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Author (up) Alves, J.M.; Botella, F.J.; Branco, G.C.; Cornet-Gomez, F.; Nebot, M.
Title The framework for a common origin of delta(CKM) and delta S-PMN Type Journal Article
Year 2021 Publication European Physical Journal C Abbreviated Journal Eur. Phys. J. C
Volume 81 Issue 8 Pages 727 - 11pp
Keywords
Abstract We analyse a possible connection between CP violations in the quark and lepton sectors, parametrised by the CKM and PMNS phases. If one assumes that CP breaking arises from complexYukawa couplings, both in the quark and lepton sectors, the above connection is not possible in general, sinceYukawa couplings in the two sectors have independent flavour structures. We show that both the CKM and PMNS phases can instead be generated by a vacuum phase in a class of two Higgs doublet models, and in this case a connection may be established. This scenario requires the presence of scalar FCNC at tree level, both in the quark and lepton sectors. The appearance of these FCNC is an obstacle and a blessing. An obstacle since one has to analyse which models are able to conform to the strict experimental limits on FCNC, both in the quark and lepton sectors. A blessing, because this class of models is falsifiable since FCNC arise at a level which can be probed experimentally in the near future, specially in the processes h up arrow e(+/-) t +/- and t -> hc. The connection between CP violations in CKM and PMNS is explicitely illustrated in models with Minimal Flavour Violation.
Address [Alves, Joao M.; Branco, Gustavo C.] Univ Lisbon, Inst Super Tecn, CFTP, Av Rovisco Pais 1, P-1049001 Lisbon, Portugal, Email: j.magalhaes.alves@tecnico.ulisboa.pt;
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1434-6044 ISBN Medium
Area Expedition Conference
Notes WOS:000685140600003 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 4938
Permanent link to this record
 
 
Author (up) Alves, J.M.; Botella, F.J.; Branco, G.C.; Cornet-Gomez, F.; Nebot, M.
Title Controlled flavour changing neutral couplings in two Higgs Doublet models Type Journal Article
Year 2017 Publication European Physical Journal C Abbreviated Journal Eur. Phys. J. C
Volume 77 Issue 9 Pages 585 - 18pp
Keywords
Abstract We propose a class of two Higgs doublet models where there are flavour changing neutral currents (FCNC) at tree level, but under control due to the introduction of a discrete symmetry in the full Lagrangian. It is shown that in this class of models, one can have simultaneously FCNC in the up and down sectors, in contrast to the situation encountered in the renormalisable and minimal flavour violating 2HDM models put forward by Branco et al. (Phys Lett B 380: 119, 1996). The intensity of FCNC is analysed and it is shown that in this class of models one can respect all the strong constraints from experiment without unnatural fine-tuning. It is pointed out that the additional sources of flavour and CP violation are such that they can enhance significantly the generation of the Bbaryon asymmetry of the Universe, with respect to the standard model.
Address [Alves, Joao M.; Branco, Gustavo C.; Nebot, Miguel] UL, IST, Dept Fis, Ave Rovisco Pais, P-1049001 Lisbon, Portugal, Email: j.magalhaes.alves@tecnico.ulisboa.pt;
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1434-6044 ISBN Medium
Area Expedition Conference
Notes WOS:000409356700001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 3293
Permanent link to this record
 
 
Author (up) Alves, J.M.; Botella, F.J.; Branco, G.C.; Cornet-Gomez, F.; Nebot, M.; Silva, J.P.
Title Symmetry constrained two Higgs doublet models Type Journal Article
Year 2018 Publication European Physical Journal C Abbreviated Journal Eur. Phys. J. C
Volume 78 Issue 8 Pages 630 - 17pp
Keywords
Abstract We study two-Higgs-doublet models (2HDM) where Abelian symmetries have been introduced, leading to a drastic reduction in the number of free parameters in the 2HDM. Our analysis is inspired in BGL models, where, as the result of a symmetry of the Lagrangian, there are tree-level scalar mediated Flavour-Changing-Neutral-Currents, with the flavour structure depending only on the CKM matrix. A systematic analysis is done on the various possible schemes, which are classified in different classes, depending on the way the extra symmetries constrain the matrices of couplings defining the flavour structure of the scalar mediated neutral currents. All the resulting flavour textures of the Yukawa couplings are stable under renormalisation since they result from symmetries imposed at the Lagrangian level. We also present a brief phenomenological analysis of the most salient features of each class of symmetry constrained 2HDM.
Address [Alves, Joao M.; Branco, Gustavo C.; Nebot, Miguel; Silva, Joao P.] Univ Lisboa UL, Dept Fis, Av Rovisco Pais, P-1049001 Lisbon, Portugal, Email: j.magalhaes.alves@tecnico.ulisboa.pt;
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1434-6044 ISBN Medium
Area Expedition Conference
Notes WOS:000441261300003 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 3690
Permanent link to this record
 
