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Author (up) Botella, F.J.; Branco, G.C.; Carmona, A.; Nebot, M.; Pedro, L.; Rebelo, M.N. url  doi
openurl 
  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. url  doi
openurl 
  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.; Rebelo, M.N. url  doi
openurl 
  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. url  doi
openurl 
  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. url  doi
openurl 
  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
 
 
Author (up) Botella, F.J.; Branco, G.C.; Rebelo, M.N. url  doi
openurl 
  Title Invariants and flavour in the general Two Higgs Doublet Model Type Journal Article
  Year 2013 Publication Physics Letters B Abbreviated Journal Phys. Lett. B  
  Volume 722 Issue 1-3 Pages 76-82  
  Keywords  
  Abstract The flavour structure of the general Two Higgs Doublet Model (2HDM) is analysed and a detailed study of the parameter space is presented, showing that flavour mixing in the 2HDM can be parametrized by various unitary matrices which arise from the misalignment in flavour space between pairs of various Hermitian flavour matrices which can be constructed within the model. This is entirely analogous to the generation of the CKM matrix in the Standard Model (SM). We construct weak basis invariants which can give insight into the physical implications of any flavour model, written in an arbitrary weak basis (WB) in the context of 2HDM. We apply this technique to two special cases, models with MFV and models with NNI structures. In both cases non-trivial CP-odd WB invariants arise in a mass power order much smaller than what one encounters in the SM, which can have important implications for baryogenesis in the framework of the general 2HDM.  
  Address Univ Valencia CSIC, Dept Fis Teor, E-46100 Burjassot, Spain, Email: fbotella@uv.es;  
  Corporate Author Thesis  
  Publisher Elsevier Science Bv Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0370-2693 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000318745300008 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1451  
Permanent link to this record
 
 
Author (up) Botella, F.J.; Branco, G.C.; Rebelo, M.N. url  doi
openurl 
  Title Minimal flavour violation and multi-Higgs models Type Journal Article
  Year 2010 Publication Physics Letters B Abbreviated Journal Phys. Lett. B  
  Volume 687 Issue 2-3 Pages 194-200  
  Keywords Multi-Higgs models; Minimal Flavour Violation; FCNC; Flavour symmetries  
  Abstract We propose an extension of the hypothesis of Minimal Flavour Violation (MFV) to general multi-Higgs models without the assumption of Natural Flavour Conservation (NFC) in the Higgs sector. We study in detail under what conditions the neutral Higgs couplings are only functions of V-CKM and propose a MFV expansion for the neutral Higgs couplings to fermions.  
  Address [Branco, G. C.; Rebelo, M. N.] Inst Super Tecn, Dept Fis, P-1049001 Lisbon, Portugal, Email: fbotella@uv.es  
  Corporate Author Thesis  
  Publisher Elsevier Science Bv Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0370-2693 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000277070800019 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ elepoucu @ Serial 457  
Permanent link to this record
 
 
Author (up) Botella, F.J.; Branco, G.C.; Rebelo, M.N.; Silva-Marcos, J.I. url  doi
openurl 
  Title What if the masses of the first two quark families are not generated by the standard model Higgs boson? Type Journal Article
  Year 2016 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 94 Issue 11 Pages 115031 - 6pp  
  Keywords  
  Abstract We point out that in the standard model there is meaningful quark mixing even in the extreme chiral (EC) limit, where only the third generation of quarks acquires mass. This mixing is in general expected to be of order 1 and the fact that |V-13|(2) + |V-23|(2) approximate to 1.6 x 10(-3) implies a novel fine-tuning problem in the SM which we point out for the first time. We propose a possible way of avoiding this fine-tuning by introducing a symmetry S which leads to V-CKM = 1, with only the third generation of quarks acquiring mass. We consider two scenarios for generating the mass of the first two quark generations and full quark mixing based on the assumption that the masses of the first two quark families are not generated by the standard Higgs. One consists of the introduction of a second Higgs doublet which is neutral under S. The second scenario consists of assuming new physics at a high energy scale, contributing to the masses of light quark generations, in an effective field theory approach. This last scenario leads to couplings of the Higgs particle to s (s) over bar and c (c) over tilde which are significantly enhanced with respect to those of the SM. In both schemes, one has scalar-mediated flavor-changing neutral currents which are naturally suppressed. Flavor-violating top decays are predicted in the second scenario at the level Br(t -> hc) >= 5 x 10(-5).  
  Address [Botella, F. J.] Univ Valencia, Dept Fis Teor, CSIC, E-46100 Burjassot, Spain, Email: fbotella@uv.es;  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000391016600004 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 2931  
Permanent link to this record
 
 
Author (up) Botella, F.J.; Branco, G.C.; Rebelo, M.N.; Silva-Marcos, J.I.; Bastos, J.F. url  doi
openurl 
  Title Decays of the heavy top and new insights on epsilon(K) in a one-VLQ minimal solution to the CKM unitarity problem Type Journal Article
  Year 2022 Publication European Physical Journal C Abbreviated Journal Eur. Phys. J. C  
  Volume 82 Issue 4 Pages 360 - 16pp  
  Keywords  
  Abstract We propose a minimal extension of the Standard Model where an up-type vector-like quark, denoted T, is introduced and provides a simple solution to the CKM unitarity problem. We adopt the Botella-Chau parametrization in order to extract the 4 x 3 quark mixing matrix which contains the three angles of the 3 x 3 CKM matrix plus three new angles denoted theta(14), theta(24), theta(34). It is assumed that the mixing of T with standard quarks is dominated by theta(14). Imposing a recently derived, and much more restrictive, upper-bound on the New Physics contributions to epsilon(K) , we find, in the limit of exact theta(14) dominance where the other extra angles vanish, that epsilon(NP)(K) is too large. However, if one relaxes the exact theta(14) dominance limit, there exists a parameter region, where one may obtain epsilon(NP)(K) in agreement with experiment while maintaining the novel pattern of T decays with the heavy quark decaying predominantly to the light quarks d and u. We also find a reduction in the decay rate of K-L -> pi(0)nu(nu) over bar.  
  Address [Botella, Francisco J.] Univ Valencia, CSIC, Dept Fis Teor, Burjassot 46100, 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:000787321000002 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5206  
Permanent link to this record
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