2018/06/30 by Chandan Hati, Girish Kumar, Jean Orloff +1
Computer Science · Physics and Astronomy · #Computational Physics and Python Applications #Flavour #Lepton #Leptoquark #MAJORANA #Neutrino #Neutrino Physics Research #Observable #Particle physics theoretical and experimental studies #Standard Model (mathematical formulation) #Yukawa potential #hep-ph
paper · pdf · doi:10.1007/jhep11(2018)011
39 pages, 11 figures, v2 includes some new and updated references
arxiv created 2018/07/20 · openalex publication_date 2018/11/01 · arxiv updated 2018/12/05 · openalex created_date 2019/06/27 · openalex updated_date 2026/08/05
A bstract Motivated by an explanation of the RK(*) <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>R</mml:mi> <mml:msup> <mml:mi>K</mml:mi> <mml:mfenced> <mml:mo>*</mml:mo> </mml:mfenced> </mml:msup> </mml:msub> </mml:math> anomalies, we propose a Standard Model extension via two scalar SU(2) L triplet leptoquarks and three generations of triplet Majorana fermions. The gauge group is reinforced by a Z 2 symmetry, ensuring the stability of the lightest Z 2 -odd particle, which is a potentially viable dark matter candidate. Neutrino mass generation occurs radiatively (at the three-loop level), and leads to important constraints on the leptoquark couplings to leptons. We consider very generic textures for the flavour structure of the h 1 leptoquark Yukawa couplings, identifying classes which succeed in saturating the RK(*) <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>R</mml:mi> <mml:msup> <mml:mi>K</mml:mi> <mml:mfenced> <mml:mo>*</mml:mo> </mml:mfenced> </mml:msup> </mml:msub> </mml:math> anomalies. We subsequently carry a comprehensive analysis of the model’s contributions to numerous high-intensity observables such as meson oscillations and decays, as well as charged lepton flavour violating processes, which put severe constraints on the flavour structure of these leptoquark extensions. Our findings suggest that the most constraining observables are K+→ π+ν ν <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mi>K</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:mo>→</mml:mo> <mml:msup> <mml:mi>π</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:mi>ν</mml:mi> <mml:mover> <mml:mi>ν</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> decays, and charged lepton flavour violating μ − e conversion in nuclei (among others). Nevertheless, for several classes of flavour textures and for wide mass regimes of the new mediators (within collider reach), this Standard Model extension successfully addresses neutrino mass generation, explains the current RK(*) <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>R</mml:mi> <mml:msup> <mml:mi>K</mml:mi> <mml:mfenced> <mml:mo>*</mml:mo> </mml:mfenced> </mml:msup> </mml:msub> </mml:math> tensions, and offers a viable dark matter candidate.