Physics Theory Seminar with Chayan Majumdar on Constraining the SMEFT with Right-Handed Neutrinos at FCC-ee

The existence of right-handed neutrinos (RHNs), or heavy neutral leptons (HNLs), is strongly motivated by the observation of small but finite neutrino masses and mixings. In this work, we have extended the Standard Model (SM) particle content with a pair of gauge-singlet fermions, which can be Dirac or Majorana in nature. Adopting a model-independent effective field theory (EFT) framework, more specifically NRSMEFT, we consider all possible operators of different Lorentz structures i.e., scalar-pseudoscalar (SP), vector-axial vector (VA), and tensor-axial tensor (TAT) types upto mass dimension 6. With these operators, we analyze the future electron positron circular collider (FCC-ee) prospects and constrain the corresponding new physics (NP) cut-off scale ΛNP in the monophoton channel with √ s = 91.2 GeV at 100 ab−1 as well as √ s = 240 GeV at 5 ab−1 integrated luminosities.

Zoom link available upon request at physics@wustl.edu.
Post-docs and students' Q&A with the speaker starts at 2:15 pm. Contact Garrett King for the Q&A Zoom link.

This lecture was made possible by the William C. Ferguson fund.