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Botella, F. J., Cornet-Gomez, F., & Nebot, M. (2020). Electron and muon g-2 anomalies in general flavor conserving two-Higgs-doublet models. Phys. Rev. D, 102(3), 035023–19pp.
Abstract: In general two-Higgs-doublet models (2HDMs) without scalar flavor changing neutral couplings (SFCNC) in the lepton sector, the electron, muon, and tau interactions can be decoupled in a robust framework, stable under renormalization group evolution. In this framework, the breaking of lepton flavor universality (LFU) goes beyond the mass proportionality, opening the possibility to accommodate in a simple manner a different behavior among charged leptons. We analyze simultaneously the electron and muon (g – 2) anomalies in the context of these general flavor conserving models in the leptonic sector (gtlFC). We consider two different models, I-gtlFC and II-gelFC, in which the quark Yukawa couplings coincide, respectively, with the ones in type I and in type II 2HDMs. We find two types of solutions that fully reproduce both (g – 2) anomalies, and which are compatible with experimental constraints from LEP and LHC, from LFU, from flavor and electroweak physics, and with theoretical constraints in the scalar sector. In the first type of solution, all the new scalars have masses in the 1-2.5 TeV range, the vacuum expectation values (vevs) of both doublets are quite similar in magnitude, and both anomalies are dominated by two loop Barr-Zee contributions. This solution appears in both models. There is a second type of solution, where one loop contributions are dominant in the muon anomaly, all new scalars have masses below 1 TeV, and the ratio of vevs is in the range 10-100. The second neutral scalar H is the lighter among the new scalars, with a mass in the 210-390 GeV range while the pseudoscalar A is the heavier, with a mass in the range 400-900 GeV. The new charged scalar H-+/- is almost degenerate either with the scalar or with the pseudoscalar. This second type of solution only appears in the I-gelFC model. Both solutions require the soft breaking of the Z(2) symmetry of the Higgs potential.
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Botella, F. J., Branco, G. C., & Rebelo, M. N. (2010). Minimal flavour violation and multi-Higgs models. Phys. Lett. B, 687(2-3), 194–200.
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.
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Botella, F. J., Cornet-Gomez, F., Miro, C., & Nebot, M. (2024). New physics hints from τ scalar interactions and (g-2)e,μ. J. Phys. G, 51(2), 025001–20pp.
Abstract: We consider a flavour conserving two Higgs doublet model that consists of a type I (or X) quark sector and a generalized lepton sector where the Yukawa couplings of the charged leptons to the new scalars are not proportional to the lepton masses. The model, previously proposed to solve both muon and electron g – 2 anomalies simultaneously, is also capable to accommodate the ATLAS excess in pp -> S -> tau(+)tau(-) with gluon-gluon fusion production in the invariant mass range [0.2; 0.6] TeV, including all relevant low and high energy constraints. The excess is reproduced taking into account the new contributions from the scalar H, the pseudoscalar A, or both. In particular, detailed numerical analyses favoured the solution with a significant hierarchy among the vevs of the two Higgs doublets, t(beta)similar to 10, and light neutral scalars satisfying m(A) > m(H) with sizable couplings to tau leptons. In this region of the parameter space, the muon g – 2 anomaly receives one and two-loop (Barr Zee) contributions of similar size, while the electron anomaly is explained at two loops. An analogous ATLAS excess in b-associated production and the CMS excess in ditop production are also studied. Further New Physics prospects concerning the anomalous magnetic moment of the tau lepton and the implications of the CDF M-W measurement on the final results are discussed.
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Botella, F. J., Branco, G. C., & Nebot, M. (2012). The hunt for New Physics in the Flavour Sector with up vector-like quarks. J. High Energy Phys., 12(12), 040–34pp.
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.
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Bernabeu, J., Botella, F. J., Mavromatos, N. E., & Nebot, M. (2017). The signal of ill-defined CPT weakening entanglement in the B-d system. Eur. Phys. J. C, 77(12), 865–10pp.
Abstract: In the presence of quantum-gravity fluctuations (space-time foam), the CPT operator may be ill-defined. Its perturbative treatment leads to a modification of the Einstein-Podolsky- Rosen correlation of the neutral meson system by adding an entanglement-weakening term of the wrong exchange symmetry, the omega-effect. In the current paper we identify how to probe the complex omega in the entangled B-d system using the flavour (f)-CP(g) eigenstate decay channels: the connection between the intensities for the two timeordered decays (f, g) and (g, f) is lost. Appropriate observables are constructed allowing independent experimental determinations of Re(omega) and Im(omega), disentangled from CPT violation in the evolution Hamiltonian Re(theta) and Im(theta). 2 sigma tensions for both Re(theta) and Im(omega) are shown to be uncorrelated.
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