Changes between Version 6 and Version 7 of HNLs

Timestamp:

Oct 28, 2021, 4:02:34 PM (3 years ago)

Author:

ManuelGonzalezLopez

Comment:

--

HNLs

@@ -29 +29 @@
 We extend the SM neutrino sector by including a fourth, heavy neutrino (or Heavy Neutral Lepton, HNL) and its interactions with SM particles. Two versions of the model are available, accounting for Dirac and Majorana neutrinos respectively. As it is a gauge singlet, the HNL will only interact via mixing with the light neutrinos, inheriting their couplings to the rest of the SM. 
 
-In particular, we focus on how the HNL interacts with mesons. In order to do so, we remove the quarks and replace them with mesons (including pions, kaons, η,  ρ's, ω, φ, D's and D_s's, with their corresponding masses and decay constants), introducing low-energy effective operators which account for the interactions of on-shell mesons with HNLs. This allows to compute HNL production via meson decay and HNL decay into lighter mesons, as well as any purely leptonic process. Note that we have only included vertices which involve mesons and leptons, and not the complete meson Lagrangian. Purely hadronic processes are beyond the scope of this model.
+In particular, we focus on how the HNL interacts with mesons. In order to do so, we remove the quarks and replace them with mesons (including pions, kaons, η,  ρ's, ω, φ, D's, D_s's, B's, B_s's and B_c's), with their corresponding masses and decay constants), introducing low-energy effective operators which account for the interactions of on-shell mesons with HNLs. This allows to compute HNL production via meson decay and HNL decay into lighter mesons, as well as any purely leptonic process. Note that we have only included vertices which involve mesons and leptons, and not the complete meson Lagrangian. Purely hadronic processes are beyond the scope of this model.
 
-The HNL interactions are controlled by its mass (set by default to 1 GeV) and its Yukawa couplings, which can be translated into its mixings to electron, muon and tau neutrinos respectively. These three mixings are set by default to 0.001. All these four parameters can be modified in order to explore wide regions of the parameter space. 
+The HNL interactions are controlled by its mass (set by default to 1 GeV) and its Yukawa couplings, which can be translated into its mixings to electron, muon and tau neutrinos respectively. The moduli of these three mixings are set by default to 0.001, and their arguments to 0. All these parameters can be modified in order to explore wide regions of the parameter space. 
 
 For the sake of generality, the models include a switch which allows to remove the mesons and restore the SM quark content, keeping the HNL interactions to W and Z bosons. This allows to study processes involving heavy neutrinos at higher energies, such as a collider environment, where the low-energy effective treatment of mesons is not valid anymore.