Extending trinity to the scalar sector through discrete flavoured symmetries
- PDF / 417,075 Bytes
- 14 Pages / 595.276 x 790.866 pts Page_size
- 110 Downloads / 205 Views
Regular Article - Theoretical Physics
Extending trinity to the scalar sector through discrete flavoured symmetries João M. Alves1,a , Francisco J. Botella2,b , Gustavo C. Branco1,c , Miguel Nebot1,d 1
Departamento de Física and Centro de Física Teórica de Partículas (CFTP), Instituto Superior Técnico (IST), U. de Lisboa (UL), Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal 2 Departament de Fìsica Teòrica and Instituto de Física Corpuscular (IFIC), Universitat de València-CSIC, 46100 Valencia, Spain
Received: 17 June 2020 / Accepted: 18 July 2020 © The Author(s) 2020
Abstract We conjecture the existence of a relation between elementary scalars and fermions, making it plausible the existence of three Higgs doublets. We introduce a Trinity Principle (TP) which, given the fact that there are no massless quarks, requires the existence of a minimum of three Higgs doublets. The TP states that each row of the mass matrix of a quark of a given charge should receive the contribution from one and only one scalar doublet and furthermore a given scalar doublet should contribute to one and only one row of the mass matrix of a quark of a given charge. This principle is analogous to the Natural Flavour Conservation (NFC) of Glashow and Weinberg with the key distinction that NFC required the introduction of a flavour blind symmetry, while the TP requires a flavoured symmetry, to be implemented in a natural way. We provide two examples which satisfy the Trinity Principle based on Z3 and Z2 × Z2 flavoured symmetries, and show that they are the minimal multi-Higgs extensions of the Standard Model where CP can be imposed as a symmetry of the full Lagrangian and broken by the vacuum, without requiring soft-breaking terms. We show that the vacuum phases are sufficient to generate a complex CKM matrix, in agreement with experiment. The above mentioned flavoured symmetries lead to a strong reduction in the number of parameters in the Yukawa interactions, enabling a control of the Scalar Flavour Changing Neutral Couplings (SFCNC). We analyse some of the other physical implications of the two models, including an estimate of the enhancement of the Baryon Asymmetry of the Universe provided by the new sources of CP violation, and a discussion of the strength of their tree-level SFCNC. a e-mail:
[email protected]
b e-mail:
[email protected]
c e-mail:
[email protected]
d e-mail: author)
[email protected]
(corresponding
0123456789().: V,-vol
1 Introduction In the Standard Model (SM), all masses are generated by the vacuum expectation value of a single Higgs doublet. Since there is no fundamental reason for having the minimal scalar sector when the fermio n space is non-trivial, multi-Higgs models can arise in a variety of well-motivated scenarios (see [1,2] and references therein). For instance, the first Two Higgs Doublet Model (2HDM) was introduced by Lee [3] to achieve spontaneous CP Violation (CPV). In general, multi-Higgs extensions of the SM generate large Scalar Flavour
Data Loading...