 
Author (up) Alves, J.M.; Botella, F.J.; Branco, G.C.; Nebot, M.
Title Extending trinity to the scalar sector through discrete flavoured symmetries Type Journal Article
Year 2020 Publication European Physical Journal C Abbreviated Journal Eur. Phys. J. C
Volume 80 Issue 8 Pages 710 - 14pp
Keywords
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 Z(3) and Z(2) x Z(2)' 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.
Address [Alves, Joao M.; Branco, Gustavo C.; Nebot, Miguel] Univ Lisboa UL, Inst Super Tecn IST, Dept Fis, Ave Rovisco Pais 1, P-1049001 Lisbon, Portugal, Email: j.magalhaes.alves@tecnico.ulisboa.pt;
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1434-6044 ISBN Medium
Area Expedition Conference
Notes WOS:000561119300002 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 4503
Permanent link to this record
 
 
Author (up) Botella, F.J.; Branco, G.C.; Carmona, A.; Nebot, M.; Pedro, L.; Rebelo, M.N.
Title Physical constraints on a class of two-Higgs doublet models with FCNC at tree level Type Journal Article
Year 2014 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.
Volume 07 Issue 7 Pages 078 - 33pp
Keywords Higgs Physics; Beyond Standard Model
Abstract We analyse the constraints and some of the phenomenological implications of a class of two Higgs doublet models where there are flavour-changing neutral currents (FCNC) at tree level but the potentially dangerous FCNC couplings are suppressed by small entries of the CKM matrix V. This class of models have the remarkable feature that, as a result of a discrete symmetry of the Lagrangian, the FCNC couplings are entirely fixed in the quark sector by V and the ratio v(2)/v(1) of the vevs of the neutral Higgs. The discrete symmetry is extended to the leptonic sector, so that there are FCNC in the leptonic sector with their flavour structure fixed by the leptonic mixing matrix. We analyse a large number of processes, including decays mediated by charged Higgs at tree level, processes involving FCNC at tree level, as well as loop induced processes. We show that in this class of models one has new physical scalars beyond the standard Higgs boson, with masses reachable at the next round of experiments.
Address [Botella, F. J.] Univ Valencia, CSIC, Dept Fis Teor, E-46100 Burjassot, Spain, Email: fbotella@uv.es;
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1029-8479 ISBN Medium
Area Expedition Conference
Notes WOS:000339805600001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 1867
Permanent link to this record
 
 
Author (up) Botella, F.J.; Branco, G.C.; Coutinho, A.M.; Rebelo, M.N.; Silva-Marcos, J.I.
Title Natural quasi-alignment with two Higgs doublets and RGE stability Type Journal Article
Year 2015 Publication European Physical Journal C Abbreviated Journal Eur. Phys. J. C
Volume 75 Issue 6 Pages 286 - 9pp
Keywords
Abstract In the context of two Higgs doublet models, we study the conditions required in order to have stable quasi-alignment in flavour space. We show that stability under the renormalisation group equations imposes strong constraints on the flavour structure of the Yukawa couplings associated to each one of the Higgs doublets. In particular, we find a novel solution, where all Yukawa couplings are proportional to the so-called democratic matrix. This solution is rather unique, since it is the only stable solution which is a good starting point for reproducing the observed pattern of quark masses and mixing. We also showthat this stable solution can be obtained by imposing on the Lagrangian a Z(3)xZ(3)' flavour symmetry. Quark masses of the lighter quark generations are generated through the breaking of this discrete symmetry, and, at this stage, scalar-mediated flavour-changing neutralcurrents arise, but they are naturally suppressed by the smallness of the light quark masses. In this way, we relate Higgs alignment to the hierarchy of the quark masses through a discrete family symmetry.
Address [Botella, F. J.] Univ Valencia, Dept Fis Teor, CSIC, E-46100 Burjassot, Spain, Email: fbotella@uv.es;
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1434-6044 ISBN Medium
Area Expedition Conference
Notes WOS:000356888300003 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 2299
Permanent link to this record
 
