Yukawa couplings in the Nextto-Minimal Supersymmetric Standard Model with right-handed neutrinos (NMSSMr) when the lightest right-handed sneutrino is the Dark Matter (DM) candidate, by exploiting a ‘dijet + dilepton + Missing Transverse Energy’ (MET or E/ T ) signature
Contrary to the miminal realisation of Supersymmetry (SUSY), the MSSM, wherein the DM candidate is typically a much heavier neutralino state, this extended model of SUSY offers one with a much lighter state as DM that can be produced at the generation of e+e− colliders with energies up to 500 GeV or so

Summary

NMSSM with right-handed neutrinos

The NMSSM extends the MSSM with an additional gauge singlet chiral superfield S [37]. By adding a singlet right-handed neutrino superfield N , we may introduce the Type-I seesaw mechanism to generate neutrino masses. As in the NMSSM, a Z3-symmetry is imposed in order to make the superpotential scale invariant When this discrete symmetry is broken spontaneously by the Vacuum Expectation Values (VEVs) of the (pseudo)scalar fields, a potential domain wall problem arises. Right-handed neutrino masses are generated when the scalar component of the singlet superfield S gets a VEV, S = vs The superpotential term λN SN N in eq (2.1) leads to a Majorana mass term MN = 2λN vs so the right-handed neutrino masses are naturally at the Electro-Weak (EW) scale. If m2RR > 0, N1 is heavier than N2 and vice versa In this case, the lighter right-handed sneutrino mass can be determined by m2RR − 2m2RR, which is defined by a set of parameters such as m2Nand λN

Right-handed sneutrino as a dark matter candidate

Finding the rare chargino decay

Event simulation

Estimating neutrino Yukawa couplings

Findings

Conclusions