Implications of a vector-like lepton doublet and scalar Leptoquark on R(D^(*))

2018/06/04 by Lobsang Dhargyal, Dhargyal, Lobsang, Santosh Kumar Rai +1
Engineering · Physics and Astronomy · #Astrophysics and Cosmic Phenomena #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph) #Particle Accelerators and Free-Electron Lasers #Particle physics theoretical and experimental studies

paper · pdf · doi:10.48550/arxiv.1806.01178

openalex publication_date 2018/06/04 · openalex created_date 2018/06/13 · openalex updated_date 2026/07/28

Abstract

We study the phenomenological constraints and consequences in the flavor sector, of introducing a new fourth generation Z₂ odd vector-like lepton doublet along with a Standard Model (SM) singlet scalar and an SU(2)_L singlet scalar leptoquark carrying electromagnetic charge of +2/3, both odd under a Z₂. We show that with little fine tuning among the various Yukawa couplings in the new physics (NP) Lagrangian along with the CKM parameters, the model is able to push the theoretical value of R(D^*)^th from 0.252 ± 0.003 to 0.263 ± 0.051 and R(D)^th from 0.300 ± 0.008 to 0.313 ± 0.158 compared to the SM value. Especially the NP contributions are able to reduce the discrepancy between experiment and theory of R(D^*) substantially compared to SM. This is quite impressive given that the model satisfy all other very stringent constrains coming from neutral meson oscillations and precision Z-pole data.

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