 
Author (up) Botella, F.J.; Branco, G.C.; Nebot, M.
Title The hunt for New Physics in the Flavour Sector with up vector-like quarks Type Journal Article
Year 2012 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.
Volume 12 Issue 12 Pages 040 - 34pp
Keywords Beyond Standard Model; Rare Decays; CP violation
Abstract We analyse the possible presence of New Physics (NP) in the Flavour Sector and evaluate its potential for solving the tension between the experimental values of A(J/Psi KS) and Br(B+ -> tau(+)v(tau)) with respect to the Standard Model (SM) expectations. Updated model independent analyses, where NP contributions are allowed in B-d(0) – (B) over bar (0)(d) and B-s(0) – (B) over bar (0)(s) transitions, suggest the need of New Physics in the bd sector. A detailed analysis of recent Flavour data is then presented in the framework of a simple extension of the SM, where a Q = 2/3 vector-like isosinglet quark is added to the spectrum of the SM. Special emphasis is given to the implications of this model for correlations among various measurable quantities. We include constraints from all the relevant quark flavour sectors and give precise predictions for selected rare processes. We find important deviations from the SM in observables in the bd sector like the semileptonic asymmetry A(SL)(d), B-d(0) -> mu(+)mu(-) and A(SL)(s) – A(SL)(d). Other potential places where NP can show up include A(J/Psi Phi), gamma, K-L(0) -> pi(0)v (v) over bar, t -> Zq and D-0 -> mu(+)mu(-) among others. The experimental data favours in this model the existence of an up vector-like quark with a mass below 600(1000) GeV at 1(2) sigma.
Address [Botella, F. J.; Nebot, M.] Univ Valencia, Dept Fis Teor, CSIC, E-46100 Burjassot, Spain, Email: fbotella@uv.es;
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1126-6708 ISBN Medium
Area Expedition Conference
Notes WOS:000313123800040 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 1344
Permanent link to this record
 
 
Author (up) Botella, F.J.; Branco, G.C.; Nebot, M.; Rebelo, M.N.
Title Flavour-changing Higgs couplings in a class of two Higgs doublet models Type Journal Article
Year 2016 Publication European Physical Journal C Abbreviated Journal Eur. Phys. J. C
Volume 76 Issue 3 Pages 161 - 17pp
Keywords
Abstract We analyse various flavour-changing processes like t -> hu, hc, h -> t e, tau μas well as hadronic decays h -> bs, bd, in the framework of a class of two Higgs doublet models where there are flavour-changing neutral scalar currents at tree level. These models have the remarkable feature of having these flavour-violating couplings entirely determined by the CKM and PMNS matrices as well as tan beta. The flavour structure of these scalar currents results from a symmetry of the Lagrangian and therefore it is natural and stable under the renormalisation group. We show that in some of the models the rates of the above flavour-changing processes can reach the discovery level at the LHC at 13 TeV even taking into account the stringent bounds on low energy processes, in particular μ-> e gamma.
Address [Botella, F. J.; Branco, G. C.] Univ Valencia, Dept Fis Teor, CSIC, E-46100 Burjassot, Spain, Email: fbotella@uv.es;
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1434-6044 ISBN Medium
Area Expedition Conference
Notes WOS:000375305100001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 2653
Permanent link to this record
 
 
Author (up) Botella, F.J.; Branco, G.C.; Nebot, M.; Rebelo, M.N.
Title Two-Higgs leptonic minimal flavour violation Type Journal Article
Year 2011 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.
Volume 10 Issue 10 Pages 037 - 21pp
Keywords Higgs Physics; Beyond Standard Model; Neutrino Physics
Abstract We construct extensions of the Standard Model with two Higgs doublets, where there are flavour changing neutral currents both in the quark and leptonic sectors, with their strength fixed by the fermion mixing matrices V(CKM) and V(PMNS). These models are an extension to the leptonic sector of the class of models previously considered by Branco, Grimus and Lavoura, for the quark sector. We consider both the cases of Dirac and Majorana neutrinos and identify the minimal discrete symmetry required in order to implement the models in a natural way.
Address [Botella, F. J.; Nebot, M.] Univ Valencia, Dept Fis Teor, CSIC, E-46100 Burjassot, Spain, Email: fbotella@uv.es
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1126-6708 ISBN Medium
Area Expedition Conference
Notes WOS:000296917100037 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 830
Permanent link to this record
 
 
Author (up) Botella, F.J.; Branco, G.C.; Nebot, M.; Rebelo, M.N.; Silva-Marcos, J.I.
Title Vector-like quarks at the origin of light quark masses and mixing Type Journal Article
Year 2017 Publication European Physical Journal C Abbreviated Journal Eur. Phys. J. C
Volume 77 Issue 6 Pages 408 - 14pp
Keywords
Abstract We show how a novel fine-tuning problem present in the Standard Model can be solved through the introduction of a Z(6) flavour symmetry, together with three Q = -1/3 quarks, three Q = 2/3 quarks, as well as a complex singlet scalar. The Z(6) symmetry is extended to the additional fields and it is an exact symmetry of the Lagrangian, only softly broken in the scalar potential, in order to avoid the domain-wall problem. Specific examples are given and a phenomenological analysis of the main features of the model is presented. It is shown that even for vector-like quarks with masses accessible at the LHC, one can have realistic quark masses and mixing, while respecting the strict constraints on processes arising from flavour changing neutral currents. The vector-like quark decay channels are also described.
Address [Botella, Francisco J.] Univ Valencia, CSIC, Dept Fis Teor, E-46100 Burjassot, Spain, Email: francisco.j.botella@uv.es;
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1434-6044 ISBN Medium
Area Expedition Conference
Notes WOS:000403504500005 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 3180
Permanent link to this record