Dipole operator constraints on composite Higgs models.

Area of Science:

• High Energy Physics
• Particle Physics
• Beyond Standard Model Physics

Background:

• Flavour- and CP-violating electromagnetic or chromomagnetic dipole operators arise in new physics models.
• These operators are constrained by experimental measurements, including the neutron electric dipole moment and flavour-changing neutral currents (e.g., B and K decays).

Purpose of the Study:

• To analyze flavour- and CP-violating dipole operators in models with partial compositeness.
• To investigate how different electroweak representations and flavour structures impact these constraints.

Main Methods:

• Model-independent analysis of relevant constraints.
• Analysis of partial compositeness models, where quarks mix with vector-like composite fermions.
• Study of various flavour structures, including flavour anarchy and flavour symmetries in the strong sector.

Main Results:

• Strong bounds are derived from the neutron electric dipole moment in models with 'wrong-chirality' Yukawa couplings, independent of flavour structure.
• Flavour anarchy models exhibit strong bounds from flavour-violating dipoles.
• Flavour-symmetric models show milder constraints from flavour-violating dipoles compared to flavour anarchy.

Conclusions:

• Partial compositeness models are significantly constrained by flavour and CP violation observables.
• The choice of flavour structure and electroweak representations critically affects the strength of these constraints.
• Neutron electric dipole moment provides a robust bound, particularly in models with specific Yukawa couplings.